Abstract：In the existing researches of ground surface deformation caused by shield construction，soil is regarded as a linear elastic material and elastic theory is adopted to predict ground settlement，which may lead to inaccuracy. In this paper，the stability of upper soil under the loading-unloading condition during and after shield tunneling was analyzed by introducing the combined strength theory，and the triaxial consolidation undrained test was carried out by simulating the stress path of the soil during and after shield tunneling. Based on the stress-strain hyperbola relationship obtained from the test data，a formula of the nonlinear tangent elastic modulus of the upper soil under vertical loading and unloading conditions was derived and the parameters were determined. The results show that，under the same confining pressure or the same consolidation stress ratio，the strength of soil under loading path is greater than that under unloading path，and that，under the same confining pressure，the principal stress of soil at failure increases with increasing the consolidation stress ratio under axial loading or unloading. For predicting surface deformation，the axial strain data are used for the stress path method，and the nonlinear tangent modulus and test parameters of loading and unloading are adopted for the elastic theory method. Taking the Jiangnan shield section of Wuhan River-crossing Tunnel as an example，the predicted heave values calculated by the stress path method and the elasticity theory method differ by 4.2% and the difference between the predicted settlement values obtained by the two methods is 13.0%. It is also revealed that the predicted heave values differ the measurements by 7.5% and 10.7% respectively，and that the predicted settlement values are consistent with the measurements of the total settlement.
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WANG Zhongkai，XU Guangli. Prediction of ground deformation caused by shield tunneling based on#br#
triaxial test and joint strength theory. , 2019, 38(9): 1928-1936.
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2019, Vol. 38 
