EFFECT OF SAMPLE DIMENSION ON EFFECTIVE SHEAR STRENGTH PARAMETERS OF REMOLDED SEDIMENTARY RESIDUAL SOIL

Abstract

The residual sedimentary soil is one of the largest residual soils in peninsular Malaysia. Its vast presence enables engineering activities to use this type of residual soil in the construction sector such as in construction of retaining walls and roads. Nevertheless, this residual soil often brings in heterogeneities because it is structurally complex and extensively weathered in most places which it can cause a structure to fail. This can be solved by determining the value of the shear strength parameter of the soil in a particular area. In order to determine the effect of sample’s dimension on the effective shear strength parameters of the samples, consolidated drained (CD) triaxial test was conducted on two different diameters size of 38 mm and 50 mm. This study shown that is has a significant effect in different sizes of sample used. 22.5 kPa and 32˚ were recorded for effective cohesion value, c' and effective friction angle, Ø’ for 38 mm soil samples and for 50 mm soil samples, the recorded c' and Ø’ values were 20 kPa and 30˚ respectively. 38 mm size soil sample recorded high values of both parameters. The small size of remolded sample will make soil particle denser hence reduce the void. This will not represent the actual condition on the site. As a result, by using small size samples for determining shear strength parameters can result in false value in designing while large sample dimension is more accurate representation of soil condition.