岩石弹塑性应力-渗流-损伤耦合模型研究(Ⅰ):模型建立及其数值求解程序

Study of the coupling model of rock elastoplastic stress-seepage-damage(Ⅰ) :Modelling and its numerical solution procedure

在地下水渗流场、应力场、损伤场的耦合作用下更易造成隧道围岩坍塌或涌水等灾害。首先,将围岩材料视作各向同性连续介质,基于Drucker-Prager准则建立岩石弹塑性损伤本构模型,采用完全隐式返回映射算法实现弹塑性损伤本构方程的数值求解。其次,以上述研究为基础根据岩石处于弹塑性状态时渗透系数动态演化公式,建立岩石弹塑性应力-渗流-损伤耦合模型,并给出三场耦合情况下的数值求解迭代方法。针对耦合模型中涉及参数较多且不易测定的问题,基于差异进化算法原理建立智能反分析方法,对耦合模型中的损伤参数进行反演。最后,利用C++语言编制相应的岩石弹塑性应力-渗流-损伤耦合程序和参数反演程序,利用所编程序进行以下计算:(1)对智能反分析程序的性能、正确性进行分析,对比不同差异策略、交叉因子、变异因子的反演精度和收敛速度。(2)分别采用弹性模型和弹塑性损伤模型进行隧道围岩位移场、应力场的计算。(3)不考虑力学作用的情况下进行孔隙水压力、渗流量的计算。(4)采用所建耦合模型计算得到隧道围岩应力场、渗流场以及损伤场的相互影响规律。研究结果表明,基于差异进化算法的智能反分析程序能够较好地解决耦合模型中损伤参数不易确定的难题,为实际工程中获得不易测定的计算参数提供了有效的方法,同时所建立的耦合模型通过应力、渗流和损伤的相互作用更能够真实地反映出岩石材料的宏观破坏现象,所编计算程序能够模拟地下水渗流场、应力场、损伤场之间的耦合特性,为受地下水影响严重的工程建设提供了方法,研究结论为后期对实际隧道工程进行耦合计算奠定基础。

It is more likely to cause the collapse of tunnel surrounding rock and water disasters under the action of the coupling effect of the groundwater seepage field, the stress field and the damage field. First of all, surrounding rock is regarded as the isotropic continuum material, and the elastoplastic damage constitutive model of rock is established based on the Drucker Prager criterion. The fully implicit return mapping algorithm is adopted to achieve the numerical solution of elastoplastic damage constitutive equations.Secondly, according to the dynamic evolution formula of permeability coefficient in elastoplastic state based on the above research,the elasoplastic stress-seepage-damage model of rock is established; and the coupling solving iterative method of many fields is presented. Back analysis program is compiled on the basis of the principle of differential evolution algorithm in order to solve the problem that elastoplastic damage model involves many parameters and not easy to determine, and the damage parameters are inversion; Finally, the corresponding coupling program of the elastoplastic stress-seepage-damage is compiled and parameters inversion program are compiled using C++ language respectively. The following calculations are conducted by using the programs:(1)The performance and the correctness of the intelligent back analysis program are analyzed, comparing the inversion accuracy and the convergence rate of the differences between the different strategies, the cross factors and the variation factors.(2) The calculationresults of the displacement field and the stress field by the elastic model and the elastoplastic model are compared.(3) The pore water pressure and the seepage flow are calculated without considering the effect of mechanics.(4) The interaction rules of the stress field,the seepage field and the damage field of tunnel surrounding rock are calculated using the coupling model. The results show that the problem of damage parameters which is difficult to determine can be better to solve in damage model by the back analysis program based on differential evolution algorithm. It provides effective method for the calculation parameters are acquired not easily determined in practical engineering. At the same time, the macro failure of rock material can be more realistically reflect through the interaction of the stress, the seepage and the damage of the built coupling model. The calculation program which provides a method for the engineering construction affected by groundwater severely can simulate the coupling characteristics of the groundwater seepage field, the stress field and the damage field. The study of this paper lays a solid foundation for the coupling calculation of the later period for actual tunnel engineering.