含水状态下膏溶角砾岩破裂全程的细观力学试验研究

Meso-mechanical testing study of microfracturing process property of gypsum breccia under condition of water damage

利用新型岩石细观力学试验系统,对石家庄—太原铁路专线太行山隧道工程6#斜井的膏溶角砾岩在单轴压缩荷载作用下的岩石细观损伤裂纹扩展直至破裂的全程进行了实时观测,得到了不同含水状态下岩石初始损伤微裂纹的萌生、扩展、连接、贯通直至宏观破裂的数字显微和全场实时图像。从岩石细观损伤机制出发,结合同时获得的应力-应变曲线,将损伤破裂过程分为4个阶段,得到了含水状态下岩石损伤发展演化的初步规律,并给出了应力损伤门槛值,发现水环境影响下造成的初始损伤微裂纹是水对膨胀软岩力学性质产生软化作用的重要因素。

Using a new type rock meso-mechanical testing system, an observation and experiment on whole process and real-time of gypsum breccia is carried out under the condition of uniaxial compression load. Digital images of germination, extension, juncture,perforation till macroscopical fracture of micro-crack which is the rock initial damage, are obtained under the condition of different water contents. On the basis of meso-damage mechanism and stress-strain curve, the process of damage and fracture is divided into four phases. Considered the condition of water damage, rule of rock damage evolvement is researched. A damage threshold value of stress is discussed. Finding out that initial damage microcrack, which is caused under the influence of water environment, is an important factor to generate softening of gypsum breccia.