地下工程岩体参数场反演分析应用研究

 在施工过程中，由于开挖方式、爆破以及支护施作滞后等因素的影响，洞周岩体会有不同程度的“劣化”。一般而言，受开挖施工影响，离洞室表面越近的岩体劣化程度越严重；支护施作滞后时间越长岩体劣化程度越严重。因此，提出参数场的概念，将洞周围岩物理力学参数看作受初始地质状态、施工影响而随空间变化的非稳定参数场。采用三维弹塑性损伤有限元及位移反演分析方法，经敏感度分析确定恰当的待反演岩体参数，使用局部断面模型快速反演计算方法获得各监测断面区域岩体参数场，再通过插值方法得到三维整体模型参数场，适当修正后即可用于洞室后期开挖围岩变形及稳定预测。结合瀑布沟水电站地下厂房工程，建立有限元模型，代入监测数据，反演获得洞周围岩参数场，并将计算结果用于预报后续洞室开挖的围岩变形趋势，结果显示岩体计算预测反演参数与实际监测值符合较好。

BACK-ANALYSIS AND APPLICATION STUDY ON SURROUNDING ROCK PARAMETER FIELD OF UNDERGROUND ENGINEERING

The quality of rock mass become unfavorable by the influence of blasting explosion，opening and lag of anchorage and support. The closer the surrounding rock near cave surface is，the worse it becomes. The longer the time after opening without anchorage and support is，the worse it becomes. So it is thought that surrounding rock is heterogeneous，but a parameter-field of space distribution，which is varied with the geological conditions；and opening and support methods are presented. Adopting 3D elastoplastic damage FEM and displacement back-analysis method，the proper parameters of surrounding rocks are determined by sensitivity analysis. Adopting local cross section model，the local parameter-field can be calculated rapidly. Then，the parameter-field of whole 3D model can be built by interpolation. Finally，combined with Pubugou underground powerhouse，the 3D FEM model is built. When monitoring data are inputted，the surrounding rock parameter-field can be obtained. The calculation results are used to predict the displacement and stabilization of surrounding rock. The results show that the distribution of parameters of surrounding rock mechanics calculated agrees well with those measured.