Displacement prediction of inclined existing buildings with a raft foundation restored by compaction grouting in clay

Abstract

Compaction grouting technique is often used to lift and rehabilitate any settled or tilted existing buildings. Prediction of building displacement prior to the grouting operation is crucial for safe remediation. However, the renovation of settled buildings using compaction grouting technique is generally empirical. In this study, we aim to propose a theoretical model to obtain the displacements of the inclined existing building with a raft foundation restored by compaction grouting in clay. The displacements of model involve two parts, (i) the ground heave displacements caused by compaction grouting, and (ii) the surface settlements resulting from a raft foundation. We estimate the displacements of the part (i) and part (ii) by means of a virtual image technique and the integration of the Boussinesqʼs displacement solutions, respectively. When the stiffness of the raft foundation is not ignored, we combine the solutions of the model with a numerical calculation method considering the interactions between soil and foundation to obtain the displacements of building. Two days of data from a engineering case are used to verify the rationality of the model. Results show that the computed displacements and the monitored displacements are in good agreement. The maximum and minimum deviations between the computed displacements and the monitored displacements are 22.3 % (monitored point S14) and 1.3 % (monitored point S5), respectively. Overall, the proposed model can be used to predict the displacements of inclined existing buildings with a raft foundation restored by compaction grouting in clay, as well as optimize the design of building rehabilitation work.