Simulation of excess pore water pressure during deep soil mixing columns installing

Most of current studies of deep soil mixing (DSM) methods are focused on the soil strength improvement and soil treatment effectiveness. But the DSM installation leads to excess pore water pressure and soil disturbance, which will bring great harm to adjacent structures, such as shell tunnels and historic buildings. The procedure of excess pore water pressure buildup while large number DSM columns are installed is complicated. In order to find methods to predict and simulate the excess pore water pressure during DSM column installation, the complicated dissipation and buildup of excess pore water pressure through in-situ test are studied in this paper. In-situ test was conducted in soft clay near the Huangpu River in Shanghai. The pore water pressure was investigated by an automatic monitoring system. Test results indicate that the excess pore water pressure induced by one DSM column installation is composed of the compaction pressure and the reversing pressure. The empirical equations of excess pore water pressure dissipation and buildup were built by mathematical fitting methods. A compound method is proposed to simulate the excess pore water pressure due to DSM installation. Using this method to predict the excess pore water pressure in the situ test, results show a well agreement between the prediction and the measurements.