**5.3. Vibro-replacement stone column**

For weak layers such as sand lenses that are difficult to remove, vibro-replacement stone columns are usually used to densify the soils to form a composite foundation. The stone columns also serve as vertical drainage paths that are beneficial to dissipate the pore pressure within the surrounding soils. In the Huangjinping ACRD [14], vibro-replacement stone columns with a diameter of 1.0 m were set to improve the sand lenses buried more than 25 m below the ground surface.
