An improvement method whereby strong compacted sand piles are created in ground to form composite ground at cohesive soil. This increases the shear resistant strength, and at the same time, it stabilises early settlement to reduce the consolidation settlement rate. For sandy ground, it increases the relative density, thus enhances the shear strength.
By using vibro-hammer to repeatedly driving in & withdraw the casing pipe, then again redrive in the casing to forcefully create the compacted sand piles into the ground. In sandy ground, due to the insertive effect of the sand piles, relative density of the entire ground is being increased, the shear strength is enhanced.In cohesive ground, the composite ground is formed by the mixture of sand piles & cohesive soil, thus they strengthen the ground.