Research On The Construction Technique Of Backfilling And Slope Deformation Of Duanxi Shallow Buried Tunnel

With the stable development of the Belt and the Road Initiative,China is in a large-scale construction of transportation system now.In the construction of railway,highway and public works,we often run into the shallow buried tunnels,it is important to handle the complex situation during construction,but it is also very difficult.We usually use open excavation method or undermining method on shallow buried tunnels.The open excavation method is easy and simple and have high construction speed,but it will cause large environmental damage;with the complicated construction technology and high difficulty,the undermining method not only cost a lot of money but also have a slow construction speed.However,this method can minimize the pollution and damage to the environment during construction.This paper based on the Duanxi tunnel of NanLong railway capacity expansion reconstruction project.The suitable excavation scheme of shallow tunnel and reasonable deformation control method is discussed.According to the monitoring measurement and numerical analysis method,we can analyse the deformation law of surrounding rock during tunnel construction and we can study the general law of deformation and displacement development of surrounding rock under the condition of shallow topography in tunnel construction.What's more,through numerical simulation,the validity and validity of the rules are further explored and verified.The main contents of this paper are as follows:1.The excavation supporting scheme and relative deformation control method of shallow buried railway tunnel are summarized in detail,which are based on the special topography of the shallow section of the tunnel.From technical difficulty,economic benefit,progress,benefit and so on several aspects to carry on the research,this paper analyzes and compares the common construction scheme of shallow tunnel and a rapid construction method of concealed tunnel in shallow buried bias section of railway tunnel.Cutting from the shallow buried section and bidirectional driving,added the construction faces and it is more advantageous for tunnel construction with long tunnel length.2.Some methods of tunnel and slope deformation control are summarized: anchorsupport,shotcrete and frame anchor are adopted to support the slope:anchor reinforcement,shotcrete,frame anchor cable,surface grouting and pipe roof.In adddition,it has better deformation control effect on the weak surrounding rock,the height of backfill soil is not large or the large range backfill when using the pile isolation scheme such as bored pile and PFC pipe pile.3.Including settlement of vault crown,tunnel border displacement and slope deformation,the monitoring measurement feedback the rationality of tunnel excavation and support construction process and verified the reliability of the numerical simulation.4.Using the Flac3 D,this paper carried out the partial simulation of the construction process,some results are obtained by simulation,including tunnel surrounding rock,initial support and stress and deformation of the lining,which are used to analyze the rationality of the excavation method and the support mode used in the tunnel construction.This paper takes the Duanxi tunnel as the object of study,summed up a set of shallow tunnel construction in the section of the hole effective safety measures and construction technology,it provide the valuable experience for the long shallow buried tunnel construction.