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Sains
Malaysiana 46(11)(2017): 2187-2193 http://dx.doi.org/10.17576/jsm-2017-4611-20 Laboratory Study of
Acoustic Velocity in Different Types of Rocks at Seismic Frequency
Band YUNLAN HE1,2*,SUPING
PENG2,
WENFENG DU2,
XIAOMING TANG2
& ZENG HU2
2State
Key Laboratory of Coal Resources and Safety Mining, China University
of Mining & Technology (Beijing) Received:
22 January 2017/Accepted: 30 May 2017 ABSTRACT In order to understand the characteristics of acoustic wave propagation
in rocks within seismic frequency band (<100 Hz), the velocities
of longitudinal and transverse waves of four different types
of rocks were tested using low-frequency stress-strain method
by means of the physical testing system of rock at low frequency
and the experimental data of acoustic velocities of four different
types of rocks at this frequency band were obtained. The experimental
results showed that the acoustic velocities of four different
types of rocks increased with the increase of temperature and
pressure within the temperature and pressure ranges set by the
experiment. The acoustic velocity of fine sandstone at 50% water
saturation was smaller than that of dry sample. The acoustic
velocities of four different types of rocks were different and
the velocities of longitudinal waves of gritstone, fine sandstone,
argillaceous siltstone and mudstone increased in turn under
similar conditions and were smaller than those at ultrasonic
frequency. Few of existing studies focus on the acoustic velocity
at seismic frequency band, thus, further understanding of the
acoustic characteristics at this seismic frequency band still
requires more experimental data. Keywords: Acoustic velocity; pressure; seismic frequency band; temperature ABSTRAK Untuk memahami ciri penyebaran gelombang akustik dalam jalur frekuensi
seismos (< 100 Hz) batuan, halaju gelombang membujur dan
melintang empat jenis batuan berbeza telah diuji menggunakan
kaedah frekuensi rendah strain-tegasan melalui sistem ujian
fizikal batuan pada frekuensi rendah dan data uji kaji halaju
akustik daripada empat jenis batuan pada jalur frekuensi ini
diperoleh. Keputusan uji kaji menunjukkan bahawa halaju akustik
daripada empat jenis batuan meningkat dengan peningkatan suhu
dan tekanan dalam julat suhu dan tekanan yang ditetapkan oleh
uji kaji ini. Halaju akustik batu pasir halus pada 50% air tepu
adalah lebih kecil berbanding dengan sampel kering. Halaju akustik
daripada empat jenis batuan berbeza dan halaju daripada gelombang
membujur batu grit, batu pasir halus, batu lodak argil dan batu
lumpur meningkat pada keadaan yang serupa tetapi lebih kecil
berbanding dengan kekerapan ultrasonik. Beberapa kajian sedia
ada memberi tumpuan kepada kelajuan akustik pada jalur frekuensi
seismos, oleh itu, pemahaman lanjut terhadap ciri akustik pada
jalur frekuensi seismos ini masih memerlukan lebih data uji
kaji. Kata kunci: Halaju akustik; jalur
frekuensi seismos; suhu; tekanan REFERENCES
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