布尔台煤矿侏罗纪沉积岩特征及对物理力学性质的影响

Characteristics of Jurassic sedimentary rocks and its influence on physico-mechanical property in Buertai Mine

为了查明布尔台煤矿侏罗纪砂岩微观特征与其物理力学性质的定量关系,通过岩石单轴抗压实验、薄片偏光显微镜试验和声波速度测定试验,研究了岩样微观结构、宏观力学性质和声波速度,并采用数理统计方法定量分析了侏罗纪砂岩平均粒径、颗粒分选性对其宏观力学性质和声波速度的影响。结果表明:布尔台煤矿沉积岩微观结构特征影响岩石的宏观力学性质,碎屑颗粒平均粒径减小、分选程度好,导致岩石密实度增大,孔隙度减小,岩石的力学性质增强,这一特征有别于石炭二叠纪煤系砂岩,后者的力学强度随粒度增加有增大趋势;岩样平均粒径、分选性影响其声波速度,当岩样平均粒径减小,碎屑颗粒分选性越好,则其致密性越高,岩样的声波速度越大。

In order to reveal the quantitative relationship between the microscopic features of the Jurassic sandstone and the physical-mechanical properties in Burtai Mine,a rock uniaxial compressive test,thin slice polarization microscope experiment and acoustic velocity measurement experiment were applied to study the micro structure of the rock sample,the macro-mechanics property and acoustic velocity. A mathematical statistics method was applied to quantitatively analyze the average particle size and particle selectivity of the Jurassic sandstone affected to the macro-mechanical properties and acoustic velocity. The results showed that the micro structure features of the sedimentary rock in Buertai Mine affected to the macro mechanics properties of the rock. The average partical size of the clastic partical was reduced and the sorting degree was good,thus the rock compaction was increased,the porosity was decreased and the rock mechanical property was enhanced. The features were different to the Carboniferous Permian coal measural sandstone. The mechanics strength of the coal measure sandstone would have an increased tendency with the partical size increased. The average partical size of the rock samples and the sorting would be affected to the acoustic velocity. When average partical size of the rock samples was reduced,the selectivity of the clastic particles would be better,the compaction would be higher and the acoustic velocity of the rock sample would be higher.