煤矿安全2025，Vol.56Issue(4)：110-119,10.DOI:10.13347/j.cnki.mkaq.20240441
反复干燥-饱水条件下煤体损伤及分形特征研究
Research on coal body damage and fractal characteristics under repeated drying and saturated water conditions
摘要
Abstract
In order to study the mechanical properties,damage mechanism,and fractal characteristics of coal under repeated drying saturated conditions,through theoretical analysis and laboratory experiments,repeated non-destructive soaking,ultrasonic velocity measurement,uniaxial compression,and acoustic emission testing were conducted on 50 mm×100 mm cylindrical coal body.The ex-perimental results of different drying and saturated cycles show that:as the number of drying and saturated cycles increases,the moisture content of the coal sample gradually increases,the uniaxial compressive strength gradually decreases,and the dissipated en-ergy increases.When the drying and saturated times are 1,2,3,and 4,the moisture content of the coal samples is 6.11%,8.11%,10.77%,and 12.38%,respectively;the average strength of coal samples is 21.6 MPa,18.2 MPa,16.3 MPa,and 13.7 MPa,respect-ively(compared with the natural state of coal,the uniaxial compressive strength of dry and water-saturated coal decreases with the increasing frequency),the total energy of the coal sample specimens is 93.2 J,84.4 J,61.1 J,and 48.2 J(respectively accounting for 80.1%,72.5%,52.5%,and 41.4%of the total energy of the natural coal sample);the damage degree of coal samples varies with dif-ferent drying and water saturation times,and cracks are dissolved and connected with each other,and the pore size,shape and distri-bution change significantly.Different drying and water saturation times caused varying degrees of damage to the coal sample,result-ing in dissolution and interconnection to form cracks,and significant changes in pore size,shape,and distribution;repeated drying and water saturation reduce the fractal dimension of coal fragmentation blocks,that is,the degree of fragmentation decreases,and the number and quality of large blocks increase.Repeated drying and water saturation reduces the fractal dimension of coal fragmenta-tion blocks,that is,the degree of fragmentation decreases,and the number and quality of large blocks increase.The fractal dimen-sion of the fragmented block ranges from 1.7 to 2.1,with an average fractal dimension of 1.92 for natural coal samples.The coal sample has obvious shear cracks and short tensile cracks after failure,and the tensile cracks are mainly through cracks,indicating that repeated drying and water saturation promote the formation of weak surface,and the weak surface penetrating cracks lead to the in-stability of coal specimen.关键词
煤体损伤/干燥-饱水/煤岩浸水强度特征/煤体力学特性/损伤特性/分形特征Key words
coal damage/dry-saturation/strength characteristic of water soaked coal/mechanical properties of coal/damage charac-teristic/fractal characteristic分类
矿业与冶金引用本文复制引用
白正平,王宁..反复干燥-饱水条件下煤体损伤及分形特征研究[J].煤矿安全,2025,56(4):110-119,10.基金项目
国家自然科学基金资助项目(51564044) （51564044）
