The Construction Technology Of Tunnel Which The Surrouning Rock Broken And Water Rich

Rich-water and broken rock is inescapable during the construction of tunnel, and it is an important subject to select the right construction method. Based on the case project of Leyuan tunnel, we studyed how to select the reasonable measure of waterproof and drainage and the optimal excavation method of tunnel when the surrounding rock broken and the water rich.Relative literature was collected and made a summary. Based on the theoretical analysis,the mechanism of effect between seepage field and stress field of tunnel which the surrounding rock broken and water rich,and then putting forward the reasonable measure of waterproof and drainage based on this mechanism. The result shows that:(1)the groundwater produces physical and chemical reaction to the structure plane of surrounding rock,impacting the stress field;(2) the groundwater changes the distribution of the stress field through mechanical functions. The permeability of rock mass is influenced because of the volume strain and porosity of rock mass is influenced by stress field."Plugging dominantly and treating synthetically" is chose to be the principle to the waterproof and drainage of tunnel. Proving the situation of water rich and broken of surrounding rock in front of the tunnel face through geological forecast,and then proceeding pouring to the disease area. In addition,decorating some drainage holes in the middle of the disease area to let out some water.Simulating the excavation when the rich-water and broken rock is grouted and not grouted through the nonlinear finite element software ADINA. The result is:The tunnel is unstable when rich-water and broken rock is not grouted,the grouting is necessary before excavating the tunnel.Then simulating the excavation of tunnel by the method of entire section method,bench method and partial excavation method. Analysis of stress distribution and bolt axial force in different working conditions. The results show that:(1) Adopting the working condition of partial excavation method,both the stress and bolt axial force is minimum,so the supporting force it needed is minimum;(2) Adopting the working condition of entire section method,the stress and bolt axial force is maximum,and the supporting force it needed is maximum;(3)The result shows that the bench method is similar with the partial excavation method.In combination with the result of numerical analysis, and considering the economy of working and the influence to the stability of tunnel face, the most meaningful working condition to the surrounding rock which is broken is bench method.