黔北地区牛蹄塘组海相页岩孔隙结构及其非均质性特征

马查拉煤系地层是昌都赋煤带主要煤系地层之一。为明确风化对西藏马查拉煤系地层孔隙结构特征的影响，本文以西藏早石炭世马查拉组剖面不同类型风化岩石为研究对象，利用氮气吸附试验及分形理论对微观孔隙结构及其复杂程度进行研究。试验结果表明：岩石的吸脱附等温线都呈现反“S”型，孔隙结构呈现同质化发展趋势。相对压力(P/P₀)可以根据岩样吸脱附曲线的上升趋势分为小于0.1、0.1~0.45及大于0.45 3个阶段。岩样孔径结构集中分布在1~5 nm范围内，其中泥质碎屑灰岩、粉矿质泥岩、粉砂岩、泥岩和灰岩在1~2 nm范围内孔隙体积较大，煤层的比表面积和孔体积与相邻岩层相比较低。风化煤岩大孔分形维数明显高于小孔，孔隙结构复杂程度更高，煤层及碳质泥岩的孔隙分形维数相较其他类型岩石更低。研究结果可服务于昌都地区开发和灾害防治。

The determination of pore volume and area distributions in porous substances. I. Computations from nitrogen isotherms

Machala coal strata is one of the main coal stratums in the coal-bearing belt of Changdu. In order to clarify the influence of weathering on the pore structure characteristics of Machala coal formation in Tibet,in this paper we took different types of weathered rocks from the Early Carboniferous Machala Formation section in Tibet as the research object,and investigated the microscopic pore structure and its complexity by using nitrogen adsorption test and fractal theory. The test results show that the sorption and desorption isotherms of the rocks show an inverse