考虑盾构隧道埋深影响和岩土特性影响的地表变形计算

盾构施工引起地层变形的众多计算方法中,随机介质理论法和Peck法是我国应用较为广泛的两种实用方法,但这两种方法的计算参数均不太容易确定。根据46例工程实测资料,绘制出地表最大沉降与隧道相对埋深的关系图。结果表明:当盾构隧道相对埋深小于5时,盾构施工引起的地表最大沉降值变化较大;当盾构隧道相对埋深大于5时,其对地表最大沉降的影响较小。对于大部分浅埋城市地铁隧道而言,应该考虑盾构隧道相对埋深对地层变形的影响。基于盾构施工引起地层移动不均匀模型的地表最大沉降计算式,依据随机介质理论法和Peck法,推导出考虑土质软硬、隧道半径和埋深影响的地层变形实用计算方法,并通过对5个工程实例的分析,验证此计算方法的合理性。

CALCULATION METHOD OF GROUND SURFACE DEFORMATION CONSIDERING INFLUENCES OF SHIELD TUNNEL DEPTH AND ROCK-SOIL CHARACTERISTICS

Peck method and Stochastic Medium Model(SMM) were widely used for predicting ground movement induced by shield tunneling in China.But it is difficult to determine the parameters of this two methods.So the relation between tunnel relative depth and maximum surface settlement was plotted according to 46 measured engineering cases.It shows that ground settlements induced by shield tunneling change greatly when tunnel relative depths are less than 5;influence of tunnel relative depth is little when it is greater than 5.Based on the maximum surface settlement calculating formula of soil non-uniform convergence model,and according to Peck and SMM method,an applied calculation method was deduced,which considered the influence of all different soil conditions,tunnel radius and depth,whose rationality was validated by the analysis of 5 engineering cases.