中隔壁法隧道围岩位移-参数相关性数值模拟分析

Numerical simulation analysis of surrounding rock displacement-parameter correlation in center diaphragm constructed tunnel

基于位移的隧道围岩参数反演分析是一种非常有效的确定围岩参数取值的方法。隧道围岩的位移与围岩物理力学参数的相关性对于围岩参数反演分析具有非常重要的意义。以某中隔壁法隧道为研究对象,基于现场监测数据和有限元数值模拟分析,研究围岩位移的时空分布特征;基于数值模拟分析,设计5因素8水平的正交试验,统计隧道围岩位移的概率分布特征,明确隧道围岩位移和参数的线性相关性;设计控制单一变量法敏感性分析试验,确定围岩位移对物理力学参数的敏感性。研究结果表明:1)随着时间的推移,中隔壁法隧道的拱顶沉降和水平收敛位移经历快速发展、发展变缓和趋于稳定3个阶段;等效塑性应变、等效平均应变、等效平均应力、水平位移和竖向位移等指标的极大值主要发生在隧道的拱顶和拱腰两侧;2)隧道围岩的拱顶沉降和水平收敛呈现明显的正态分布特征;3)弹性模量与拱顶沉降和水平收敛有明显的线性负相关性;泊松比与拱顶沉降线性负相关,与水平收敛线性正相关;容重、内摩擦角和黏聚力与围岩位移的相关性较弱;4)拱顶沉降对弹性模量非常敏感,对泊松比和容重比较敏感,对内摩擦角和黏聚力不敏感;水平收敛对泊松比和弹性模量非常敏感,对容重比较敏感,对内摩擦角和黏聚力不敏感。研究成果揭示了中隔壁法隧道的位移时空演化特征,验证了常规位移监测方法的正确性;揭示了围岩位移的概率分布特征和位移-参数相关性特征,明确了基于位移的隧道围岩参数反演分析的可行性。

Tunnel surrounding rock parameter back analysis based on displacement,is a very effective method to determine surrounding rock parameters.Correlation between tunnel surrounding rock displacement and physical and mechanical parameters of surrounding rock is very meaningful to surrounding rock parameter back analysis.Taking a center diaphragm(CD)constructed tunnel as research object,spatial and temporal distribution characteristics of surrounding rock displacement were studied based on field monitoring data and finite element numerical simulation analysis;based on numerical simulation analysis,orthogonal test with 5 factors-8 levels were designed,probability distribution feature of surrounding rock displacement were counted,and linear correlation between surrounding rock displacement and parameters was ascertained;sensitivity analysis test of linear displacement to parameters was designed by controlling single variable method,and sensitivity of displacement to parameters was determined.Study results show that:1)displacement development of arch subsidence and horizontal convergence of CD method constructed tunnel experience three stages including rapid development,development slowing down and tending to stable;maximum values of equivalent plastic strain,equivalent mean strain,equivalent mean stress,horizontal displacement and vertical displacement occur at arch crown and haunch;2)arch subsidence and horizontal convergence of tunnel surrounding rock present obvious Gaussian distribution characteristic;3)elastic modulus is negatively linear-correlated to arch subsidence and horizontal convergence distinctly,poisson ratio is negatively linear-correlated to arch subsidence and positively linear-correlated to horizontal convergence,unite weight,inner friction angel and cohesion are weakly correlated to surrounding rock displacement;4)arch subsidence is very sensitive to elastic modulus,relatively sensitive to poisson ratio and unite weight,and not sensitive to inner friction angel and cohesion;horizontal convergence is very sensitive to elastic modulus and poisson ratio,relatively sensitive to unite weight,and not sensitive to inner friction angel and cohesion.Present study has revealed displacement spatial and temporal distribution of CD method constructed tunnel,verified the correctness of traditional displacement monitoring method;revealed the probability distribution feature and displacement-parameter correlation characteristic of surrounding rock displacement,specified the feasibility of parameter back analysis of tunnel surrounding rock based on the displacement.