溃散性滑坡成因机理初探

Study on Formation Mechanism of Diffuse Failure Landslide

通过对多起由饱水松散颗粒材料构成的滑坡案例的调查研究,总结了此类滑坡的共性特征,即表现出显著的整体性坍塌并伴有突然破坏、静态液化和高速远程流动性运动等独特现象,认为其与国际土力学界新发现的溃散性破坏(diffuse failure)极为吻合,是区别于局部化破坏(localized failure)的一类新的失稳破坏模式.借助物理模拟手段,初步探讨了溃散性滑坡的成因机理.结果表明:溃散性滑坡一般发生于松散且具有明显应变软化特征的饱水颗粒材料(粉土、砂、碎石土等)中,当土体受力达到临界失稳状态时,外界微小扰动都可能产生突然整体性破坏;在失稳破坏时表现出明显的孔隙水压力激增和静态液化现象,失稳后土体呈流体状远程运动,易造成灾难性后果,应引起高度重视.

An investigation was made into several landslide cases in recent years to summarize common characteristics of the landslides composed of saturated loose granular materials. These landslides typically exhibited complete collapse accompanied by unique phenomena such as abrupt failure, static liquefaction, and high-speed and long-runout motion. Their failure mechanism was extremely similar to the diffuse failure as discovered in the field of soil mechanics, and hence can be viewed as a new type of landslide failure mode. In addition, the primary failure mechanism of the diffuse landslide was discussed through physical simulation experiment. The results indicate that diffuse landslides generally occur to saturated loose granular materials with evident strain-softening characteristics, such as silt, sand, and gravel soil. As the stress in the soil reaches the critical state, any external micro-disturbance may trigger an abrupt failure of the slope. The abrupt failure is typically accompanied by an excess pore water pressure and a phenomenon of static liquefaction. After loss of stability, the soil generally undergoes a rapid flow-like mass movement, which may result in catastrophic geological disasters and should be highly valued.