偏转角度对滑坡-碎屑流运动影响的模型试验

Model Tests on Influence of Deflection Angle on the Movement of Landslide-Debris Avalanches

本文基于模型试验,对不同偏转角度(θ)作用下的碎屑流运动堆积特征进行初步研究。试验结果表明,在偏转作用下,碎屑流的运动经历了加速、持速和减速三个阶段。碎屑流的前缘速度在持速阶段表现出明显的波动性,偏转角度越大,碎屑流前缘速度波的动性越显著;但偏转角度对碎屑流的运动时间的影响并不显著。对碎屑流受偏转作用后的水平运动距离进行分析表明较小的偏转角度更有利于碎屑流的运动。偏转作用下碎屑流的堆积过程表现出"多次叠加堆积"特征,偏转角度越大"多次叠加堆积"的现象越明显。同时,碎屑流的堆积厚度分布也明显受控于偏转角度的影响。横断面上,堆积厚度沿受冲击碰撞一侧向对侧减小,两侧堆积厚度的差异随偏转角度的增大呈抛物线变化,θ=20°时最大。纵断面上,碎屑流在坡脚附近的堆积厚度随偏转角度的增大而增大。

The deflection angle（ θ） were considered as an influence factor to study the movement and deposit characteristics of landslide-debris avalanches based on model tests. The test results showed the movement of landslidedebris avalanches included three stages： acceleration,constant-speed and deceleration. The front velocity of landslide-debris avalanches showed obvious fluctuation at stage of constant-speed. The larger the deflection angle was,the more obvious fluctuation of front velocity was. However,the deflection angle had no significant influence on the movement time of landslide-debris avalanches. Smaller deflection angle was more favorable to the movement of landslide-debris avalanches through statistical analysis. The depositing process of debris avalanches under the action of deflection showed the characteristics of multiple depositing,and the phenomenon was more obvious with the increase of deflection angle. Meanwhile,the stacked thickness distribution of debris avalanches was also controlled by the deflection angle. In the cross section,the stacked thickness decreased along the impact side to the other side,and the difference in accumulation thickness between the two sides was greatest at θ = 20°. On the vertical section,the accumulation thickness of debris avalanches near the slope toe increased with the deflection angle.