共和隧道页岩饱水软化试验研究

 渝湘高速公路共和隧道地质条件十分复杂，隧道施工遇到很大困难，隧道开挖后初期支护多处纵向开裂。隧道开裂段围岩为页岩，现场实际监测资料表明页岩层理、节理发育，易风化，亲水性较强，有水软化倾向。页岩的这些性质对隧道初期支护结构的效果及隧道长期稳定可靠性具有重要影响。针对这一施工难题，先进行页岩基本力学试验，获得页岩基本力学参数；然后采用声波探测与单轴抗压试验相结合的方法进行页岩的饱水软化试验，得到页岩动弹模量及强度的饱水软化方程。试验结果表明共和隧道页岩弹性模量及强度均较低；弹性模量和强度随饱水时间的增加而逐渐减小，服从负指数函数变化规律，饱水软化方程能很好的反应页岩的实际饱水软化规律；用声波探测和单轴抗压试验相结合的方法进行页岩饱水软化试验，可以大量减少岩石试样的数量，同时可以提高试验精度。试验成果为共和隧道高地应力大变形破坏段的初期支护结构重新设计及隧道衬砌结构的长期可靠性分析提供基本参数。

EXPERIMENTAL STUDY OF MECHANICAL PROPERTIES OF WATER-SATURATED WEAKEN SHALE IN GONGHE TUNNEL

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.