顶管施工引起地面变形的计算方法研究

STUDY ON CALCULATION METHODS OF GROUND DEFORMATION INDUCED BY PIPE JACKING CONSTRUCTION

假定土体不排水固结,利用弹性力学的Mindlin解,推导了顶管正面附加推力、掘进机和后续管道与土体之间的摩擦力引起的地面变形计算公式,结合土体损失引起的地面变形计算公式,得到顶管施工引起的总的地面变形计算公式,该方法适用于施工阶段。算例分析表明,顶管施工引起地面产生三维变形,随着掘进机的顶进而不断产生变化。正面附加推力引起开挖面前方地面隆起,后方地面沉降,以开挖面正上方为轴线呈反对称分布,在正常施工时产生的地面变形较小;掘进机与土体之间的摩擦力引起的地面变形较大,分布规律与正面附加推力相似,轴线位于掘进机中间部位正上方。后续管道与土体之间的摩擦力引起的地面变形分布规律与正面附加推力相似,轴线位于后续管道中间部位正上方,注浆时引起的地面变形较小。

By assuming that soil is not drained, the computing formulas of ground deformation induced by bulkhead additive thrust, force of friction between shield and soil, and force of friction between follow-up pipes and soil are derived from the Mindlin solution in elastic mechanics. Combining the formulas of ground deformation induced by ground loss, the formula of total ground deformation induced by pipe jacking construction is obtained. This method is applied to the construction phase. As is shown in analytical calculation, ground deformation induced by pipe jacking construction is three-dimensional and changing with the jacking-in of shield. Bulkhead additive thrust will make the frontal soil of excavation face heave and the rear soil subside. Surface deformation induced by bulkhead additive thrust is small during normal construction, and the curves are asymmetry with axes of excavation face. The surface deformation induced by force of friction between shield and soil is great. Its distribution curve is similar to that of bulkhead additive thrust with the axes at the middle of shield. The surface deformation induced by force of friction between follow-up pipes and soil is small during injecting slurry. Its distribution curve is similar to that of bulkhead additive thrust with the axes at the middle of follow-up pipes.