基于流固耦合理论下不同开挖方式的位移影响分析——以阿嘎下隧道为例

Displacement Influence Analysis of Different Excavation Methods Based on the Fluid-solid Coupling Theory:A Case Study of Agaxia Tunnel

针对富水区阿嘎下隧道穿越断裂活动带的工程地质和施工特点,采用有限元midas GTS NX,建立基于不同开挖方式下的阿嘎下隧道模型。对比考虑流固耦合作用下的围岩位移,研究表明:对于3种开挖方式,当开挖间距不变时,随着注浆圈从0.1d增至0.5d(d为隧道净宽),地表沉降量减小;当注浆圈不变时,随着开挖间距从1d增至5d,地表沉降量减小。考虑渗流作用对围岩地表沉降的影响,建议类似阿嘎下隧道工程采用环形开挖预留核心土法,开挖间距为3d、注浆圈为0.3d较合适;对比不同开挖方式下0.3d注浆圈和3d~4d开挖间距导致的沉降量,结果表明CRD开挖法引起的地表沉降量最小,环形开挖预留核心土法沉降量最大。

According to the engineering geology and construction characteristics of Agaxia tunnel which cuts cross fault active zone in water rich area,the finite element method called midas GTS NX is adopted to establish the model of Agaxia tunnel based on different excavation methods.Based on the comparison of the surrounding rock displacement under the fluid-solid interaction,the research shows,when the excavation spacing is constant,the surface settlement decreases with the grouting circle increasing from 0.1d to 0.5d for the three excavation methods.When the grouting circle is constant,the surface settlement decreases with the excavation spacing increasing from 1d to 5d.Considering the effect of seepage on the surrounding rock surface settlement,it is suggested to adopt the circular excavation with reserving core soil method,similar to the Agaxia tunnel project,in which the excavation spacing is 3d and the grouting circle is 0.3d.Comparing the settlement caused by 0.3d grouting circle and 3d-4d excavation spacing under different excavation methods,the results show that the surface settlement caused by CRD excavation method is the smallest,and the settlement caused by circular excavation with reserving core soil method is the largest.