Abstract:

It is assumed that the grouting pressure at shield tail was uniformly distributed in existing researches of ground surface heave induced by grouting pressure at shield tail, which is not consistent with the actual situation. In order to precisely predict the ground surface heave, the computational formula of ground surface heave induced by grouting pressure at shield tail is deduced by image method and Mindlin Solutions based on analysis of ground surface heave induced by uniform grouting pressure. In the formula, the actual distribution of grouting pressure (upper small and lower large) is taken into consideration, and the effect of grouting pressure at shield tail on the surrounding soils is simplified as an expansion process of cylindrical hole in semiinfinite elastic solid. And then, the solution deduced, Yefei Solution, Lincungang Solution, Vesic Solution and numerical solution are taken into comparison through case study. The results show that: 1) The curve of the transversal ground surface heave induced by grouting pressure at shield tail shows Gaussian distribution. It is irrational to ignore the ground surface heave induced by grouting pressure at shield tail in prediction of ground settlement. 2) The abovementioned formula is available in predicting the ground surface heave induced by grouting pressure at shield tail; and Vesic Solution and Lincungang Solution need to be modified according to actual project.

Key words: soft ground, shield method, synchronous grouting, grouting pressure at shield tail, ground surface heave