废石尾砂充填结构体应力分布与覆岩变形移动规律研究

Study on Stress Distribution and Movement Law of Overburden Deformation of Waste Rock Tailings Filling Structure

废石尾砂交替充填采场由废石和尾砂构成的充填结构体支撑采场顶板,其承载特性无法简单地由某一种材料的变形和强度参数描述,为了探究该充填结构体的应力分布与覆岩变形移动规律,利用大尺寸相似模拟装置对典型缓倾斜薄矿床废石尾砂交替充填开采过程进行模拟,采集、处理并分析采场顶板应力、未采矿岩应力、地表沉降、充填体承载情况和安全系数等指标的演化特征,在此基础上分析了废石尾砂充填结构体的承载和稳定状态。结果表明:废石尾砂充填结构体中由废石充填体承载采区顶板施加的大部分荷载,而尾砂充填体未充分发挥其承载作用,充填效率不高;借鉴高应力巷道柔性支护有效调动围岩自承载能力的理念提出了基于柔性接顶的应力协调思路,即利用弹性模量低于废石充填体的柔性材料前期收缩变形释放顶板一部分压力,调动矿岩和尾砂充填体承载能力并对废石充填体进行卸压。该思路有助于改善废石尾砂充填结构体的不均匀承载状态,提高采场整体安全性和充填效率。

The roof of stope is supported by the filling structure composed of waste rock and tailings in the alternate filling stope with waste rock and tailings,and its bearing characteristics cannot be simply described by the deformation and strength parameters of a certain material.In order to explore the stress distribution and movement law of overburden deformation,the large-scale similar simulation device is used to simulate the alternate filling mining process of waste rock and tailings in a typical gently inclined thin deposit.The evolution characteristics of stope roof stress,unmined rock stress,surface subsidence,filling body bearing and safety coefficient are collected,processed and analyzed.On this basis,load-bearing and stability of waste rock and tailings filling structure are analyzed.The results show that most of the load applied by the roof of the mining area is carried by the waste rock filling body in the waste rock tailings filling structure,and the tailings filling body does not give full play to its bearing effect,and the filling efficiency is not high.Referring to the concept of flexible support in high stress roadway to effectively mobilize the self-bearing capacity of surrounding rock,the idea of stress coordination based on flexible roof connection is proposed,the elastic modulus of the flexible material is lower than that of the waste rock filling body.The early shrinkage deformation of the flexible material releases part of the roof pressure,mobilizes the bearing capacity of the ore rock and tailings filling body and relieves the pressure of the waste rock filling body.This idea helps to improve the uneven bearing state of waste rock tailings filling structure,and improve the overall safety and filling efficiency of stope.