基于离散元法的采空区诱发斜坡变形破坏过程研究

Discrete element method-based study on failure process of goaf area-induced slope deformation

为研究节理条件下采空区对岩质斜坡变形破坏过程的影响,以贵州省清镇市小二岩危岩体为研究对象,运用PFC 2D模拟采空区影响下岩质斜坡渐进破坏过程,并在模拟过程中分别对斜坡坡顶、坡脚、采空区、采空区上方地表四个位置进行监测。初步研究发现:小二岩斜坡为缓倾上硬下软型结构,由于地下采煤导致小二岩斜坡出现变形,在开采作用下其主要的变形方式有采空沉陷和坡顶拉裂;研究区内节理裂隙发育,岩体被节理切割成块体,地下开采后,引起坡顶岩体应力变化,拉裂隙沿节理面产生,岩体发生累进性破坏,为崩塌的发生提供了积极条件;分析认为在对斜坡体进行节理化后,节理对于斜坡的变形具有指引作用,斜坡在采空区变形位置沿节理向陡崖顶部产生大量的拉张裂隙并且最终贯通,与小二岩斜坡的实际变形相近。

In order to study the impact from goaf area on the failure process of rocky slope deformation under joint condition,the progressive failure process of rocky slope under the impact from goaf is simulated with PFC 2D by taking the dangerous rock mass of Xiaoer Rock Formation in Qingzheng City of Guizhou Province,while the four locations,i.e.the rocky slope crest,the slope toe,the goaf area and the ground surface upon the goaf area,are monitored respectively during the simulation.The preliminary study finds out that the slope of Xiaoer Rock Formation is a gently inclined upper-soft and lower-hard structure.Due to the deformation of the slope of Xiaoer Rock Formation caused by underground coal mining,the goaf-settlement and the tensile splitting of slope crest are the main deformation modes under the mining effect.The joint fissures develop within the study area,and then the rock masses are cut into blocks by the joints.After the underground mining,the stress of the rock mass on the slope crest changes,while tensile fissures occur along joint planes,thus progressive failures of the rock masses occur and provide the active condition for the occurrence of collapse.The relevant analysis considers that joint has a leading role on the deformation of the slope after jointing the slope rock mass,while large amount of tensile fissures occur from the deformation location of the goaf area to the crest of the steep cliff along joints and finally break through,which is similar to the actual deformation of the slope of Xiaoer Rock Formation therein.