Sains Malaysiana 43(10)(2014): 1477–1484

 

Rainfall Infiltration through Unsaturated Layered Soil Column

(Penyusupan Air Hujan melalui Tanah Tak Tepu pada Tiang Tanah)

 

 

ANIZA IBRAHIM1,2, MUHAMMAD MUKHLISIN1,3* & OTHMAN JAAFAR1

 

1Department of Civil and Structural Engineering, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor, Malaysia

 

2Department of Civil Engineering, Faculty of Engineering, Universiti Pertahanan Nasional Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur, Malaysia

 

3Department of Civil Engineering, Polytechnic Negeri Semarang, Indonesia

 

Diserahkan: 18 Jun 2012/Diterima: 18 Februari 2014

 

 

ABSTRACT

Infiltration caused by rainfall will lead to the changes of moisture content and soil pore water pressure or matric suction of the soil. These changes indicate the behavior of the soil especially during wetting and drying process. This paper presents the experimental test result of rain water infiltration into soil column for two samples of soils. The main objectives were to study the effect of rainfall intensity and duration of soil infiltration process for the forest soil and to compare its result to the gravelly sand. Infiltration experimental in this study involved three main components; water supply system, soil column and instrumentations, including percolation collection system. This study uses two types of tensiometers; 5 and 10 cm long. The results of TDR and tensiometers which were used to obtained moisture content and matric suction, respectively, shows that the system was successfully developed. For the forest soil, the result showed that moisture content of the top section is higher compared with the other sections. On the other hand, for gravelly sand, the moisture content in middle section is higher compared with the top and bottom section of the soil. Meanwhile, matric suction for both soils dropped during rainfall and gradually increases towards drying process. Other than that the comparison of soil matric suction between 5 and 10 cm tensiometers shows significant results for gravelly sand compared to forest soil.

 

Keywords: Infiltration; matric suction; soil column; soil moisture

 

ABSTRAK

Penyusupan yang disebabkan oleh hujan akan merubah kandungan lembapan dan tekanan air liang tanah. Perubahan ini adalah merupakan penanda kepada sifat tanah terutamanya semasa proses pembasahan dan pengeringan daripada hujan yang turun. Kertas kerja ini memaparkan keputusan yang dicapai daripada uji kaji makmal berdasarkan ujian air hujan yang menyusup ke dalam dua sampel tanah. Objektif utama kajian ini adalah untuk mengkaji kesan daripada keamatan dan tempoh air hujan untuk sampel tanah dari kampus dan dibandingkan dengan sampel pasir berkerikil. Ujian penyusupan ini terbahagi kepada tiga komponen; sistem bekalan air, tiang tanah dan instrumentasi dan juga sistem pengaliran keluar air. Kajian ini menggunakan dua jenis tensiometer; 5 dan 10 cm panjang. Keputusan yang diperoleh menunjukkan tanah dari kampus mempunyai kandungan lembapan yang tinggi pada bahagian atas tiang dibandingkan dengan bahagian yang lain. Manakala pasir berkerikil pula, tanah pada bahagian tengah tiang menunjukkan kandungan lembapan yang tertinggi. Selain daripada itu, tekanan air liang tanah untuk kedua jenis tanah ini menunjukkan pengurangan semasa hujan, tetapi beransur meningkat semasa proses pengeringan. Selain daripada itu, didapati tekanan air liang antara 5 dan 10 cm tensiometer menunjukkan kesan pada pasir berkerikil berbanding dengan tanah dari kampus.

 

Kata kunci: Kandungan lembapan; penyusupan; tekanan liang; tiang tanah

RUJUKAN

Bujang, B.K., Ali, F.H. & Low, T.H. 2006. Water infiltration characteristics of unsaturated soil slope and its effect on suction and stability. Geotechnical and Geological Engineering 24: 1293-1306.

Gasmo, J.M., Rahardjo, H. & Leong, E.C. 2000. Infiltration effects on stability of a residual soil slope. Computers and Geotechnics 26: 145-165.

Gofar, N., Lee, L.M. & Asof, M. 2006, Transient seepage and slope stability analysis for rainfall-induced landslide: A case study. Malaysian Journal of Civil Engineering 18: 1-13.

Gofar, N., Lee, L.M. & Kassim, A. 2008. Instrumented soil column model for rainfall infiltration study. Geotropika 2008. International Conference of Geotechnical & Highway Engineering.

Indrawan, I.G.B., Rahardjo, H. & Leong, E.C. 2007. Drying and wetting characteristics of a two-layer soil column. Canadian Geotechnical Journal 44: 20-32.

Lee, L.M., Kassim, A. & Gofar, N. 2011. Performance of two instrumented laboratory models for the study of rainfall infiltration into unsaturated soils. Engineering Geology 117: 78-89.

Mukhlisin, M. & Taha, M.R. 2012. Numerical model of antecedent rainfall effect on slope stability at a hillslope of weathered granitic soil formation. Journal Geological Society of India 79: 525-531.

Mukhlisin, M. & Taha, M.R. 2009. Slope stability analysis of a weathered granitic hillslope as effects of soil thickness. European Journal of Scientific Research 30(1): 36-44.

Mukhlisin, M., Baidillah, M.R., Taha, M.R. & ElShafie, A. 2011. Effect of soil water retention model on slope stability analysis. International Journal of the Physical Sciences 6(19): 4629-4635.

Mukhlisin, M., Kosugi, K., Satofuka, Y. & Mizuyama, T. 2006. Effects of soil porosity on slope stability and debris flow runout at a weathered granitic hillslope. Vadose Zone J. 5: 283-295.

Rahardjo, H., Ong, T.H., Rezaur, R.B., Leong, E.C. & Fredlund, D.G. 2010. Response parameters for characterization of infiltration. Environment Earth Science 60: 1369-1380.

Yang, H., Rahardjo, H. & Leong, E.C. 2006. Behavior of unsaturated layered soil columns during infiltration. Journal of Hydrologic Engineering 11(4): 329-337.

 

 

 

*Pengarang untuk surat-menyurat; email: mmukhlis@vlsi.eng.ukm.edu.my

 

 

 

 

sebelumnya