梯形载荷煤柱底板偏应力分布规律与工程案例

Engineering cases and deviatoric stress distributions under trapezoidal load in coal pillar floor

  • 摘要: 建立梯形载荷作用下底板偏应力分布的力学模型,推导出煤柱底板最大主偏应力公式, 并得出不同载荷跨度与不对称系数等因素下的底板偏应力场响应特征。结果表明:①随着载荷 跨度减小,底板偏应力值整体呈减小趋势,两侧底板区域的高偏应力集中区不对称程度减弱,且 最终会出现汇合,形成一个连续的“苹果”形高偏应力区。②当1<λ≤4时,呈现出与载荷高低相 一致的不对称马鞍型分布;随着λ值增加,不对称性加剧,高载荷侧极大值增长速率明显高于低 载荷侧;极小值呈线性增长,且其位置向低载荷侧转移。③载荷跨度为3 5m时,随着深度增加, 偏应力非对称性趋势变缓,而在底板一定范围内存在一个较为明显的低偏应力区,可作为巷道布 置的较理想区域。结合新阳矿地质生产条件和力学分析结果,将新10 2材料巷布置在 x=15m 处,确定了高预应力强力锚杆(索)支护方案,进行了现场试验,取得了良好的控制效果,为近距 离下部煤层巷道布置和围岩控制提供了理论依据和技术借鉴。

     

    Abstract: A mechanical model of the deviatoric stress distribution of the floor under the trapezoidal load was established , and the maximum principal stress formula of the floor under coal pillar was derived, and the response characteristics of the deviatoric stress field of the floor under the different load spans and the asymmetry coefficient were obtained.With the decrease of the load spans, the deviatoric stress value of the floor was decreased ,and the degree of asymmetry of the high deviatoric stress concentration area in the two sides of the floor was weakened , and eventually there was convergencing to form a contimuous high deviatoric stress area shaped like“apple”".When l<入≤4, the distribution is asymmetry saddlle type consistent with the load level.With the increase of 入 value , the asymmetry was increased,and the growth rate of the high load side was significantly higher than that of the low load side.The minimum value increased linearly , and its position is shifted to the low load side.When the load span was 35 m,with the increase of depth , the asymmetric trend of the deviatoric stress became slow , while there was a relatively obvious low deviatoric stress area in a certain range of the floor , which could be used as the ideal area of roadway layout.Combined with the geological conditions and mechanical analysis of Xinyang coal mine , the Xin No 102 material roadway was arranged at x= 15 m, and the supporting scheme of the high prestress and intensive bolt ( cable) was determined.We carried out the field tests and achieved good control effects. These provide theoretical basis and technical reference for the roadway layout and control of surrounding rock in the lower seam of close distance coal seams.

     

/

返回文章
返回