深部矿区煤岩体强度测试与分析

TEST AND ANALYSIS OF COAL AND ROCK MASS STRENGTH IN DEEP COAL MINE

基于钻孔触探法原理,开发出小孔径井下煤岩体强度测定装置。在实验室对34个煤岩样品进行试验:在煤岩块上钻取标准试件,测量单轴抗压强度;在留下的钻孔中,用煤岩体强度测定装置测定探针临界载荷,分析探针破坏钻孔壁煤岩的形态;然后确定煤岩块单轴抗压强度与探针临界载荷的关系。试验表明,探针破坏钻孔壁煤岩的形状、深度及范围与煤岩性质密切相关。煤岩体强度越高,破坏范围、侵入深度越小,破坏形状越规则。结合井下实测数据,回归得出描述探针临界载荷与煤岩体单轴抗压强度关系的公式。同时,分析临界载荷的离散性及控制措施,讨论结构面对煤岩体强度的影响及测试分析方法,并在典型的深部矿区——新汶矿区进行井下原位测试。新汶矿区巷道顶板不同岩性的岩层强度相差很大,不同矿井的岩层强度也存在明显差别。煤层强度由于煤帮出现破碎区、煤层性质不均匀、煤层结构面分布不均匀等原因变化较大,出现明显的波动。基于井下煤岩体强度实测数据的巷道支护设计,符合井下环境中的煤岩体条件,设计的合理性与可靠性显著提高,巷道围岩稳定性与支护状况得到明显改善。最后分析钻孔触探法存在的问题,并提出改进建议。

The borehole penetrating method can rapidly and accurately test the uniaxial compressive strength（UCS） of coal and rock mass. Based on the principle of this method, the underground testing apparatus for coal and rock mass strength with small borehole is developed. 34 pieces of coal and rock blocks are tested. The standard samples are drilled from the coal and rock blocks. The uniaxial compressive strengths of the samples are measured; the critical load of the penetrating needle is measured with the testing apparatus in the reserved borehole; and the coal and rock damage patterns on the borehole walls are analyzed. Then the relation between the UCS of coal and rock blocks and the critical load of the penetrating needle is determined. The experiment points out that the forms, depths and scopes of the damage pits caused by the needle in the borehole walls are closely related with coal and rock properties; the higher the coal and rock strength is, the smaller the damage area and the penetrated depth are, and the more regular the pit form is. The formula describing the relation between the penetrating needle critical load and the UCS of coal and rock mass is obtained by the regression of laboratory data combined with underground measurement data. Meanwhile, the discrete property of the critical load and its controlling measures are analyzed; and the influence of structural planes on the coal and rock mass strength and its testing methods are discussed. The in-situ tests are carried out in typical deep coal mining area--Xinwen coal mines. There are great differences among the strengths of roadway roof strata with different lithological characters; and the strata strengths are also different in various coal mines. The coal seam strengths vary and fluctuate considerably along the test borehole because of the broken zone around coal sides, coal heterogeneity and nonuniform distribution of structural weakness planes in coal mass. The supporting designs accord with the coal and rock mass conditions in underground mines on the basis of the in-situ measurement of coal and rock strengths; and the rationality and reliability of the roadway supporting designs are improved remarkably. The stability of the surrounding rock and roadway supporting states are obviously improved. Finally, the present problems of the borehole penetrating method are analyzed; and the improvement proposals are put forward.