基于矿柱失稳风险分析的采空区关键矿柱重定义与辨识

Redefinition and identification of critical pillars in goaf based on the risk analysis of pillar instability

采空区大规模坍塌是地下矿山典型灾害之一,采空区内关键矿柱失稳是其发生的重要诱因。为精准辨识采空区内的关键矿柱,基于采空区矿柱群连锁失稳机制与风险理论,完善采空区关键矿柱基本概念,并创新提出一种基于矿柱失稳风险分析的关键矿柱识别方法,主要包含以下步骤:(1)通过现场调研或经验估计,获得采空区矿柱强度分布特征,进而构建采空区矿柱强度概率密度函数;(2)引入应力扩散最大距离公式,计算各矿柱承载应力,从而获得各矿柱的失稳概率;(3)假定任意矿柱率先失稳,通过矿柱应力动态更新迭代方法,计算单矿柱失稳诱发柱间应力传递与矿柱群系统失稳特征;(4)利用采空区矿柱群承载面积损失率指标定量表征单矿柱失稳致灾性(单矿柱失稳诱发采空区坍塌灾害的严重程度);(5)联合矿柱失稳概率及其致灾性,确定各矿柱失稳风险值,取失稳风险值最高矿柱为采空区关键矿柱。将提出方法应用于Fetr6矿区进行验证,结果表明,该方法所需参数较易获取,计算过程简单,物理意义明确,较传统安全系数法结果更科学、合理,有望在实际工程中取得广泛应用。

The large-scale collapse of goaf is one of the typical disasters in underground mines.This disaster is primarily triggered by the instability of the critical key pillar within the goaf.In this paper,to accurately identify the critical pillar in the goaf,the fundamental concept of the critical pillar in goaf is developed based on the cascading failure mechanism of pillar group in goaf and the principles of risk theory.Additionally,a novel method for recognizing the critical pillar is proposed based on a comprehensive risk analysis of pillar instability.The methodology involves several key steps:(1)obtaining the distribution characteristics of pillar strength through field research or empirical estimations,and then establishing the probability density function for pillar strength within the goaf;(2)computing the stress on each pillar by introducing the formula of maximum stress diffusion distance,subsequently,calculating the instability probability for each pillar;(3)utilizing a dynamic updating iterative approach to assess the stress transfer and instability patterns within the pillar group system,considering any pillar as the initial failure point;(4)quantitatively characterizing the consequence of any single pillar instability by using the index of the bearing area loss rate of the pillar group within the goaf,specifically measuring the severity of goaf collapse disasters induced by individual pillar instability;(5)determining the instability risk value for each pillar by calculating the product of the instability probability and its associated consequence.Accordingly,identifying the critical pillar within the goaf as the one with the highest instability risk value.The proposed method is applied to Fetr6 mining area for verification.The results demonstrate that this method is easy to implement,involving straightforward parameter acquisition and calculation processes,while also offering clear physical significance.Furthermore,it proves to be more scientifically and logically sound than the traditional safety factor method.Thus,this method holds promise for wide-ranging applications in practical engineering scenarios.