复杂地下洞室围岩开挖扰动空间效应参数化研究

复杂地下洞室围岩开挖扰动区的形成和发展具有明显的空间效应。岩体开挖扰动损伤总体上表现为岩体变形模量的劣化。考虑到基于厚壁圆筒弹性力学分析的弹性模量压力和半径相关模型的应用局限性,提出开挖扰动区岩体变形模量的半径-位移相关模型,并对模型的多洞室适用性和参数敏感性进行了分析。该模型实质上是一个参数场模型,通过变形模量劣化参数场分布量化揭示开挖扰动的空间效应。以瀑布沟水电站大型地下厂房洞室群工程为例,基于位移监测信息,应用半径-位移相关模型对主厂房围岩开挖扰动的空间效应及围岩稳定性进行了参数化分析。围岩变形模量劣化参数场沿厂房轴线具有明显的空间不均匀性,沿深度方向呈现指数函数分布特征。结果表明:该模型为开挖扰动区岩体变形模量参数的确定提供了合理的数值计算方法;通过岩体变形模量半径-位移相关模型参数化分析开挖扰动的空间效应,对于地下洞室施工期快速监测反馈和围岩安全稳定性评判以及支护优化设计具有显著的工程适用性。

Parametric Analysis of Spatial Effect of Excavation Damaged/Disturbed Zone Around Complex Underground Openings

Spatial effect of the excavation disturbed zone(EDZ) around complex underground openings is evident and hardly identified with the formation and development.Generally,the characteristics of the EDZ are behaved as the deterioration of the deformation modulus of the surrounding rock.In order to analyze the spatial effect of the EDZ,by considering the limited application of the pressure or radius dependent Young’s modulus model based on the elasticity analysis of the thick-walled hollow cylinder,a numerical model of the EDZ using radius-displacement-dependent deformation modulus was proposed for complex openings.And the applicability to multi-caverns and parameter sensitivity of the model were basically analyzed with synthetic data.This model is actually a parameter field model,which can be used to reveal the spatial effect of the EDZ on the working state by quantifying the deterioration of the deformation modulus.The model was further studied by its application in the large underground powerhouse of Pubugou Hydropower Plant.The spatial effect of EDZ and impact on stability were analyzed through parametric analysis using the model.The deterioration parameter field along the longitudinal axis of main powerhouse was evidently non-homogeneous in space and distributed as exponential along the radius from the opening.It was indicated that the model provides a numerical method with rationality to evaluate the deformation modulus of EDZ,and the parametric analysis method to analyze the spatial effect of EDZ is of reasonable applicability to the rapid feedback for the underground construction process,the stability assessment of the surrounding rock and providing scientific basis of support optimization.