考虑刀盘摩阻因素的盾构施工引起地层横向位移分析

为了全面和准确地计算盾构施工引起的地层横向总位移值，依据弹性力学Mindlin解，在已有研究的基础上，增加考虑面板式及辐条式刀盘的摩擦力对地层横向位移的影响，给出刀盘的简化计算模型，通过坐标转化和积分的方法分别推导2种结构形式刀盘正面及圆周面摩擦力产生的地层横向位移计算公式，并采用位移叠加的方法，给出盾构施工引起地层横向总位移计算公式，并对已有工程算例计算和分析，将结果与实测值对比。结果表明：计算结果可以反映盾构施工阶段地层横向变形的特点；在盾尾附近的一定范围内，同步注浆压力和盾壳摩擦力对地层横向位移的影响程度较大，为主要影响因素；在刀盘附近的一定范围内，盾壳摩擦力，刀盘圆周面环向摩擦力和刀盘正面摩擦力对地层横向位移的影响程度不可忽略；各因素产生的地层横向位移值随着深度的增加而衰减并向深层土体逐渐扩散；地层横向位移值受刀盘不同结构形式的影响程度较小，分布规律相仿；在刀盘推进面周围的一定范围内，地层横向总位移值正负区域的分布与刀盘的旋转方向有关。

Analysis of Lateral Displacement of Stratum Caused by Shield Tunneling Considering Friction Resistance of Cutter Head

In order to fully and accurately calculate the total lateral stratum displacement due to shield tunneling based on Mindlin's solution to elasticity and the existing research, the impact of friction force of panel-type and spoke-type cutter head on the lateral stratum displacement was additionally considered to yield a simplified cutter head computing model. Coordinate transformation and integration methods were used to deduce the computing formula for the lateral stratum displacement generated by friction force at the front and circumferential faces of the two types of cutter head. Moreover, a displacement overlapping method was used to obtain the computing formula for the total lateral stratum displacement due to shield tunneling. Computing and analysis and comparison to measured values were conducted on existing engineering examples. The computing results reflect the characteristics of the lateral stratum deformation during shield tunneling. The synchronous grouting pressure and shield friction are the major factors that affect the lateral stratum displacement significantly within certain area of the shield tail. However, within a certain area close to the cutter head, the lateral stratum displacement is affected by the shield friction; the circumferential friction at the circumferential face and the friction at the front face of the cutter head cannot be ignored.The lateral stratum displacement caused by these major factors reduces as the depth increases and gradually spreads to the deeper soil mass. The lateral stratum displacement is less affected by the cutter head with different structures and is distributed in similar rules. Within a certain area surrounding the driving face of the cutter head, the distribution of positive and negative areas of the total lateral stratum displacement is correlated to the rotation direction of the cutter head.