高级检索

采动影响下底板岩体及巷道破坏时空演化特征分析

Analysis of spatiotemporal evolution characteristics of floor rock mass and roadway failure under mining influence

  • 摘要: 明确工作面底板采动应力分布规律,实现采动影响下底板岩体及巷道破坏程度的精准把握,能有效防止底板巷道的变形失稳。为此,根据极限平衡理论,构建煤岩体超前采动应力力学模型,获得支承压力扰动阶段和采空区卸压阶段底板岩体的力学分布规律,并基于压剪破坏准则及岩体卸荷损伤机制,得到底板岩体及巷道围岩破坏时空演化特征,进一步采用数值模拟进行可靠性验证。结果表明:采高增大,工作面前方煤体塑性区范围增大,超前支承压力集中系数减小;超前采动支承压力越大,底板岩体内主应力差越小,莫尔应力圆半径小,对底板的影响强度减弱,具体表现为底板岩体压剪破坏深度的减小;卸荷后底板岩体受力状态相同,岩体卸荷起点的增大,卸荷量增加,卸荷张拉破坏加剧,底板岩体塑性区呈“马鞍形”;推进过程中巷道围岩塑性区发生由“椭圆形”−“蝶形”−“竖直椭圆形”时空演化特征,采动支承应力越大,巷道破坏越严重,破坏主要集中在顶板及肩角位置。设计初采高度为3.5 m,通过布设光纤测试系统,得到采动过程中底板岩体及巷道随工作面推进变形与破坏的时空演化规律,测得底板岩体破坏深度最大为16.7 m,巷道围岩破坏深度最大为5.2 m ,巷道围岩体在整个监测期间内保持稳定,没有发生破坏性影响,满足生产安全需求。

     

    Abstract: Clarifying the distribution law of mining induced stress in the working face floor, achieving precise grasp of the degree of damage to the floor rock mass and roadway under the influence of mining, can effectively prevent deformation and instability of the floor roadway. To this end, according to the limit equilibrium theory, the mechanical model of advanced mining stress of coal and rock mass is constructed, and the mechanical distribution law of floor rock mass in the supporting pressure disturbance stage and the goaf unloading stage is obtained. Based on the compression shear failure criterion and rock unloading damage mechanism, the spatiotemporal evolution characteristics of floor rock and tunnel surrounding rock failure were obtained, and further reliability verification was conducted using numerical simulation. The results show that as the mining height increases, the range of plastic zone in front of the working face increases, the concentration coefficient of advanced support pressure decreases; The larger the supporting pressure of the advanced mining, the smaller the principal stress difference in the bottom slate rock body, and the smaller the Mohr stress circle radius, and the strength of the impact on the bottom plate weakens, specifically manifested as a decrease in the depth of rock compression shear failure in the bottom plate; After unloading, the stress state of the bottom rock mass is the same. With the increase of the unloading starting point of the rock mass, the unloading amount increases, and the unloading tension failure intensifies. The plastic zone of the bottom rock mass presents a “saddle shaped” shape; During the advancement process, the plastic zone of the surrounding rock of the tunnel undergoes a spatiotemporal evolution from “elliptical” to “butterfly” to “vertical elliptical”. The greater the mining support stress, the more severe the tunnel damage, and the damage is mainly concentrated in the roof and shoulder corners. The initial mining height is designed to be 3.5 m. Through the deployment of an optical fiber testing system, the spatiotemporal evolution of deformation and failure of the floor rock mass and roadway during the mining process as the working face advances was obtained. The maximum depth of damage to the floor rock mass was measured to be 16.7 m, and the maximum depth of damage to the roadway rock mass was 5.2 m. The surrounding rock mass of the tunnel remains stable throughout the entire monitoring period, without any destructive effects, meeting production safety requirements.

     

/

返回文章
返回