土岩复合地层地铁区间隧道施工力学特性分析

Analysis of Construction Mechanics Characteristics of Subway Tunnels in Soil-rock Composite Stratum

浅埋地铁隧道复杂地层下穿施工难度大,失稳和地陷事故屡有发生。以贵阳某区间隧道为例,采用理论分析和FLAC3D数值模手段,对该浅埋隧道复合地层段的施工应力、位移、塑性区分布规律进行分析,据此提出降低风险的针对性超前加固方案。结果表明:地表沉降在洞口位置最影响显著,其它断面的沉降随着掌子面推进而逐渐减小;针对红黏土特殊地质,采用钢插板辅助注浆加固,可有效防止浆土混合体从缝隙流失,注浆效果改善显著。

The geology of the subway tunnel in the upper soft and the lower hard formation is complicated,and the construction is difficult,and the surrounding rock instability and surface settlement are prone to occur during the construction.In order to solve this engineering problem,taking a section of Guiyang tunnel as an example,the numerical software FLAC3D is used to analyze the construction mechanics characteristics and the vault settlement law of the subway tunnel passing through the upper soft and lower hard strata,and then proposes for the soil in front of the tunnel.Reinforcement scheme.The research shows that the analysis shows that the surface settlement at the entrance of the cave has a significant impact,while the settlement change of the remaining sections gradually decreases with the increase of the excavation distance;in order to prevent the slurry-soil mixture from losing from the gap between the leading small pipes,When the red clay in front of the face is reinforced by grouting,the steel insert plate is used to assist the reinforcement,and the grouting effect is obviously improved.