Study on the Grouting Pre-Reinforcement Mechanism and Effect Evaluation in Water-rich Loess Tunnel

In order to solve the problem of water-rich loess tunnel in construction process, the paper based on the idea of underground water environmental balance, use the Kuniaki Sato empirical formula and underground runoff modulus to build correlation function, get the permeability coefficient. Then we combine the engineering practice condition of the Qiaoyuan tunnel, use the duplex pipe grouting to reinforce the water-rich loess tunnel, and evaluate the grouting effect. Results show that there are a great lot of obvious grouting veins on tunnel face, and the bedding is clear. There are not bleeding phenomenon on tunnel face. The surrounding rock is stable, no such phenomenon occurred as collapse, instability, gushing water or mud, etc. The soil strength has increase dramatically, and the permeability has reduced significantly. The permeability coefficient of grouting soil meets the requirements of underground water environmental balance.