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边坡的渐进破坏特征一直以来是边坡计算仿真中的一个难点。实际边坡的破坏很少是一个整体达到极限状态,突然滑动的过程,往往是逐步发展由局部破坏到最终整体失稳,即临界状态小扰动导致的链式多米洛骨牌式失稳。利用颗粒流软件,设计了0.1 m粒径高10 m土坡的数值模型,粒间黏聚力为36 kPa,摩擦系数为0.36。初始模型在重力作用下不会发生破坏,通过单独折减粒间黏聚力到18 kPa使得边坡破坏,监测竖向颗粒组group的变化获取每20 000个时间步的边坡破坏形态,实现200 000个时间步内边坡的渐进破坏过程。边坡总是从局部开始破坏,坡体物质的运移造成次一级破坏,形成最终的近似弧形的滑动面,说明滑体不是整体下滑,不是刚体,不是整体达到极限状态;坡体内应力的变化也不是单调的,有涨有落,均区别于当前极限平衡法中有限条块的刚体假设;滑动面上同时达到极限状态假设,问题本身是静不定的,通过给出条间力的传递方式使之静定可解;整体分析不能考虑破坏的局部化和渐进特征。这说明边坡计算方法的未来在于能反映动力问题和材料破坏特征的离散元方法。
The progressive failure of slope has always been a difficult point in the calculation and simulation of slope. The actual failure of the slope is seldom a sudden sliding process. It is often the step-by-step development of the chain-domino domino-style instability caused by the partial destruction to the eventual global destabilization, ie the small-critical disturbance. Using particle flow software, a numerical model of 0.1 m particle size and height of 10 m was designed. The intergrain cohesion was 36 kPa and the friction coefficient was 0.36. The initial model will not collapse under the action of gravity, and the slope failure will be destroyed by reducing the intergrain cohesion to 18 kPa alone. The change of the vertical group of particles will be monitored to obtain the slope failure form every 20 000 time steps. Progressive destruction process of slopes within 200 000 time steps. The slope always begins to destruct from the local part. The displacement of the slope material causes sub-level damage and finally the sliding surface is formed, which shows that the sliding body is not the whole sliding, not the rigid body, not the whole reaching the limit state. The internal stress Is not monotonous, there are up and down, are different from the current limit equilibrium method of finite pieces of rigid body assumption; sliding surface at the same time reach the limit state hypothesis, the problem itself is static, by giving the force The way of transmission makes it statically determinable; the overall analysis can not consider the localized and gradual characteristics of destruction. This shows that the future of slope calculation method lies in the discrete element method which can reflect the dynamic problems and the material failure characteristics.