基于盾构施工过程,利用弹性力学Mindlin解,通过坐标变换经积分推导刀盘与土体之间摩擦力所引起的地面变形计算公式,并得到盾构施工引起的总地面变形计算公式。结合杭州地铁一号线工程中具有代表性的粉砂土层,分析盾构与土体的复杂相互作用,并对盾构与土体相互作用引起的土体变形特征进行计算。通过计算发现,盾构施工中盾壳摩擦和正面推力是盾构推力设置的主要因素,而刀盘与土体摩擦是刀盘扭矩设置的主要因素,盾构前方土体隆起主要由盾壳摩擦引起,刀盘摩擦作用主要引起地表沉降的非对称分布,地表沉降主要由盾尾空隙产生。通过实例计算并与实测结果对比发现,使用盾构变形计算公式适用范围在盾构机头前后±2L距离处,对指导实际盾构施工具有重要意义。
Derived from Mindlin solution, the deformation formula induced by torque between cutterhead and soil is obtained by integration and coordinate transformation, which leads to the total deformation formula induced by shield tunneling. The deformation characteristics and complicated interactions between shield and soil are analyzed based on the Line No.1 of Hangzhou Metro with sandy silt. It is shown that the friction force and bulkhead thrust are the main factors of shield thrust setting, while the friction between the cutterhead and soil is the main factors of cutterhead torque setting. Friction force between shield and soil would make front soil of shield upheave, and subsidence of surface soil is induced by ground loss when the friction force between the cutterhead and soil results in the surface settlement asymmetrical distribution. Compared with the field measurements, the formula is suitable for the distance within the shield cutterhead(±2L), which can help guiding actual tunnel construction.