基于PFC2D的缓倾顺层滑移-溃曲型岩质滑坡破坏机制分析

The deformation mechanism analysis of gently inclined and consequent sliding-buckling rock landslides based on PFC2D

摘要:

川东红层地区岩层倾角通常较缓，在缓倾顺向斜坡上出现了一种较为特殊的滑移-溃屈变形破坏形式。相对于缓倾岩层的顺层滑移，其破坏、受力和变形显得较为复杂。本文在分析兴浪坡滑坡变形模式的基础上，基于PFC2D软件对其进行破坏过程及微观力学分析。结果显示：受川东宽缓褶皱影响滑坡所处地形呈上陡下缓的特点，岩层变缓和老滑坡堆积造成的应力集中是斜坡发生滑移-溃曲的原因。变形破坏模式解析其分为滑移-弯曲鼓胀、强烈弯曲-隆起和滑移-溃屈破坏3个阶段。模型破坏云图位移显示滑坡中部监测点2位置存在应力集中导致的岩体错断和剪断特征，与实际调查相符合。滑坡中部溃曲处在滑动前主要表现为压应力集中，当应力集中到一定程度，岩体沿着层面或破碎带剪切贯通，形成滑移-弯曲-溃曲变形模式。研究结果对于其他类似边坡的稳定性评价和识别具有参考意义。

Abstract:

The dip angle in the red bed of eastern Sichuan is generally relatively small， a special form of sliding-buckling deformation appears on the gently inclined and consequent slope. Compared to bedding-sliding， its failure、 stress and deformation are more complicated. In this paper， based on the analysis of the deformation mode of Xinglang slope， the damage process and micromechanical analysis are carried out based on PFC2D software. The results revealed that： due to the topographic features of steep at the top and slow at the bottom which affected by the wide and gentle folding in east Sichuan， the main reason why the sliding-buckling happens is the stress concentration caused by the gentle rock stratum and old landslide accumulation. The deformation damage mode is analyzed into three stages： sliding-bending bulging， strong bending-bulging and sliding-buckling. The displacement of the model damage nephogram shows that the rock body faults and shear characteristics due to stress concentration exist at the location of monitoring point 2 in the middle of the landslide， which is consistent with the actual investigation. The central buckling of the landslide shoed compressive stress concentration before sliding， when the stress concentrated to certern degree， the rock mass sheared along the bedding or the break zone， by which the deformation pattern of sliding-bending-buckling formed. The research has referrencical significance for the stability evaluation of other similar slope.