Abstract: In the light of the actual condition of Shanghai very soft water saturated ground and the remedial maintenance of metro tunnel, slight soil disturbance grouting disposal method, which is the renewal of fracture grouting, was performed to treat unequal settlement of Shanghai metro tunnel with relatively simple equipment and easy handling which are suited to local condition of Shanghai. The method was carried out in operated tunnel by use of the accumulative times of nightly stopping of subway operation. The choice of grout technology, grout equipment and grout construction parameters were described. Through the engineering example, this paper detailed the design and construction of this grouting program as well as the result of practice. The results indicate that this method can treat unequal settlement of Shanghai metro tunnel by minimizing soil disturbance induced by grout injection and achieve good compensation effect of ground settlement.

Key words: soft ground, metro tunnel, unequal settlement, grouting disposal