复杂地质条件下调压室三维有限元参数反分析

在地下洞室施工过程的3维有限元模拟过程中,数值计算结果受到地应力场及岩体力学参数的影响。在参数反演过程中,地应力场和岩体力学参数对洞室围岩应力变形的大小影响过程非常复杂,要同时反演这两方面参数比较困难,因此依托复杂地质条件下柳坪水电站调压室工程,采用3维非线性有限元分析,把地应力场岩体力学参数分两步进行反演,首先利用洞室围岩变形之间的规律对地应力场进行反分析,岩体力学参数选取参考范围的中值,在获得计算模型的地应力场数值及分布规律后,再对岩体力学参数进行反分析,反演得到岩体的力学参数,得出微新围岩、断层、弱风化带、强风化带变形模量分别为19、0.45、4.5、2.25 GPa,泊松比分别为0.21、0.35、0.25、0.30。反分析位移与监测位移对比表明,平均相对误差符合计算精度要求,可为类似工程的研究、分析提供参考。

Three-dimensional finite element back analysis method for mechanical parameters of surge chamber under complicated geological condition

The three-dimensional finite element simulation of the construction process of underground tunnels,is effected by crustal stress and rock mass mechanical parameters.Based on the surge chamber of liuping hydropower station under complicated geological condition,the three-dimensional finite element back analysis way was used to analyze the crustal stress and rock mass mechanical parameters in two steps.Firstly,the regularity of surrounding rock’s deformation was used to the back analysis of the crustal stress,the median value of the rock mechanical parameters’reference ranges was selected,and the crustal stress’s distribution rule of the calculating model was obtained.Secondly,the back analysis way was used to analyze the rock’s mechanical parameters.The deformation modulus of the rock’s mechanical parameters of recent fresh surrounding rock,fault,moderately weathered zone,tensely weathered zone,were 19,0.45,4.5and 2.25 GPa,respectively.and the Poisson’s ratio were 0.21,0.35,0.25 and 0.30,respectively.By comparing the monitoring displacement and the back analysis displacement,it was indicated that the average relative error was corresponding with the precision requirement,and it can provide reference for similar engineering’s study and analysis.