不同煤层富油煤的孔隙发育与强度特征关联性研究

Study on correlation between pore development and strength characteristics of tar-rich coal in different coal seams

在煤矿开采过程中,煤体受外力作用致使孔隙贯通、强度下降,容易引发巷道围岩失稳、顶板垮落等工程灾害。为研究孔隙分布与强度特征间的相关关系及影响机理,选取中国陕北地区榆神府矿区3组代表性煤样(N22、H52、H42煤样),分别开展其孔径分布与强度特征试验,并基于皮尔逊相关系数与能量演化进行分析,研究结论如下:3组煤样均以微孔、过渡孔发育为主,大孔发育极差,抗压强度以N22煤样最高,为31.3 MPa,其次为H52、H42煤样,分别为14.2、12.5 MPa;煤样的总孔隙率及大孔、中孔和过渡孔的分孔隙率均与抗压强度表现出负相关关系,微孔孔隙率与抗压强度呈现出正相关关系;在压缩过程中,微孔有利于煤样压缩时积累弹性应变能U_(e),在一定程度上有利于提高煤样的抗压能力,大孔、中孔及过渡孔则消耗耗散能Ud相互贯通形成裂隙。

In the process of coal mining,the coal body is subjected to external force,resulting in pore penetration and strength decline,which is easy to cause engineering disasters such as roadway surrounding rock instability and roof collapse.In order to study the correlation and influence mechanism between pore distribution and strength characteristics,three groups of representative coal samples(N22,H52 and H42 coal samples)from Yushenfu Mining Area in northern Shaanxi Province of China were selected to carry out the pore size distribution and strength characteristics tests,and the results were analyzed based on Pearson correlation coefficient and energy evolution.The research conclusions are as follows:the three groups of coal samples are mainly developed with micropores and transition pores,and the development of macropores is extremely poor.The compressive strength of N22 coal sample is the highest,which is 31.3 MPa,followed by H52 and H42 coal samples,which are 14.2 MPa and 12.5 MPa,respectively.The total porosity of coal samples and the porosity of large pores,middle pores and transition pores are negatively correlated with compressive strength,and the porosity of micropores is positively correlated with compressive strength.During the compression process,the micropore is beneficial to the accumulation of elastic strain energy U_(e) during the compression of coal samples,and to a certain extent,it is beneficial to improve the compressive capacity of coal samples.Large pores,middle pores and transition pores consume dissipation energy Ud and form cracks through each other.