Abstract

In an ordinary theory mentioning that Bored pile type is non-displacement pile instead of driven pile as displacement type. To change the bored pile become displacement type, need an effort to displace surrounding soil in the vicinity of bored pile, the compaction of concrete during installation is one of the solution. During compaction, the soil displaced and excess pore water pressure increase, then by allowing pore water pressure to dissipate, the ground improvement is happening. The modelling of pile loading test (PLT) were carried out in various w/c ratio in ambient condition on first liquidity index (LI1 ), LI2 and LI3 , The direct shear test (DST) of clay soil (at LI1 , LI2 and LI3 ) and at combination of clay + cement mortar at various w/c ratio were also carried out to encourage and endorse the simulation work. The ground improvement occurs as a results of : 1. Chemical reaction between cement and clay, 2. Enlargement of slip surface diameter at the interface between soil – soil cement mix hardened, 3. Increasing effective stress as an effect of allowing pore water pressure dissipation after compaction. This stabilization produce increasing strength properties up to 75 % at the optimum w/c ratio 0,4. Based on this findings, it recommends to include the ground improvement effect to bored pile foundation.