盾构接收掘进中有限土体划分及土仓压力设定研究

Study on Finite Soil Boundary and Pressure Setting of Soil Chamber in Shield Tunneling

盾构无障碍接收过程中,土仓压力对地表沉降和围护结构变形的影响均较为明显,对于这一阶段土仓压力的设定,目前的理论研究较少。针对这一问题,以库伦土压力理论和有限土压力理论为基础,建立开挖面前方有限土体的计算模型,根据土体滑裂面倾角分析,确定从半无限土体到有限土体的分界位置;通过对有限土体极限平衡状态的分析,得到接收阶段土仓压力设定的理论公式,并与数值模拟和工程监测数据相比较。结果表明:根据有限土体滑裂面位置判断有限土体分界位置的方法是可靠的;在接收掘进阶段,土仓压力设定可利用实时的有限土体模型计算,计算结果与实际工程状态相符,且对于地表沉降和围护结构变形的控制均较为良好。

During the barrier-free receiving of the shield,the influence of soil chamber pressure on the surface settlement and the deformation of enclosure structure is relatively obvious,and there are few theoretical studies on the setting of soil chamber pressure at this stage.In view of this problem,this paper establishes the calculation model of the finite earth in front of the excavation face based on the coulomb earth pressure theory and finite earth pressure theory,and determines the boundary position from semi-infinite soil to finite soil according to the analysis of the angle of shear failure in finite soil.At the same time,through the analysis of the limit equilibrium state of the finite soil,the theoretical formula of the pressure setting in the acceptance stage is obtained and compared with the numerical simulation and engineering monitoring data.The results show that it is reliable to judge the boundary of finite soil according to the location of shear failure surface;in the receiving excavation stage,the finite soil model can be used to calculate the pressure setting of the soil chamber;the calculated results are consistent with the actual engineering state,and the control effect of surface settlement and envelope deformation is good.