Experimental Study on the Uplift Correction of Raft Foundations in Saturated Silty Clay

Although grouting technology has been widely applied for lifting and rectifying tilted structures, theoretical research remains underdeveloped and lags behind the practical demands of engineering applications. In this study, a self-developed experimental setup was utilized to conduct model tests on the lifting and rectification of a raft foundation in saturated silty clay. The evolution patterns of ground surface displacement, excess pore water pressure, and foundation-additional pressure induced by grouting were systematically analyzed. Furthermore, the influence of grouting depth and injection rate on surface displacement, excess pore water pressure, foundation-additional pressure, and grouting parameters (grout volume and pressure) was investigated. The key findings are summarized as follows: The grouting efficiency (η) ranged between 0.72 and 0.81. A power-exponential dual-function model was proposed to quantify the spatiotemporal evolution of excess pore water pressure, achieving a distance–decay power function with R2 > 0.89 and a time-dependent dissipation exponential function with R2 > 0.94. The maximum surface uplift displacement decreased by 20.6% and 8.9% with increasing grouting rates, respectively. The dissipation time of excess pore water pressure exhibited a negative correlation with the grouting rate, and grouting efficiency declined as excess pore water pressure dissipated. The maximum foundation-additional pressure occurred directly above the grouting center and gradually diminished as the horizontal distance from the grouting location increased. Variations in surface displacement, excess pore water pressure, and additional base pressure induced by grouting were systematically analyzed.