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强夯、冲击碾压工法广泛应用于水库堤坝、港口等水利工程。目前,冲击荷载作用下,复杂的动力响应研究主要依据室内模型试验和工程经验,数值模拟研究较少。本文结合离散单元法和有限差分法的优点,建立了冲击荷载作用的离散-连续耦合数值模型。冲击荷载作用中心区域采用PFC2D中的滞回阻尼模型进行精细模拟,周围区域采用FLAC2D中的摩尔-库伦模型进行模拟。在离散模型中,得到离散颗粒作用于边界墙的合力与合弯矩,根据力的平衡原理,分配到连续模型边界节点上,同时考虑到耦合边界不能承受拉应力,进行二次调整,实现边界面应力的传递;并通过接收连续模型中边界节点的速度,来指定离散模型中边界墙的速度,实现边界面速度的传递。对比模型试验结果验证了冲击荷载耦合模拟的可行性,为今后堤坝、码头堆场等加固处理及动力稳定性分析提供一种新的研究手段。
Dynamic compaction, impact rolling method is widely used in reservoir dams, ports and other water conservancy projects. At present, under the action of impact load, the study of complex dynamic response mainly depends on the indoor model test and engineering experience, and there are few numerical simulations. Combining the advantages of discrete element method and finite difference method, this paper established the discrete-continuous coupling numerical model of impact load. The center of the impact load is modeled using the hysteresis damping model in PFC2D and the surrounding area is modeled using the Mohr-Coulomb model in FLAC2D. In the discrete model, the resultant force and the combined bending moment of the discrete particles acting on the boundary wall are obtained and distributed to the boundary nodes of the continuous model according to the principle of force balance. At the same time, considering that the coupling boundary can not bear the tensile stress and the secondary adjustment is carried out, Interface stress transfer; and by receiving the continuous model of the speed of the boundary nodes to specify the speed of the boundary wall in the discrete model to achieve the speed of the boundary surface transfer. The comparison of the model test results validates the feasibility of the impact load coupling simulation and provides a new research method for the consolidation treatment and dynamic stability analysis of dams and docks yard in the future.