【摘要】 高温作用会引起岩石热损伤。对经历20℃(常温),200℃,400℃和600℃温度处理后的粗粒大理岩试样开展40 MPa围压范围内的常规三轴压缩试验,研究热损伤对孔隙率、纵波波速、裂纹发育的影响,分析高温处理和围压共同作用下大理岩的强度与变形特征,并采用GSI弱化方法,基于Hoek-Brown模型提出一种可以描述热损伤岩石强度规律的GSI弱化模型。结果表明:随热处理温度升高,热损伤微裂纹逐渐增多,孔隙率增大,纵波波速迅速下降,岩石的延性得到显著增强;热损伤作用会显著降低岩石的强度,而随着围压逐渐增大,不同温度处理后的岩石强度逐渐趋于一致,表明在高围压条件下围压是影响岩石强度的主要因素;通过试验数据和3组热损伤大理岩试验数据验证可以发现,提出的GSI弱化模型可以较好地反映热损伤岩石的强度随围压的变化规律,GSI指标的变化可以表征热损伤程度的大小。更多还原

【Abstract】 High temperature treatment can induce thermal damage to rock. Conventional triaxial compression tests on coarse-grained marble specimens after exposure to different high temperatures are conducted. The influence of thermal damage on porosity,P-wave velocity,and thermal micro-cracking behavior is investigated and the combined effects of thermal damage and confinement on the strength and deformation behavior are studied. A GSI-softening model,which is based on the widely used Hoek-Brown model,is also proposed to capture the strength behavior of thermally-damage rock. The main findings of this study are as follows:As the treatment temperature gradually increases,more thermally-induced micro-cracks can be observed in the specimen. The porosity increases and the P-wave velocity decreases with the increase in the treatment temperature. The ductility of the rock is enhanced as the treatment temperature increases. High temperature treatment can greatly reduce the rock strength. However,as the treatment temperature gradually increases,the strengths of rock specimen under different temperature treatments approach the same,indicating that the confinement is the main factor that controls the rock strength when the confining pressure is high. Based on test data in this study and three sets of test data from previous publications,it is found that the variation of rock strength with confining pressure for thermal damaged rock can be well captured using the proposed GSI-softening model. The variation of GSI in the model can represent the thermal damage in the rock to some extent.更多还原