煤炭地下气化顶板砂岩高温致裂规律实验研究  

Experimental study on high-temperature fracturing law of roof sandstone in underground coal gasification

作　　者：辛林[1,2] 王欣[1] 牛茂斐 杨敏[1] 李华龙 徐伟豪 尚振杰 刁垌彤 XIN Lin;WANG Xin;NIU Maofei;YANG Min;LI Hualong;XU Weihao;SHANG Zhenjie;DIAO Tongtong(College of Safety and Environmental Engineering,Shandong University of Science and Technology,Qingdao 266590,China;Key Laboratory of Ministry of Education for Mine Disaster Prevention and Control,Shandong University of Science and Technology,Qingdao 266590,China)

机构地区：[1]山东科技大学安全与环境工程学院,山东青岛266590 [2]山东科技大学矿山灾害预防控制省部共建国家重点实验室培育基地,山东青岛266590

出　　处：《煤炭工程》2025年第2期163-170,共8页Coal Engineering

基　　金：国家自然科学基金项目(52374211,52304190,52304060);山东省自然科学基金项目(ZR2023QE117)。

摘　　要：煤炭地下气化过程中,随着气化工作面的扩展,燃空区产生的高温会对顶板岩石造成不同程度的结构损伤。为了研究不同温度(100、200、300、400、500、600℃)造成的热损伤对砂岩声发射特征及破裂机制的影响,利用自主研发的单向加热实验设备,对试验过程中声发射信号进行采集分析,研究表明:累计声发射事件数与内部裂纹数的正相关性能够较好地反映砂岩宏观破坏规模,400~500℃砂岩破裂最为明显。微观上,试样各个温度快速升温阶段裂纹发展速度快,随温度升高,低频占比减少56.02%,高频占比增加57.1%,主频由低频为主转为高频为主,即砂岩破坏由晶间滑移主导转变为裂隙扩展主导。砂岩热破裂是膨胀变形、裂纹的萌生、快速发展以及裂纹持续贯通到破坏的过程。砂岩裂纹萌生,裂纹发育及裂纹非稳定发育分别对应分形维数数值变化≥0.35、-0.15~0.35、≤-0.15,分形维数曲线不规则波动阶段和突降阶段之间的突变点,可作为预测岩石热破裂时内部宏观裂隙形成的信号,为煤炭地下气化设计合理的采宽提供理论支持。The high temperatures in the combustion area during underground coal gasification can cause structural damage to the roof rock.In order to study the effect of thermal damage caused by different temperatures(100,200,300,400,500,600℃)on the acoustic emission characteristics and rupture mechanism of sandstone.The acoustic emission signals were collected and analyzed during the test using the self-developed unidirectional heating experimental equipment.The results showed that the positive correlation between the cumulative number of acoustic emission events and the number of internal cracks can better reflect the macroscopic damage scale of sandstone,with the most obvious fracture occurring at 400~500℃.On the micro-damage,the cracks develop fast in the rapid warming stage of each temperature of the specimen.With the increase of temperature,the proportion of low-frequency decreased by 56.02%,and the proportion of high-frequency increased by 57.1%,and the main frequency changes from low-frequency dominated to high-frequency dominated,i.e.,the damage of sandstone is transformed from the dominance of intergranular slip to the dominance of fissure extension.Thermal damage of sandstone is a process of expansion and deformation,crack initiation,rapid development and cracks continue to develop through to destruction.Sandstone crack sprouting,crack development and crack nonstationary development correspond to changes in fractal dimension values of 0.35,0.15 to 0.35,and-0.15,respectively.The mutation point between the irregular fluctuation phase and the sudden drop phase of the fractal dimension curve can be used as a signal to predict the formation of internal macroscopic fissures during the thermal rupture of the rock,which provides theoretical support for the design of reasonable mining width for underground coal gasification.

关 键 词：煤炭地下气化 砂岩 单向加热 声发射 裂隙演化 分形维数 

分 类 号：TD844[矿业工程—煤矿开采]