Effective shear strength parameters of remoulded residual soil

Abstract

Residual soil is widely used as construction materials in Malaysia. As the economic development in the country is growing rapidly due to the increase in population; there is increasing number of major civil engineering construction projects that involved residual soils. An understanding of soil properties in the construction site, enabling the geotechnical structures design more easy, safe and economic. However, it is very important to conduct extensive and intensive studies on the residual soils characteristics and properties to determine the viability of building on this type of soil. Shear strength of soil is the result of the resistance to movement of molecules connected with each other (particles interrelated physical and chemical bonds). For that, Shear strength of soil must be suitable, appropriate and adequate to the purpose of carrying various stresses of the buildings loads and installations by making sure the possibility of carrying these loads. This research focuses on comparison of effective shear strength parameters of remoulded residual soil. Laboratory triaxial compression tests were performed on remoulded samples with 100 and 200 kpa consolidation pressure, CU test with pore water pressure measurement and CD tests were conducted in order to evaluate the effective shear strength parameters of remoulded residual soil that were collected from UTM area at a depth of 1.5 m to 2.5 m below the ground surface. CU test results were higher than CD results in term of effective parameters. CD test results are more reliable data that idealize the soil behavior in the real condition, but this test not as common as the CU test because of it may require a longer time to run. This test procedure is similar to the CU test except that drainage is allowed during shearing stage and the rate of shearing is very slow to prevent the build up of excess pore water pressure. This test may take days to perform, making it expensive. Therefore this study gives a reduction factor for the effective friction angle (?') between CU and CD tests which is in the range of 0.89 to 0.92. This factor helps to estimate the effective friction angle (?') of CD test from CU test result.