Engineering geological aspects of clastic metasediments in the Kuala Lumpur area, Peninsular Malaysia


Author : I. KomooPublication : Bulletin of the Geological Society of MalaysiaVolume : 19Page : 597-612Year : 1986


Description

Bulletin of the Geological Society of Malaysia, Volume 19, April 1986, pp. 597 – 612

 

Aspek geologi kejuruteraan batuan metasedimen klastik di sekitar Kuala Lumpur, Semenanjung Malaysia

(Engineering geological aspects of clastic metasediments in the Kuala Lumpur area, Peninsular Malaysia)

IBRAHIM KOMOO

Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia

 

Abstrak: Metasedimen klastik memenuhi hampir 50% dari kawasan perbandaran di Kuala Lumpur. Litologi batuan ini boleh dibezakan kepada tiga kumpulan utama: batuan meta-arenit, batuan meta-argilit dan formasi batuan skis. Kadar luluhawa yang tinggi telah mengubah kebanyakan dari batuan metasedimen klastik kepada tanah baki dan bahan bumi terluluhawa.

Cerapan lapangan menunjukkan ketebalan zon dan kadar luluhawa berbeza untuk kumpulan litologi yang berbeza. Batuan meta-argilit memenuhi kawasan zon terluluhawa sederhana hingga tinggi, dan batuan skis memenuhi kawasan zon terluluhawa sedikit hingga sederhana. Zon terluluhawa tinggi dicirikan oleh lapisan bahan bumi terluluhawa gred VI dan V yang tebal (melebihi 10 m). Bahan buminya mempunyai kandungan butiran halus yang tinggi dan peratus kandungan air yang sederhana. Walaupun bahan bumi pada zon ini baik sebagai bahan pembinaan, tetapi darjah kestabilan sebagai bahan cerun (potongan atau tambakan) rendah, dan untuk bahan gred V, kemampuannya untuk bertahan dengan tindakan hakisan juga rendah.

Zon terluluhawa sederhana dicirikan oleh kehadiran lapisan tanah baki (Gred VI) yang nipis dan bahan bumi terluluhawa (Gred V, IV dan III) yang sangat tebal. Batuan terluluhawa gred IV dan III apabila terdedah akan terluluhawa pada gred yang lebih tinggi (V dan VI) dengan pantas, dan sering menimbulkan masalah kegagalan cerun dan hakisan. Zon terluluhawa sedikit hanya dijumpai pada kawasan formasi skis. Zon ini dicirikan oleh lapisan bahan bumi terluluhawa yang nipis hingga sederhana menindih batuan segar. Kekuatan mampatan batuan segar boleh mencapai hingga 227 MPa, apabila terluluhawa kekuatannya menurun hingga mencapai 31 MPa. Kehadiran ketakselanjaran yang rapat, dan dengan kekerapan yang tinggi boleh menimbulkan masalah kegagalan cerun batuan pada kawasan perbukitan.

 

Abstract: Clastic metasediments cover almost 50% of the urban area in Kuala Lumpur. The rocks can be differentiated into three main lithological groups, namely meta-arenite, meta-argillite and schist formations. The relatively high rate of weathering has changed most of these clastic sedimentary rocks into residual soil (grade VI) and weathered earth material (grades V, IV and III).

Field observation shows different weathering rate and thickness zones for the different lithological groups. Generally, the highly weathered zone was occupied by meta-argillite, the meta-arenite covers moderately to highly weathered zone, and the schist formation covers slightly to moderately weathered zone. Highly weathered zone is characterised by the thick layers of weathered earth materials grades VI and V (more than 10 m), and the material contains a high percentage of fines with moderate water content. Although the earth material in this zone is suitable as construction material, its degree of stability as a slope material (cut or filled) is low, and the ability for the grade V material to withstand erosion is also relatively low.

The moderately weathered zone is characterised by the presence of a thin layer of residual soil and generally very thick layer of weathered earth material. Weathered rock grades IV and III when exposed at the surface will be rapidly weathered to higher grades (V and VI), and tend to give rise to problems of slope failure and erosion. The slightly weathered zone is only restricted to the schist formation. This zone is characterised by thin to moderately thick layer of weathered earth material on top of fresh rock (grade I). The Compressive Strength of the fresh rock can reach up to 227 MPa, but when weathered, for instance to grade III, the strength is reduced to as low as 31 MPa. The occurrence of discontinuities at close spacing with relatively high frequency, and the hilly land can lead to the problem of rock slope failure. 

https://doi.org/10.7186/bgsm19198644