压缩应力条件下花岗岩损伤演化特征及其对渗透性影响研究

发布时间：2018-04-06 04:22

本文选题：岩石力学　切入点：北山花岗岩　出处：《岩石力学与工程学报》2014年02期

【摘要】：基于岩石三轴压缩应力应变全过程渗透特性试验,结合三维声发射监测信息,研究花岗岩在不同围压条件下力学损伤演化机制及其对岩石渗透特性影响规律。本研究对常规渗透试验方法进行改进,通过在试样两端加工渗透小孔,实现岩石不同破坏形式下渗透性变化规律的测量。试验结果表明,在压缩应力作用下,花岗岩的损伤演化始于微裂隙的产生和扩展,并在岩石破坏时和峰后阶段发展迅速。该损伤演化的阶段性特征与声发射监测数据一致,进一步说明了裂隙扩展是导致花岗岩力学特性劣化的根本原因。随着微裂隙的扩展,岩石渗透性不断增强,但在峰前加载阶段渗透性变化明显滞后于损伤演化过程。该结果表明,在裂隙贯通并产生宏观破坏面之前,裂隙扩展对花岗岩渗透性影响非常有限。在低围压条件下,岩石渗透性随围压增大迅速减小;当围压增大到一定程度后,该趋势逐渐减弱。结合声发射监测数据,对不同应力条件下损伤演化与渗透特性的相互关系进行分析,并提出花岗岩渗透率与损伤和围压的相关经验公式。
[Abstract]:Based on the permeability characteristics test of rock under triaxial compression stress and strain, combined with 3D acoustic emission monitoring information, the mechanism of mechanical damage evolution of granite under different confining pressures and its influence on rock permeability characteristics are studied.In this study, the conventional permeation test method was improved, and the permeability change law was measured under different failure forms by processing the permeability holes at the two ends of the specimen.The experimental results show that the damage evolution of granite under compressive stress begins with the generation and expansion of microcracks and develops rapidly during rock failure and post-peak stage.The stage characteristics of the damage evolution are consistent with the acoustic emission monitoring data, which further shows that the crack propagation is the fundamental cause of the deterioration of the mechanical properties of granite.With the extension of microcracks, the permeability of rock increases, but the change of permeability obviously lags behind the process of damage evolution in the pre-peak loading stage.The results show that the influence of crack propagation on the permeability of granite is very limited before the fracture passes through and produces the macroscopic failure surface.Under the condition of low confining pressure, the permeability of rock decreases rapidly with the increase of confining pressure, and when the confining pressure increases to a certain extent, the trend gradually weakens.Based on acoustic emission monitoring data, the relationship between damage evolution and permeability characteristics of granite under different stress conditions is analyzed, and the empirical formulas for permeability, damage and confining pressure of granite are put forward.
【作者单位】：核工业北京地质研究院环境工程研究所;核工业北京地质研究院中核集团高放废物地质处置评价技术重点实验室;四川大学水力学与山区河流开发保护国家重点实验室;
【基金】：国家自然科学基金资助项目(11202069,51120145001,51104101)
【分类号】：TU45

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