A Novel Blend of Karst Grouting and Micropile Placement Techniques for Stabilizing Difficult Foundation Conditions in Weak Vuggy Limestone

This case study describes the grouting aspects of the foundation improvements carried out to remediate the settlement distress of a partially constructed new building located on the west coast of the Caribbean island of Barbados. The foundation remediation ultimately included the construction of a 280-foot-long sub-surface ‘sea-wall’, the installation of 174 micro-piles (providing direct and indirect support to the building) and the grouting of voids and interconnected fissures/fractures in the weak, vuggy, uncemented coralline limestone strata underlying the building foundations. An investigation of the cause(s) of the settlement, a flexible remediation design, and close monitoring of the drilling and grouting operations during construction were essential to the success of the project. In addition, contractor procurement and operation, based on an ‘Alliance’ contractual concept resulted in an excellent consultant-contractor team relationship throughout. This was key to the completion of the work within the tight schedule required by the owner.