Abstract of Publications (1999-2002)

 

 

1.     Abdul Rahim Samsudin, Rahman Yaccup, Umar Hamzah, Abdul Ghani Rafek & Khairul Anuar Mohd Nayan, 1999, Geophysical characterisation of the weathering profile of a quartz-mica schist at km67 east west highway, Malaysia, Proc. 2nd. Asian Symposium on Engineering Geology and the Environment, Bangi, Malaysia, 2.1 – 2.4.

 

Geophysical characterisation of  the weathering profile  OF a quartz-mica schist AT KM67 EAST WEST HIGHWAY, MALAYSIA

Abdul Rahim Samsudin, Rahman Yaccup, Umar Hamzah,Ab.Ghani Rafek & Khairul Anuar Mohd Nayan*

School of Environment and Natural Resource Sciences

Faculty of Science and Technology,

Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia

Department of Civil Engineering*

Faculty of Engineering

Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia.

 

Abstract : Seismic refraction and resistivity imaging were performed to characterise the weathering profile of  a quartz mica schist slope cut at km67 east west highway, north of Peninsular Malaysia (Figure1). Insitu seismic P-wave velocities and geoelectrical resistivities of the rock mass were measured along several terraces of the slope cut. Subsurface variation of the measured velocities and resistivities were used to establish empirically correlation between these parameters with the weathering grade of the rock mass.

The refraction seismic survey was conducted using an ABEM Terraloc MK3 , 24-channel seismograph with a 10-kg sledgehammer source energy  and 14Hz.-geophones spaced

at 3m intervals. A seven point energy source position configuration ( -25.0m, 1.5m, 17.5m, 34.5m, 52.5m, 67.5m and 94m) was employed for all seismic spreads. The seismograph enables seismic records obtained to be stored in 3.5 inches floppy disks which can subsequently be retrieved for data processing using the IBM PC based software – REFRACT (Walker et al, 1991) .

Weathering characterisation of the quartz mica schist was investigated  based on the International Association of Engineering Geology’s (IAEG, 1981) weathering index which resulted in a weathering profile map as shown in Figure 2.  The profile shows that rock mass with weathering  of  index 1 and 2 were clearly mappable , whereas for those of index 3 and 4 were restricted mainly to the eastern and western flanks of the slope . Weathered rock mass of  index 5 and 6 were relatively thin and mostly occur at the top and western flank of the slope. The rock mass of index 1 and 2 which is basically fresh rock could be correlated with higher P-wave velocities of greater than 5000m/s. On the other hand, the weathered rock mass of index 6 which is basically soil, the P-wave velocities are lowest between 300 – 500m/s. The seismic velocities for weathered material of index 4 and 5 range from 600 to 1800m/s and moderately weathered rock of index 3 has a  P-wave velocities between 2000m/s to 3000m/s. However in areas where the rock mass is highly fractured , the seismic velocity appears to be lower than the expected values.

The 2-D geoelectrical resistivity imaging employing a multi-electrode Wenner  configuration system was performed using ABEM ES464 Lund system and SAS300C resistivity meter (Griffiths and Barker, 1993). The geoelectrical resistivity lines were established exactly along the same seismic profiles to enable both results as well as the weathering profile of the rock mass to be correlated. The resistivity data for each of the profiles measured was processed using RES2DINV inversion programme (Loke & Barker,1996). The bulk resistivity of index 6 weathering profile gives values ranging from 200 ohm.m  to 1300 ohm.m, whereas for index 4 and 5, the resistivity values appear to be high (1500 ohm.m to 5000 ohm.m). The moderately weathered rock of index 3 has resistivity values ranging from 5000 ohm.m to 8000 ohm.m. Index 1 and 2 which represents the fresh rock could be correlated with very high range of resistivity values (>8000 ohm.m). However certain sections of the slope face of the fresh rock were observed to be more fractured which explains the occurrence of localised regions with relatively low resistivities. This zone of low resistivity is possibly associated with the fractured part of the rock mass with significant water accumulation. Figure 3 shows the measured apparent resistivity pseudosections and inversed model of subsurface resistivity images for sections along terrace 8 and 7 which includes weathered rock mass from index 6 to 1.

The results of  the present study illustrate that the geophysical parameters (seismic P-wave velocities and geoelectrical resistivities) could be used to map different grades of weathered rock mass and other geological structures related to a slope cut problem. The geophysical study can also become more useful if the measured parameters  could be correlated with geotechnical parameters and changes in those parameters can be estimated by the proper combinations of field procedures. The data can be used for rock characterization and for the development of new methods to keep pace with the increasingly difficult nature of the slope cut failure problem.

 

2.     Abdul Rahim Samsudin, Mohammed I.Abu Shariah and Umar Hamzah, 1999, The use of electrical and seismic methods for imaging shallow subsurface structure of limestone at Batu Cave, Kuala Lumpur, Malaysia, Bulletin Geological Society of Malaysia Special Publication, No. 43, 215 – 225.

 

The Use of Electrical and Seismic Methods for Imaging Shallow Subsurface Structure of Limestone at Batu Cave, Kuala Lumpur

Malaysia

                              Abdul Rahim Samsudin, Mohammed I. Abu Shariah & Umar Hamzah

Department of Geology, Universiti Kebangsaan Malaysia,

43600 UKM Bangi, Selangor D. E. Malaysia

 

Abstract

 

Geoelectrical resistivity and seismic surveys were conducted to investigate subsurface structure of a selected limestone area at Batu Cave, Kuala Lumpur. The limestone in the area belongs to the Kuala Lumpur Limestone Formation.. The formation generally shows two geomorphologic expression, one above the ground and the other buried beneath alluvium. The buried limestone shows highly irregular karst topography with pinnacle structures. These features have caused variety of geotechnical problems in both the design and construction of structural foundation in the area.

Two dimensional (2-D) geoelectrical imaging survey was carried out along two traverses by using ABEM SAS 300C Terrameter. The first traverse which comprises of three resistivity profiles with a total length of 144 meters was established by using Wenner configuration, and the second traverse was located on cavities at depth ranging from 15 to 26 meters below ground.

Result of the two dimensional resistivity inverse model of the first traverse indicates anomalous area of low resistivity in the middle ( approximately 50m width) and high resistivity at both ends of the traverse. The subsurface low resistivity anomaly is interpreted as buried channel at shallow depth and the high resistivity is associated with massive pinnacle limestone bedrock. The second traverse has also detected the presence of water-filled cavities which are indicated as zone of low resistivity in the inversion model.

Seismic refraction and reflection surveys conducted on  both of the traverses substantiate the presence of pinnacle structures and possible channel in the limestone of the first traverse and cavity filled up with water in the second traverse.

 

 

3.     Abdul Rahim Samsudin, Tan,C.A.,Bashillah Baharudin &Mohd. Tadza Abdul Rahman, 1999, The use of geoelectrical imaging to study groundwater pollution at Gemencheh waste disposal site, Negeri sembilan, Abs. Annual Geological Conference 1999, Johor, 62-63.

 

The use of geoelectrical imaging to study groundwater

pollution at Gemenceh waste disposal site, Negeri Sembilan

 

Abdul Rahim Samsudin1, Tan, C.A.1, Bashilah Baharudin1

& Mohd Tadza Abdul Rahman2

1 Department of Geology

Universiti Kebangsaan Malaysia

Bangi, Selangor,Malaysia

2Malaysian Institute of Nuclear Technology (MINT),

Ministry of Science, Technology and Environment

Bangi, Selangor, Malaysia

 

Abstract: Geoelectrical imaging method is now frequently used for environmental pollution studies. The resistivity imaging surveys carried out in the present study basically measures and maps the resistivity of subsurface materials. It provides the general information on subsurface stratification of the soil and wastes and the depth to the bedrock below the lines of traverse. The survey was conducted using ABEM LUND Automatic imaging system. Ground water that has been contaminated by leachate frequently has a significantly lower resistivity value.

This paper briefly describes some preliminary results of the electrical resistivity imaging survey to assist in understanding the underground conditions and to study the ground water pollution at Gemenceh waste disposal site in Negeri sembilan. The geoelectrical imaging technique  was used in this study  to help delineating contaminated ground water at the disposal site. The quality and contaminated zone of the underground water was determined based on the measured geoelectrical resistivity value of subsurface materials. Two dimensional resistivity profiles and subsurface geological information from both bore hole  as well as seismic refraction data were used to interpret  the extension and direction of the contaminant flow within the underground water system  in the area being studied.

The contaminated zone of the ground water aquifer gives relatively low resistivity value of less than 10.0 ohm-m compared to that of the uncontaminated groundwater which resistivity value ranges from 10 to 100 ohm-m. The geoelectrical resistivity and chemical analysis of the water samples indicate that the underground water aquifer in all bore holes except bore holes SP8 and SP12 have been contaminated by the leachate. In comparison, the ground water sample from bore hole SP4 is highly contaminated. However the ground water contamination in this area appears to be confined within the vacinity of the dumping ground. The resistivity profiles suggest a flow of contaminant towards north east which follows the regional trend of ground water flow of the area.

 

4.     Abdul Rahim Samsudin, Abdul Ghani Rafek, Umar Hamzah & Khairul anuar Mohd. Nayan, 1999, Pencirian Geofizik di kawasan pembangunan untuk kajian geoteknik dan geosekitaran rantau tropika, Laporan Penyelidikan & Pembangunan (separuh Penggal RMK-7), Pusat Pengurusan Penyelidikan, UKM, 49 – 52.

 

Pencirian Geofizik di tapak pembangunan untuk kajian geoteknik dan sekitaran di rantau tropika

(Geophysical characterisation of development site for geotechnical and geoenvironmental investigation in tropical region)

Abdul Rahim Samsudin, Abdul Ghani Rafek,

Umar Hamzah & Khairul Anuar Mohd Nayan*

Fakulti Sains Fizis dan Gunaan

*Fakulti Kejuruteraan

UKM

 

Ringkasan  laporan Program

Program diatas telah diluluskan pada bulan Ogos 1998 dan telah mula dijalankan pada bulan Oktober 1998. Kajian telah dijalankan mengikut perancangan seperti berikut.

Kajian literatur dan beberapa kerja lapangan awal telah dijalankan. Kerja lapangan yamg dilakukan adalah seperti berikut:

a.       Menguji keberkesanan kaedah geofizik (kaedah kerintangan dan kaedah  seismos) untuk mengesan lohong/rongga didalam batu kapur di bawah permukaan bumi. Kawasan kajian yang dipilih terletak di sekitar Batu Caves , K.L., di Lembah Kinta, Ipoh, Perak dan di Bau, Sarawak.

b.      Penggunaan kaedah geofizik secara bersepadu untuk mengkaji tanah runtuh di kawasan cerun runtuh di Km 7,  jalan Temerloh-Mentakab, Pahang.

c.       Penggunaan kaedah geofizik bersepadu untuk mengesan zon pencemaran air bawah tanah di Kawasan pembuangan sisa sampah di Gemenceh, N.Sembilan.

d.      Pencirian batuan dan profil luluhawa dengan menggunakan parameter geofizik di Km 67 Lebuhraya Timur Barat (Grik-Jeli) dan di Km 73 Jalanraya Kuching - Lundu, Sarawak..

e.       Penggunaan gelombang permukaan untuk mengkaji perlapisan tanah di sekitar bandar Baru Bangi .

f.        Penggunaan gelombang P & S untuk mengkaji sifat keisotropikan bahan bumi di cerun batuan igneus (riolit) di Genting Highland.

g.       Penggunaan pengimejan geoelektrik dan seismos pantulan cetek untuk mengesan akuifer dan  sempadan intrusi air masin terhadap air bawah tanah di Olak Lempit , Banting Selangor.

h.       Penggunaan kaedah  seismos dan pengimejan untuk mengkaji tapak Kamsis H di Kampus UKM, Bangi, Selangor.

 

Kajian dilakukan dengan menggunakan peralatan geofizik yang sedia ada termasuk yang baru diperolehi melalui peruntukan IRPA termasuk perisian komputer untuk tujuan pemprosesan data. Alat-alat tersebut  adalah :

 

q       Seismograf 24-saluran (MKIII) (telah sedia ada di Jabatan Geologi, FSFG, UKM)

q       Terrameter SAS 300C (telah sedia ada di Jabatan Geologi, FSFG, UKM)

q       Sistem LUND ES464 dan Lund Cables (Diperolehi pada bulan Disember 1998)

q       Geofon berfrekuensi tinggi (100Hz)

q       Perisian Gremix untuk pemprosesan data seismos biasan

q       SPW  untuk pemprosesan data seismos pantulan

q       Perisian RES2DINV  untuk memproses data pengimejan kerintangan geoelektrik

 

Untuk tujuan mendapatkan teknologi terbaru dalam penggunaan gelombang permukaan untuk kajian geoteknik satu kursus pendek telah dijalankan dengan bantuan dua orang pakar dari Amerika Syarikat. Kursus berlangsung selama  6 hari iaitu daripada 15hb – 20hb Disember 1998 dan bertempat di Kampus UKM. Kursus ini telah dihadiri oleh semua penyelidik dan pembantu penyelidik serta beberapa kakitanga akademik dari dalam dan luar UKM termasuk institusi penyelidikan awam seperti IKRAM, JKR, MINT, UM, UPM dan lain-lain.

Seramai 4 orang pembantu penyelidik telah dilantik daripada kalangan pelajar siswazah dan juga daripada pelajar pascasiswazah yang baru dilantik untuk menjalankan penyelidikan ini. Dua pelajar menjalankan penyelidikan untuk ijazah sarjana manakala dua lagi untuk ijazah doktor falsafah. Diantara kerja lapangan yang dijalankan sepanjang tahun 1998 dan awal 1999 ialah seperti berikut:

§         Survei seismos biasan ,pantulan dan pengimejaan geoelektrik di tiga kawasan pembinaan di Lembah Kinta ,Ipoh  iaitu di Kawasan pembinaan kuaters guru sekolah, Pengkalan Pegoh, Ipoh, Dikawasan pembinaan Jambatan Pengkalan Industri dan di kawasan Masjid Jalan Dairy, Ipoh.

§         Survei seismos biasan dan pengimejaan geoelektrik di kawasan tapak pembuangan sampah domestik di Gemenceh , N.Sembilan

 

§         Survei pengimejan geolektrik di kawasan tanah runtuh di Km7 Jalan Mentakab-Temerloh, Pahang.\

§         Survei ketakselanjaran dan survei seismos biasan dengan menggunakan gelombang P dan S di kuari batuan riolit (igneus) Genting Highland, Selangor.

§         Survei seismos biasan dan pengimejan geolektrik di Km 67 lebuh raya timur barat (Grik – Jeli), Perak/Kelantan.

§         Survei seismos biasan dan pengimejan geoelektrik di km73 jalanraya  Kuching –Lundu, Sarawak

 

 

5.     Abdul Rahim Samsudin, Rahman Yaccup, Khairul Anuar Mohd Nayan , Ab.Ghani Rafek & Umar Hamzah, 1999, Integrated geophysical and engineering geological techniques in landslide investigation: A case study at Temerloh, Pahang, Malaysia, Proc. Geotropika’99, Johor Bahru, 261-270.

 

Integrated geophysical and engineering geological techniques in landslide investigation: A case study at Temerloh, Pahang, Malaysia

 

Abdul Rahim Samsudin,  Rahman Yaccup , Khairul Anuar Mohd Nayan,

Ab.Ghani Rafek & Umar Hamzah 

Universiti Kebangsaan Malaysia, Bangi, Selangor,Malaysia

 

Abstract

 

     A landslide at Km6 of Temerloh-Mentakab highway was investigated using integrated geophysical and engineering geological techniques.  The geophysical investigation includes insitu surface seismic refraction as well as P & S-waves downhole logging. The engineering geological study includes conventional site investigation methods such as wash drilling boreholes,  JKR probe testing (Raj,1984), and Standard penetration testing (SPT) as well as determination of velocity of the drilling penetration of  the boreholes. This is supported by a standard laboratory analyses that includes basic sieve analysis and Atterberg limits determination. The mesured geophysical and engineering geological parameters such as velocity of seismic P and S waves, SPT (N) values, grain size distributions, Atterberg limits, drilling penetration velocities as well as lithology of subsurface material were used to determine sliding planes associated with the failed slope. The interpreted surface and down hole seismics as well as engineering geological results show that the landslide in the study area has occurred as a result of multiple failures. Three sliding planes have been identified, each of which are at depths of 5.45m, 10.1m and 15.5m from the surface.

 

6.     Abdul Rahim Samsudin, Teng, K.J. & Mohd. Tadza Ab.Rahman, 2000, Migrasi dan Sebaran Bahan Pencemaran Dalam Sistem Air Bawah Tanah di Tapak Pelupusan Sisa Domestik Gemencheh, Negeri Sembilan, Malaysia, Prosiding Seminar Kimia Bersama ITB – UKM Keempat, 485 - 492.

 

7.     Abdul Rahim Samsudin, Rahman Yaacup & Lakam Mejus, 2000. Geoelectrical Resistivity Imaging for geotechnical Site Investigation : Malaysia Case Studies, Proceedings of the 2nd International Conference on Advanced in Strategic Technologies (ICAST 2000),1491-1500.

 

Geoelectrical resistivity imaging for geotechnical site investigation:

Malaysian case studies

 

Abdul Rahim Samsudin, Rahman Yaacup & Lakam a/k Mejus

School of  Environmental  Science and  Natural Resources

Faculty of  Science and Technology

Universiti  Kebangsaan  Malaysia

43600,  Bangi,  Selangor D.E.

 

Abstract

Although a geoelectrical resistivity imaging has been frequently and successfully used for environmental pollution studies, this geophysical method however is not fully exploited for application in geotechnical site investigation. This paper briefly describes some preliminary results of three case studies where the electrical resistivity imaging was used to assist in understanding the underground conditions at three development sites in Peninsular Malaysia. The resistivity imaging surveys carried out in the study basically measures and maps the resistivity of subsurface materials. It provides the general information on subsurface stratification of the soil and structures and the depth to the bedrock below the lines of traverse. The survey was conducted using Abem SAS300C resistivity meter and Lund automatic imaging system. The measured two dimensional resistivity profiles had been interpreted using 2-D resistivity inversion programme (RES2DINV) and the inversion results were compared to the actual subsurface geological information derived from the borehole data.

 

The geoelectrical imaging technique was used, in these studies, to help in delineating bedrock profile at the first two sites, whereas for the third site, the technique was employed  to investigate the soil profile and geological structure of a failed slope. In the first case study , results of the resistivity imaging has been successfully used to determine whether the drilling bit has actually hit the bedrock or boulder below ground. This information is very useful for geotechnical site assesment as well as for foundation design purposes. The second case study involved measurement of resistivity imaging in a development area with limestone bedrock. The study was conducted to investigate the topography of  the limestone bedrock  and to confirm whether the piles driven in the area have actually rested on the solid rock. The third case study demonstrates the applicability of the geoelectrical resistivity imaging to delineate the subsurface problematic area which has caused a slope failure at a housing development site.

Results of the three case studies indicate that the geoelectrical resistivity imaging  technique in conjunction with a limited borehole data can be effectively used in subsurface soil investigation especially for bedrock depth determination and geological structure associated with slope failure studies. The geoelectrical resistivity technique is relatively cheap and fast compared  to commonly used seismic refraction technique for geotechnical site investigation.

 

8.     Abdul Rahim Samsudin, Rahman Yaccup, Lakam Mejus & Umar Hamzah.2000. Penggunaan pengimejan keberintangan geoelektrik 2-D dan survei seismos biasan dalam kajian geologi kejuruteraan: Kajian kes di lebuh raya Grik-Jeli, Perak. Prosiding FIZIK 2000: Seminar Fizik Kebangsaan.(ms: 1-8)

 

Penggunaan pengimejan keberintangan geoelektrik  2-D dan survei biasan seismos  dalam kajian geologi kejuruteraan: kajian kes di lebuh raya grik-jeli, perak, MALAYSIA

 

Abdul Rahim Samsudin, Rahman Yaacup, Lakam a/k Mejus & Umar Hamzah,

Pusat Pengajian Sains Sekitaran & Sumber Alam,

Fakulti Sains & Teknologi, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia

 

Abstrak

Survei seismos biasan dan keberintangan geoelektrik telah dijalankan untuk mengkaji  profil luluhawa batuan syis mika kuarza di keratan jalan di km67 lebuhraya timur barat, Semenanjung Malaysia.. Pengukuran seismos biasan dan keberintangan geoelektrik 2-D dilakukan pada beberapa teres batuan disepanjang cerun potongan tersebut dan perubahan halaju gelombang P dan keberintangan geoelektrik bahan di bawah permukaan digunakan untuk mendapatkan hubungannya dengan profil luluhawa batuan yang telah dibuat mengikut indeks yang dikemukakan oleh  IAEG(1981). Hasil kajian menunjukkan secara umumnya kedua-dua nilai halaju gelompang P dan keberintangan geoelektrik bertambah dengan penurunan indeks luluhawa batuan. Namun demikian terdapat pengecualian di beberapa bahagian jasad batuan tersebut dimana nilai parameter geofizik (halaju gelombang P dan keberintangan geoelektrik) yang diukur lebih rendah daripada yang dijangkakan. Anomali ini ditafsirkan berasosiasi dengan ketumpatan ketakselanjaran dan kandungan air di dalam jasad batuan tersebut.  Keputusan kajian ini menunjukkan bahawa parameter-parameter geofizik (halaju gelombang P dan keberintangan geoelektrik) boleh digunakan dengan berkesan untuk memetakan profil luluhawa dan struktur bagi potongan cerun batuan yang bermasalah.  Kaedah geofizik yang digunakan adalah relatif cepat dan lebih kos efektif berbanding kaedah penyiasatan geoteknik konvensyenal.

Kata kunci :  Geofizik , geoteknik, keberintangan geoelektrik, seismos biasan

 

Abstract (English Version)

Seismic refraction survey and geoelectrical resistivity imaging were conducted to investigate the weathering profile of a quartz mica schist cut slope at km67 east west highway of Peninsular Malaysia. 2-D seismic refraction and resistivity imaging lines were established along several terraces of the slope. Subsurface variation of the measured p-wave velocities and resistivities  were used to obtain their empirical correlation with the weathering grade of the rock mass which was investigated based on the International Association of Engineering Geology’s (IAEG, 1981) weathering indices. Results of the study illustrate that both p-wave velocities and geolectrical resistivities of the rock mass increase as the weathering grades decrease. However , there are certain parts of the slope section of the rock mass show p-wave velocities and resistivities which are lower than expected.  These anomalous zones are interpreted to be associated with the occurrence of fractures and ground water accumulation within it. The results of the present study reveal that the geophysical parameters ( seismic p-wave velocities and geoelectrical resistivities) can be effectively used to map different grades of weathered rock mass and other geological structures related to a slope cut problem. The geophysical  methods are relatively cheap and more cost effective compared to a conventional geotechnical investigation.

Keywords : Geophysics,  geotechnique , geoelectrical resistivity , seismic refraction

 

9.     Abdul Rahim Samsudin, Umar Hamzah, Abd.Ghani Rafek & Rahman Yaacup, 2000, Application of Geoelectrical Resistivity Imaging for Site Investigation, Proceedings Annual Geological Conference 2000, 375 – 380.

 

Application of  Geoelectrical Resistivity imaging for site investigation

Abdul Rahim Samsudin, Umar Hamzah, Abd.Ghani Rafek & Rahman Yaacup

Pusat Pengajian Sains Sekitaran dan Sumber Alam

Universiti Kebangsaan Malaysia

43600, Bangi, Selangor,Malaysia

 

Abstract

Two dimensional geoelectrical resistivity imaging has the ability to image the subsurface by analysing the resistivity distribution within the earth. It provides the general information on subsurface geological strata and the depth to the bedrock below the lines of traverse. The resistivity imaging surveys carried out basically measures and maps the resistivity of subsurface materials. The resistivity anomalies may indicate the presence of geological features which may introduced geotechnical hazard in area of development sites. This paper briefly describes some results of the geoelectrical resistivity imaging surveys to assist in understanding the underground conditions at three development sites in Malaysia. The surveys were conducted using ABEM SAS300C terrameter with LUND ES464 electrode selector system.  The resistivtiy imaging surveys in these studies were used to investigate the occurrence of sinkholes and cavities in the limestone bedrock, to help in delineating the bedrock profile at the development sites and to characterise the weathering profile of  a quartz mica schist slope cut at km67 east west highway, north of Peninsular Malaysia.

 

10. Abdul Rahim Samsudin, Rahman Yaacup, Umar Hamzah & Abdul Ghani Rafek.2000. Penggunaan kaedah geofizik untuk mencirikan profil luluhawa syis mika-kuarza di Km 67, lebuh raya timur-barat. Prosiding seminar IRPA RMK-7. Penerbitan PPP UKM jilid II (ms: 121-124)

 

11. Abdul Rahim Samsudin, Rahman Yaacup &Lakam a/k Mejus, 2001, Some case studies on application of geolectrical resistivity imaging for geotechnical site investigation in Malaysia, Proceedings International Conference on Insitu Measurement of soil Properties and Case Histories INSITU 2001, Bali, May 21-24, 177-181.

 

SOME CASE STUDIES on Application of  Geoelectrical Resistivity imaging for GEOTECHNICAL site investigation in malaysia

Abdul Rahim Samsudin, Rahman Yaacup & Lakam a/k Mejus

School of  Environmental  Sciences and  Natural Resources

Faculty of  Science and Technology

Universiti  Kebangsaan  Malaysia

43600,  Bangi,  Selangor D.E.

 

Abstract

Geoelectrical resistivity techniques have the ability to image the subsurface in two or three dimensions by analysing the resistivity distribution within the earth. It provides the general information on the subsurface geological strata and the depth to the bedrock below the lines of traverse. The resistivity imaging surveys carried out basically measures and maps the resistivity of subsurface materials. The resistivity anomalies may indicate the presence of geological features which may introduced geotechnical hazard in area of development sites. This paper briefly describes some results of the geoelectrical resistivity imaging surveys to assist in understanding the underground conditions at three development sites in Malaysia. The 2-D resistivity survey was conducted using an ABEM SAS300C resistivity meter and a Lund automatic imaging system. The measured two dimensional resistivity profiles have been interpreted using 2-D resistivity inversion programme (RES2DINV) and the inversion results were compared to the actual subsurface geological information derived from the borehole data.

The geoelectrical imaging technique was used in this study to help in delineating bedrock profile at the first two sites, whereas for the third site, the technique was employed  to investigate the soil profile and geological structure of a failed slope. In the first case study  results of the resistivity imaging has been successfully used to determine whether the drilling bit had actually hit the bedrock or boulder below ground. This information is very useful for geotechnical site assesment as well as for foundation design purposes. The second case study involved measurement of resistivity imaging in a development area with limestone bedrock. The study was conducted to investigate the topography of  the limestone bedrock  and to confirm whether the piles driven in the area have actually rested on the solid rock. The third case study demonstrates the applicability of the geoelectrical resistivity imaging to delineate the subsurface problematic area which has caused a slope failure at a housing development site.

Results of the three case studies indicate that the geoelectrical resistivity imaging  technique in conjunction with a limited borehole data can be effectively used in subsurface soil investigation especially for bedrock depth determination and geological structure associated with slope failure studies. The geoelectrical resistivity technique is relatively cheap and fast compared  to the commonly used seismic refraction technique for geotechnical site investigation.

 

12. Abdul Rahim Samsudin, Khairul Anuar Mohd Nayan & Mohd Azmi Ismail, 2001, Penggunaan analisis spectrum gelombang permukaan (SASW) dalam kajian geologi kejuruteraan, Prosiding Seminar Sehari Geofizik, Julai 2001, UKM Bangi, 1-1 – 1-6.

 

Penggunaan Analisis Spektrum Gelombang Permukaan (SASW)

Dalam Kajian Geologi Kejuruteraan

 

1Abdul Rahim Samsudin, 2Khairul Anuar Mohd Nayan & 1Mohd Azmi Ismail

1Program Geologi, Pusat Pengajian Sains Sekitaran & Sumber Alam, Fakulti Sains & Teknologi

2Jabatan Kejuruteraan Awam & Struktur, Fakulti Kejuruteraan,Universiti Kebangsaan Malaysia

43600 Bangi, Selangor Darul Ehsan

Abstrak

Maklumat mengenai sifat-sifat elastik seperti kekukuhan dan kekuatan tanah di sesuatu tapak selalunya diperolehi dari pengukuran di makmal. Namun demikian kaedah makmal adalah terdedah kepada gangguan terhadap sampel, saiz sampel yang kecil, dan perbezaan keadaan tegasan dan terikan berbanding dengan keadaan asal. Oleh yang demikian penggunaan kaedah pengukuran lapangan, khususnya kaedah geofizik, semakin mendapat perhatian. Analisis Spektrum Gelombang Permukaan (SASW) adalah kaedah baru geofizik yang digunakan bagi mendapatkan profil halaju gelombang ricih di bawah permukaan secara in situ. Kaedah ini berdasarkan kepada penghasilan dan pengesanan gelombang Rayleigh yang merambat di sepanjang permukaan bebas. Kaedah SASW mengandaikan bahawa struktur di bawah permukaan adalah terdiri daripada susunan lapisan mendatar yang homogen. Punca hentaman di permukaan menghasilkan gelombang Rayleigh berbagai frekuensi yang merambat di sepanjang permukaan. Analisis dari maklumat fasa bagi setiap frekuensi menghasilkan halaju gelombang yang bergerak di antara dua pengesan. Hasil pengukuran kaedah SASW yang dilakukan ke atas dua tapak pembinaan dibentangkan.

Abstract

Information on the elastic properties of soil sites, such as stiffness and strength have traditionally been derived using laboratory investigation. Laboratory procedures, however, are subject to sampling disturbance, unrepresentative sampling, and differences in natural stress and strain conditions. Thus, there has been a move to use field methods for such measurements, particularly geophysical methods. Spectral Analysis of Surface Waves (SASW) is a new geophysical method for in situ profiling of the subsurface. The method is based on the generation and detection of Rayleigh waves propagating along the free surface.  It assumes that the subsurface structures consist of a stack of horizontally homogeneous layers. Transient impact source on the ground surface is used to generate Rayleigh wave of different frequencies into the medium. From analysis of phase information for each frequency, the velocity of the waves is determined between two receivers. Results of the SASW measurements on two construction sites are presented. 

 

13. Abdul Rahim Samsudin, and Ngoo, C.N., 2001, Insitu measurement of geoelectrical resistivity  in relation to weathering profile of a sedimentary rock mass at Lubuk Paku, Maran, Pahang : A case study, Proceedings Annual Geological conference 2001, Pulau Pangkor, Perak, Sept. 2001, 205-208.

 

14. Abdul Rahim Samsudin, Umar Hamzah and Zuraidah Ramli, 2001, Geophysical Investigation of the Olak Lempit Quaternary Basin, Selangor, Malaysia, 30th Annual Convention Indonesian Association of Geologists & 10th GEOSEA Regional Congress, Yogyakarta, Indonesia, Abs. , 280 – 282.

 

Geophysical Investigation of  the Olak Lempit  Quaternary Basin,

Selangor , Malaysia

Abdul Rahim Samsudin, Umar Hamzah and Zuraidah Ramli

School of Environment and Natural Resource Sciences

Faculty of Science & Technology

Universiti Kebangsaan Malaysia

Bangi, 43600, Selangor, Malaysia

Tel.: 6 03-89292396

Fax.: 6 03-89292490

Email : abrahim@pkrisc.cc.ukm.my

Abstract

An integrated geophysical study was conducted to investigate the subsurface regional structure and the presence of a Quaternary sedimentary basin in the Olak Lempit - Banting area of Selangor, Malaysia. A regional gravity survey and the high resolution reflection seismic were employed to determine the thickness and areal distribution of the alluvial sedimentary basin as well as to investigate the depth and topography of  the bedrock in the study area. The sedimentary basin hosts one of the most important coastal alluvial aquifer which was used to cater the shortage of domestic water supply during the worst water crisis that hit the state of Selangor in 1998. The surface geological map shows that in general 70% of the study area is covered by Quaternary deposits of Beruas, Gula and Simpang Formations which overlie the sedimentary bedrock of Kenny Hill Formation. The Beruas Formation consists of mainly clay, sandy clay and peat of Holocene fluviatile-estuarine deposits, whereas the Gula Formation represents Holocene marine to estuarine sediments which mostly consists of clay and minor sand. The Simpang Formation (Pleistocene) is a continental deposit comprising of gravel, sand, clay and silt. The underlying Kenny Hill Formation consists of a monotonous sequence of interbedded shales, mudstones and sandstones. The rock is Carbonaceous in age and it forms an undulating surface topography in the eastern  part of the study area.

A total of 121 gravity stations were established using a La Coste Romberg gravity meter and the elevations of most of the stations were determined barometrically using Tiernan-Wallace altimeters. Bench marks wherever available were used as control stations in order to minimise the error of the elevations measured. The high resolution seismic reflection using the common mid point (CMP) or roll along technique was carried out using a 24 channel signal enhancement seismograph and high frequency geophones. Emulex 150 explosives with electric detonators were used for generating seismic source. The offset shot during the survey was 50 meters and it was moved at intervals of 10meters with geophones fixed at 5 meters spacing. This configuration produced 12-fold CMPs seismic sections, which were conventionally processed to produce a migrated stacked seismic section. A total length of about 1.7 km stacked seismic section has been acquired in this survey and a nearby borehole data was used  for interpretation.

A relative Bouguer anomaly map shows an elongated zone of low gravity anomaly trending approximately NW-SE which is interpreted to be the deposition center of the Quaternary basin. The interpreted gravity profiles running across the central area of the study area show that the basin has thickness varies from tenth to several hundred meters with maximum depth to bedrock of about 275m. A gravity profile which passes through the eastern edge of the basin was modeled with depth to bedrock of about 178m below ground which agrees very well with those obtained from the interpreted seicmic section and borehole data. 

The stacked seismic section shows several high amplitude parallel to sub-parallel reflection overlying discontinuos and low reflection pattern.  Reflections on the eastern part of the section is much shallower than the one observed on the western part which clearly indicates the presence of  basinal structure with a total interpreted depth to bedrock of about 200 meters.

 

Keywords: Quaternary basin, seismic section, gravity modeling and subsurface structure

 

15. Abdul Rahim Samsudin and Mohd Azmi Ismail, 2001. Pengukuran insitu tapak geoteknik menggunakan kaedah ‘SASW’,  Abstrak persidangan Kebangsaan Penyelidikan dan Pembangunan Institusi Pengajian Tinggi Awam, 25-26 Okt, 2001 Kuala Lumpur, ms.33.

 

 

Pengukuran insitu tapak geoteknik menggunakan kaedah ‘SASW’

Abdul Rahim Samsudin dan Mohd Azmi Ismail

Pusat Pengajian Sains Sekitaran dan Sumber Alam

Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia

abrahim@pkrisc.cc.ukm.my

Abstrak

Kaedah penganalisisan spektrum gelombang permukaan (gelombang Rayleigh) atau kaedah ‘SASW’ boleh digunakan untuk mendapatkan halaju gelombang ricih dan profil modulus ricih  sesuatu tapak geoteknik secara insitu. Maklumat ini amat penting untuk mengukur kekukuhan tanah dan untuk tujuan reka bentuk kejuruteraan sesuatu tapak pembangunan. Oleh kerana kaedah SASW ini bersifat ‘non-intrusive’ dan tidak memerlukan lubang gerudi, maka  kaedah geofizik ini menjadi semakin popular untuk digunakan dalam kajian tapak kejuruteraan. Selain cepat, kaedah ini relatif murah berbanding kaedah konvensyenal yang menggunakan lubang-lubang gerudi yang memerlukan perbelanjaan lebih mahal. Kaedah SASW ini berdasarkan kepada penghasilan dan pengesanan gelombang Rayleigh yang merambat di sepanjang permukaan bebas. Kaedah ini mengandaikan bahawa struktur tanah di bawah permukaan adalah terdiri daripada susunan lapisan mendatar yang homogen. Punca hentaman di permukaan menghasilkan gelombang Rayleigh berbagai frekuensi yang merambat di sepanjang permukaan. Analisis dari maklumat fasa bagi setiap frekuensi menghasilkan halaju gelombang yang bergerak di antara dua pengesan. Kertas ini membincangkan teknik dan hasil pengukuran kaedah SASW yang dilakukan ke atas dua tapak pembinaan di Bandar Baru Bangi, Selangor.

 

 

16. Abdul Rahim S. and Abdul Ghani R., 2002, An integrated approach for managing saltwater intrusion in coastal area. Proceeding Regional Symposium on Environment and Natural Resources, Kuala Lumpur, 436 – 444.

 

An Integrated approach for managing

saltwater intrusion in coastal area

Abdul Rahim Samsudin and Abdul Ghani Rafek

School of Environment and Natural Resource Science

Universiti Kebangsaan Malaysia, Bangi

Email: abrahim@pkrisc.cc.ukm.my

Abstract

Saltwater intrusion generally refers to the movement of salty waters into freshwater aquifers or to the encroachment of saline water into freshwater aquifers or estuaries. Saline ground water can also occur naturally in inland aquifers as well as in coastal areas, and has similar implications upon ground water use as saltwater intrusion. Saltwater intrusion has been a major problem in the exploitation of coastal aquifers for decades. In Malaysia, north Kelantan and other coastal areas, which depend upon ground water are particularly affected.  Population growth leads to increased ground water consumption, thus increasing the saltwater intrusion problem. The four components approach of measurement, monitoring, modeling and modification as an integrated approach in managing the critical problem of saltwater intrusion and protection of ground water resources is discussed in this presentation.

 

17. Abdul Rahim Samsudin, Abdul Ghani Rafek, Umar Hamzah & Khairul Anuar Mohd Nayan, 2002, Pencirian geofizik di tapak pembangunan untuk kajian geoteknik dan sekitaran di rantau tropika, Prosiding Seminar IRPA RMK-7 Pusat Pengurusan Penyelidikan, UKM, Jilid I, 29 – 32.

Pencirian Geofizik di tapak pembangunan untuk kajian geoteknik dan sekitaran di rantau tropika

Abdul Rahim Samsudin, Abdul Ghani Rafek,Umar Hamzah & Khairul Anuar Mohd Nayan*

Fakulti Sains & teknologi

*Fakulti Kejuruteraan

UKM

 

Ringkasan  laporan Program

Program penyelidikan ini ditumpukan kepada penggunaan kaedah geofizik untuk mencirikan beberapa sifat fizik bahan di bawah permukaan bumi di kawasan pembangunan atau yang berkaitan dengannya. Kaedah geofizik lazim yang digunakan ialah kaedah keberintangan geoelektrik, kaedah seismos biasan dan kaedah seismos pantulan. Kaedah graviti dan magnet juga telah digunakan di beberapa kawasan kajian yang dipilih. Objektif utama penyelidikan ini adalah seperti berikut:

 

·        Mengukur parameter-parameter fizikal dan mekanikal beberapa jenis bahan dan jasad batuan (batuan igneus, batuan sedimen dan batuan metamorf) dengan menggunakan kaedah geofizik permukaan dan bawah permukaan.

 

·        Mendapatkan korelasi antara parameter geofizik dan geomekanik bagi ketiga-tiga jenis batuan di atas dan kebergunaannya dalam kajian tapak kejuruteraan  dan sekitaran.

·        Membangunkan dan menentukan kaedah survei geofizik permukaan yang berkesan dan kos efektif untuk memetakan struktur dan sifat-sifat fizik bahan di bawah permukaan tapak pembangunan dan kawasan sekitarnya. 

Projek ini secara umumnya melibatkan pengukuran teknik-teknik geofizik di atas permukaan dan dalam hal-hal tertentu pengukuran dilakukan di bawah permukaan melalui penggunaan lubang gerudi.  Kajian yang dijalankan mencakupi empat aspek utama:

i)                    pemilihan kawasan kajian ditiga jenis batuan utama iaitu batuan igneus, batuan sedimen dan metamorf, yang telah atau sedang dibangunkan ,

ii)                   pencirian sifat-sifat fizik bahan bumi di lapangan dan makmal untuk ketiga-tiga jenis batuan tersebut

iii)                 penentuan struktur bawah permukaan berdasarkan perubahan sifat fizik bahan secara dua dimensa untuk kajian tapak kejuruteraan dan menilai bencana geologi serta mengkaji masalah pencemaran air bawah tanah


iv)                 membuat penilaian tentang keberkesanan, kesesuaian dan keefektifan kos bagi setiap teknik geofizik yang digunapakai dalam mencirikan sifat fizik bahan yang dikaji.

 

Sejumlah sepuluh lokasi telah dipilih sebagai kawasan kajian. Kawasan ini meliputi tiga jenis batuan iaitu batuan igneus, metamorf dan batuan sedimen.  Bagi batuan igneus, kawasan kajian yang dipilih terletak di zon peranginan Genting Highland yang secara umumnya terbentuk daripada batuan riolit. Kawasan keratan cerun batuan syis kuarza mika di km67 lebuhraya Gerik-Jeli mewakili batuan metamorf, manakala kajian batuan sedimen tertumpu di kawasan Olak Lempit, Selangor, Lubuk Paku & Temerloh, Pahang serta keratan jalan Kuching-Lundu (Sarawak). Kewujudan lohong dalam batu kapur juga turut dikaji untuk mencari kaedah yang lebih mudah dan kos efektif bagi mengesannya. Formasi Batu Kapur Kuala Lumpur dan beberapa lokasi batu kapur di kawasan Lembah Kinta (Ipoh), Perak telah dipilih untuk kawasan ujian.  Kawasan pembuangan sisa domestik di Gemencheh, Negeri Sembilan adalah satu-satunya lokasi yang telah digunakan untuk menguji keberkesanan kaedah geofizik dalam mengesan pencemaran terhadap sistem air bawah tanah. 

Kajian dilakukan dengan menggunakan peralatan geofizik yang sedia ada termasuk yang baru diperolehi melalui peruntukan IRPA termasuk perisian komputer untuk tujuan pemprosesan data. Alat-alat tersebut  ialah Seismograf 24-saluran (MKIII),Terrameter SAS 300C , Sistem LUND ES464 dan  OR25 Spectrum Analyzer. Manakala perisian yang telah diperolehi ialah GREMIX, SPW,RES2DINV  untuk memproses data seismos dan keberintangan geoelektrik. Adalah dianggarkan bahawa kerjalapangan penyelidikan ini telah mencapai 70% selesai, baki 30% yang sedang maju melibatkan:

a)      Penggunaan gelombang permukaan untuk kajian tanah dan geoteknik

b)      Seismos pantulan untuk mengesan batuan dasar

c)      Seismos biasan untuk kajian ketakisotropian bahan bumi

d)      Pengimejan keberintangan geoelektrik dalam kajian geologi kejuruteraan

Selain itu kerja-kerja analisis dalam makmal masih dijalankan termasuk kerja-kerja mengukur sifat-sifat fizik bahan bumi dan pemodelan keberintangan menggunakan komputer. Diantara parameter-parameter yang ditentukan ialah:

A.     Bahan batuan : Ketumpatan; Keliangan; Mineralogi dan petrografi, Kekuatan

B.     Jasad batuan:   Ketakselanjaran; Profil luluhawa:Kekuatan; Halaju geombang P dan

                               S; Keberintangan geoelektrik

 

18. Abdul Rahim Samsudin, Mohd azmi Ismail & Khairul Anuar Mohd Nayan, 2002, Teknik analisis spectrum gelombang permukaan (kaedah SASW) untuk pengukuran insitu tapak geoteknik, Prosiding Seminar IRPA RMK-7 Pusat Pengurusan Penyelidikan, UKM, Jilid II, 60 – 66.

 

Teknik analisis spektrum gelombang permukaan (Kaedah SASW) untuk Pengukuran insitu tapak geoteknik

Abdul Rahim Samsudin, Mohd Azmi Ismail & *Khairul Anuar Mohd Nayan

Fakulti Sains & Teknologi

*Fakulti Kejuruteraan

 

Abstrak

 

Teknik penganalisisan spektrum gelombang permukaan (gelombang Rayleigh) atau kaedah ‘SASW’ boleh digunakan untuk mendapatkan profil bawah permukaan tapak geoteknik secara insitu dan tanpa musnah. Kaedah ini mengandaikan bahawa struktur lapisan tanah di bawah permukaan berupa susunan lapisan mendatar yang homogen. Punca hentaman di permukaan menghasilkan gelombang Rayleigh berbagai frekuensi yang merambat di sepanjang permukaan. Analisis dari maklumat fasa bagi setiap frekuensi menghasilkan halaju gelombang yang bergerak di antara dua pengesan dan gabungan hasil berbagai jarak pengesan akan memberikan lengkung penyerakan halaju gelombang. Lengkung penyerakan gelombang ini kemudiannya dimodelkan dengan menggunakan proses songsangan secara iteratif sehingga lengkung penyerakan sebenar diperolehi. Keputusan ini boleh di tukarkan kepada profil kekukuhan mengikut kedalaman yang digunakan untuk tujuan reka bentuk kejuruteraan geoteknik. Kertas ini membincangkan teknik dan hasil pengukuran kaedah SASW yang dilakukan ke atas dua tapak pembinaan di Bandar Baru Bangi, Selangor.

 Abstract(English version)

Spectaral analysis of surface wave (SASW) technique for insitu measurement of geotechnical site

The SASW (Spectral-Analysis-of-Surface-Waves) technique can be used to obtain non-destructively insitu subsurface profile of a geotechnical site. The method assumes that the subsurface structures consist of a stack of horizontally homogeneous layers. Transient impact source on the ground surface is used to generate Rayleigh wave of different frequencies into the medium. From analysis of phase information for each frequency, the velocity of the waves is determined between two receivers and combination of results from various receivers spacing were integrated to produce an experimental velocity dispersion curve. Modelling of the dispersion curve was then carried out through an iterative inversion process and the final dispersion curve was then validated. The results were then converted to a soil stiffness profile with depth for applications in geotechnical engineering design. This paper describes technique and results of the SASW measurements conducted at two geotechnical sites  of  Bandar Baru Bangi, Selangor.

 

19. Gravity investigation of a “suspect” meteorite impact crater in Langkawi Island,  Malaysia

Abdul Rahim Samsudin*, Umar Hamzah*,

 Tjia Hong Djin** & Lim Cheng Han*

*School of Environment and Natural Resource Science,

Faculty of Science and Technology

Universiti Kebangsaan Malaysia, Selangor D.E., Malaysia

**Petronas Research and Scientific Services,

 Serdang , Selangor D.E., Malaysia

 

Abstract

A horseshoe-shaped ridge structure has been spotted on a false colour Landsat TM imagery of the southwestern part of Langkawi Island, Malaysia. This horseshoe-shaped structure known as ‘Mahsuri Ring’ provides morphological evidence for a possible remnant of a meteorite impact crater. A subsequent study on lineaments of the area, based on aerial photograph clearly indicates the semi-circular rim of the impact crater. Samples of rocks taken from the crater area show the presence of shocked quartz grains which is interpreted to have been developed as a result of shock metamorphic affects of the meteorite impact. The rock exposed in the area are mudstone, siltstone and sandstone of Singa Formation that make up the rim of the impact crater. The interior area of the impact crater is mainly covered by recent alluvial clay deposit. A detailed Gravity survey was carried out to investigate the subsurface features of the interpreted impact crater. The Gravity measurements were made at about 100 stations using a La Coste & Romberg gravity meter with distances between stations  ranging from 200 to 500metres. In general, the gravity values are lower in the central portion of the impact structure and are relatively higher along the rim. The residual gravity anomalies along the E-W and NE-SW profiles were interpreted to obtain the depth and subsurface structure of the impact crater. The east-west profile shows two basin-like structures with the first one having a maximum depth of depression of about 107m and 2 km in diameter. Another basin is found about 0.5 km to the west with depth of about 45m and 2.5km in diameter. These basins are mostly covered with Quaternary alluvium. The profile along the NE-SW direction across the impact crater also shows a depression structure with maximum depth of about 103 metres and 1.8km in diameter.

 

 

20. Abdul Rahim Samsudin,Bashillah Baharuddin, Masrita Mustapa & Sanisah Soed, 2002, Geophysical mapping of saltwater intrusion in Kerpan coastal area , Kedah, Proceedings Annual Geological conference 2002, Kota Bharu, Kelantan, Mei 2002,Bull. Geol. Soc. No.45, 135-138,

Geophysical mapping of saltwater intrusion in

Kerpan coastal area , Kedah

Abdul Rahim Samsudin1, Bashillah Baharuddin 2 , Masrita Mustapa1 dan Sanisah Soed1

1Pusat Pengajian Sains Sekitaran & Sumber Alam

Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia, 43600  Bangi, Selangor

2 Institut Penyelidikan Teknologi Nuklear Malaysia,

Bangi, 43000 Kajang, Selangor, Malaysia

Abstract

The salinity of the ground water in the coastal alluvial aquifer between Kerpan-Air Hitam and Sanglang area in Kedah was investigated using both vertical electrical sounding (VES) and 2-D resistivity imaging techniques.  The resistivity measurements were made using ABEM SAS 300C and SAS4000 terrameters.  A total of 61 VES stations  were established over an area of approximately 100km2 of Quaternary alluvium. The 2-D imaging was used to study the lateral and vertical changes in resistivity of the alluvial sediments. Salinity of the ground water was interpreted based on the apparent resistivity values.  Ground water with resistivity values less than 5 ohm-m is considered as saline and those of greater than 100ohm-m is fresh water. The resistivity values ranging from 5 to 100ohm-m is for brackish water. The VES and imaging results show that the ground water has resistivities ranging from 0.53 to 670.5ohm-m.  The results of spatial distributions of apparent resistivity indicate that the ground water is mainly brackish with the salt-water affected aquifer is confined to the coastal part of the study area. Vertical variation of the resistivity values plotted along profiles perpendicular to the coastal line, indicate that the saltwater has significantly affected the ground water at depth and far away from the coastal area.

 

21.K.A. Mohd. Nayan, M.R. Taha, A. Kasa, A.R. Shamsuddin, and A. Ismail, Spectral-Analysis-of-Surface Waves Method: An initial Assessment of Its Applications, Proceeding of the Sixth Geotechnical Engineering Conference (Geotropika 2001), 5-7 November 2001-Hilton Kuching, Sarawak

 

Spectral-Analysis-of-Surface-Waves Method: An Initial Assessment of It’s Application

Khairul Anuar Mohd Nayan*, Mohd. Raihan Taha*,Anuar Kasa*, Abd. Rahim Samsuddin@, Azmi Ismail@

*Department of Civil and Structural Engineering

Faculty of Engineering ,

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor.

@Geology Programme,

School of Environmental and Natural Resource Sciences,

Faculty of Science and Technology,

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor.

 

Abstract

The SASW (Spectral-Analysis-of-Surface-Waves) method for profiling the subsurface non-destructively is discussed. The method assumes that the subsurface structures consist of a stack of horizontally homogeneous layers. Transient impact source on the ground surface is used to generate Rayleigh wave of different frequencies into the medium. From analysis of phase information for each frequency, the velocity of the waves is determined between two receivers and combination of results from various receivers spacing were integrated to produce an experimental velocity dispersion curve. Modelling of the dispersion curve was then carried out through an iterative inversion process and the final dispersion curve was then validated. The results were then converted to a soil stiffness profile with depth for applications in geotechnical engineering design. Some case histories were presented from tests conducted at various geotechnical sites as comparisons and their accuracies are evaluated.

 

 

22.The Use of Electrical and Seismic Methods for Imaging Shallow Subsurface Structure of Limestone at Batu Cave, Kuala Lumpur - Malaysia .                 

Abdul Rahim Samsudin & Mohammed Abu Shariah

Department of Geology, Universiti Kebangsaan Malaysia,

43600 UKM Bangi, Selangor D. E. Malaysia

 

Abstract

 

Geoelectrical resistivity and seismic surveys were conducted to investigate subsurface structures of a selected limestone area at Batu Cave, Kuala Lumpur. The limestone in the Batu Cave area belongs to Kuala Lumpur Limestone Formation. It composes of fine to coarse - grained white to gray calcitic and dolomitic marble. In general the Kuala Lumpur Limestone Formation shows two geomorphologic expression one above ground and the other buried beneath alluvium. The limestone beneath the alluvium shows highly irregular karst topography with pinnacles surface. These features have caused variety of geotechnical problems in both the design and construction of structural foundation.

Two dimensional geoelectrical imaging survey was carried out along two traverses with a total length of 144m and 98m respectively by using ABEM SAS 300C Terrameter. The first traverse which comprises of several resistivity profiles was established using Wenner configuration, and the second traverse was established on the cavity area as indicated by bore hole data. The bore hole data indicates the presence of several cavities at different depth ranging from 15 to 26 meters below ground.

Two dimensional geoelectrical resistivity inverse section for the first traverse indicated anomalous area of low resistivity in the middle ( approximately 50m length) and high resistivity at both ends of the line . The inversion model mapped the low resistivity as a pinnacle structure and buried channel at the shallow depth , whereas the high resistivity is associated with massive limestone bedrock ( Figure 1 ). The second resistivity traverse has successfully detected the presence of water-filled cavities which is indicated as a zone of low resistivity in the inversion model ( Figure 2 ).

Seismic refraction and reflection surveys were also carried on the same location of  the first traverse by using ABEM Terraloc Mark III 24-channel seismograph.  The surveys used 10kg hammer as an energy source with 3m geophone spacing. The interpreted seismic sections obtained also indicates the presence of pinnacle structure and possible channel in the limestone.

 

 

 

 

 

 

 

 

  Figure 2 :  Limestone cavity survey at Batu Cave. ( a )  Measured apparent resistivity

pesudosection of the Wenner configuration. (b) The Geoelectrical resistivity inverse model section showing possible cavity.

 

 

 

23. Syarahan Perdana, UKM Ogos 2002

Geofizik : Teknologi ke Arah Pemahaman Yang Lebih Baik Terhadap Alam Sekitar

(Geophysics : Technology for Better Understanding of Our Environment)

 

Abstrak

Geofizik adalah cabang sains geologi yang menggunakan prinsip fizik untuk mengkaji bumi. Bidang sains ini telah berkembang pesat sejak beberapa dekad yang lalu dan menjadi teknologi utama dalam mengkaji struktur dalaman bumi serta banyak membantu ahli geologi memahami teori tektonik global yang digunapakai pada masa ini.  Dengan mengukur perbezaan sifat-sifat fizik bahan di dalam bumi, ahli-ahli geofizik boleh merakamkan keadaan dan berjaya meneroka jauh kebawah permukaan bumi sehingga dapat mengeksploitasi  sumber hidrokarbon yang menjadi nadi kepada pembangunan industri negara-negara maju didunia. Kemajuan dalam instrumentasi geofizik yang berasaskan elektronik dan digabungi dengan teknologi pemprosesan mikrokomputer telah menjadikan teknologi geofizik semakin efisien dan lebih kos efektif terutama dalam penjelajahan sumber bumi, membantu penyiasatan geoteknik dan penyelesaian masalah alam sekitar. Teknologi geofizik juga mempunyai potensi besar untuk dimajukan dalam kerja-kerja carigali arkeologi. Pemakaian teknologi geofizik untuk menyelesaikan masalah kejuruteraan semakin meningkat pada masa ini terutama untuk memeta zon-zon lemah dan bermasalah di bawah permukaan bumi. Kemajuan dalam teknologi lapangan dan penafsiran geofizik  telah berjaya digunapakai untuk mengkaji pencemaran air bawah tanah dan menilai kawasan-kawasan tanah tercemar .

 Untuk mengharungi abad ke 21 yang bakal tiba, cabaran utama yang dihadapi oleh ahli-ahli geofizik adalah untuk mengubah paradigma hala tuju penyelidikan daripada terlalu taksub kepada hanya penjelajahan hidrokarbon kepada lain-lain penyelidikan dalam bidang sains gunaan seperti kejuruteraan geoteknik dan kajian alam sekitar. Selain itu, dana serta keuntungan yang diperolehi daripada sumber bahan api ini seharusnya digunakan untuk menaja atau menampung kos penyelidikan bidang sains gunaan yang dinyatakan di atas di samping meneroka teknologi tenaga mesra alam yang baru untuk menjadi sumber tenaga alternatif di masa akan datang. Teknologi geofizik juga harus diperkenalkan kepada jurutera dan ahli arkeologi dan kerjasama kedua-dua kumpulan jurutera dan geofizik ini amat diperlukan untuk membolehkan data geofizik digunapakai dalam analisis kejuruteraan. Bidang geofizik sekitaran yang pesat berkembang ini perlu diperkenalkan kepada para pentadbir yang pembuat polisi dan perancangan pembangunan negara serta keseluruhan komuniti industri kewangan.

 

Abstract(English version)

Geophysics is a branch of earth sciences which uses principles of physics to study the interior of the earth.  This field of science has developed for several decades and becomes very important technology to unravel the earth internal structures as well as to help geologists to either credit or discredit the well known global tectonic theory of the earth. By measuring different physical properties of the earth material , geophysicists have been successfully mapped subsurface structures deep enough to enable exploitation of hydrocarbon resources which is the lifeline of the modern industrial nations in the world. The rapid development of electronically based geophysical field equipment assisted with microcomputer data processing technology have increased the efficiency and cost effectiveness of the geophysical technology especially in exploration of natural resources as well as solving many geotechnical and geoenvironmental problems. There is also a great potential for this technology to be used for archaeological investigation. In recent years the application of geophysics for solving geotechnical problems has increased especially in mapping subsurface weak structures and problematic zones. Improved geophysical technology  and interpretation procedures have been successful to delineate pollution in the ground water and assessment of contaminated land area.

The greatest challenge that faces the geophysicists in the 21st century is to have  paradigm shift in their research orientation from a strong bias towards hydrocarbon industry to other important area of applied sciences such as for geotechnical engineering and environmental applications. The wealth accumulated from the hydrocarbon industry should be invested in these kind of studies as well as venturing in research for future sources of environmentally friendly alternative energy resources. In addition, there is an obvious need for geophysics to  be introduced to all the engineers and archaeologists. In order for geophysics to become more useful to the geotechnical engineers better means of communication are necessary between these two groups of scientists. The rapidly expanding discipline of environmental geophysics  needs to be brought to the attention of policy-makers and planners as well as to the whole community of finance industries.

 

24. The Application of geophysical methods for Geotechnical site investigation: Malaysian case study

 

Abdul Rahim Samsudin

School of Environmental and Natural Resource Sciences

Faculty of  Science & Technology

Universiti Kebangsaan Malaysia

abrahim@pkrisc.cc.ukm.my

Tel: 03-89215396; Fax: 03-89215490

Abstract

Geophysics is a branch of earth sciences which uses principles of physics to study the interior of the earth. This field of science has developed for several decades and has become an important technological tool in exploration of natural resources as well as resolving many geotechnical and geoenvironmental problems. In geotechnical engineering applications, the geophysical methods are mainly used for site characterisation . Only a few geophysical methods have been accepted by geotechnical engineers for solving specific problems. The main reasons for the under use of geophysical methods in geotechnical engineering are inadequate communication, different methods of data presentation between the geophysicists and the geotechnical engineers, and the slow development of specific techniques which can provide solutions to geotechnical problems. A survey of the current geophysical methods application in geotechnical engineering practice shows that there are several methods which have been used successfully at a few sites but only seismic refraction has been accepted widely for detecting lithological changes.

    The failure of the general acceptance of other methods for solving specific problems is found in the inadequate testing of the methods, emphasis on the apparent accuracy of the results and inability to provide the parameters which can be used for rock quality assessment.  There are several combination of geophysical methods which can provide more economical and more accurate geotechnical data than those given by the currently used geotechnical methods.  There are many geotechnical problems for which new, non-destructive geophysical methods may be developed to provide fast and complete solutions. These would be superior to extrapolations based on the point to point information obtained by the present day geotechnical methods. Geophysics can also become more useful if geotechnical parameters  and changes in those parameters can be estimated by the proper combinations of field procedures. The data can be used for rock characterization and for the development of new methods to keep pace with the increasingly difficult nature of the geotechnical problem.

This paper discusses various branches of geophysics and their applications and results of the geoelectrical resistivity imaging surveys to assist in understanding the underground conditions at three development sites in Malaysia. The geoelectrical imaging technique was used in these studies to help in delineating bedrock profile at the first two sites, whereas for the third site, the technique was employed  to investigate the soil profile and geological structure of a failed slope. In the first case study results of the resistivity imaging has been successfully used to determine whether the drilling bit had actually hit the bedrock or boulder below ground. This information is very useful for geotechnical assesment of development site as well as for foundation design purposes. The second case study involved measurement of resistivity imaging in a development area with limestone bedrock. The study was conducted to investigate the topography of the limestone bedrock and to confirm whether the piles driven in the area have actually rested on the solid rock. The third case study demonstrates the applicability of the geoelectrical resistivity imaging to delineate the subsurface problematic area which has caused a slope failure at a housing development site.

Results of the three case studies indicate that the geoelectrical resistivity imaging  technique in conjunction with a limited borehole data can be effectively used in subsurface soil investigation especially for bedrock depth determination and geological structure associated with slope failure studies. The geoelectrical resistivity technique is relatively cheap and fast compared to the commonly used seismic refraction technique for geotechnical site investigation.

 

25. PEMETAAN AIR MASIN DALAM AKUIFER PANTAI DI SEKITAR PEKAN-NENASI, PAHANG.

Umar Hamzah, Abdul Rahim Samsudin, Ismail C. Mohamad,

 Norhafizi Khalid & Shahimi Sali

Program Geologi, Pusat Pengajian Sekitaran & Sumber Alam

Fakulti Sains & Teknologi, UKM

 

Abstrak

Masalah kejatuhan paras air bawah tanah dan peningkatan jumlah kemasinan dalam air tawar yang terdapat dalam akuifer aluvium di sekitar Pekan-Nenasi, Pahang telah dikesan melalui kerja-kerja pemantauan air bawah tanah. Sebahagian daripada input pemantauan termasuk data survei geofizik yang digunakan serentak dengan data hidrogeologi kawasan kajian. Survei geofizik yang digunakan dalam kajian pemantauan ini ialah teknik geoelektrik termasuk duga dalam dan pengimejan khususnya untuk menganggarkan sempadan zon-zon air tawar-payau-masin dan perlapisan akuifer dalam enapan aluvium. Hasil survei yang dilakukan menunjukkan zon-zon konduktif yang mewakili kawasan pengaruh air masin-payau lebih tertumpu berhampiran dengan muara-muara sungai dan tepi pantai di sekitar 4-5 kilometer. Keputusan awal menunjukkan pencapaian yang diperolehi dari survei geoelektrik hanya terbatas pada kedalaman tidak melebehi 20-30 meter. Oleh itu akuifer yang terdapat di bahagian yang lebih dalam tidak dapat diselidiki dengan survei geoelektrik.

 

26. Simposium Malaysian Science and Technology Congress MSTC 2002

Spectral analysis of Surface Wave (sasw) measurements for insitu characterisation of soil

 

Abdul Rahim Samsudin*, Mohd Azmi Ismail*, Khairul Anuar Mohd Nayan#

Abdul Ghani Rafek* & Umar Hamzah*

*School of Environment and Natural Resource Sciences

Faculty of Science & Technology

#Department of Civil and Structure

Faculty of Engineering

Universiti Kebangsaan Malaysia

abrahim@pkrisc.cc.ukm.my

ABSTRACT

Subsurface information relating to in situ strength and stiffness of soil are important for geotechnical design and have been obtained traditionally using laboratory investigation techniques. Soil material at any development site should ideally be characterized in situ at its natural stress and saturation levels, and should cover a large volume of the soil. In the laboratory, however, such conditions may not be achieved. In additions, sampling disturbances, small volume of sampled soil, and limited stress configurations and strain measurement range in laboratory tests introduce uncertainties in the characterization. This paper describes an application of spectral analysis of surface wave (SASW) technique for in situ characterization of soil material. Surface wave technique is a non-destructive seismic technique that can be used to determine the low-strain dynamic properties of sub-surface material. This technique can either be performed on soil or pavement surfaces. By generating and measuring surface waves in the field, a dispersion curve of surface wave velocity versus wavelength is constructed. An inversion of the dispersion data was then employed to produce the actual stiffness profile of the site. The test method has a broad range of civil engineering applications. Results from surface wave tests on two different sites of cut and compacted fill terraces are presented. The results from surface wave test were then compared to the standard test of the SPT and the pressure-meter tests.

 

27. Proceeding of the second IKRAM International Geotechnical Conference (IGEO-2), 28-29 Oct. 2002, K.L., 169-180.

 

The Application of geophysical methods for geotechnical

site investigation: Malaysian case study

 Prof. Dr. Abdul Rahim Samsudin

Universiti Kebangsaan Malaysia

Malaysia

Abstract

Geophysics is a branch of earth sciences which uses principles of physics to study the interior of the earth. This field of science has developed for several decades and has become an important technological tool in exploration of natural resources as well as resolving many geotechnical and geoenvironmental problems. In geotechnical engineering applications, the geophysical methods are mainly used for site characterisation and only a few of the methods have been accepted by geotechnical engineers for solving specific problems. The main reasons for the under use of geophysical methods in geotechnical engineering are inadequate communication, different methods of data presentation between the geophysicists and the geotechnical engineers, and the slow development of specific techniques which can provide solutions to geotechnical problems. A survey of the current geophysical methods application in geotechnical engineering practice shows that there are several methods which have been used successfully at a few sites but only seismic refraction has been accepted widely for detecting lithological changes.

The failure of the general acceptance of other methods for solving specific problems is found in the inadequate testing of the methods, emphasis on the apparent accuracy of the results and inability to provide the parameters which can be used for rock quality assessment.  There are several combination of geophysical methods which can provide more economical and more accurate geotechnical data than those given by the currently used geotechnical methods.  There are many geotechnical problems for which new, non-destructive geophysical methods may be developed to provide fast and complete solutions. The data can be used for rock characterization and for the development of new methods to keep pace with the increasingly difficult nature of the geotechnical problem. These methods would be superior to extrapolations based on the point to point information obtained by the present day geotechnical methods.

This paper discusses roles of geophysics, their applications and some results of case studies where the geophysical methods were used to assist in understanding the underground conditions at various development sites in Malaysia. The resistivity imaging technique was used in these studies to help in delineating bedrock profile, to investigate the cause of subsidence in a residential area with limestone bedrock, to study the soil profile and geological structure of a failed slope and to determine either bedrock or boulder underneath a proposed condominium site.

Keywords: Geophysical techniques, engineering geophysics, site investigation, case studies

 

28. Ismail I, Hamid AA, Tangang FT (Eds) Prosiding Seminar UKM-UNRI Ke –2, 8-9hb Oktober 2002, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia. Jld.1: 1-7

 

KEMASINAN AIR BAWAH TANAH DALAM AKUIFER PANTAI : KAJIAN KES DI NENASI PAHANG

Abdul Rahim Samsudin, Umar Hamzah, Ismail C. Mohamad,

 Norhafizi Khalid & Shahimi Sali

 Pusat Pengajian Sains Sekitaran & Sumber Alam

 Fakulti Sains & Teknologi, UKM

ABSTRAK

 Penurunan paras air dan peningkatan kemasinan air bawah tanah dalam akuifer pantai di sekitar kawasan Nenasi, Pahang telah dikesan melalui program pemantauan air bawah tanah. Data geofizik dan hidrogeologi kawasan kajian telah digunakan untuk tujuan pemantauan tersebut. Data geofizik yang digunakan dalam kajian pemantauan ini adalah data keberintangan geoelektrik yang diperolehi melalui teknik duga dalam dan survei pengimejan geoelektrik bawah permukaan bumi. Data keberintangan ini telah digunakan untuk menganggarkan sempadan zon-zon air tawar, payau dan masin dalam akuifer pantai yang terbentuk daripada enapan aluvium. Taburan keberintangan bawah permukaan secara menegak yang diperolehi menunjukkan wujudnya zon-zon konduktif yang mewakili kawasan pengaruh air masin dan payau di kawasan kajian. Zon air masin ini didapati tertumpu di kawasan berhampiran muara-muara sungai dan kawasan sekitar 4-5 kilometer lebar daripada garis pantai. Keputusan awal menunjukkan pencapaian yang diperolehi dari survei geoelektrik hanya terbatas pada kedalaman tidak melebehi 20-30 meter. Oleh itu akuifer yang terdapat di bahagian yang lebih dalam tidak dapat diselidiki dengan survei geoelektrik.

 

29. Bul. Geol. Soc. No.45, 329- 334.

Penggunaan teknik gelombang permukaan dalam ujian geoteknikal

MOHD AZMI ISMAIL1, ABDUL RAHIM SAMSUDIN1,

KHAIRUL ANUAR MOHD NAYAN2 DAN ABDUL GHANI RAFEK1

1Program Geologi, Un iversiti Kebangsaan Malaysia, 43600 Bangi

2Jabatan Kejuruteraan, Un iversiti Kebangsaan Malaysia, 43600 Bangi

Abstrak

Teknik gelombang permukaan adalah teknik seismos tanpa musnah yang digunakan untuk menentukan sifat-sifat dinamik permukaan bumi pada tahap terikan yang rendah. Ujian lapangan boleh dilakukan samada di permukaan tanah atau sistem turapan. Dengan penghasilan dan pengukuran gelombang permukaan di lapangan, lengkong serakan, iaitu plot halaju gelombang permukaan melawan panjang gelombang akan dihasilkan. Lengkung serakan ini seterusnya akan menjalani songsangan di pejabat. Kelebihan ini menyebabkan teknik ini berpotensi untuk digunakan dalam berbagai bidang kejuruteraan. Hasil ujian gelombang permukaan yang dilakukan ke atas dua jenis tapak yang berlainan, iaitu tapak geologi asal dan tapak tambakan termampat adalah dibentangkan. Kaedah-kaedah rujukan seperti ujian tusukan piawai (SPT) dan meter-tekanan telah digunakan sebagai perbandingan.

Abstract

Surface wave technique is a non-destructive seismic technique that can be used to determine the low-strain dynamic properties of ground surface. The field test can be performed on either soil or pavement surface. By generating and measuring surface waves in the field, a dispersion curve, a plot of surface wave velocity versus wavelength, is constructed. This dispersion curve is then inverted in the office. Because of these capabilities, the test method has a broad range of engineering applications. Results from surface wave tests on two different sites, i.e. sites with natural geological condition and compacted filled ground. Reference methods, such as standard penetration testing (SPT) and pressure-meter are used for comparison.

 

30. Prosiding Annual Geological Conference 2000, 375-379

 

Application of  Geoelectrical Resistivity imaging for site investigation

Abdul Rahim Samsudin, Umar Hamzah & Rahman Yaacup

Pusat Pengajian Sains Sekitaran dan Sumber Alam

Universiti Kebangsaan Malaysia,43600, Bangi, Selangor,Malaysia

 

Abstract

Two dimensional geoelectrical resistivity imaging has the ability to image the subsurface by analysing the resistivity distribution within the earth. It provides the general information on subsurface geological strata and the depth to the bedrock below the lines of traverse. The resistivity imaging surveys carried out basically measures and maps the resistivity of subsurface materials. The resistivity anomalies may indicate the presence of geological features which may introduced geotechnical hazard in area of development sites. This paper briefly describes some results of the geoelectrical resistivity imaging surveys to assist in understanding the underground conditions at three development sites in Malaysia. The surveys were conducted using ABEM SAS300C terrameter with LUND ES464 electrode selector system.  The resistivtiy imaging surveys in these studies were used to investigate the occurrence of sinkholes and cavities in the limestone bedrock, to help in delineating the bedrock profile at the development sites and to characterise the weathering profile of  a quartz mica schist slope cut at km67 east west highway, north of Peninsular Malaysia.

 

31 Proceeding MALAYSIAN SCIENCE AND TECHNOLOGY CONGRESS 2002:

SYMPOSIUM A: PHYSICAL SCIENCES, ENGINEERING

AND TECHNOLOGY

page 111-120

INVESTIGATION OF OLAK LEMPIT QUATERNARY BASIN BY

SURFACE GEOPHYSICAL TECHNIQUES

Abdul Rahim Samsudin, Umar Hamzah & Zuraidah Ramli

School of Environment and Natural Resource Sciences

Faculty of Science & Technology

Universiti Kebangsaan Malaysia

Bangi, 43600 Selangor, Malaysia

Tel: 03-89215396

Fax: 03-89215490

Email : abrahim@pkriscc.cc.ukm.my

ABSTRACT

An integrated surface geophysical study was conducted to investigate the subsurface

regional structure and the presence of a Quaternary basin in the Olak Lempit area of

Selangor. A regional gravity survey and the high resolution seismic reflection survey

were conducted to determine the thickness and areal distribution of the basin as well as

to investigate the depth and topography of the bedrock in the study area. The

sedimentary basin hosts one of the most important coastal alluvial aquifer which was

used to cater the storage of domestic water supply during the worst water crisis that hit

the state in 1998. The surface geological map shows that in general 70% of the study

area is covered by Quaternary deposits of Beruas, Gula and Simpang Formations which

overlie the sedimentary bedrock of Kenny Hill Formation. The Beruas Formation

consists of mainly clay, sandy clay and peat of Holocene fluviatile-estuarine deposits,

whereas the Gula Formation represents Holocene marine to estuarine sediments which

mostly consists of clay and minor sand.The Simpang Formation is a continental deposit

comprising of gravel, sand, clay and silt of Pleistocene in age. The underlying Kenny

Hill Formation consists of a monotonous sequence of interbedded shales, mudstones and

sandstones. The rock is Carbonaceous in age and it forms an undulating surface

topography in the eastern part of the study area. A total of 121 gravity stations were

established using the La Coste Romberg gravity meter and the elevations of most of the

stations were determined using the Tiernan-Wallace altimeters. Benchmarks wherever

available were used as control stations in order to minimise the error of the elevations

measured. The high resolution seismic reflection using the common mid point (CMP) or

roll along technique was carried out using a 24 channel signal enhancement seismograph

and high frequency geophones. Emulex 150 explosives with electrical detonators were

used for generating seismic source. The offset shot used in the survey was 50 meters and

the whole spread was moved at intervals of 10 meters with geophones fixed at 5 meters

spacing. This configuration produced 12-fold CMPs seismic gathers which were

conventionaly processed to produce migrated stacked sections. A total length of about

1.7 kilometer stacked section has been acquired in this survey and a nearby borehole

data was used in the interpretation. A relative Bouguer anomaly map shows an elongated

zone of low gravity anomaly trending approximately NW-SE which is interpreted to be

the depocenter of the Quaternary basin. The interpreted gravity profiles running across

the central area show that the basin has a thickness that varies from tenth to several

hundred meters with maximum depth to bedrock of about 275m. A gravity profile which

passes through the eastern edge of the basin was modeled with a depth to bedrock of

about 178m below the ground. This agrees quite well with those obtained from the

interpreted seismic section and borehole data. The stacked seismic section shows several

high amplitude parallel to sub-parallel reflection overlying discontinuos and low

reflection pattern. Reflections on the eastern part is much shallower than the one

observed on the western part which clearly indicates the presence of basinal structure

with a total interpreted depth to bedrock of about 200m.

 

32 Proceeding MALAYSIAN SCIENCE AND TECHNOLOGY CONGRESS 2002:

SYMPOSIUM A: PHYSICAL SCIENCES, ENGINEERING

AND TECHNOLOGY

page 649-659

 

SPECTRAL ANALYSIS OF SURFACE WAVE (SASW) MEASUREMENTS FOR INSITU

CHARACTERISATION OF SOIL

Abdul Rahim Samsudin*, Mohd Azmi Ismail*, Khairul Anuar Mohd Nayan#

Abdul Ghani Rafek* & Umar Hamzah*

*School of Environment and Natural Resource Sciences

Faculty of Science & Technology

#Department of Civil and Structure

Faculty of Engineering

Universiti Kebangsaan Malaysia

Bangi, Selangor.

Tel: 03-89215396, Fax: 03-89215490

abrahim@pkrisc.cc.ukm.my

ABSTRACT

Subsurface information relating to in situ strength and stiffness of soil are important for geotechnical design and have been obtained traditionally using laboratory investigation techniques. Soil material at any development site should ideally be characterized in situ at its natural stress and saturation levels, and should cover a large volume of the soil. In the laboratory, however, such conditions may not be achieved. In additions, sampling

disturbances, small volume of sampled soil, and limited stress configurations and strain measurement range in laboratory tests introduce uncertainties in the characterisation. This paper describes an application of spectral analysis of surface wave (SASW) technique for in situ characterisation of soil material. Surface wave technique is a non-destructive  seismic technique that can be used to determine the low-strain dynamic properties of subsurface material. This technique can either be performed on soil or pavement surfaces. By generating and measuring surface waves in the field, a dispersion curve of surface wave velocity versus wavelength is constructed. An inversion of the dispersion data was then employed to produce the actual stiffness profile of the site. The test method has a broad range of civil engineering applications. Results from surface wave tests on two

different sites of cut and compacted fill terraces are presented. The results from surface wave test were then compared to the standard test of the SPT and the pressure-meter tests.

 

Keywords: Surface wave, spectral analysis, dispersion curve, low-strain dynamic properties, in situ characterisation