基于对洞室位移反分析中开挖扰动区处理方法的总结分析,探讨将节理岩体损伤本构应用于反分析研究中的实现方法.通过FLAC3D预留的二次开发接口,修改其内置应变软化模型的数值计算格式,即对位于屈服面以外的应力点采用修正应力张量分量的方式替代主应力修正的方式,使修改后的本构模型可适用于各向异性的节理岩体,同时结合FISH语言编制的节理裂隙几何参数随开挖过程的演化程序实现对节理岩体等效柔度张量的更新,从而完成节理岩体损伤本构的FLAC3D二次开发.采用基于支持向量回归机与PSO-DE优化算法的增量位移反分析方法,应用该本构模型对思林水电站地下厂房围岩参数进行反分析.研究结果表明:对于开挖于含成组展布且相对结构尺寸为小量的断续节理岩体内的地下洞室位移反分析问题,将节理岩体损伤本构引入其中是一个很好的尝试,扰动区内围岩的等效弹模平均降低约为20.13％,计算增量位移值与量测值的相对误差在7.54％～16.56％,反分析成果是合理和可靠的.%Based on the overview of back analysis methods for excavation disturbance zone (EDZ), the implementation of employing damage mechanics constitutive model for jointed rock mass (JRM) in displacement-based back analysis is discussed. Following the guide of writing constitutive model in FLAC3D, the damage mechanic constitutive model for JRM is developed successfully by modifying the basic strain-softening model. Specifically, in order to make the strain-softening model capable of handling the case when elastic flexibility tensor is anisotropic such as the equivalent elastic compliance tensor of JRM, a correction is made to the six components of stress tensor instead of the three principal stresses for the stress point located above the yield surface. Meanwhile, a FISH program is written to update characteristic parameters of joint sets, so the equivalent elastic compliance tensor of each zone in numerical model can be updated accordingly. Applying the damage mechanics constitutive model to numerical simulation of underground opening excavation of Silin hydropower station, the back-analysis of rock mass deformation and strength parameters is conducted using the displacement monitoring data from multi-point extensometers. The result shows that for underground opening excavated within jointed rock mass containing a considerable number of intermittent joints with stable trending, employing the damage mechanics constitutive model for JRM in back-analysis is a good attempt, the influence of EDZ can be taken into consideration reasonably, the average decrease of equivalent elastic modulus of rock mass in EDZ is around 20.13%, the fractional errors of calculated incremental displacements are in the range of 7.54%-16.56%, and the result of back-analysis is reliable.
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