基于统一解的重叠盾构隧道施工土体变形研究

Research onthe soil deformation of overlapped shield tunneling based on unified solution

针对重叠盾构隧道施工引起土体变形问题,综合考虑了土体损失、开挖面附加推力、盾构机侧壁摩擦力和注浆压力4种因素引起的土体变形。对于掘进过程中土体损失引起的土体变形,修正了统一土体移动模型三维解,考虑了掘进过程中土质条件对纵向土体变形的影响,采用叠加法得到由于土体损失产生的重叠隧道施工土体变形计算公式;对于开挖面附加推力、盾构机侧壁摩擦力和注浆压力3种因素引起的土体变形,采用Mindlin解进行计算,并根据重叠隧道计算模型将上下线的计算公式进行叠加,得到考虑以上3种因素产生土体变形的计算公式;将公式进行组合,最终推导出重叠盾构隧道施工过程中多重因素共同作用下土体变形的计算公式。结合工程案例对该方法进行验证,对比发现:修正后的三维统一解适用的土质条件范围更广,且预测值更为吻合;考虑多种因素比仅考虑土体损失的预测结果更贴合实测值,证明了该方法的可行性。

For the soil deformation caused by shield construction of overlapping tunnels,the soil deformation due to soil loss,the additional thrust of the excavation face,the friction of the side wall of the shield machine and grouting pressure are considered comprehensively.First,to calculate the soil deformation due to soil loss,a three-dimensional solution of the unified soil movement model is modified so that it can consider the influence of soil conditions on the longitudinal soil deformation during the excavation process.The calculation formula of soil deformation of the overlapping tunnel caused by soil loss is obtained by the superposition method.Second,the Mindlin solution is used to calculate the soil deformation due to the additional thrust of the excavation face,the friction force of the side wall of the shield machine and grouting pressure.The calculation formulas of the upper and lower lines are superposed according to the computational model of overlapping tunnels and the calculation formula of soil deformation caused by the above three factors is obtained.Finally,by combining the above formulas,a calculation formula of soil deformation due to shield tunneling is obtained.By comparing this method with a practical engineering case,it is found that the modified three-dimensional unified solution has a wider range of soil conditions than those of the original formula and the predicted values are more consistent.The predicted results considering various factors are more consistent with the measured values compared with those considering only soil loss,which confirms the feasibility of this method.