粘弹性软土中盾构隧道的长期沉降

LONG-TERM SURFACE SETTLEMENT OF SHIELD TUNNEL IN VISCO-ELASTIC SOFT SOIL

本文将列车荷载等效为矩形循环荷载,采用Merchant三元件模型模拟土体粘弹性,得到相应的粘弹性本构模型,并采用迭代递推方法考虑固结过程中土体渗透性的变化,得出了列车荷载作用下局部渗漏隧道的超孔压解析解,进而获得长期地表沉降解析解。通过预测地表沉降值与非线性固结解析解预测值和上海地铁实测沉降数据的对比,验证了上述解析解的合理性。分析结果表明:在长期沉降分析中,土体的粘弹性表现十分显著,同时列车荷载加剧了隧道的地表长期沉降;隧道衬砌渗漏程度与地表沉降增加量呈正相关。

Train loading was equivalent as rectangular cyclic load in the paper. Merchant model was adopted to simulate the viscoelasticity of soil, and corresponding viscoelastic constitutive model was obtained. The variety of the permeability of soil was considered by using the iterative recursive method. Analytical solution of the eess pore pressure of local leakage tunnel under train load was obtained, and the analytical solution of the long-term surface subsidence was further derived. The rationality of the a- bove-mentioned analytical solution was verified, by comparing in the predicted settlement of viscoelastic analytical solution and the non - linear consolidation analytic solution with the field measured settlement of Shanghai Metro. The results show that the viscoelastic behavior of the soil is very significant during the long-term deformation of soil, and the long-term surface subsidence of the tunnel is aggravated by the train load. The increase of the surface settlement is positively related to the seepage condition.