高位远程滑坡动力侵蚀犁切计算模型研究

A dynamic erosion plowing model of long run-out landslides initialized at high locations

高位远程滑坡通常具有典型的动力侵蚀特征,导致滑坡体积明显放大和运动距离明显增加,从而因成灾范围的误判引发严重的地质灾害。本文提出一种适用于滑坡动力侵蚀过程计算的犁切模型,该模型建立在滑块–弹簧模型和犁耕阻力模型的基础上,认为:在滑坡失稳剪出后的运动过程中,滑块底部阻力会对堆积物产生铲刮力,形成铲刮层。铲刮层推挤前部堆积物,并受到阻力,类似犁推挤土垡变形,即犁切阻力。根据犁切阻力、犁切被动区与运动轨迹之间关系,提出犁切模型挤压式与剪出式两种形式,建立相应的力学表达式和编制相应的二维计算程序。运用该程序分析新疆新源阿热勒托别滑坡远程运动特征,揭示不同比阻条件下计算所得犁切体积和深度的趋势。此外,进一步与已有的雪橇模型、等效流体模型、液化模型计算结果对比分析,表明:犁切模型总体趋势上与等效流体模型和雪橇模型较为接近,并较液化模型稳定,但速度峰值均小于上述其他模型,其主要原因是空间犁切造成的耗能作用。作为一种可定量计算动力侵蚀过程中滑坡体积增量的力学模型,该模型概念清晰,计算简便,是滑坡动力学分析的一种新方法。

The high-location and long run-out landslides usually have typical dynamic erosion characteristics,resulting in obvious increments of both the landslide volume and the moving distance,and consequently,inducing serious geological disasters due to misjudgment of the disaster area. In this paper,a new dynamic erosion model for evaluating the plowing behaviors of a long run-out landslide through the substrate’s surface material was proposed based on the sliding block-spring model and the plowing resistance model. The developed model describes that,during the movement of sliding blocks,the resistance at the base produces a scraping force on the substrate’s surface material and a scraping layer forms,and that the scraping layer pushes against the front accumulation,similar to plowing a field,and will be subjected to reaction named as plowing resistance. According to the relationships among the plowing resistance,the plowing passive zone and the motion path,two detailed kinds of plowing models including pushing and shearing types were put forward. The corresponding mechanical expressions of the base resistance were established and a two-dimensional program was compiled. Areletuobie flowslide in Xinyuan county,Xinjiang Autonomous region,was illustrated to analyze the motion features of long run-out landslides, and variations of the plowing volume and depth with the specific resistance were revealed. Comparisons among the developed model,sled model,equivalent fluid model and liquefaction model show that the developed model has a similar trend with the equivalent fluid model and the sled model,and is more stable than the liquefaction model. It is also shown that the peak value of the movement velocity calculated by the developed model is smaller than that by the other three models,which is mainly due to the energy dissipation of spatial plowing effect. As a mechanical model which can quantitatively calculate the volume increment of landslides in the process of dynamic erosion,the developed model has clear concept and simple calculation,and provides an effective supplement to the kinematic model of landslides.