大型洞室群稳定性分析与智能动态优化设计的数值仿真研究

NUMERICAL SIMULATION METHOD FOR STABILITY ANALYSIS AND INTELLIGENT AND DYNAMIC OPTIMIZATION DESIGN OF LARGE CAVERN GROUP

为实现数值仿真计算结果能准确反映大型洞室围岩实际力学行为,结合锦屏二级水电站地下厂房枢纽洞室群稳定性分析,在阐述大型地下洞室群数值仿真计算要点基础上,首先重点从岩体本构模型识别和力学参数识别2个方面详细介绍如何实现数值仿真计算的正确化。采用考虑空间分布协调的多元监测信息的6次岩体力学参数跟踪识别,获得锦屏二级地下厂房岩体的等效力学参数,从而通过参数反分析的方法在一定程度上证明岩体等效力学参数具有相对稳定性和可识别性。同时,结合数值模拟展现出的围岩应力、变形、塑性区等方面计算结果与工程岩体的具体地质条件和洞室群结构特点,论述锦屏二级水电站地下厂房上游高边墙变形较大、下游侧拱围岩与喷混凝土破坏、母线洞环状开裂、交叉洞口局部塌落等洞室围岩的变形与破坏机制。最后,结合锦屏二级地下厂房枢纽洞室群稳定性分析与实践的研究认识,对大型地下洞室修建中诸如结构面密集的高边墙支护问题、围岩应力集中区支护问题、工程区地下水对围岩稳定性影响等问题进行论述,并探讨如何通过数值仿真计算、现场监测与经验丰富的专业人员的有机结合来实现大型地下洞室群稳定性设计的科学化。

For purpose of accurately sameness between numerical simulation and practically mechanical behaviors of cavern,key principles of numerical simulation method for underground caverns are described firstly.Then,right ways of rock constitutive model recognition and parameter recognition are introduced in detail,taking Jinping II hydrpower station underground caverns as an example.On one hand,model recognition is carried out and checked from some aspects,including failure mode analysis of rock,deterioration rule of mechanical parameters,fitting of testing curves,simulation of testing tunnel,etc.On the other hand,six times dynamically intelligent back analysis of rock mechanical parameters considering spatial distribution multi-information have been done,which provide actually equivalent parameters for 3D simulation.With reasonable constitutive model and exact parameters,the calculation result of 3D numerical simulation about caverns excavation exposes reasonable deformation,redistributed stress and plastic zone of surrounding rock,which can be used to explain special mechanical behaviors of surrounding rock,such as large deformation of powerhouse＇s upstream,failure of rock and shotcrete,circularity cracks of busbar tunnel,local slumping of fork rock,etc.What＇s more,based on the accumulation and experiences of Jinping II hydropower station underground cavern＇s study,some supporting issues in design,such as high sidewall with dense joint,position with concentrated stress and groundwater in surrounding rock,are also discussed,which provide legible instance and cues for study and design optimization of large underground engineering.