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裸洞隧道在长期使用过程中,围岩遭受风化、地下水及区域地应力等不利因素的作用,导致岩体性质恶化,影响隧道的正常使用。在调研统计的基础上,选取319国道重庆至武隆段大溪河裸洞隧道为研究对象,对其表层及深层灰岩进行了室内单轴压缩、三轴压缩力学特性试验并对单轴压缩作用下的声发射特性进行了研究。结果表明:单轴压缩作用下两种岩样均出现脆性破坏特征,三轴压缩条件下,两种岩样呈压缩为主的延性扩容破坏,声发射可较好地表征岩石单轴压缩破坏过程;获得了两种岩样的基本力学参数,深层岩样强度为表层岩样强度的2.13倍,弹性模量、泊松比、内聚力、内摩擦角分别是表层岩样的1.04倍,0.63倍,1.45倍,1.37倍。研究结果可为该地区裸洞隧道的长期安全性与稳定性提供有益的理论支撑。
In the long-term use of open-hole tunnels, the surrounding rock is exposed to unfavorable factors such as weathering, groundwater and regional stress, resulting in the deterioration of rock mass and affecting the normal use of the tunnel. Based on the survey statistics, the tunnel of the Daxihe tunnel in Chongqing to Wulong section of 319 national highway was selected as the research object, and the uniaxial and uniaxial compression tests on the surface and deep limestone were carried out. The acoustic emission characteristics were studied. The results show that both of the rock samples show brittle failure under uniaxial compression. Under triaxial compression, both samples show compression-dominated ductile expansion failure, and acoustic emission can characterize the uniaxial compression failure of rock The basic mechanical parameters of two kinds of rock samples were obtained. The strength of deep rock samples was 2.13 times that of surface rock samples. The elastic modulus, Poisson's ratio, cohesion and internal friction angle were 1.04 times and 0.63 times of those of surface rock samples, respectively. 1.45 times, 1.37 times. The results can provide useful theoretical support for the long-term safety and stability of the tunnel in the area.