Sains Malaysiana 29: 233-255 (2000)                                                                          Sains Bumi/

        Earth Sciences

Ciri Fizikal Tanah Pada Kegagalan Cerun Sepanjang Jalan

Utama Bangi Lama, Selangor Darul Ehsan

(Physical Characteristics of Soil at the Slope Failure Region Along the

Main Road of Bangi Lama, Selangor Darul Ehsan)

Zulfahmi Ali Rahman, Sahibin Abd Rahim & Hazizi Esa

Program Sains Sekitaran,Fakulti Sains Sumber Alam

Universiti Kebangsan Malaysia

43600 UKM Bangi, Selangor D.E.,Malaysia

ABSTRAK

Survei taburan kegagalan cerun tanah dijalankan tertumpu di sepanjang jalan utama kawasan Bangi Lama. Beberapa lokasi cerun gagal yang terdiri daripada tanah luluhawa bergred VI dikenalpasti. Secara keseluruhannya, jenis kegagalan cerun yang utama dikelaskan sebagai jenis gelonsoran dengan membabitkan isipadu tanah yang tinggi. Manakala runtuhan cerun jenis gelinciran biasanya menyebabkan pergerakan isipadu tanah yang lebih rendah. Skala cerun gagal berjulat antara 2 meter hingga 18 meter lebar manakala ketinggian cerun gagal mencapai 20 meter. Kesan alur hakisan air yang aktif dan ketiadaan tumbuhan penutup bumi pada bahagian cerun menyumbang kepada keruntuhan tanah cerun. Nilai sudut kecuraman cerun di beberapa lokasi berjulat antara 15 hingga 55 darjah. Sebahagian besar cerun menunjukkan potensi gerakan jisim berdasarkan pengembangan saiz bukaan rekahan pada struktur penahan. Beberapa parameter fizikal tanah dilakukan terhadap sampel tanah terdiri daripada kandungan air tanah dan air tanah tepu, kandungan bahan organik, pH, keliangan, aggregat, kekuatan mekanik (ASSB), taburan saiz partikel dan penentuan had Atterberg. Berdasarkan tekstur, tanah cerun dapat dikategorikan kepada jenis lempung dan 10M. Nilai indek keplastikan (I) dan had cecair menunjukkan tanah terdiri dari jenis lodak dengan keplastikan sederhana (MI). Manakala keaktifan koloid (A) pula adalah jenis lempung tidak aktif.

ABSTRACT

Survey of slope failure distribution was carried out concentrates along the main road in the Bangi Lama area. Several locations of slope failures involved weathered soil of grade VI. Most of the slope failures were classified as slump failure involving large volume of soil mass. The slide type of slope failure is associated with small volume of soil movement. The scale of failure ranges from 2 metres to 18 metres width and can reach 20 metres height. The presence of the erosion gullies due to active water run-off and absence of slope vegetation contribute to the slope failure. Slope angle of some locations of slope failure range from 15 to 55 degrees. Majority of the slopes tend to associate with slope movement regarding to the development of the size of fracture of retaining walls. Several physical parameters of soil were analysed including water content of soil and saturated soil, organic content, pH, porosity, soil aggregation, mechanical strength (ASSB), particle size distribution and Atterberg limit identification. Based on textures, slope soil can be classified as clay and loam. The values of the plasticity index (I_p) and liquid limit suggest that the soils consist of silt with moderate plasticity (MI). Meanwhile, the colloid activity (A_c) suggest that the soils are classified as inactive clay.

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