基于声发射的岩质工程边坡潜在滑动面及滑动面力学参数标定

Based on knowledge that acoustic emission (AE) rate is corresponding to the damage of rock mass, it is pointed that AE not only could be used to detect the location of damage, but also could be used to determine the damage quality of rock mass. Based on the research of AE information including damage coordinate, magnitude, density and resource size of released energy, etc. obtained with experimental and in-situ test, a relationship between AE information and the variation of mechanical parameters of rock mass is proposed to calibrate the mechanical properties of the potential sliding surface. Then two rock slopes in construction are employed as the background models. The real-time monitoring micro-fractures are selected as the initial damage of the sliding surface and the calibrated mechanical properties are selected as the input parameters, the space-time location of the potential sliding surface is calibrated based on the evolution law of AE and stress field obtained from numerical results of three-dimensional geological model. Finally, based on the laboratory experiments on centrifugal loading of slopes, AE information, numerical analysis and the investigating results in-situ, the influences of unloading sequence, schedule and magnitude on the space-time location of the potential sliding surface and the stability of rock slopes are investigated. The accommodated conditions and applied scope of the proposed method in this research are illustrated.

基于"声发射率与岩体损伤具有一致性"的物理力学基础，突破声发射对区域岩体损伤定位的单一作用，有效利用声发射物理信息中关于破裂点的时空坐标及能量释放的量值、密度、源尺寸相关的数据，通过对室内岩样声发射及现场边坡体声发射物理信息的整合研究，建立起声发射物理信息与滑动面区域岩体力学参数变化的表征关系，实现对边坡滑动面力学参数的实时修正；以两个已安装有声发射监测系统的岩质工程边坡为背景模型，以实时监测得到的微破裂作为滑动面的初始损伤，以实时修正的滑动面力学参数为输入，通过对声发射活动性（破裂点出现及其能量释放的平静、迁移和加速规律）和三维地质力学模型精细数值表征（应力的集中、释放与转移模式）的相结合，实现对滑动面时空基准的标定；基于对离心机模型实验、声发射试验、数值分析及现场实际勘测结果的综合分析，揭示卸荷扰动对岩质工程边坡潜在滑动面时空基准影响的基本规律，界定所提出方法的适用条件和适用范围。

水电工程高陡岩质边坡在卸荷开挖、大坝浇筑及蓄水运行的整个服役生命周期内，卸荷扰动、爆破、地震、暴雨、库水位升降等一系列人工和自然活动，都可能诱发坡体的损伤及损伤积累。本项目根据“边坡岩体渐进损伤（微震活动性）是边坡失稳前兆本质特征”这一思路，着重开展了基于微震监测与数值计算的岩质边坡滑动面形成机理及稳定性分析研究。首先，开展了大量岩样室内岩石力学实验，包括应力应变、声发射、破坏模式测试等，并在两个已安装有微震监测系统的岩质工程边坡-大岗山水电右岸边坡和锦屏一级水电站左岸边坡进行了现场坡体微震活动信息测试，特别是对蓄水期大岗山水电站右岸边坡的微震活动进行了全程测试。其次，对室内岩样声发射及现场边坡岩体微震物理信息进行了整合研究，包括震级、能级、震源尺寸、微震活动性与卸荷扰动的关系、微震活动性与蓄水水位变化的关系、微震空间分布与不良地质构造发育状态的关系，进而根据震源能级对坡体渗透性演化进行了分级研究，并建立起了微震物理信息与坡体内损伤区岩体力学参数变化的表征关系，实现了相应的计算模型以及大规模科学计算程序模块。最后，以大岗山水电右岸边坡等实际工程为背景模型，开展了卸荷扰动、蓄水期变水位边界、抗剪洞加固等条件下的边坡潜在滑动面形成机理研究。通过对微震活动位置、能量迁移规律和数值计算的应力集中、释放与转移模式的解读，分析了边坡滑动面岩桥区强度不断受到应力腐蚀和环境腐蚀，由细观拉张性破坏汇集形成宏观剪切带的演化过程，初步实现了岩质边坡稳定性的动态、实时评价。虽然研究方法仍有一定的局限性，但部分地解决了实际依托工程—大岗山水电站右岸高边坡整体稳定性评价、抗剪洞加固效果评价、蓄水期边坡稳定性评价的问题，特别是开挖卸荷和蓄水期的边坡潜在滑动面圈定以及安全储备系数评估，丰富了岩石边坡稳定性的研究方法和理论。研究成果为岩质边坡工程的稳定评价和安全预警提供了进一步的理论基础和技术支撑。