级配与拦挡位置对滑坡碎屑流运动影响研究

Study on the influence of particle gradation and retaining position on debris flow movement of landslide

为了研究不同级配的高位滑坡碎屑流经多级偏转后冲击不同拦挡结构的运动特性以及致灾效应,结合自然地形构建固定坡度和偏转角度均为45°的离散元模型,并利用DEM软件进行数值模拟分析不同拦挡工况和不同级配对碎屑流颗粒运动过程中能量耗散、最终堆积形态,以及碎屑流冲击挡板的作用高度的影响,进而建立相关冲击力学模型。研究结果显示:(1)上下均设置挡板的工况能有效减缓碎屑流颗粒的平均动能和势能,且能有效降低颗粒流翻越挡板的数量,并降低颗粒流的最大运动距离从而减小致灾范围;随着颗粒组级配的增大,势能时程曲线分散点出现的时间越晚,颗粒流最终堆积面积中细颗粒组最大,粗颗粒组最小。(2)当滑槽底部反作用力位置取2/3静止堆积体长度时,计算所得碎屑流最大冲击作用高度与模拟试验结果相接近,力学模型计算的冲击作用高度在0.017~0.138 m。在实际工程中,可按研究相似比对此范围进行加强抗冲击防护。(3)由于侧板的切向力和“颗粒分选效应”,大颗粒会主要冲击挡板的中上部,小颗粒主要冲击挡板的下部,并受偏转角影响集中在一侧,因此工程设计可根据实际情况避免在沟道偏转方向的反向建设工程。研究结果可为高位滑坡碎屑流灾害的治理防护提供参考。

To study the motion characteristics and disaster-causing effects of different grades of high-level landslide debris flow impacting different blocking structures after multi-stage deflection,a discrete element model with a fixed slope and deflection angle of 45°is constructed and numerically simulated by DEM software,and the effects of energy dissipation,final accumulation pattern,and debris flow impacting the baffle in the process of different blocking conditions and different grades of debris flow particle motion are analyzed.The impact mechanics model is established.The results show that:(1)the average kinetic energy and potential energy of the particles can be effectively reduced by setting baffles on the top and bottom,the number of particles over the baffles can be effectively reduced,and the maximum movement distance of the particles can be reduced,thus reducing the disaster-causing range;as the gradation of the particles increases,the dispersion point of the potential energy curve appears later,and the final accumulation area of the particles is the largest for the fine particles and the smallest for the coarse particles.(2)When the reaction force position at the bottom of the chute is taken as 2/3 of the length of the static pile,the maximum impact height of the calculated debris flow is close to the results of this simulation test,and the impact height range calculated by the mechanical model is 0.017~0.138 m,and the impact protection can be strengthened in the actual project according to the similar ratio of this range.(3)Due to the tangential force of the side plate and"particle sorting effect",large particles mainly impact the middle and upper part of the baffle plate,and small particles mainly impact the lower part of the baffle plate and are influenced by the deflection angle and concentrated on one side.So the engineering design can be based on the actual avoidance of reverse construction in the direction of trench deflection,and the research results can provide a reference for the high landslide debris flow disaster.The research results can provide a reference for the management and protection of high landslide debris flow disasters.