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为研究煤炭地下气化过程中覆岩的运移规律,以乌兰察布煤炭地下气化试验区工程地质条件为研究背景,首先进行了高温下煤层顶板的物理力学特性测试,获得了不同温度下岩体(粉砂岩、泥岩、细砂岩、粗砂岩、砂质泥岩)的比热容、导热系数、单轴抗压强度及弹性模量;其次建立了相似材料物理模型,分析了燃空区覆岩运移规律。结果表明:在100~1 000℃内,随温度升高比热容及导热系数呈现下降趋势,而在100~750℃内,随温度升高单轴抗压强度呈现增大趋势;乌兰察布煤层气化时,覆岩运移规律与井工开采类似,具有初次来压及周期来压特征,初次来压步距为42 m;亦存在明显的三带分布,即冒落带、垮落带和弯曲下沉带,导水裂隙带高度为28 m;覆岩运移过程中对燃气管亦产生较大的影响,其中1#燃气管在煤层顶板上方26~28 m处受到的水平应力最大,为最易变形断裂位置;在现场用钻孔探测法进行验证,得出导水裂隙带的高度为31.21 m,与相似模拟试验得出的数据吻合,证明了相似材料物理模型的合理性。
In order to study the rule of overburden strata migration during coal underground gasification process, taking the engineering geological conditions of WUMC as an example, the physical and mechanical properties of coal seam roof under high temperature were tested first, The specific heat capacity, the thermal conductivity, the uniaxial compressive strength and the elastic modulus of the lower rock mass (siltstone, mudstone, fine sandstone, coarse sandstone and sandy mudstone). The similar material physical model was established and the overburden rock Movement rules. The results show that the specific heat capacity and thermal conductivity decrease with increasing temperature from 100 to 1 000 ℃, while the uniaxial compressive strength increases with increasing temperature from 100 to 750 ℃. The Wulanchabu coal seam During gasification, the law of overlying strata migration is similar to that of the well excavation. It has the characteristics of initial compressive force and periodic compressive force. The pressure step for the first time is 42 m. There are also obvious three-zone distributions, that is, the caving zone, caving zone And bending sink zone, the height of water-conducting fractured zone is 28 m. During the course of overburden migration, the gas pipe also exerts great influence. The horizontal stress of 1 # gas pipe at 26 ~ 28 m above the roof of coal seam is the largest , Which is the easiest to deform and rupture. On the spot, the hole detection method is used to verify that the height of the water-conducting fracture zone is 31.21 m, which is in good agreement with the data from similar simulations. It proves the rationality of physical models of similar materials.