Study On Interaction Of The Shallow-buried Tunnel Mining And The Ancient Buildings

With the development of urbanization, the utilization rate of the aboveground space in a city is increasing greatly, while that of urban underground space is still not high, and the less economically developed the region is, the lower the utilization rate of urban underground space is. With the continuous economic development and the increasing average possession of vehicles of urban residents, it is not only challenging the urban transport, but also a big challenge for urban parking lots. So it is a major trend to develop the urban underground space in the future, especially for cities like Lanzhou which is surrounded by mountains. There is no doubt that urban underground space development, such as the construction of subway, the excavation of underground tunnels, the construction of underground parking, or the construction of underground shopping malls, etc., will undoubtedly impact the aboveground building. Many scholars have done researches in this field, which provide great practical significance to current study. Based on the project of excavating underground tunnel under the ancient buildings on Baita Mountain in Lanzhou, this paper makes a study on the mutual influence between tunnel excavation and the aboveground building with theoretical and Flac3 D numerical analysis methods.1. Taken finite element software to research the excavation sequence of two side-wall pilot tunnel method that applies to this project,in order to control surface subsidence better,when excavating double track tunnel,the excavation of deep side of the tunnel and shallow buried side drift should be preferential.2. With the help of the finite element software Flac3 D, the surface subsidence during tunnel excavation is studied in this paper. Some objective laws of tunnel subsidence with double side heading method are discovered, such as biggest vault subsidence occurs during pilot tunnel, which accounts for 30% to 40% of the vault subsidence, the tunnel vault subsidence of deep buried side is bigger than shallow buried side, and the level convergence in shallow buried side is higher than deep side.3. Summarized results of research on Peck formula, main two parameters in the Peck formula uses the following methods to compute: Coefficient of settlement trough width obtained through averages three different formulas;Ground loss obtained by experience. Choose the conservative 1% and 3% as the minimum and maximum ground loss ratio calculated a range of ground loss. Using Peck formula Calculated settlement range of the sticking point of the tunnel, as a theoretical settlement range of reference for follow-up studies. Also, using numerical simulation method to verify the reasonableness of Peck formula4. On the basis of the theoretical calculation of Peck formula, combined with numerical simulation method to study the interactions between the tunnel excavation and adjacent buildings, this paper finds that the surface construction of adjacent buildings scarcely effects the tunnel subsidence, but the tunnel excavation will cause uneven settlement of some adjacent buildings.5. researched some factors of tunnel subsidence, that surface subsidence can be controlled effectively by choosing proper excavation sequence,shoring timely and choosing proper support pattern as well as support parameter.