砂岩试件加载-卸荷-加载损伤弱化试验分析

发布时间：2018-04-19 20:56

本文选题：加载-卸荷-加载 + 能量积聚　；参考：《煤炭学报》2016年12期

【摘要】：为研究深部巷道围岩开挖和回采全过程中岩体强度的弱化规律,通过对砂岩试件进行不同加载速率的单轴加载、不同围压的三轴加载以及不同程度的三轴加载-卸荷-单轴加载试验对砂岩试件在加载、卸荷和再加载过程中的损伤、弱化机理进行研究。结果表明:试件的峰值强度与加载速率之间呈幂函数关系,与围压之间呈线性关系,加载速率和围压越大,砂岩试件强度越高。砂岩在三轴加载-卸荷-单轴加载时试件最终破坏形态与其受载历史无关,与岩石的最终受力状态相关。岩石的最终强度与其受载速率、围压大小和加卸-载扰动等受载历史相关,初始轴压越大加载速率越小试件的初始损伤越大,卸载后再加载的最终强度越小。此外,提出了基于能量密度的岩石损伤度指标和一种基于加载过程状态的强度弱化计算方法,经计算验证该方法是可行的。
[Abstract]:In order to study the weakening law of rock mass strength in the whole process of excavation and mining of deep roadway surrounding rock, the sandstone specimen was subjected to uniaxial loading with different loading rates. The damage and weakening mechanism of sandstone specimens during loading unloading and reloading are studied by triaxial loading with different confining pressures and triaxial load-unloading uniaxial loading tests. The results show that there is a power function relationship between the peak strength and the loading rate of the specimen, and a linear relationship between the peak strength and the confining pressure. The higher the loading rate and the confining pressure, the higher the strength of the sandstone specimen. The ultimate failure pattern of sandstone under triaxial loading unloading uniaxial loading has nothing to do with its loading history and is related to the ultimate stress state of rock. The ultimate strength of rock is related to its loading rate, confining pressure and loading disturbance. The higher the loading rate of the rock is, the greater the initial damage of the specimen is, and the smaller the ultimate strength of the specimen is after unloading. In addition, a rock damage index based on energy density and a strength weakening method based on the state of loading process are proposed. The calculation results show that the method is feasible.
【作者单位】：湖南科技大学煤矿安全开采技术湖南省重点试验室;南方煤矿瓦斯与顶板灾害预防控制安全生产重点实验室;湖南科技大学页岩气资源利用湖南省重点实验室;
【基金】：国家自然科学基金重点资助项目(51434006);国家自然科学基金面上资助项目(51374106) 页岩气资源利用湖南省重点实验室开放基金资助项目(E1641)
【分类号】：TD315

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