水封洞库施工过程稳定性评价及断层影响分析

Stability evaluation and faults influence analysis of water-sealed caverns during construction

为研究多个断层与地下洞群相交情况下的围岩稳定性,基于Hoek-Brown修正后的岩体物理力学参数,采用FLAC^(3D)软件中的莫尔-库仑模型作为本构模型,对某地下水封洞库项目的围岩稳定性进行研究。研究结果表明:随着开挖阶段的推进,主洞室侧墙位移逐渐增大;在全断面开挖后,主洞室侧墙位移普遍大于拱顶和底板位移,大部分洞室的侧墙以及部分洞室的底板和拱顶出现应力集中现象和塑性区;当断层靠近主洞室但未与其相交时,洞室和断层之间形成不稳定岩体区域,该区域的岩体会向洞室内部滑动,并会产生较大的位移;当断层与主洞室相交时,不稳定岩体区域消失,此时位移形式与无断层时类似,断层会引发围岩应力的释放,并会使附近围岩出现较为严重的塑性变形。在地下水封洞库施工过程中,需要重点监测直接穿越断层位置及其前后位置。

The stability of surrounding rock within an underground water-sealed cavern project was investigated to examine the stability of surrounding rock under the intersection of multiple faults and underground caverns.The Hoek-Brown modified rock mass physical-mechanical parameters were utilized,and the Mohr-Coulomb model in the FLAC^(3D)software was employed as a constitutive model.The results showed that the sidewall displacement of the main chamber gradually increased with the progress of the excavation stage.After the entire section was completely excavated,the lateral displacement of the primary cavern′s sidewall generally surpassed that of both its vault and bottom plate.Stress concentration and plastic deformation were observed in the sidewalls of most caverns,as well as in the top sections of select caverns.In caverns adjacent to,but not intersecting with faults,unstable rock mass areas were formed between the cavern and the fault,where the rock mass tended to slide into the cavern,resulting in significant displacement.In caverns directly intersecting with faults,the unstable rock mass areas disappeared and a similar displacement pattern was observed as that without faults.Stress release in the surrounding rock was induced by the fault and significant plastic deformation of adjacent rock near the cavern was resulted.In the construction process of an underground water-sealed cavern,the position of the direct fault crossing needs to be monitored,and attention should be paid to its anterior and posterior positions.