Sains Malaysiana 40(10)(2011): 1065–1073

 

Soil-root Shear Strength Properties of Some Slope Plants

(Sifat Kekuatan Ricih Tanah-Berakar Beberapa Tumbuhan Cerun)

 

 

Normaniza Osman* & Mohamad Nordin Abdullah

Institute of Biological Sciences, Faculty of Science, University of Malaya

50603 Kuala Lumpur, Malaysia

 

Faisal Haji Ali

Department of Civil Engineering, Faculty of Engineering, University of Malaya

50603 Kuala Lumpur, Malaysia

 

Diserahkan: 21 Mei 2010 / Diterima: 10 Februari 2011

 

ABSTRACT

 

Rapid development in hilly areas in Malaysia has become a trend that put a stress to the sloping area. It reduces the factor of safety by reducing the resistant force and therefore leads to slope failure. Vegetation plays a big role in reinforcement functions via anchoring the soils and forms a binding network within the soil layer that tied the soil masses together.  In this research, three plant species namely Acacia mangium, Dillenia suffruticosa and Leucaena leucocephala were assessed in term of their soil-root shear strength properties. Our results showed that Acacia mangium had the highest shear strength values, 30.4 kPa and 50.2 kPa at loads 13.3 kPa and 24.3 kPa, respectively. Leucaena leucocephala showed the highest in cohesion factor, which was almost double the value in those of Dillenia suffruticosa and Acacia mangium. The root profile analysis indicated Dillenia suffruticosa exhibited the highest values in both root length density and root volume, whilst Leucaena leucocephala had the highest average of root diameter.

 

Keywords: Angle of friction; cohesion factor; factor of safety; root length; shear strength

 

ABSTRAK

Pembangunan pesat di kawasan berbukit di Malaysia menjadi satu trend dan ini memberi tekanan kepada kawasan cerun. Ianya mengurangkan faktor keselamatan dengan pengurangan daya tahan yang boleh menyebabkan ketidakstabilan cerun. Vegetasi memainkan peranan penting dalam fungsi penguatan dengan membentuk rangkaian ikatan pada lapisan tanah. Berlandaskan kepada kepentingan terhadap penguatan tanah-akar ini, kajian telah dijalankan ke atas tiga spesies tumbuhan iaitu Acacia mangium, Dillenia suffruticosa dan Leuceana leucocephala dan pokok-pokok ini diuji daripada segi ciri-ciri kekuatan ricih tanah-akarnya. Keputusan menunjukkan Acacia mangium mempunyai kekuatan ricih yang tinggi iaitu 30.4 kPa dan 50.2 kPa pada beban 13.3 kPa dan 24.3 kPa, secara berturutan.  Leucaena leucocephala menunjukkan nilai faktor kohesi yang paling tinggi iaitu hampir dua kali ganda berbanding Dillenia suffruticosa dan Acacia mangium. Daripada segi analisis profil akar, Dillenia suffruticosa menunjukkan nilai yang tinggi bagi kedua-dua ketumpatan akar dan juga isipadu akar manakala Leucaena leucocephala mempunyai nilai purata diameter akar yang paling tinggi.

 

Kata kunci: Faktor kohesi; faktor keselamatan; kekuatan ricih; panjang akar; sudut geseran

 

 

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*Pengarang untuk surat-menyurat; email: normaniza@um.edu.my

 

 

 

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