基于离散元法的采动顺层岩质斜坡变形破坏响应特征研究

Deformation and failure response of the bedding rock slope induced by the underground mining activities based on the distinctive element method

地下采矿影响下顺层岩质斜坡极易发生采动顺层滑坡,且往往规模大,危害极严重。采用UDEC离散元法,将不同地表斜坡与采空区之间的空间位置关系归纳为地下单区段开采、跳采、顺坡开采、逆坡开采4种开采程序,并分别研究其对顺层岩质斜坡的变形破坏响应特征。结果表明:4种地下开采程序影响下,顺层岩质斜坡均出现拉裂、破裂、滑移破坏现象,但变形破坏程度不同;开采影响范围内,顺层岩质斜坡坡面出现明显上开口、下开口2类裂缝,由坡面受拉伸变形引起上开口裂缝,因岩体向采空区方向卸荷下沉产生下开口裂缝;顺层岩质斜坡的上层岩体不仅向采空区方向下沉,还沿岩层面或软弱夹层向临空方向滑移;逆坡开采诱发顺层岩质斜坡变形破坏最为严重,且发生失稳滑坡的危险性最大。采动顺层岩质斜坡变形破坏响应特征研究为采动顺层岩质斜坡机理研究奠定了基础,可为采动顺层岩质斜坡稳定性分析提供一定的理论支撑。

The given paper intends to trace and examine the movement,deformation and failure of the bedding rock slope induced in the mountainous areas. As is well known,underground mining often leads to the development of geological disasters,such as landslides and collapses. It is just for the reasons of such accidents that we have developed and adopted the so-called UDEC numerical simulation analysis method to deal with the slowly inclined single coal seam by the long-wall mining method,with the goaf being treated by the full subsidence method. And,then,we have traced and examined the deformation and failure response mining modes under the bedding rock slope through 4 mining steps,including the single-section mining,leaping mining,mining along the slope,and mining against the slope. The results of our examination and investigation show that: Different underground mining steps can help to formulate different positional relations among the slopes and goaves,which are likely to lead to different degrees of deformation and destruction in the slopes. However,when the rock mass were to be unloaded and deformed towards the goaf in the 4 types of mining steps,the bending and tension failure would occur in all the strata and then lead to plastic deformation in the weak interbeds,resulting in the so-called tension cracking,fracture,and,then,the slip failure;There were two kinds of cracks in the bedding rock slope body under the influence of mining,which were the upper opening and the lower opening. The upper opening cracks occurred at the boundary of mining influence area,which were mainly caused by the tensile deformation of slope surface. While the lower opening cracks occurred in the middle of the mining influence area,which were mainly caused by the movement of rock mass and surface to the goaf;And,next,the impact of the underground mining would not only be induced to cause the upper rock mass of the bedding rock slope to sink in the direction of the goaf,but also is likely to lead to the outward dipping slid towards the rock surface or the weak interlayer. And,Under the mining impact,it would be inevitable to induce slip by the mining activities,though such mining bed landslide does not occur after mining in all the cases. And,therefore,among the 4 mining steps,the most serious unhappy ones are the deformation and failure of the bedding rock slopes induced by the so-called mining against the slope due to the instability and landslide. Thus,it can be concluded that the results of our study in this paper on the deformation and failure response specialties of bedding rock slope induced by the underground mining can be expected to lay a foundation for the studies in this line and,therefore,can be taken as a faithful theoretical support for the stability analysis of the mining-influenced bed-rock slopes.