隧道前方溶洞对盾构机掘进影响分析

城市岩溶地质对盾构施工易造成盾构机陷落、故障,溶洞坍塌；针对盾构掘进前方隧道范围内溶洞对施工影响这一问题,依托大连地铁5号线后后区间工程,基于理论分析和MIDAS GTS数值模拟试验,以地表沉降、洞周变形、塑性区作为分析指标,选取溶洞尺寸、溶洞充填情况作为分析工况,盾构掘进至溶洞距离作为变量,结合溶洞预处理后与处理前对比分析。研究结果表明：不同溶洞尺寸和不同填充物对洞顶上方和地表竖向变形影响不大；当掘进施工靠近溶洞时,洞腰水平变形和靠近掘进面的临空面纵向变形呈现非线性增长且与溶洞大小相关；掘进面与溶洞之间塑性区贯通距离与溶洞大小呈近线性关系,理论计算结果与数值模拟结果较为一致；处理后的溶洞变形得到有效控制,数值模拟结果与实测数据接近。研究结果为岩溶识别处理和施工提供参考。

Analysis on The Impact of Front Karst Cave on Shield Tunneling

The urban karst geology is easy to cause the shield machine to fall and fault, and the cavern collapses. The problem of the influence of the karst cave on the tunnel in front of the shield tunneling depends on the Dalian Metro Line 5, based on theoretical analysis and MIDAS GTS numerical simulation test, with surface subsidence, deformation of the tunnel and plastic zone as the analysis index, the size of the cave and the filling of the cave were selected as the analysis conditions, and the distance from the tunneling to the cave was taken as a variable, contrast analysis after pretreatment with karst caves and before treatment. The results show that different cave sizes and different fillers have little effect on the top of the cave roof and the vertical deformation of the surface. When the tunneling is close to the cavern, the horizontal deformation of the tunnel waist and the longitudinal deformation of the temporary plane near the heading surface show a nonlinear growth. It is related to the size of the cave; the plastic zone penetration distance between the tunnel face and the cave is linear with the size of the cave. The theoretical calculation results are consistent with the numerical simulation results. The deformation of the cave after treatment is effectively controlled, and the numerical simulation results are close to the measured data. The research results provide reference for karst identification treatment and construction.