The Applied Research Of The Design Of Twin Tunnels With Small Clear Distance And The Key Technologies Of Construction

In recent years the number of highway tunnel increases unceasingly, due to the limit of construction method, geology, topography condition, the interval of twin tunnels is not able to reach the request of the code, so need to use the small interval tunnel or multiple-arch tunnel, and other special structure forms, among them, small interval tunnel can overcome existent quality problem of twin tunnels effectively, there are more technical problems in small interval tunnel design and construction, for example: the select of reasonable clear interval value and reasonable construction method for different levels of rock, different geological and terrain conditions, special working conditions of small interval tunnel, the reinforcement method of containing rock, the long-term safety evaluation at construction process and after tunnel completioned, so the more thorough study to small interval tunnel is very necessary.According to engineering data of the Huamugou small interval tunnel project of Xingtai-Fenyang expressway and the basic theory of lithomechanics, the small interval tunnel model is built by MIDAS / GTS. The tunnel excavation process of three different construction method is simulated. Through comparative analysis to the horizontal and vertical displacement, principal stress distribution, plastic zone distribution of surrounding rock and retaining structure of tunnel, the reasonable construction method to this small interval tunnel project is confirmed. And based on the analysis of the relationship between principal stress distribution, plastic zone distribution of surrounding rock and interval value, the reasonable interval suggested values of the small interval tunnel project is ascertained by simulating the excavation process of tunnel under different interval condition.