不同pH浸润煤样三维分形力学特征与失稳机制  

Three-dimensional fractal mechanical characteristics and instability mechanism of different pH wetting coal specimens

作　　者：姬红英[1,2] 褚尉荃 张东营 辛亚军 高忠国[3] JI Hongying;CHU Weiquan;ZHANG Dongying;XIN Yajun;GAO Zhongguo(School of Resources and Environment,Henan Polytechnic University,Jiaozuo,Henan 454000,China;Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization,Jiaozuo,Henan 454000,China;Qianxi Jinpo Coal Industry Co Ltd,Bijie,Guizhou 551700,China;School of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo,Henan 454000,China)

机构地区：[1]河南理工大学资源环境学院,河南焦作454000 [2]煤炭安全生产与清洁高效利用省部共建协同创新中心,河南焦作年454000 [3]黔西金坡煤业有限责任公司,贵州毕节551700 [4]河南理工大学能源科学与工程学院,河南焦作454000

出　　处：《采矿与安全工程学报》2023年第6期1301-1314,共14页Journal of Mining & Safety Engineering

基　　金：国家自然科学基金项目(51374091,51674101);河南省重点研发与推广专项(科技攻关)项目(232102321132,232102320253)。

摘　　要：水环境是影响煤体强度和孔隙发展的重要因素。基于不同pH浸润条件对煤样内部孔隙的影响,分析了不同浸润煤样三维分形与含水率关系,建立了浸润煤样三维分形与强度、弹性模量数学模型,开展了不同pH浸润条件下4组共12个煤样动态浸润试验,研究了不同pH浸润煤样含水率、分形维数、孔洞分数与抗拉强度、峰值应变、弹性模量的关系,探讨了不同pH浸润煤样细观裂隙扩展规律与宏观失稳破裂机制。结果表明:水-煤作用下,煤样孔隙结构增大主要由矿物成分膨胀消蚀和圆润颗粒带走所致,酸性浸润对孔隙影响最大,碱性次之,中性最小;浸润煤样分形维数可通过含水率进行表征,分形维数与煤样抗拉强度、弹性模量呈近似反向线性关系;浸润煤样含水率、分形维数与时间呈幂函数关系,且前期含水率、分形维数增加较快,后期趋势相对稳定,相同浸润时间、3种pH浸润下,煤样分形维数及增幅均为pH=5>pH=9>pH=7,浸润12d煤样分形维数为2.041~2.163;孔洞分数增量与分形维数呈正线性关系,随着分形维数(孔洞分数增量)的增加,不同pH浸润煤样的抗拉强度、峰值应变和弹性模量均呈降低趋势;浸润煤样较未浸润煤样的峰值抗拉强度降低超过28.37%,所对应的峰值应变降低超过16.55%,弹性模量降低超过14.21%;酸性浸润易导致多含量CaMg(CO_(3))_(2)快速溶蚀搬运,碱性浸润易导致少含量NaAlSi3O8溶蚀搬运,不同pH环境对浸润煤样微裂隙扩展和劣化度表现为pH=5>pH=9>pH=7,不同pH浸润煤样破坏形态可分为中轴拉伸破坏(pH=7)、多裂隙拉剪破坏(pH=5)、偏中轴拉伸-拉剪破坏(pH=9);分形维数-抗拉强度、弹性模量关系试验结果与理论曲线较为吻合,相关系数分别为0.950和0.997。Water environment is an important factor affecting the development of coal body strength and pores. Based on the influence of different pH wetting conditions on internal pores on coal specimens,the relationship of three-dimensional fractal and water content was analyzed,the mathematical models of three-dimensional fractal and strength,elasticity modulus was established,dynamic wetting test on four groups of 12 coal specimens in4groups were conducted under different pH wetting conditions. The relationships of water content,fractal dimension,void fraction and tensile strength,peak strain,elasticity modulus were studied. And the mechanism of macroscopic instability fracture and the laws of mesoscopic fracture propagation were discussed. The results show that pore development of coal specimens is mainly caused by the expansion and erosion of mineral components and the removal of round particles under water-coal function. Acidic infiltration has the greatest effect on pores,followed by alkaline infiltration and neutral infiltration. The fractal dimension of wetting coal specimens can be characterized by water content,and the fractal dimension is inversely proportional to the strength of the coal specimens. Power function can show the relationships of time and water content,fractal dimension of wetting coal specimens,water content and the fractal dimension increased rapidly in the early stage,and the trend is relatively stable in the later stage. Under the same wetting time,both of the fractal dimension and the increase rate are pH= 5>pH= 9>pH= 7,and the fractal dimension of the coal specimens with12d wetting range from2. 041to2. 163. The relationship of the pore fraction increment and the fractal dimension is positive linear,and the tensile strength,peak strain and elastic modulus of the wetting coal specimens under different pH wetting conditions all decrease with the increase of fractal dimension(pore fraction increment). Compared with the unwetting coal specimens,the peak tensile strength of the wetting coal specim

关 键 词：浸润煤样 分形维数 力学模型 强度特征 破坏形态 

分 类 号：TD315[矿业工程—矿井建设]