地震作用下土质边坡永久位移分析的能量方法

边坡的永久佗移可以为边坡工程的抗震设计和坡体稳定性判识提供有力的依据,为了提出一种计算永久位移的新方法并使计算结果相对准确,论文基于塑性极限分析的上限定理,推导了潜在滑坡体的正、反向临界加速度,探讨了滑动面倾角和竖向加速度对临界加速度的影响;利用能量守恒原理,建立了地震作用下滑坡体系的能量反应方程,探讨了地震时滑坡体系中能量的传递、转化和耗散过程;定义了边坡的临界输入功率,推导了基于能量法的边坡永久位移计算公式,分析了莺力势能降对永久位移的贡献.研究表明:当滑动面倾角较小,且地震加速度较大或坡体自身稳定性较差时,反向位移不容忽略;考虑竖向加速度后临界加速度成为一个随时间变化的临界加速度时程;全面考虑正、反向临界加速度和竖向加速度的影响,可使永久位移的计算结果相对准确;地震对滑坡主要产生触发作用,边坡的永久位移量主要由重力势能降决定.

Energy Method for Evaluating Earthquake Induced Permanent Displacement of Soil Slopes

Since the permanent displacement induced by earthquake can be regarded as an effective criterion for stability estimation and anti-seismic design of slopes, a new method for evaluating the displacement and improve its estimating accuracy was proposed. The forward and reverse critical acceleration of potential landslide were derived based on the limit analysis upper bound theorem, and the influence of sliding surface angle and vertical acceleration on critical acceleration was then discussed. According to the principle of energy conservation, the energy response equations of landslide system were established, the process of energy transferring, transforming and dissipating during earthquake were analyzed. A permanent displacement calculation formula of the slope with energy method was presented. In addition, the contribution of gravitational potential energy to permanent displacement was analyzed. Result showed that the reverse displacement can not be neglected when the slope has a small angle of sliding surface and weak stability, while the earthquake is strong. The critical acceleration will become an acceleration time history varying with time when take the vertical acceleration into account. Farther precision in displacement calculation can be reached via considering the effect of reverse critical acceleration and vertical acceleration wholly. Earthquake plays an important role on triggering landslides, and the permanent displacement is mainly determined by gravitational potential energy.