近距离上行卸压开采间隔层损伤破裂演化及稳定性评价理论

In deep mining, such dynamic disasters as rock burst, coal and gas bump are getting more and more hazardous. Ascending mining is an effective approach for relieving high stress. The stability of inter-layer is a key problem for ascending mining. This project aims at the goal to investigate the mechanical stable criteria of inter-layer which influenced by up and down twice mining actions. The innovative works are needed to research: (1)Scan the micro-structure of rock by SEM, design an experiment by combining digital speckle correlation method, sonic wave test, and MTS815 servo-test system as a integer,in order to modify the Hoek-Brown failure criteria by using sonic wave velocity and fractal dimension of fissures. The modification can satisfy the damage evolution of large scale strata affected by multi-mining actions.(2)Investigate the failure distribution and gradation within the inter-layer affected by up and down twice mining actions,especially obtain the new failure increment affected by the up mining action.(3) Set a mechanical damage model for analysing the stability of inter-layer as well as for recognizating the key strata, by considering strata mechanical properties,mining depth, mining height, mining region, twice mining actions, and so on, in order to obtain a criteria for estimating an optimal thickness of inter-layer which can satisfy both effective relieving stress and keeping inter-layer in a stable state.The research will overcome the shortcoming of determining inter-layer thickness based on mining-coefficient adopted widely at home and abroad, and will supply a theoritcal support for safe and scientific deep mining in our country.

随着开采深度增加，冲击地压、煤与瓦斯突出等动力灾害日趋严重。实践表明，上行卸压开采是有效防治动力灾害的手段，而间隔层稳定性是上行卸压开采安全的关键问题之一。本项目以受上下两次采动影响间隔层稳定性评价为目标，拟开展如下创新性研究工作：(1)在对岩石细观结构SEM扫描基础上，进行数字散斑、声波测试与MTS815伺服系统同步试验，采用声波速度和裂隙分形特征修正Hoek-Brown准则，并用于研究煤矿大范围岩层受多次采动影响损伤破坏演化规律；(2)揭示上下煤层两次采动影响下间隔层内破裂分布及梯度变化规律，特别是上部二次采动导致新增破裂分布；(3)考虑岩层力学性质、采深、采高、开采范围、上下两次采动等因素，建立间隔层损伤破裂演化力学模型并提出稳定性力学条件，获得满足有效卸压与间隔层稳定并举的厚度力学判据。本项目将突破国内外基于采动影响系数来确定间隔层厚度的现状,为深部科学上行卸压开采提供理论支持。

本项目按照计划任务书的要求，采用理论研究、实验室试验、数值模拟与现场监测相结合的方法，围绕近距离上行卸压开采间隔层损伤破裂演化及稳定性评价理论，开展研究取得了如下创新性成果：.（1）建立岩石波速与不同加载条件岩石破裂展布与分维间的关系，并受采动影响岩石破坏 Hoek-Brown准则进行了初步修正，研究结果表明：① 砂岩试件表现为典型的硬岩-脆性破坏，采动影响加剧了岩石的损伤，岩石强度随采动次数增加而越低；② 岩石裂纹越多，岩石破裂越严重，其分维数越大，m、s值及岩体波速都呈线性降低的趋势，表达式为mD=56.4-29.9Dm、sD=5.63-3.06Dm、vD=7693.8-3993.1Dm。（2）研究了上行开采岩层破裂规律. ①发明了间隔层破裂范围与结构特征探测系统，提出岩层破坏度综合评价指标将间隔层破裂程度划分为完整区、轻微破裂区、中等破裂区和严重破裂区，其取值范围分别为0~0.1、0.1~0.3、0.3~0.7、0.7~1.0，其中轻微破裂区关键承载层；② 通过深部多点位移实时监测研究表明，只要下部煤层开采后，间隔层内有稳定关键层，上部煤层开采对间隔层挠动影响很小。（3）对比模拟研究了下行开采岩层破断规律。①对大同矿区试验研究初步发现，近距离煤层开采时，先开采上部煤层后，再下部煤开采后时间隔层将严重破坏、裂隙贯通，形成破断顶板群结构并易诱发强矿压；②得到了多煤层下行开采工作面支护强度计算式。（4）提出了多煤层采动影响下沿空巷旁“柔-强”复合巷旁支护结构力学模型。.发表SCI 论文11篇、EI论文13篇；国内外学术报告23次；获得省部级一等奖2项、二等奖5项；授权国家发明专利14项；培养博士后2名(已出站1名)，博士4名(已毕业2人)、培养硕士13名(已毕业12名)。在覆岩破断群结构演化致灾机理方面取得的理论成果，有力指导了冲击地压灾害防治、无煤柱沿空巷道支护等，获得了显著经济效益和社会效益。