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Abstract The boundary element method with displacement controlled pattern is presented to analyze the response of shield tunnelling-induced undrained layered soil deformation. The elastic layered half space soil model is combined with the method to consider the soil nonhomogeneous characters，whereas solutions only existed in homogeneous soils by the simplified method before. The oval-shaped ground deformation pattern is imposed to the tunnel opening boundary；and the boundary integral equations are established for the opening boundary value problems of multilayered soils. Then the low-order constant elements in the boundary discrete equations are replaced by the high-order isoparametric elements；and the fundamental solutions for multilayered soils are coupled with the boundary element method，whereas Kelvin and Mindlin solutions based on homogeneous materials are chosen previously. Finally the undrained soil displacements on the condition of given opening boundary displacements are obtained. It is shown that the method can solve the problems subjected to homogeneous soils as well as nonhomogeneous soils. The results indicate that as for the layered soils where the differences of elastic parameters among successive layers are large；the error is not negligible，which is obtained employing average elastic modulus and average Poisson¢s ratio based on homogeneous soils converted from layered soils. It may provide certain basis to draw up correctly protective measurements of environmental effects influenced by adjacent shield tunnelling.
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Received: 19 May 2009
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