Study On Prediction Technique Of Mianmao Road Lanjiayan Tunnel Water Gushing

The object of study in the context is the Lanjiayan tunnel from Mianzu to Maoxian in sichuan Province, aim of this paper is water-rich soft rock tunnel construction gushing prediction. At first,in this paper, making use of the theoretical and numerical analysis and geological radar to predict Inflow. And then, make use of traditional forecasting methods and neural network forecasting combining to predict Inflow. At last, calculate Inflow during excavation tunnel grouting around up and down stairs by num.erical analysis methods.In this paper, the main research contents and achievements have the following several aspects:1.After analyzing the local geological and hydrological conditions, found the greatest difficulty of the project is a lot during excavation tunnel face sudden gushing. There are mainly three types of interference seen gushing internal tunnel, that tunnel conditions,geological conditions hydrology, engineering geological conditions(tunnel excavation site)by Combining theoretical knowledge and references. The key elements of the tunnel including the length of the working conditions, working conditions and tunnel construction tunnel construction tunnel excavation radius. Hydrogeological conditions covered surface water gushing environmental interference, environmental average annual rainfall, the head height; Engineering geological conditions(tunneling site) has five areas of interfering elements, namely karst geology, tunnel surrounding rock permeability, maximum depth of the tunnel, the tunnel surrounding rock level, the geological structure of the excavation site.2.In this paper, the actual project which geological advanced prediction of radar technology, as ground penetrating radar for geological disasters accurate advance forecast function, so in the incidence of water gushing able alerts, thus it allows engineers to take in the construction process in a timely manner to deal with effective measures to allow the works to avoid major economic losses staff, making the premise of protecting the safety of construction projects construction.3.First, through in-depth analysis of the key features of the tunnel gushing can find the core factors affecting tunnel water inflow to the geological structure of the tunnel site construction, excavation and rock permeability tunnel radius, the local average annual total precipitation, both inside and outside the tunnel head height。At the same time, it analyzes the relationship between the emergence of Water Gushing these five factors and actual tunnel excavation process. Finally, the use of BP neural network to build a deep water-rich soft rock tunnel water inflow forecasting model, and the focus of gushing water tunnel segments were predicted and compared with the actual value, the error in the 10% range..4.For the characteristics of the tunnel construction, the use of finite element analysis software ANSYS focus on tunnel gushing water inflow during excavation area down stairs is calculated before and after grouting. Then the two conditions of gushing value compared the results can be analyzed by comparing the effectiveness of their water shut off after grouting area closed significantly.