THE INCREASING OF UNDRAINED SHEAR STRENGTH AND SHEAR MODULUS OF SOFT BANGKOK CLAY BY SILICA POWDER USING UNCONFINED COMPRESSION TEST WITH BENDER ELEMENT

Abstract

The present study aims to increase the undrained shear strength and shear modulus of soft
Bangkok Clay soil by silica powder when they were subject to unconfined compression test with the bender
element. The shear wave velocity was measured using a pair of bender elements installed at the top cap and
pedestal of the unconfined cell. The undrained shear strength was conducted step by step so that the variation
of shear modulus could be determined. The undrained shear strength was carried out at the strain rate of 1%
per minute during which the shear modulus was continuously recorded. The result found that when the soil
was mixed with silica powder an increased rate, the undrained shear strength and shear modulus were
increased but the strain was decreased. Therefore, the improvement of soil quality using silica powder can be
increased the efficiency of the construction such as embankment and road construction.