苏门答腊岛西北海域大型海底滑坡过程反分析

针对苏门答腊岛西北海域大型海底滑坡，建立基于欧拉-欧拉多相流理论的滑坡模型，对滑坡体动态运动过程开展模拟反分析。通过与BING程序和解析模型结果对比，考虑土体分段软化后的多相流模型能够较好的重现该滑坡体的运动过程，能获得与实际海底滑坡相近的沉积形态和滑动距离。分析结果表明滑动首先从坡角较大处开始，并逐渐推动中、前部坡度较小处土体滑动；滑坡体整体启动后沿斜坡逐渐加速，当滑动至斜坡底部时端部峰值速度达到最大值43 m/s，之后逐渐减速并在深海平原处停止运动；土体扰动以及混水后土体强度降低是海底滑坡长距离运移的根本原因，同时滑动过程中滑坡体端部发生的滑水效应，减小了海床摩擦力的影响，增加了滑坡体的运动距离。

BACK CALCULATION OF SUBMARINE LANDSLIDE IDENTIFIED IN THE NORTHWEST COAST OF SUMATRA

A numerical model based on Eulerian-Eulerian multi-phase flow model is established to back-calculate the behavior of the submarine landslide identified in the deep water off the northwest coast of Sumatra. Compared with the BING results and analytical results, the numerical model with the consideration of soil strength reduction can provide a valuable mass movement process for the submarine landside, with final deposition patterns and runout distance similar to the identified parameters. The result shows that:the landslide takes place firstly at the part with larger slope angle, and then the left part with lower slope is pushed forward; the landslide is accelerated gradually along the slope, until reaching the slope toe with a peak front velocity of 43 m/s, then it is decreased gradually and stopped on the abyssal plain. Soil strength reduction, caused by disturbance and invasion of ambient water, is the basic reason for the longer runout distance of the submarine landslide. Hydroplaning was proved to occur during the movement, which could reduce the seabed friction and promote the moving distance obviously.