城市地铁穿越施工中无缝轨道与隧道结构相互作用规律研究

Interaction between track and tunnel lining affected by traversing excavation in urban subway is investigated, and a methodology is proposed to compute the deformation and internal forces of the seamless track caused by the deformation of bottom plate of the tunnel. The interaction between track and tunnel lining is summarized and classified into basic patterns of deformation. Taking into account axial tensile force and axial extension of the continuously welded track, control differential equations to describe the deformation of the track are derived out. Both analytical and numerical solutions for the differential equation are approached and compared. Analitical and numerical investigation on the rigidity of the ballastless track beds, both block sleeper track bed and floating slab track bed, are conducted. Equivalent track bed coefficients for the two monolithic track beds are determined. Finite element method is employed to simulate the deformation behavior of the track for different patterns of deformation. Typical subway tunnels will be selected in Beijing to do case studies, where the settlement of the track, track bed and tunnel lining will be measured. Knowledge coming out of numerical simulation and in-situ instrumentation will contribute in promoting the analytical model. This research will improve our understanding to the regulation of interaction between the track and the tunnel, and will also enhance the accuracy and applicability of the calculation method for the deformation of the track in urban subway.

对城市地铁穿越工程，研究轨道与隧道的相互作用，建立因隧道底板变形引起的无砟无缝轨道变形和内力的计算方法。具体研究内容包括：总结归纳轨道与隧道相互作用的变形型式。考虑轴向拉力和伸长，推导钢轨变形的控制微分方程。探求控制微分方程的解法，进行不同方法求解精度的比较。进行支承块式和浮置板无砟道床刚度的理论和数值分析，确定整体道床的等效道床系数。对盾构隧道和矿山法隧道，进行轨道与隧道的不同相互作用变形型式的数值模拟。在北京选择典型地铁工点，实地测量钢轨、道床和隧道底板变形。根据数值模拟和现场测量结果，对理论模型进行修改完善。项目研究的意义在于全面掌握轨道与隧道的相互作用规律，提高城市地铁穿越施工中轨道变形计算方法的准确性和适用性。

穿越施工引起既有地铁隧道结构变形，进而引起其上的轨道结构产生变形。钢轨变形值的大小决定着新建工程设计方案和施工方法的选择，也决定着既有线列车运营采取的安全保证措施。因此，迫切需要对隧道沉降条件下钢轨的变形和内力进行准确计算，做出科学的评估和判断，以保障地铁列车的运营安全。.研究了轨道与隧道间的相互作用和变形规律，建立了因隧道底板变形引起的无缝轨道变形和内力的计算方法。完成的具体研究内容包括：考虑轴向拉力和轴向伸缩，分连续梁及带接头梁，建立了控制微分方程。确定了钢轨下无砟道床的等效道床系数。对所建立的微分方程进行了傅里叶级数求解和差分法求解。分支承块式道床和钢弹簧浮置板道床，进行了轨道与隧道变形与脱空的数值计算。在北京地铁选择两个工点，完成了隧道沉降和钢轨沉降的现场监测。.得到的主要研究结论如下：.(1) 在隧道沉降槽宽度一定时，钢轨的沉降、脱空范围（如果产生的话）及内力均随隧道沉降量的增加而增大。.(2) 在扣件正常连接条件下，道床沉降槽半宽3m沉降值达到30mm时，钢轨与道床间将产生沉降差。.(3) 在扣件失效情况下，道床沉降槽半宽3m沉降值达到4mm时，钢轨与道床间将产生沉降差。.(4) 隧道底板沉降槽半宽3m沉降值达到12mm时，道床与隧道底板间将产生沉降差。.(5) 沉降槽半宽3m且道床沉降50mm可作为支承块与道床脱空产生的条件。沉降槽半宽3m且隧道底板沉降15mm可作为道床与隧道底板脱空产生的条件。.(6) 在接头处，由于刚度有突变，导致钢轨在该处产生弯折。在一定长度内钢轨接头越多，钢轨的柔性越强，其变形越趋近于底板变形。.(7) 差分解在级数解的基础上进一步考虑了轴力的非均匀性，所得结果介于线性解(未考虑轴力)与级数解(考虑轴力)之间。.(8) 理论计算结果、数值模拟结果及现场监测结果，具有很好的一致性。.通过项目研究更全面地掌握了轨道与隧道的相互作用规律，提高了轨道变形计算方法的准确性和适用性。