动水荷载作用下粉土围坝力学响应研究

摘要

In order to reveal the change ru le of mechanical parameters of silt dam under hydrodynamic load, mechanical response of silt dam under cyclic wetting-drying and stormy waves was studied respectively through laboratory test and numerical simulation. The results showed that shear strength of undisturbed silt decreased significantly after more than 2 times of cyclic wetting-drying, and the decreasing amplitude decreased gradually with the increase of cycle number. Excess pore water pressure of silt dam upstream slope oscillated under wave load and accumulated dynamically with time, which led to decrease of effective stress seriously. The pore water pressure would tend to be stable when it increased to a certain value. The pore pressure stabilization time increased as the wave period increased. This conclusion established the theoretical foundation for stability evaluation of natural silt dam slope in short term and long-term, revealing landslide mechanism of silt dam and prediction model establishment of dam slope collapse.%为揭示动水荷载作用下粉土围坝力学参数的变化规律，通过室内试验和数值模拟，分别研究了干湿循环及风浪影响下粉土围坝的力学响应。结果表明：原状粉土在经历2次以上干湿循环后，抗剪强度显著降低，且随干湿循环次数的增加，降低幅度逐渐减小；在周期性波浪荷载作用下，粉土围坝迎水坡产生震荡超孔隙水压力，且随时间动态累积，有效应力降低严重；孔隙水压力增大到一定值后将趋于稳定，孔压稳定时间随波浪周期的增大而增大。该结论的得出为天然粉土坝坡的短期和长期稳定性评价、揭示粉土围坝滑坡机理以及建立坝坡坍塌预测模型奠定了理论基础。