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Title
Experimental study of the temperature influence onmode Ⅰ fracture toughness of sandstonespecimens with different porosities
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作者
黄彦华陶然韩媛媛陈笑罗一鸣武世岩
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Author
HUANG Yanhua;TAO Ran;HAN Yuanyuan;CHEN Xiao;LUO Yiming;WU Shiyan
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单位
中国矿业大学力学与土木工程学院中国矿业大学深地工程智能建造与健康运维全国重点实验室中国矿业大学电气工程学院
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Organization
School of Mechanics and Civil Engineering, China University of Mining and Technology
State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China University of Mining and Technology
School of Electrical Engineering,China University of Mining and Technology
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摘要
高温岩石力学特性是煤炭地下气化等岩石工程围岩稳定分析和支护设计的重要依据。 为揭示高温后岩石断裂特性,对两组不同孔隙率砂岩进行高温(25~800 ℃)处理,采用图像处理技术获得砂岩热裂纹分布特征,探究高温后砂岩微裂纹面积比演化规律;对高温后砂岩进行三点弯曲试验,分析高温对砂岩载荷-位移曲线、Ⅰ型断裂韧度及破裂模式的影响规律。 结果表明:高温后砂岩微裂纹面积比随温度升高呈先减小后增大趋势,较高孔隙率 C 组砂岩微裂纹面积比更大;相同温度条件下,A 组砂岩Ⅰ型断裂韧度高于 C 组砂岩;随着温度的升高,两组砂岩Ⅰ型断裂韧度均先增大后减小,阈值温度分别为 200 ℃和 400 ℃;三点弯曲作用下,从预制裂隙尖端萌生的裂纹扩展导致砂岩试样破坏,且温度越高,砂岩破坏程度越明显。
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Abstract
The mechanical properties of hot rock are important basis for rock stability analysis and sup-port design of deep rock projects such as underground gasification of coal. In order to reveal the evolu-tion of fracture behavior of rock after high temperature, a series of tests on sandstone specimens with twoporosities after different high temperatures (25-800 ℃) were carried out. Digital image processing tech-niques were used to analyze the distribution characteristics of thermal cracking, and calculate the microc-rack area ratio. Three-point bending tests were performed on semicircular bend sandstone specimens afterhigh temperature treatment. Based on the test results, the effects of high temperature on load-displace-ment curves, mode Ⅰ fracture toughness and failure modes of sandstone specimens were analyzed. Theresults show that:the microcrack area ratio tends to decrease first and then increase with increasing tem-perature, and the microcrack area ratio of Group C sandstone with higher porosity is higher than that ofGroup A sandstone with lower porosity. The mode Ⅰ fracture toughness of Group A sandstone is higherthan that of Group C sandstone under the same testing temperature. As the temperature increases, themode Ⅰ fracture toughness of sandstone specimens first increase and then decrease. The threshold tem-peratures of the two groups of sandstones are 200 ℃ and 400 ℃, respectively. The crack initiated fromthe prefabricated notch tip under three-point bending leads to the failure of sandstone specimens. Thehigher the temperature, the more obvious the degree of fracture of the sandstone specimens.
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关键词
岩石力学高温作用Ⅰ型断裂韧度微观结构图像处理
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KeyWords
rock mechanics;high temperature treatment;mode Ⅰ fracture toughness;microstructure;image processing
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基金项目(Foundation)
国家自然科学基金项目( 51909260);江苏省自然科学基金项目 ( BK20221547);国家级大学生创新创业训练计划项目
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文章目录
1 试验方案
1.1 岩性特征
1.2 试验系统及试验条件
2 高温后砂岩微观结构
2.1 SEM图像处理
2.2 微裂纹分布特征
2.3 微裂纹面积比
3 高温后砂岩断裂特性
3.1 载荷-位移曲线
3.2 Ⅰ型断裂韧度
3.3 破坏模式
4 结 论
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DOI