Civil Engineering and Architecture Vol. 12(1), pp. 361 - 374
DOI: 10.13189/cea.2024.120127
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Interface Shear Strength Progressive between Weathered and Fresh Clay Shales


Idrus M. Alatas 1, Pintor Tua Simatupang 2,*
1 Department of Civil Engineering, Institut Sains dan Teknologi Nasional, Indonesia
2 Department of Civil Engineering, Universitas Mercu Buana, Indonesia

ABSTRACT

The slope instability on clay shale soil is generally triggered by the formation of an interface between the weathered and fresh clay shale layers. This type of soil causes many slope failures in Indonesia. The weathered clay shale can be considered as an overburden layer (OBL) to the interface plane. The slope instability is supposed to be governed by the interface shear strength between weathered and fresh clay shales. The progressive interface shear strength is meant as a decrease in shear strength due to increased water content in the OBL. The behavior of weathered clay shale to change moisture content will be investigated by defining weathered clay shale as compacted weathered clay shale (CWCS). Through laboratory studies, the progressive interface shear strength between weathered clay shale and fresh clay shales was obtained using the Multistage Reversal Progressive Shear Test (MRPST) method. The density of OBL varied between 100% and 85% of the maximum density from standard Proctor tests in the laboratory. At each OBL density, the interface shear strength was determined with variations in water content until the OBL reached the degree of saturation Sr = 100%. In the CWCS at the optimum moisture content with a density of 100% of maximum dry density , the ratio of maximum interface shear strength is 1.89. The interface shear strength ratio will decrease until it reaches 0.56 or the remaining 29% due to the increase in moisture content until the CWCS becomes saturated (Sr=100%). If the CWCS density decreases to 85% of , then the interface shear strength ratio will decrease until the remaining 10% due to an increase in water content reaches fully saturated.

KEYWORDS
Clay Shale, Weathered, Interface, Progressive, Interface Shear Strength, MRPST

Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Idrus M. Alatas , Pintor Tua Simatupang , "Interface Shear Strength Progressive between Weathered and Fresh Clay Shales," Civil Engineering and Architecture, Vol. 12, No. 1, pp. 361 - 374, 2024. DOI: 10.13189/cea.2024.120127.

(b). APA Format:
Idrus M. Alatas , Pintor Tua Simatupang (2024). Interface Shear Strength Progressive between Weathered and Fresh Clay Shales. Civil Engineering and Architecture, 12(1), 361 - 374. DOI: 10.13189/cea.2024.120127.