软土中盾构隧道的长期非线性固结变形研究
发布时间：2018-07-28 17:49
【摘要】：目前对软土盾构隧道的研究主要集中于开挖造成的短期地表及隧道沉降、施工扰动,及盾构开挖对隧道支护内力的影响。然而对已建成地铁盾构隧道的现场监测表明：软土地铁盾构隧道的长期沉降量很大,达到沉降稳定状态所需的时间亦十分漫长,且沉降在隧道纵向呈现出很大的不均匀性。地铁隧道长期沉降的影响因素十分复杂,其中初始超孔隙水压力分布、隧道衬砌和周边土体的相对渗透性等对地铁长期沉降造成的影响尤为显著。对于埋置于深厚软土地区的地铁隧道而言,列车荷载的长期作用会引起隧道周边饱和软土应力、应变和孔隙水压力变化,导致土的刚度降低、强度衰减、变形加剧。本文采用解析方法,结合已有工程实测数据,对渗漏隧道周边土体长期非线性固结过程中稳定渗流状态、超孔隙水压力消散、地表沉降等问题展开研究,主要创新工作如下： 1.采用经典的e-lgσ'和e-lg k经验公式模拟土体非线性固结过程中体积压缩性和渗透性的变化,根据土体自由应变和连续性条件得到了土体非线性固结控制方程。 2.将隧道衬砌透水条件理想化为完全透水及完全不透水极端边界条件,从而得到了隧道作为一个排水边界时,对土体非线性固结过程中超孔压消散、固结度增长、地面沉降发展影响的上下限。并进一步采用Li(1999)提出的半渗透边界条件将存在局部渗漏通道的隧道衬砌等效为均质透水体,建立局部渗漏边界条件,求解隧道周边土体的非线性固结本构方程,得出了不同程度的衬砌局部渗漏条件下的隧道周边软土非线性固结解析解。进而对衬砌不同程度渗漏对隧道周边土体长期固结、超孔隙水压力压力消散、长期沉降的影响进行了分析。 3.通过将列车荷载等效为矩形循环荷载,求得了列车荷载作用下理想化渗漏隧道周边土体非线性固结解析解。通过等效矩形循环荷载参数的调整,分析了列车荷载对土体固结、地表沉降的影响规律,以及列车荷载与衬砌渗漏情况的耦合作用。 4.采用Merchant三元件模型模拟土体长期变形的粘弹性,建立隧道周边土体粘弹性流变固结控制方程,并引入e-lg k关系考虑土体渗透性在固结过程中的非线性变化,并采用迭代递推的办法获得了列车荷载作用下局部渗漏隧道周边土体的长期沉降解析解。 5.以上海地铁1号线和2号线为工程背景,通过本文得到的解析解预测值和上海地铁三个测点实测沉降数据的对比验证了本文非线性固结解析解以及粘弹性流变固结解析解的合理性。
[Abstract]:At present, the research on soft soil shield tunnel is mainly focused on the short-term ground surface and tunnel settlement caused by excavation, construction disturbance, and the influence of shield excavation on the internal force of tunnel support. However, the site monitoring of the completed metro shield tunnel shows that the long-term settlement of the soft soil and iron shield tunnel is very large, and the time required to reach the stable state of settlement is also very long, and the settlement presents a great inhomogeneity in the longitudinal direction of the tunnel. The factors affecting the long-term settlement of subway tunnel are very complex, especially the initial excess pore water pressure distribution, the relative permeability of tunnel lining and surrounding soil, etc. For the subway tunnel buried in the deep soft soil area, the long-term action of train load will cause the change of saturated soft soil stress, strain and pore water pressure around the tunnel, resulting in the decrease of soil stiffness, strength attenuation and increase of deformation. In this paper, the analytical method is used to study the steady seepage state, excess pore water pressure dissipation and surface subsidence during the long-term nonlinear consolidation of soil around the seepage tunnel. The main innovation work is as follows: 1. The classical e-lg 蟽 'and e-lg k empirical formulas are used to simulate the change of volume compressibility and permeability in the process of nonlinear soil consolidation. According to the free strain and continuity condition of soil, the governing equation of soil nonlinear consolidation is obtained. 2. The condition of tunnel lining permeation is idealized as the extreme boundary condition of complete permeability and complete impermeability. Thus, when the tunnel is a drainage boundary, the superpore pressure dissipates and the degree of consolidation increases during the nonlinear consolidation of soil. The upper and lower limits of the influence of land subsidence development. Furthermore, the semi-permeable boundary condition proposed by Li (1999) is used to equate the tunnel lining with local leakage channel to homogeneous water body. The local seepage boundary condition is established and the nonlinear consolidation constitutive equation of the surrounding soil is solved. The nonlinear consolidation analytical solution of soft soil around the tunnel is obtained under the condition of different degree of partial leakage of lining. Furthermore, the effects of lining leakage on long-term consolidation, excess pore water pressure dissipation and long-term settlement around the tunnel are analyzed. By equivalent the train load to the rectangular cyclic load, the nonlinear consolidation analytical solution of the soil around the idealized seepage tunnel under the train load is obtained. Through the adjustment of equivalent rectangular cyclic load parameters, the influence of train load on soil consolidation, surface settlement and coupling action between train load and lining leakage is analyzed. The Merchant three-element model is used to simulate the viscoelasticity of soil mass during long-term deformation, and the governing equation of viscoelastic rheological consolidation of soil around the tunnel is established. The e-lg k relation is introduced to consider the nonlinear change of soil permeability during the consolidation process. An iterative recursive method is used to obtain the long-term settlement analytical solution of the soil around the local seepage tunnel under the train load. Based on the engineering background of Shanghai Metro Line 1 and Line 2, The comparison between the predicted values of the analytical solution obtained in this paper and the measured settlement data at three points of the Shanghai Metro proves the rationality of the analytical solution of nonlinear consolidation and the analytical solution of viscoelastic rheological consolidation in this paper.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U455.43;U452.1
本文编号：2151128
[Abstract]:At present, the research on soft soil shield tunnel is mainly focused on the short-term ground surface and tunnel settlement caused by excavation, construction disturbance, and the influence of shield excavation on the internal force of tunnel support. However, the site monitoring of the completed metro shield tunnel shows that the long-term settlement of the soft soil and iron shield tunnel is very large, and the time required to reach the stable state of settlement is also very long, and the settlement presents a great inhomogeneity in the longitudinal direction of the tunnel. The factors affecting the long-term settlement of subway tunnel are very complex, especially the initial excess pore water pressure distribution, the relative permeability of tunnel lining and surrounding soil, etc. For the subway tunnel buried in the deep soft soil area, the long-term action of train load will cause the change of saturated soft soil stress, strain and pore water pressure around the tunnel, resulting in the decrease of soil stiffness, strength attenuation and increase of deformation. In this paper, the analytical method is used to study the steady seepage state, excess pore water pressure dissipation and surface subsidence during the long-term nonlinear consolidation of soil around the seepage tunnel. The main innovation work is as follows: 1. The classical e-lg 蟽 'and e-lg k empirical formulas are used to simulate the change of volume compressibility and permeability in the process of nonlinear soil consolidation. According to the free strain and continuity condition of soil, the governing equation of soil nonlinear consolidation is obtained. 2. The condition of tunnel lining permeation is idealized as the extreme boundary condition of complete permeability and complete impermeability. Thus, when the tunnel is a drainage boundary, the superpore pressure dissipates and the degree of consolidation increases during the nonlinear consolidation of soil. The upper and lower limits of the influence of land subsidence development. Furthermore, the semi-permeable boundary condition proposed by Li (1999) is used to equate the tunnel lining with local leakage channel to homogeneous water body. The local seepage boundary condition is established and the nonlinear consolidation constitutive equation of the surrounding soil is solved. The nonlinear consolidation analytical solution of soft soil around the tunnel is obtained under the condition of different degree of partial leakage of lining. Furthermore, the effects of lining leakage on long-term consolidation, excess pore water pressure dissipation and long-term settlement around the tunnel are analyzed. By equivalent the train load to the rectangular cyclic load, the nonlinear consolidation analytical solution of the soil around the idealized seepage tunnel under the train load is obtained. Through the adjustment of equivalent rectangular cyclic load parameters, the influence of train load on soil consolidation, surface settlement and coupling action between train load and lining leakage is analyzed. The Merchant three-element model is used to simulate the viscoelasticity of soil mass during long-term deformation, and the governing equation of viscoelastic rheological consolidation of soil around the tunnel is established. The e-lg k relation is introduced to consider the nonlinear change of soil permeability during the consolidation process. An iterative recursive method is used to obtain the long-term settlement analytical solution of the soil around the local seepage tunnel under the train load. Based on the engineering background of Shanghai Metro Line 1 and Line 2, The comparison between the predicted values of the analytical solution obtained in this paper and the measured settlement data at three points of the Shanghai Metro proves the rationality of the analytical solution of nonlinear consolidation and the analytical solution of viscoelastic rheological consolidation in this paper.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U455.43;U452.1
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