基于颗粒流程序分析河道采砂对堤防稳定性的影响

Analysis of the influence of sand mining on the stability of embankment based on particle flow code

为了研究河道采砂对河堤稳定性的影响,采用颗粒流程序(PFC)从细观角度监测并分析采砂坑形状、离堤脚的距离及采砂坑深度3个参数的变化对堤防稳定性的影响,得到堤防坡顶、坡中和坡底筑堤材料孔隙率随采砂坑参数变化的规律;运用强度折减法原理和特征点位移判据法计算堤防抗滑稳定安全系数,得出河道采砂方式与堤防抗滑稳定性的内在联系。研究结果表明:孔隙率变化可反映土体细观颗粒变化,利用孔隙率可以追踪在不同采砂条件下河堤各部位细观土体的流失破坏过程;河道采砂方式对堤防抗滑稳定性有较大的影响,采砂坑离堤脚越近,堤防抗滑稳定安全系数越低。因此,在正常设计中采砂坑与堤脚之间应保持足够的安全距离。

In order to study the influence of sand mining on the stability of river embankment,particle flow code(PFC)was used to monitor and analyze the influence of three parameters,namely,the shape of sand mining pit,the distance from the foot of the dike and the depth of sand mining pit,on the stability of the dike.The change regularity of the porosity of the materials used to build the dike with the parameters of sand mining pit was obtained.Based on the principle of strength reduction method and the method of characteristic point displacement criterion,the safety coefficient of anti-sliding stability of the embankment was calculated,and the internal relation between the way of sand mining in river channel and the anti-sliding stability of the embankment was obtained.The results show that the change of porosity can reflect the change of soil mesoscopic particles,the porosity can be used to track the loss and destruction process of the soil body in various parts of the embankment under different sand mining conditions.The way of sand mining in river channel has a great influence on the anti-sliding stability of the embankment.The closer the sand mining pit is to the foot of the embankment,the lower the safety coefficient of the anti-sliding stability of the embankment is.Therefore,a sufficient safety distance should be kept between the sand mining pit and the foot of the embankment in the normal design.