高温热处理砂岩Ⅰ-Ⅲ混合断裂特性试验研究  

Experimental study on the mixed modeⅠ-Ⅲ fracture behaviors of sandstone after high temperature treatment

作　　者：李卫 苏海健[1] 蔚立元[1] 刘日成[1] 陈广印 LI Wei;SU Haijian;YU Liyuan;LIU Richeng;CHEN Guangyin(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;Shandong Energy Group Luxi Mining Co Ltd,Heze,Shandong 274700,China)

机构地区：[1]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏东徐州221116 [2]山东能源集团鲁西矿业有限公司,山东菏泽274700

出　　处：《采矿与安全工程学报》2023年第6期1281-1289,共9页Journal of Mining & Safety Engineering

基　　金：国家自然科学基金项目(52209151,52274100);中央高校基本科研业务费专项资金项目(No.2021-11188)。

摘　　要：煤炭地下气化等工程均涉及显著的高温热效应,导致地下煤岩体的强度、变形和断裂特性变得异常复杂。采用预制裂隙圆盘三点弯曲加载方法,对25~800℃高温热处理砂岩试样的Ⅰ-Ⅲ混合断裂特性进行了试验研究,探讨了温度对有效断裂韧度、断裂能以及微观结构的影响。研究结果表明:砂岩的有效断裂韧度随断裂混合系数Me13的增大而线性增大,相同条件下Ⅰ型断裂韧度最大,而Ⅲ型断裂韧度最小;随着温度的逐渐升高(25~800℃范围内),有效断裂韧度和断裂能均呈现先缓慢增大,400℃以后急剧减小的趋势,这主要与石英的相变有关;400℃热处理后砂岩微观形态以沿晶裂纹为主,而800℃时由于矿物相变和分解,形成了较多的穿晶裂纹;砂岩的Ⅲ型和Ⅰ型断裂韧度总体服从线性规律,即K_(ⅢC)=0.65K_(ⅠC),同时,Ⅲ型和Ⅰ型断裂韧度与抗拉强度均呈现较好的正相关性。The underground coal gasification and other projects involve significant high temperature thermal effect,which makes the strength,deformation and fracture characteristics of underground coal and rock become extremely complex. Based on the three-point bending loading method of disc with prefabricated fissure,mixed modeⅠ-Ⅲ fracture properties of sandstone specimens after subjected to high temperatures(25-800℃)are studied,to investigate the influence of temperature on the effective fracture toughness,fracture energy and micro-structure. The results show that,the effective fracture toughness of sandstone presents a linear increase trend with the increasing fracture mixed coefficient M_(13)~e. The modeⅠfracture toughness is the largest under the same condition,however,that of mode Ⅲ is the smallest. With the gradual increase of temperature(in the range of25-800℃),both the effective fracture toughness and fracture energy first increase slowly,and decrease sharply after400℃,which is mainly related to the phase transformation of quartz. At400℃,intergranular cracks are the main microscopic morphology of sandstone after high temperature treatment,while at800℃,more transgranular cracks are formed due to the mineral phase transformation and decomposition. The mode Ⅲ fracture toughness of sandstone generally obeys the linear law with that of modeⅠ,namely K_(ⅢC)=0. 65KⅠC.Meanwhile,both the mode Ⅲ and modeⅠfracture toughness appear a great positive linear relationship with the tensile strength.

关 键 词：岩石力学 Ⅰ-Ⅲ混合断裂 高温 断裂韧度 抗拉强度 

分 类 号：TD45[矿业工程—矿山机电]