中文摘要：

启裂应力是岩石压缩破坏过程中的关键应力水平之一。准确确定该应力值对于客观描述岩石的力学性质以及评价地下工程围岩稳定性具有重要意义。在总结国际上已有的岩石启裂应力识别方法的基础上,探讨其各自优缺点及适用性,通过分析岩石在压缩过程中的声发射信号特征,提出了基于累计声发射撞击数客观判读岩石启裂应力的方法。与其他应变法相比,该方法克服了人工取值的随机性,保证了求解的惟一性。以国内高放废物地质处置库新疆预选区天湖花岗闪长岩为例,采用岩石力学试验机和声发射监测系统,获得了岩石在单轴压缩条件下的应力-应变关系及对应的声发射数据,通过对比不同方法求解启裂应力的结果,验证了提出的累计声发射撞击数法的合理有效性。鉴于国际岩石力学与工程学会目前尚未形成明确的求解岩石启裂应力建议方法,建议采用应变测量结合声发射监测手段对该值进行判读。

英文摘要：

Crack initiation stress is one of the key stress thresholds in the process of rock failure under compression conditions. Accurate determination of crack initiation stress is very important for characterizing mechanical properties of rocks and for evaluating the stability of underground excavations. At present, the ISRM has established a commission on rock spalling, and one of the important objectives of the commission is to develop suggested guidelines for determining the crack initiation stress of rocks. By analyzing and summarizing the previous approaches to identifying crack initiation stress of rocks, a new method based on accumulative acoustic emission （AE） hit number is proposed to determine crack initiation stress. Compared with other strain methods, a significant advantage of this developed method is to remove the user＇s subjective judgment. Using rock mechanics testing machine and AE monitoring system, uniaxial compression tests on granodiorite samples collected from the Tianhu rock block in Xinjiang Autonomous Region, have been conducted to obtain stress-strain relationships and corresponding AE data. According to the comparison of crack initiation stress values obtained from different methods, the effectiveness and reasonability of the proposed accumulative AE hit method are verified. Due to the fact that ISRM has not provided clear guidelines for establishing crack initiation stress of rocks, it is suggested that the strain in combination with AE measurements be used to identify this critical stress threshold of rocks subjected to compressive conditions.