Vibro stone columns in soft clay soil: A trial to study the influence of column installation on foundation performance

In order to assess the performance of a group of stone columns installed by the dry bottom-feed method, as support for a raft foundation, an instrumented trial has been undertaken at the Bothkennar soft clay test bed site. Close examination of the ground response to treatment has shown significant disturbance, including approximately 0.4 m heave at the surface of the treated ground, high pore water pressure response and a prolonged period of dissipation. Ground recovery was continuing one year after treatment. The implications for similar installations are discussed.