Soil Strengthening – Use of Pressure Injection Grouting as a means of Improving Load Bearing Capacity of Existing Foundations

Introduction

This Paper describes the procedure for improving the Load bearing capacity of the foundations by means of strengthening the soil under and around the foundations. Use of Injection grouting in the soil as a viable means of achieving this objective has been explored. The real life dilemma faced by designers of the need for proffering solutions/ remedial measures for rehabilitating/ strengthening already constructed structures is a reality. The dearth of literature in the field of injection grouting has prohibited the use of this technology on a wider scale. The availability of standards in the field of grouting is limited to recommendations for niche areas like rock grouting. The response of pressure grout varies considerably in different types of soils and is quite different in its fundamental aspect in case of rocks.

Most of the standard rehabilitation works fall under the gamut of distortions/debilitations/physical imperfections in manmade structures. The aim of rehabilitation work procedures is often restricted to inducing stress release in overtly stressed elements, either by strengthening the members themselves or by introducing additional robust members. Seldom is the environment in which the structure is placed subjected to modifications for achieving the desired results. For a structural engineer, soil is the closest environmental element which overtly interacts with the structure. Soil serves the dual purpose of acting as a supporting medium and also as a transmitting agency for debilitating actions of forces like earthquake and water. The properties of the soil, as enumerated in the geo-technical report, available at the time of designing are dovetailed with the structural response at the time of designing the structure. The Structural configuration which most judicially transmits the loads coming on it to the supporting medium becomes the final choice of the designer. Changing the properties of supporting medium, in response to the changed loadings after the structure has been erected is an ingenious method of controlling the ill effects of increased loads on the structure.