SOME CHANGES ON ENGINEERING PROPERTIES OF SUBANG CLAYSTONES DUE TO WEATHERING

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

SOME CHANGES ON ENGINEERING PROPERTIES OF
SUBANG CLAYSTONES DUE TO WEATHERING

Imam A. Sadisun

Research Division on Applied Geology
Faculty of Earth Science and Technology - Bandung Institute of Technology
Jl. Ganesha No.10, Bandung 40132 INDONESIA

ABSTRACT

On account of deterioration characteristics of Subang claystone, the method applied for identifying the development of degree of weathering is specific, i.e. development of platy fracture and discoloration index within the rock. With a descriptive system, each degree of weathering of the claystones has profound characteristic. The claystone can be divided into six zones, which are fresh rock, slightly weathered (1.1 - 3.1 m thick), moderately weathered (0.6 - 2.3 m thick), strongly weathered (0.4 - 1.4 m thick), completely weathered (0.3 - 1.2 m thick), and residual soil (0 - 1.4 m thick). There are various patterns of change of engineering properties with the increasing of weathering. Effective porosity in this case tends to increase geometrically, density decreases exponentially, point load strength index decreases logarithmically, cohesion and internal friction angle decrease linearly. It is obvious that the weathering is the main responsible factor for the changes of engineering properties of the claystones.