Parameter design of coal pillar in highwall mining under action of dynamic-static load
JIANG Juyu;LU Ye;CAO Lanzhu;FU Tianguang;WANG Dong;WANG Laigui;CAI Mingxiang;LI Lei
应用端帮采煤机开采工艺回收端帮压覆滞留煤资源时,支撑煤柱合理宽度的确定是影响其安全、高效推广应用的一个关键性要素,尤其是考虑爆破振动效应对支撑煤柱稳定性的影响。以平朔安太堡露天矿南端帮为工程背景,采用现场测振试验、理论分析、数值计算研究边坡三角载荷和爆破振动作用下端帮开采支撑煤柱稳定性及其参数设计方法。基于极限平衡理论和尖点突变理论,运用Mohr-Coulomb屈服准则,分析了煤柱弹塑性区分布规律;建立了受采高、采宽、上覆岩层载荷应力、煤柱黏聚力与内摩擦角等因素影响下的煤柱极限强度函数表达式;建立了不同安全储备系数条件下煤柱最大允许塑性屈服区宽度及煤柱留设宽度计算式。建立了支撑煤柱三维简谐振动响应模型,研究了单响药量、高程差、爆心水平距等爆破参数对煤柱瞬时最大动应力响应影响规律,揭示了爆破动载效应对支撑煤柱塑性区宽度和稳定性的影响机制,提出了爆破动载作用下支撑煤柱参数设计方法。研究结果表明:爆破振动对支撑煤柱稳定性影响较大,爆破动载作用下煤柱瞬时最大动应力响应与单响药量呈正相关关系、与高程差和水平距离呈负相关关系。随煤柱瞬时最大动应力响应增加,煤柱塑性区宽度呈正比例增大,煤柱安全系数以近似线性规律衰减。确定动−静载下煤柱留设宽度为5 m,经工程实践,验证了其合理性。
In view of the application of end slope shearer mining technology to recover a large amount of residual coal, the determination of reasonable width of supporting coal pillar is a key factor whether it can be safely and efficiently popularization and application, especially considering the influence of blasting vibration on the stability of supporting coal pillar. Based on the southern end slope at the open-pit coal mine of Pingshuo, field vibration test, theoretical analysis and numerical calculation were used to study the web pillar stability in open-pit highwall mining and its parameter design under the action of triangular load and blasting vibration on the side slope. Based on the theory of limit balance and the mutation theory, the stress distribution at the coal pillar was analyzed, combined with Mohr-Coulomb failure criterion. Besides, the ultimate strength function expression of coal pillar under the influence of mining height, mining width, load stress of overlying strata, cohesion and internal friction angle of coal pillar is established. The calculation formula of the maximum allowable plastic zone width and rational width of web pillar under different safety reserve factor conditions are established. The three-dimensional simple harmonic vibration response model of the supported coal pillar was established, and the blasting parameters such as the amount of single shot, elevation difference and horizontal distance of the blast center were studied on the response of the maximum instantaneous dynamic stress of the coal pillar, which revealed the influence mechanism of the blasting dynamic load effect on the width and stability of the plastic zone of the supported coal pillar and proposed the design method of the parameters of the supported coal pillar under the blasting dynamic load. The results show that the blasting vibration has a greater influence on the stability of coal pillar, and the instantaneous maximum dynamic stress response of coal pillar under the blasting dynamic load is positively correlated with the amount of single shot, and negatively correlated with the elevation difference and horizontal distance. With the increase of the maximum instantaneous dynamic stress response of coal pillar, the width of plastic zone of coal pillar increases proportionally, and the safety factor of coal pillar decays in an approximately linear pattern. The width of coal pillar under dynamic-static load is determined to be 5 m, and its reasonableness is verified by engineering practice.
open-pit mining;dynamic and static loads;highwall mining;coal pillar;parameter design
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会