EXPERIMENTAL STUDY OF MECHANICAL PROPERTIES OF WATER-SATURATED WEAKEN SHALE IN GONGHE TUNNEL
TENG Hongwei1，REN Song1，JIANG Deyi1，YANG Chunhe1，2
(1. Key Laboratory for Exploitation of Southwestern Resources and Environmental Disaster Control Engineering，Ministry of Education，Chongqing University，Chongqing 400044，China；2. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：The geological condition of Gonghe tunnel of Chongqing—Changsha highway is very complex. There are many difficulties when the tunnel is being constructed. There are many vertical cracks in the primary support after the tunnel is excavated. The surrounding rock of the cracking position is shale，which is easily weathered，and strong hydrophilic and water-softening have identified beddings and joints. All these characteristics have an important impact on the primary support and the long-term stability of the tunnel. At first，the basic mechanical parameters of the shale are gotten from the basic mechanical test of the shale. And then，the water-saturated softening experiment of the shale is carried out with the combination of sound wave test and uniaxial compression test，and the water-saturated softening equations of the shale are obtained. The test results show that both strength and elastic mould are low；the strength and elastic modulus will be lower in the process of water-saturated time，which meets the rule of a negative exponential function，and can agree well the actual water-saturated softening rule of the shale. The combination of sound wave test and uniaxial compression test can significantly reduce the need of rock samples，and also can improve test accuracy. The research achievements provide the basic parameters for re-designing the primary support structure and analyzing the long-term stability of the tunnel lining structure.
