基于数值分析的岩石块体稳定性评价一般性方法

为解决岩石块体在各种复杂条件下的稳定性评价问题,在已有的岩石块体识别的单元重构–聚合方法基础上,进一步提出基于数值分析的块体稳定性评价一般性方法。该方法以含有块体信息的网格模型为出发点,首先引入界面单元,实现块体–围岩结构面滑移和脱开的模拟。其次,提出可动块体的定义和基于数值分析的块体运动形式判别方法。然后,基于结构面强度折减思路,提出块体安全系数定义和加固分析方法,从而实现基于数值分析的块体稳定性评价。该方法相比于刚体极限平衡法,能够考虑初始地应力、围岩变形和非滑面抗剪性能对块体稳定性影响,且在一定条件下,分析结果可与刚体极限平衡法结果基本等同。最后,通过算例验证了该方法的可靠性、有效性,并论证了其与刚体极限平衡法分析结果的关系。算例结果同时表明:该方法可综合考虑块体几何形态、块体埋深和块体出露高度对其稳定性的影响,能够适应复杂条件下工程岩体开挖过程的块体稳定性评价。该方法与已提出的块体识别方法,构成一套有关岩石块体的"识别–可动性判别–运动形式确定–稳定性评价–加固分析"的完整方法体系,总体平行于当前块体力学分析的常用方法(如块体理论),为研究块体在各种复杂条件下的稳定性演化提供了新的实现思路。

General method for stability evaluation of rock blocks based on numerical simulation

In order to evaluate the stability of rock blocks under various complicated conditions，a general method for stability evaluation of blocks using numerical approach was proposed based on the existed block identification method using element reconstruction and aggregation technique. The proposed method places the focus on the meshes that contain block information. Firstly，interface elements were introduced to simulate the slip and open behavior of rock block surfaces. Then，the method of determining the removability and kinematic patterns of blocks was proposed. Afterwards，the definition of the safety factor of block and its reinforcement method are proposed based on the strength reduction concept. The stability evaluation of blocks is thus realized using the numerical approach. Compared to the rigid body equilibrium method，the proposed method is able to take the influences of the initial geo-stress，rock deformation and anti-shear capacity of non-slipping interfaces into account in evaluating the block stability. Under certain conditions，the results of proposed method are equivalent to those of rigid body equilibrium. Finally，the reliability and effectiveness of the proposed method and its relationship with the rigid body equilibrium method are verified through several examples. The examples also indicate that the proposed methodology is able to reflect the influences of geometry，overburden depth and exposure height of blocks，is thus suitable for the stability evaluation of blocks during the excavation process under complicated conditions. The proposed method together with the existed block identification method form a complete system，including the identification，removability determination，kinematic pattern determination，stability evaluation and reinforcement method, which is parallel to the current methods for mechanical analysis of rock blocks (e.g. block theory).