大变形回采巷道蝶叶型冒顶机理与控制

大变形回采巷道冒顶控制问题一直以来是制约煤矿安全高效回采的重大难题,根据巷道围岩蝶形塑性区理论,以保德矿大变形回采巷道围岩非均匀破坏为背景,分析了回采巷道采动应力场的非均匀演化规律及其作用下的塑性区形态特征。研究表明:1高偏应力环境下巷道围岩塑性区会呈现蝶形分布,蝶形塑性区具有方向性,蝶叶位置会随着主应力方向的变化而改变;2受采动影响后,回采巷道围岩中会产生较大偏应力,且最大主应力方向向回采工作面一侧发生倾斜偏转,使蝶叶位于巷道顶板;3顶板蝶叶内岩石遭到严重破坏,同时伴有巨大膨胀压力和强烈变形,当锚杆(索)不能承受蝶叶内围岩重量时,巷道便发生蝶叶型冒顶。提出采用接长锚杆控制大变形巷道蝶叶型冒顶的方法,现场应用效果良好,为大变形回采巷道冒顶控制提供了新手段。

Falling principle and support design of butterfly-failure roof in large deformation mining roadways

The roof falling control of large deformation mining roadways has been an important hurdle for safety and high-efficiency production in the past decades in China.This paper,based on the field engineering background of Baode mine and the butterfly-failure theory of mining roadways,analyses the non-uniform evolution law of mining stress field and the characteristics of plastic zones under its influence.The results show that the plastic zone of mining roadways could be a butterfly-failure distribution under the high deviatoric stress condition,and the butterfly-failure zone is direction independent which means the position of butterfly-failure wing is variable with the direction change of principle stress.High deviatoric stress may occur around the roadways under the influence of mining disturbance,and the direction of maximum principle stress tilts towards working face,which keeps the butterfly-failure wing stay at the roadway roof direction.The roof strata staying in this butterfly-failure wing suffers heave damage companying with strong dilation and deformation.In addition,when the rock weight in this butterfly-failure wing exceeds the loading threshold of bolts or anchor cables,it triggers the roof falling.Also,the authors proposed a support design with long bolts to control the butterfly-failure-trigged roof falling,and the field application gives a good feedback.The long bolts support design offers a new solution for roof falling control in large deformation roadways.