中文摘要：

采用岩石三轴试验机和声发射监测系统,研究我国高放废物地质处置库北山预选区深部花岗岩在单轴和三轴压缩条件下的破裂过程和强度特性。基于试验结果,分析岩石应力–应变曲线及其与声发射事件的时空分布关系,揭示岩石在压缩变形各个阶段的破裂演化机制,探讨3个特征应力水平（裂隙初始强度（ci）、裂隙损伤强度（cd）和峰值强度（c））对围压的依赖性。研究表明：（1）在低围压（0-2 MPa）条件下,大量分散或沿轴向应力方向分布的声发射事件与岩石宏观上的高密度竖向破裂相对应,从而导致岩石黏结力弱化,随着围压的增加,岩石逐渐从劈裂破坏向剪切破坏模式过渡,且裂隙增量最大值发生在应变软化阶段,其与岩石扩容率的变化规律一致;（2）采用提出的累计声发射撞击数方法结合应力–应变测量,可准确识别ci,与cd相比,ci对围压的依赖性较不敏感,该行为在低围压条件下更为突出;（3）单一的Hoek-Brown强度准则不足以充分描述岩石在劈裂和剪切并存条件下的峰值强度变化规律,赋予2个材料参数mi值的分段式Hoek-Brown强度曲线应更为合理。

英文摘要：

Acoustic emission（AE） and strength characteristics of the Beishan granite at depth under uniaxial and triaxial conditions were investigated using a servo-hydraulic compression machine and a real-time AE measurement system. Based on the experimental results,complete stress-strain curves associated with 3D AE event distribution characteristics were analyzed. The fracture evolution mechanisms of the rocks at different loading and deformation stages were revealed,and the confining stress dependent behaviors of the three characteristic stress thresholds（i.e. crack initiation,crack damage and peak strengths） were discussed. The research results indicate as follows：（1） At low confining stresses（0–2 MPa）,the rock sample tends to present dispersive mircocracking or axial splitting throughout each loading stage,which is agreement with the dense distribution of AE events throughout the rock,indicating that certain amount of cohesion strength of rock is lost. With increasing confining stresses,a gradual transition from axial splitting failure to shear failure can be observed. The distributions of incremental AE events indicate that the maximum gradient of crack growth occurs at the strain softening stage,which corresponds to the maximum dilation rate in the stress-strain curve;（2） Using the proposed cumulative AE hit method in combination with stress-strain measurement data,the crack initiation strength can be identified accurately. Compared with the crack damage strength,the crack initiation strength is less sensitive to confining stress,especially for low confinements;（3） A single failure criterion is not sufficient to describe the complete failure envelope. Hence,a bi-segmental representation of the Hoek-Brown strength envelope is suggested for the Beishan granite.