采空区顶板-矿柱支撑系统失稳破坏研究

Study on Instability and Failure of Roof-Pillar Support System in Goaf

为研究采空区顶板-矿柱的失稳破坏机制,在现场调查某地下大理岩矿的基础上,以采空区最薄弱区域为对象,构建了顶板-矿柱支撑系统力学模型,推导出顶板-矿柱支撑系统最大拉应力计算公式,分析了矿柱间距、矿柱宽度、顶板厚度及顶板跨度对采空区顶板最大拉应力的影响。结果表明:受上覆围岩荷载作用,采空区最薄弱区域为中部区域,应力主要集中于顶板,失稳破坏形式为顶板受拉破坏;其他因素不变的条件下,矿柱间距为12 m时,采空区顶板最大拉应力值最小,最大拉应力随矿柱间距增大先减后增;采空区顶板的拉应力与矿柱宽度、顶板厚度呈负相关,随着矿柱宽度增大,最大拉应力逐渐减小;随着顶板厚度增大,最大拉应力急剧减小;顶板跨度越大,最大拉应力越大,增大速率保持稳定。数值模拟结果及工程实例验证了理论计算公式的科学性和合理性。

In order to study the instability and failure mechanism of the roof-pillar in the goaf,based on the field investigation of an underground marble mine,taking the weakest area of the goaf as the object,a mechanical model of the roof-pillar support system was constructed,and the maximum tensile stress calculation expression of the roof-pillar support system was derived.The influence of pillar spacing,pillar width,roof thickness and roof span on the maximum tensile stress of goaf roof were studied.The results are concluded as follows.Firstly,under the load of overlying surrounding rock,the weakest area of the goaf is the middle area,the stress is mainly concentrated on the roof,and the form of instability failure is roof tension failure.Secondly,keeping other factors unchanged,the maximum tensile stress decreases firstly and then increases with the increase of pillar spacing,and it reaches the minimum point when the pillar spacing is 12 m.Thirdly,the pillar width and roof thickness are negatively correlated with the tensile stress.With the increase of pillar width,the maximum tensile stress gradually decreases.With the increase of roof thickness,the maximum tensile stress decreases sharply.Finally,the larger the roof span,the greater the maximum tensile stress,and the increasing rate remains stable.Combined with numerical simulation and engineering examples,the scientificity and rationality of theoretical calculation have been verified.