奥陶系灰岩卸荷力学特性试验研究

摘要岩石在卸荷状态下的力学特性与其在加载状态下有着明显区别，对奥陶系灰岩进行了常规三轴与卸荷三轴的对比试验分析。试验结果表明，卸荷状态下岩石的变形以侧向变形为主，且扩容显著；卸荷状态下岩样没有出现明显的塑性阶段，峰后出现了明显的应力跌落，表明灰岩的脆性特征在卸荷状态下相对明显。相对于加载，卸荷岩石的黏聚力c和内摩擦角φ均有所减小；卸荷状态下峰值抗压强度和残余抗压强度明显减小，并且随围压增加其减小的幅度也减小。

Mechanical Property Test on Limestone Stress-relief of Ordovician System

Rock burst and rock stability are important factors for in deep and long tunnel construction and its safe operation.Rock burst is often encountered during brittle rock excavation in high ground stress conditions,for example,since one year’s construction of Qirehata’er diversion tunnel, about 600m long segments has occurred minor to moderate rock burst,resulting a certain delay of construction period.The text analyzes the characteristics of rock burst via studying the engineering practice and in combination with the excavation process.It makes a prediction to the strength of rock burst with different chainages,and discusses the prevention measures for different levels of rock burst.