地震时岩体损伤对层状复合岩体斜坡响应的影响及机理研究

The layered complex rock slope has a slope structure commonly seen in nature, with the rock masses consisting of multiple lithology layer by layer. In the “5.12” Wenchuan earthquake, several large-scale catastrophic landslides were triggered in this kind of slope. However, there is still lack of knowledge how the rock structure can influence the dynamic responses of the slope when subjected to an earthquake. For this reason, a typical earthquake-triggered landslide occurring in the layered complex rock slope will be employed as the research object, and the effect of rock structure on seismic responses of the slope will be explored as well as its mechanism, from the view of rock damage. Firstly, with the help of PFC2D numerical tests, laboratory load test and acoustic emission technique, the microscopic damage evolution of the layered complex rock and its effect on the macroscopic mechanical properties will be studied. Next, a coupling numerical simulation of FLAC code and PFC2D code and a shaking table test will be performed on the layered complex rock slope. Based on the simulation results and the test results, the dynamic responses of the slope will be firstly analyzed. Then combining the microscopic damage analysis and the stress state analysis, the response mechanism will be explored. This research will be conducive to get a better understanding of the dynamic behavior and the failure mechanism of the layered complex rock slope during an earthquake, and also makes the seismic slope stability evaluation much more targeted.

层状复合岩体斜坡是自然界中常见的一种坡体，斜坡岩体包含多种岩性，且成层状分布。“5.12”汶川地震正是在这类斜坡中触发了多起规模巨大的灾难性滑坡。然而，人们对这种岩体结构在斜坡地震动力响应过程中产生的影响仍然缺乏认识。为此，本申请课题以汶川地震诱发的一典型层状复合岩体滑坡为研究对象，拟从研究层状复合岩体损伤的角度，探索这种岩体结构对斜坡地震动力响应的影响及机理。首先，借助PFC2D数值试验、室内载荷试验和声发射技术，研究层状复合岩体的微细观损伤演化过程及其对岩体宏观力学特性的影响。在此基础上，开展FLAC/PFC2D耦合数值模拟和振动台试验，在分析斜坡动力响应特征的同时，结合岩体的微细观损伤特征和应力状态分析，探索斜坡的动力响应机理。本研究有助于人们更深入地认识层状复合岩体斜坡在地震作用下的动力响应行为和变形破坏机制，从而有针对性地开展该类斜坡的地震稳定性评价工作。

层状复合岩体斜坡是自然界中常见的一种坡体，斜坡岩体包含多种岩性，且成层状分布。“5.12”汶川地震正是在这类斜坡中触发了多起规模巨大的灾难性滑坡。然而，人们对这种岩体结构在斜坡地震动力响应过程中产生的影响仍然缺乏认识。为此，本项目以汶川地震诱发的一典型层状复合岩体滑坡(青川县东河口滑坡)为研究对象，从岩体试样和斜坡两种尺度结构损伤的角度，采用室内岩体力学试验、物理模型试验和数值模拟相结合的方法，依次研究了岩体的动力学特性、微细观损伤演化过程、层状复合岩体斜坡的地震动力响应特性及机理。主要研究成果体现在：（1）岩体在静力和动力荷载条件下表现出截然不同的力学特性，主要体现在应力-应变曲线特征、弹性模量、峰值强度、残余强度和破坏应变等几个方面。（2）岩体在静力和动力荷载条件下在裂纹萌生、扩展和联合贯通过程以及最终破坏形态方面有一定的差异，且与围压和加载速率密切相关。（3）模型边坡在水平向和竖直向激振条件下的固有频率总体呈现出三阶段降低趋势，但在两个方向下的振动形态不同，表明两个方向的地震波对模型边坡产生的地震作用效应不同；（4）模型边坡竖直向加速度的高程放大效应弱于水平向加速度，但模型边坡对竖直向输入波的改造作用更明显；（5）碳质板岩层在激振强度增大时出现鼓胀变形，变形程度超过上部岩体，呈现出一定的控滑作用；（6）模型边坡上部在破坏时出现近乎垂直的拉裂面，裂缝深入到千枚状板岩层内部，下部沿层面滑动，呈现出拉裂-剪切破坏模式。本研究有助于人们更深入地认识层状复合岩体斜坡在地震作用下的动力响应行为和变形破坏机制，从而有针对性地开展该类斜坡的地震稳定性评价工作。