多层钒矿体开采应力迁移规律和分布研究

Study on Stress Transfer Rule and Distribution of Multi-layer Vanadium Orebody Mining

针对多层钒矿体重叠分布、相邻矿层开采重复扰动、围岩应力分布复杂等问题,采用理论分析和数值模拟方法,建立了单层矿体矩形采空区围岩应力分布平面模型,并结合数值模拟结果,拟合了单层矿单采场采空区围岩垂直应力峰值变化率与其跨度关系式,分析了单层矿多采场围岩应力叠加特征;在此基础上,定义了双层矿体开采时采空区相对位置关系类型,研究了双层矿采空区不同跨距和垂距对其围岩应力分布特征的影响规律。研究表明:钒矿体采空区围岩存在典型的应力释放、应力跌落、应力增高和原始应力等4区分布特征,采空区跨度越大,其应力峰值越高,且应力增高区以深围岩内的应力变化率随着与应力峰值点距离的增大按照幂函数关系减小,应力跌落区内的应力变化率随着与应力峰值点距离的增大而增大;相邻采空区的应力增高区会在两者间的矿柱内叠加,矿柱内某点的应力变化率为两侧采空区分别在该点引起的应力变化率之和;当下层采空区应力释放区与上层采空区应力增高区重叠时均导致围岩内拉应力增高,当上层采空区的应力释放区与下层采空区任一区域重叠时均导致压应力降低;上下采空区重叠与非重叠区域的交汇处应力变化显著;根据多层矿体开采应力迁移规律,提出采空区强、弱扰动距,划分强扰动区、弱扰动区和无扰动区,为多层矿体开采时合理确定回采参数与回采顺序提供参考。

Aiming at the problems of overlapping distribution of multi-layer orebodies,repeated disturbance of adjacent mining layers and complex stress distribution of surrounding rock,etc.,theoretical analysis and numerical simulation methods are used to establish a plane model of surrounding rock stress distribution in the rectangular goaf of single-layer orebodies,and combine the numerical simulation results to fit the relationship equation between the change rate of the vertical stress peak in surrounding rock in the goaf of single-layer mine and its span,and analyze the characteristics of superposition of surrounding rock stress in multiple stopes of single-layer mine.On this basis,the type of relative position relationship of the goaf during the mining of double-layer orebody is defined,and the influencing pattern of different span and vertical distance of the goaf of double-layer mine on the characteristics of its surrounding rock stress distribution is studied.The study results show that there are four typical distribution characteristics of stress release,stress drop,stress increase and original stress in the surrounding rocks of the vanadium orebody,the larger the span of the extraction zone,the higher the stress peak,and the stress change rate in the deep surrounding rocks of the stress increase zone decreases with increasing distance from the stress peak point accord-ing to the power function relationship,and the stress change rate in the stress drop zone increases with increasing distance from the stress peak point.The stress increase zones in adjacent goafs will be superimposed in the column between them,and the stress change rate at a point in the column is the sum of the stress change rates caused by the goafs on both sides at that point.When the stress release zone in the lower goaf overlaps with the stress increase zone in the upper goaf,it will result in higher tensile stresses in the surrounding rock,and when the stress release zone in the upper goaf overlaps with either area in the lower goaf,it will result in lower compressive stresses.Significant stress changes at the intersection of the overlapping and non-over-lapping areas of the upper and lower goafs.According to the stress migration patterns of multi-layer orebody mining,the strong and weak disturbance distance of the goaf is proposed,and the strongly disturbed area,weakly disturbed area and undisturbed area are divided to provide reference for determing reasonable recovery parameters and recovery sequence of multi-layer ore-body mining.