竖井掘进机施工过程中侧壁围岩稳定性及破坏模式分析

Analysis of Stability and Failure Mode of Shaft′s Surrounding Rock during Excavation of Shaft Boring Machine

竖井掘进机(Shaft Boring Machine,以下简称SBM)在软弱破碎地层中掘进时,竖井侧壁围岩如果出现过大变形甚至失稳破坏,会导致推进反力不足而无法掘进,因此需要研究SBM掘进过程中侧壁围岩稳定性及其破坏模式。文章以国内研制的首台矿山型SBM为依托,对掘进过程中岩机相互作用进行了三维数值模拟。结果表明:竖井侧壁围岩早期破坏模式为压剪破坏,后期为剪切滑移破坏;随着掘进深度增加、竖井直径减小以及围岩等级提高,围岩破坏单元减少且承载力提高,其中围岩等级的影响最大。所得侧壁承载力与水平隧道侧壁承载力的对比表明了结论的合理性。研究结果对于评估软弱地层条件下SBM掘进过程中竖井侧壁围岩的稳定性有重要指导意义。

During shaft boring machine(SBM)tunnelling in weak and fractured strata,excessive deformation or failure of the underlaying surrounding rock of gripper may lead to insufficient support reaction.Therefore,it is necessary to study the deformation process,failure mode and ultimate bearing capacity of underlaying surrounding rock of gripper.On the basis of the first shaft boring machine of China,the interaction between gripper and surrounding rock is herein investigated.The results show that the failure mode of surrounding rock underlaying gripper is mainly shear-slip failure;the deeper the excavation,the smaller the diameter of shaft and the higher the grade of surrounding rock,the higher ultimate bearing capacity and less failure elements of surrounding rock.Comparing comprehensively,the influence of surrounding rock grade is the greatest.The ultimate bearing capacity obtained in this paper is compared with that of surrounding rock in horizontal TBM tunnel,and the results coincide fairly well.The results of this investigation are helpful to evaluate the stability of underlaying surrounding rock of shaft boring machine gripper under difficult ground conditions.