| 浸泡作用下砂岩断裂力学特性及劣化机理 |
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| 引用本文： | 邓华锋,原先凡,李建林,罗 骞,何 明.浸泡作用下砂岩断裂力学特性及劣化机理[J].地球科学,2014,39(1):108-114. |
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| 作者姓名： | 邓华锋 原先凡 李建林 罗 骞 何 明 |
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| 作者单位： | 1.三峡地区地质灾害与生态环境湖北省协同创新中心, 湖北宜昌 443002 |
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| 基金项目： | "973"计划前期研究专项课题2012CB426502国家自然科学基金资助项目51309141湖北省自然科学基金资助项目2012FFB03805三峡大学土木与建筑学院优秀硕士学位论文培育项目资助PY201314 |
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| 摘 要： | 岩石的断裂韧度对于定量评价工程的安全及稳定具有重要意义, 而岩石的破坏常常有水参与, 在库水长期浸泡作用下, 岩石的断裂力学特性将如何变化值得深入研究.基于此, 以库岸边坡典型砂岩为研究对象, 设计了长期浸泡试验, 并基于断裂韧度、变形破坏特征和微观结构变化进行综合分析.试验结果表明: (1)浸泡作用下, 砂岩的断裂韧度具有明显的劣化趋势, 而且劣化幅度有一个先增大后减小的趋势, 浸泡5~6月后, 劣化趋势逐渐减缓；(2)砂岩三点弯曲试验的P-CMOD关系曲线可以比较明显地分成3个阶段: 弹性阶段、屈服阶段、裂纹开展及破坏阶段, 随着浸泡时间的增长, 弹性阶段逐渐变短, 屈服阶段逐渐变长, 裂纹开展阶段曲线下降趋势逐渐变缓, 而且达到开裂峰值荷载对应的切口张开位移逐渐增大, 砂岩有逐渐“变软”趋势, 脆性逐渐减弱, 塑性逐渐增强；(3)浸泡作用导致的润滑、软化和砂岩内部微观结构的变化, 特别是微观裂纹、裂隙的发展是导致砂岩断裂韧度及其他力学参数劣化的根本原因.研究成果对于把握库水长期浸泡作用下砂岩断裂力学特性具有比较重要的参考价值.
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| 关 键 词： | 长期浸泡 水-岩作用 三点弯曲 断裂韧度 工程地质 |
| 收稿时间： | 2013-06-21 |
Fracture Mechanics Characteristics and Deterioration Mechanism of Sandstone under Reservoir Immersion Interaction |
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| Abstract: | The fracture toughness of rock is of great significance in quantitative evaluation of engineering safety and stability. Rocks often destruct with water, so it is worthwhile to do study on the issue as how the rock fracture toughness and associated mechanical parameters change under long-term immersion of reservoir water. In this paper, a long-term immersion test is designed and carried out and a comprehensive analysis is done in aspects such as the fracture toughness, deformation failure characteristics and microstructure change characteristics. The results show that: (1) under the water-rock interaction, the fracture toughness has a significant deterioration trend, and the deterioration rate increased in prophase and lowered in anaphase; and the deterioration rate gradually becomes slow after 5 or 6 months' immersion. (2) The P-CMOD relation curves of the sandstone three-point bending test can be divided into three stages, namely elastic stage, yield stage, and crack development and damage phases; and with the immersion time, the elastic stage gradually becomes shorter, the yield stage gradually becomes longer, and the downward trend of crack development phase gradually becomes slow, meanwhile, the incision opening displacement which is corresponding to cracking peak load gradually increases. The sandstone brittleness gradually weakens, and plasticity gradually enhances. (3) Lubrication, softening and changes of sandstone's inner microscopic structure caused by water-rock interaction, especially the micro-cracks and the development of the cracks are the basic reasons which lead to the deterioration of the sandstone fracture toughness and other mechanical parameters. The research results facilitate the understanding of the degradation law of sandstone fracture toughness under long-term reservoir water immersion. |
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