Stabilisation of subsoil using colloidal silica beneath shallow foundation: a case study

Shallow foundations are commonly used to support the various equipment in industrial projects. If the subsoil is too weak to withstand the equipment loads, the settlement or tilting of the foundations takes place. To avoid further distress to such foundations, weak soil beneath the damaged foundation is required to be strengthened. This paper presents a similar case study wherein the strengthening of subsoil was performed beneath the shallow foundations that experienced settlement and tilting beyond the permissible limits due to the presence of weak subsoil. The stabilisation of soil was performed using injection grouting with colloidal silica–based chemical grout to prevent further settlement and tilting of the shallow foundations. The particulars of the chemical stabilisation programme, injection methodology, chemical consumption, field trials, and laboratory test results are explicated in this paper with the details of post-rectification performance of the test foundation. The properly executed injection grouting using chemical components was observed to be an effective measure to stabilise the subsoil by enhancing its engineering properties to a certain extent. The key factors that can affect the performance of colloidal silica-based chemical grout and precautions to be considered during soil stabilisation are also discussed in this paper.