Abstract Due to the fluctuation of strata boundaries and a wide variation of parameters for strata passed through by a shield tunnel, the accuracy of load calculations is affected by the selection of calculation parameters. Based on Terzaghi′s soil relaxation pressure formula, the vault load calculation method for a shield tunnel in fluctuating strata was studied. Correction methods for vault load calculations were determined by considering the conditions of horizontal and tilted strata. Regarding the boundary in a horizontal stratum, a method for sliding surface width value selection is given by analyzing the proportion of the upper strata in a tunnel section. Regarding the boundary in a tilted stratum, the sliding surface widths of the left and right sides of the shield tunnel were analyzed and value selection is given based on the experience with the horizontal stratum. A field test of the lateral earth pressure was conducted aiming at a shield tunnel with a diameter of 6 m in fluctuated strata, and the results are compared with those obtained by the classical theoretical formula; the two sets of results agree very well.
Abstract：
Due to the fluctuation of strata boundaries and a wide variation of parameters for strata passed through by a shield tunnel, the accuracy of load calculations is affected by the selection of calculation parameters. Based on Terzaghi′s soil relaxation pressure formula, the vault load calculation method for a shield tunnel in fluctuating strata was studied. Correction methods for vault load calculations were determined by considering the conditions of horizontal and tilted strata. Regarding the boundary in a horizontal stratum, a method for sliding surface width value selection is given by analyzing the proportion of the upper strata in a tunnel section. Regarding the boundary in a tilted stratum, the sliding surface widths of the left and right sides of the shield tunnel were analyzed and value selection is given based on the experience with the horizontal stratum. A field test of the lateral earth pressure was conducted aiming at a shield tunnel with a diameter of 6 m in fluctuated strata, and the results are compared with those obtained by the classical theoretical formula; the two sets of results agree very well.
2017, Vol. 54 