论文部分内容阅读
地震滑坡会造成巨大灾害,但对其动力学机制的认识还十分有限.本文根据汶川地震中主要滑坡体的几何及运动特征,抽象出一般的概念模型.通过基于不连续变形体动力过程的有限单元方法,对滑坡的运动特征及动力学过程进行数值模拟.计算结果定量给出了在地震动的作用下,滑坡体运动的全部历程,特别是展示了滑坡的启动、滑移、抛射、碰撞、飞行以及爬升等典型的运动学特征.计算结果表明,在地震动惯性力及重力的共同作用下,当克服了滑坡体与滑床之间的摩擦力后,滑坡启动,滑坡体沿滑床由慢到快滑行,直至从滑床上抛射出去.根据对地震动加速度进行的频谱分析以及对山体进行振型研究的结果可以推知,汶川大地震很有可能让震中及附近地区的山体发生共振,加上高山地形本身的放大效应,致使山坡上的地震动得到显著增大,从而导致了汶川地震诱发的滑坡事件特别频繁,滑坡灾害极其严重.模拟结果还显示:地震动的方向、振幅、频率、持续时间以及接触面上的摩擦关系对滑坡体的稳定性影响很大.因此,本研究对于认识地震滑坡的动力学机制、评估地震灾害以及对于研究地震动态触发问题等有重要的科学意义.
Earthquake landslides can cause great disasters, but the understanding of their dynamic mechanism is still very limited.This paper abstracts a general conceptual model based on the geometry and movement features of major landslides in the Wenchuan earthquake, and through the finite finite element method based on discontinuous deformation Element method to simulate the movement characteristics and dynamic process of the landslide.The results of the calculation quantitatively give the whole history of the landslide movement under the action of the earthquake and especially show the characteristics of the landslide initiation, slippage, projectile, collision , Flight and climbing etc. The results show that landslide starts when the friction between landslide body and slide bed is overcome under the combined action of inertial force and gravity of earthquake, From slow to fast taxiing until it is ejected from the slide bed.According to the spectrum analysis of the acceleration of the earthquake and the result of the modal study on the mountain body, it can be deduced that the Wenchuan earthquake is likely to resonate the mountain body in and near the epicenter, Coupled with the amplification effect of the alpine terrain itself, resulting in a significant increase in ground motion on the slopes, resulting in the Wenchuan earthquake-induced slip The slope events are particularly frequent and the landslide disaster is extremely serious.The simulation results also show that the direction, amplitude, frequency, duration and the frictional relationship of the ground contact have a great influence on the stability of the landslide.Therefore, The dynamic mechanism of landslide, the evaluation of earthquake disaster and the research on the dynamic triggering of earthquake have important scientific significance.