Using a self-developed micro shield machine, a laboratory-scale experimental scheme for shield tunnelling and supporting was designed, and the soil displacement law and earth pressure on the segments during tunnel construction were studied. Based on a nonlinear elastic constitutive model describing the characteristics of loess, the UMAT subroutine was redeveloped and verified by conventional triaxial tests. It was then applied to the numerical simulation of shield tunnelling and supporting. The following are the findings: 1) The disturbance modes of surrounding rock directly above the shield tunnel under different boundaries are similar. The main disturbances occur approximately 4 m above the shield tunnel, extending to a distance of one segment outer diameter on either side of the tunnel's central axis. 2) The pressures on the top and bottom of the segments can be divided into rapid increase, slow increase, and stable fluctuation. These stages correspond to the processes of the segments getting out of the shield shell and the soil collapsing. 3) The largest surrounding rock pressure is at the vault, followed by that at the arch bottom, and the smallest is at both sides of the arch waist, which is consistent with the law obtained based on laboratory-scale model tests. The surrounding rock pressure values of the vault in the numerical simulation are consistent with the laboratory-scale model test results. These verify the reliability of the laboratory-scale model test and the UMAT subroutine based on the nonlinear elastic constitutive model of loess in simulating the shield tunnel construction in loess strata.

中文翻译：

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低含水黄土盾构掘进及支护围岩位移与压力


利用自主研发的微型盾构机，设计了盾构掘进及支护实验室规模试验方案，研究了隧道施工过程中土体位移规律和管片土压力。基于描述黄土特性的非线性弹性本构模型，重新开发了UMAT子程序，并通过常规三轴试验进行了验证。随后将其应用于盾构掘进及支护数值模拟。研究结果如下： 1）不同边界条件下盾构隧道正上方围岩扰动模式相似。主要扰动发生在盾构隧道上方约4 m处，延伸至隧道中轴线两侧一个管段外径的距离。 2）分段顶部和底部的压力可分为快速增加、缓慢增加和稳定波动。这些阶段对应于盾片脱离盾壳和土壤塌陷的过程。 3）拱顶围岩压力最大，拱底次之，拱腰两侧最小，这与室内模型试验得出的规律一致。数值模拟中拱顶围岩压力值与室内模型试验结果一致。验证了实验室模型试验和基于黄土非线性弹性本构模型的UMAT子程序模拟黄土地层盾构隧道施工的可靠性。