冰雹作用下土质边坡模型试验方法

Model Test Method of Soil Slope under Hail Action

为研究冰雹灾害对土质边坡稳定性的影响,自主设计了一套冰雹降落装置,采用自制冰球对模型边坡进行加载.共进行了3组试验,通过高灵敏度动土压力监测系统获得土压力,拟合冲击力;通过摄影测量技术(PIV)监测冰球冲击坡面时的速度向量,计算法向和切向恢复系数,同时监测加载过程中位移变化规律;通过含水率监测系统监测坡体含水率,分析试验前后的水分迁移规律.试验结果表明:在加载密度和加载次数较大时,冲击会使边坡产生浅层滑动,落于坡顶面的冰球重新分布形成堆积,逐渐融化,向下形成渗流;加载瞬时形成冲击荷载,可将其拟合为衰减的半正弦波形;法向恢复系数较小,切向恢复系数较大,冰球在冲击过程中倾向于沿坡面运动;含水率传感器从上到下依次响应,边坡后端融水渗流速度比前端更快,融水主要影响坡顶平台,坡顶平台中层水分迁移速度最快;静土压力与坡顶堆载和冰球融化渗流有直接联系;坡体整体变形较小,最大变形位于坡顶转角处;试验结果反映了冰雹降落对边坡稳定性影响的3个方面:冲击作用、堆载作用、渗透作用,可为冰雪极端灾害条件下的边坡安全预警提供参考和依据.

In order to study the influence of hail disaster on the stability of soil slope,a set of hail falling device was designed independently and the model slope was loaded with self-made ice balls.Three groups of tests were car⁃ried out in this paper.The earth pressure was obtained through a high-sensitivity dynamic earth pressure monitoring system,and the impact force was fitted.Particle Image Velocimetry(PIV)was used to monitor the velocity vector change when the puck impinged on the slope,and the normal and tangential restitution coefficients were calculated.At the same time,the displacement change law during the loading process was monitored.The moisture content of slope was monitored by a moisture content monitoring system,and the rule of the water migrating before and after the test was analyzed.The experimental results show that when the loading density and loading times are large,the im⁃pact causes shallow sliding of the slope,and the ice puck on the top surface of the slope can redistribute and form ac⁃cumulation,gradually melt,and form seepage downward.The impact load is formed instantaneously after loading,and it can be fitted as a decaying half-sine waveform.The normal recovery coefficient is small,and the tangential re⁃covery coefficient is large.The puck tends to move along the slope during impact.The water content sensor responds sequentially from top to bottom,the melt water seepage velocity at the rear end of the slope is faster than that at the front end,and water mainly affects the slope top platform.The middle layer of the slope top platform has the fastest water migration speed.The static earth pressure is directly related to the load on the slope top and the seepage of the ice ball melting.The overall deformation of the slope is small,and the maximum deformation is located at the corner of the top of the slope.The experimental results reflect three aspects of the influence of hail falling on slope stability:impact,stacking and infiltration,which can provide a reference and basis for slope safety warning under the condi⁃tion of extreme snow and ice disaster.