汶川地震中锚固岩质边坡的动力响应特征

Dynamic response characteristics of an anchored rock slope during Wenchuan earthquake

岩质边坡的地震响应是当前岩土工程界所关注的重要问题之一。以紫坪铺工程进水口边坡为研究对象,以现场监测数据为基础,从时间和空间的角度综合分析了汶川地震前、后支护荷载和边坡位移的变化特征,并讨论了坡体形态、岩体结构以及支护荷载对地震力作用的协同影响。研究结果表明:受地震力作用影响,坡体变形和支护荷载发生突变,主要受主震影响;地震引起的支护荷载变化量在100 k N以内,未超出设计荷载的5%;边坡水平向产生的永久位移在12 mm范围内,岩体变形深度受结构面分布控制;边坡中部变形最大,沿水平方向具有明显的临空面放大效应,而沿高程方向,没有明显垂直放大效应。研究成果可加深对锚固岩体动力响应机制的认识,同时为以位移控制的边坡工程抗震设计提供参考。

The seismic response of rock slope is one of the most significant issues in the field of geotechnical engineering. In this study, the intake slope of Zipingpu project is investigated to study the influence of Wenchuan earthquake based on the monitoring data. From the perspectives of time and space, the characteristics of supporting load and slope displacement have been analyzed before and after Wenchuan earthquake. Furthermore, the synergistic effect of slope shape, rock mass structure and supporting load under seismic force is discussed. The results show that the sudden increases both in deformation and supporting load of slope are principally caused by the seismic force, and thus earthquake is regarded as the main influencing factor. It is found that the change of supporting load caused by the earthquake is below 100 k N, which is less than 5% of the design load. Permanent displacement of the slope in horizontal direction is within the range of 12 mm and the deformation distribution in depth is controlled by the structural plane of rock mass. Particularly, the maximum displacement concentrates in the middle part of the slope. Free surface amplification effect has been found along the horizontal direction, while there is no obvious vertical amplification effect along the elevation direction. Therefore, this research can not only underpin the understanding of the dynamic response mechanism of anchored rock mass, but also provide references for the aseismic design of slope engineering controlled by the displacement.