基于组合楔形体原理的采动坡体稳定性研究

地下采煤通常会引起地表严重开裂,甚至发生滑坡、崩塌等地质灾害,采动坡体的稳定性研究一直是工程实际关心的问题。本文以贵州省都匀市煤洞坡采动坡体为例,在斜坡破坏机制分析基础上,采用组合楔形块体原理构建了采动坡体稳定性系数计算方程,并从实验、经验类比、采空率等方面对采动坡体的强度指标进行了综合取值,计算了采动坡体在天然、饱水及裂隙水作用下的安全系数。结果表明:煤洞坡山体是处于稳定状态的,这与坡体上的裂缝位移监测成果是相符的。但在长时间降雨或暴雨情况下,煤洞坡山体稳定性就会逐渐变差,甚至发生滑动; 坡体稳定性安全系数随内摩擦角的降低而降低,随裂隙水充水高度的增加而降低; 一旦后缘块体挤压前缘块体时,就会存在一个安全系数急剧降低的阀值。从裂缝水柱高度与降雨渗入裂缝的雨水量关系出发,建立了裂缝水柱高与降雨量之间关系式。经计算当降雨量(短时间内)超过192mm,斜坡就会失稳。

STABILITY OF MINING SLOPE USING PRINCIPLE OF COMBINING WEDGE BLOCKS

The underground mining can usually cause the surface crack and even geological disasters such as collapse and landslide. Stability of mining slope has been the practical concern. This paper takes the Meidongpo slope of underground mining as an example. It is in Duyun city of Guizhou province. The paper formulates a stability calculation equation of mining slope on combined wedge block principle. The formulation is based on slope failure mechanism analysis. The calculation of slope safety factor is carried out under the natural, water-saturated and fissure water filling situation. The comprehensive value of strength parameters is based on experiment, and analogy experience method, and mining empty rate. These results show that the Meidongpo mining slope is usually in a stable state, but its stability becomes worse in long-time rainfall or rainstorm condition, and even unstable. The safety factor of Meidongpo slope decreases as the internal friction angle decreases and the height of fissure water filling increases. Once the back block extrudes front block, there can be a threshold that the safety factor decreases sharply. It formulates a formula of depth of fracture water with rainfall from the relationship between depth of fracture water and rainfall infiltration of crack. It finds that the slope can fail when the rainfall exceeds more than 192mm in a very short time.