卸荷条件下岩石破坏能量演化试验研究进展

发布时间：2018-10-26 21:30

【摘要】：岩石在变形破坏过程中不断与外界交换着物质和能量,是一个能量耗散的损伤演化过程,岩石破坏的实质是能量驱动下的状态失稳现象。综合介绍了在开挖瞬间,迅速增大的轴向应力随着时间增长逐渐趋于稳定和围压瞬间卸载的应力重分布情况,目前主要采用轴压升高、围压降低而轴压不变、围岩降低的室内试验方案。结果表明:岩石卸荷破坏具有明显的围压效应,总应变能、弹性应变能和耗散能与初始围压呈正相关关系;随着卸荷速率的增加,能量转化速率不断减小,岩石容易产生瞬间动态破坏;不同卸荷水平下能量演化存在明显的差异;碎屑岩块分形维数越大,扩容现象越明显,穿晶、沿晶裂纹越发育,消耗能量越多。基于现有的研究成果,提出完善试验系统、采用与工程实际相符合的应力路径、开展微细观裂纹研究、深入能量转化敏感阶段研究的发展趋势。
[Abstract]:In the process of deformation and failure, rock is constantly exchanging matter and energy with the outside world, which is a damage evolution process of energy dissipation. The essence of rock failure is the phenomenon of state instability driven by energy. In this paper, it is introduced that the rapidly increasing axial stress tends to be stable with the time increase and the stress redistribution at the moment of confining pressure unloading during the excavation moment. At present, the axial pressure is increased, the confining pressure is reduced, but the axial pressure is not changed. Indoor test scheme for lowering surrounding rock. The results show that the unloading failure of rock has obvious confining pressure effect, and the total strain energy, elastic strain energy and dissipation energy are positively correlated with the initial confining pressure. With the increase of unloading rate, the energy conversion rate decreases and the rock is prone to instantaneous dynamic failure, and there are obvious differences in energy evolution at different unloading levels. The larger the fractal dimension of clastic rock block, the more obvious the expansion phenomenon is, the more the intergranular crack develops, the more energy is consumed. Based on the existing research results, this paper puts forward the development trend of improving the test system, adopting the stress path consistent with the engineering practice, carrying out the micro-crack research, and deepening the research on the sensitive stage of energy conversion.
【作者单位】：北京科技大学土木与资源工程学院;金属矿山高效开采与安全教育部重点实验室;鄂尔多斯市营盘壕煤炭有限公司;
【基金】：国家重点研发计划项目(编号:2016YFC0600801) 国家自然科学基金重点项目(编号:51534002)
【分类号】：TU45

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