Shallow foundations are commonly used to support 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 which 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 foundations. The particulars of the chemical stabilisation program, 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 and precautions to be considered during soil stabilisation are also discussed in this paper.

Soil liquefaction is an important problem that threatens the safety of buildings during earthquakes due to its destructive effects caused by a serious decrease in soil strength. In addition to the existing soil improvement methods, a reasonable approach to tackle this problem could be a superabsorbent polymer called sodium polyacrylate (SPA), which has a 125 ml/gr water absorption capacity as well as an extraordinary swelling pressure, used as grouting inside the liquefiable soil. This mitigates the effects associated with liquefaction -induced damage by changing the phase of excess water into a gel formation within the ground without changing the soil skeleton. In this study, the use of SPA is evaluated against post -liquefaction problems of saturated liquefiable soil, such as pore pressure generation, surface settlement and bearing capacity both in shaking table tests in a laboratory and full-scale in -situ tests thanks to its viscous gel structure and swelling potential. Firstly, an optimum SPA column spacing was determined to be four times the drilling diameter according to the shaking table tests in terms of pore water pressure generation and surface settlement. After this, an original chemical grouting device was designed, produced, and mounted on a drilling machine with two different mechanisms that provides multiple injections in a dry state and multiple boring at the same time. Finally, the results of the full-size liquefaction tests within an 8 m3 test pit demonstrate that generation of excess pore pressure is dissipated at up to 150%, settlements are reduced, and liquefaction resistance is increased due to the maximum 0.4 pore water pressure ratio value, after improvement through single, double, and triple SPA column application.