Research methods: In combination with the engineering practice of reinforcing the foundation of deep foundation pits of Yanjizhong Road and Huangxin Road stations in Bidding III on M8 Line of Shanghai subway, the research was made on two techniques of grouting and deep-seated mixture pile to reinforce weak strata through scheme design, site experiment, monitoring, survey, comparison and analysis.
Research results: Two-shot grouting was adopted to reinforce foundation in silt clay. The result of it was of crack with slurry distributing in layer and moving irregularly underground. The formed reinforced-body was not even with bad uniformity and the reinforced area had not distinctly restraint effect on the deformation of diaphragm of foundation pit. Cement mixture pile was adopted to reinforce foundation with good result of controllable working site, even cement-soil and effective restraining the deformation of foundation pit.
Research conclusions: The technique and result of two-shot grouting were not good as that of cement mixture pile, but it had features of simple operation and low cost. The technique of two-shot grouting would be improved, such as changing grouting from primary grouting into secondary grouting, increasing grouting pressure of secondary grouting and improving uniformity of reinforced soil mass.
2006, Vol. 23 
