Study On The Support Mechanism Of The Advanced Small Pipeduring Excavation Of The Tunnel

With the rapid development of transportation science or technology, convenient transportations such as the subway or highway tunnels across the mountain areas has been more and more. As a way of using the underground space by the human, the constructions of the tunnel project will only become more common, in order to solve the traffic pressure brought by rapid urban growth. In the rapid development, some problems on the tunnel excavation also need to be resolved.In the process of tunnel excavation, most time the rocks around the tunnel face have poor self-stability, at this time we need to make the pre-reinforcement which is the advanced support. Advanced small pipe, as a process method of the tunnel excavation engineering, has gradually became one of the new technologies to solve the problem of the tunnel excavation, mainly used for weak rock, Shallow Section, the hole bias section, sand section, sand and gravel segment, fault fracture zone and other area where need the advanced support. During the construction, along the excavation contour line and the axial direction of the tunnel, a series of steel tubes will be driven into the frontage ground in a certain order with a particular machine. Then grout through the tubes into the surrounding rock around the pipes, making the front wall rock consolidation to achieve the desired effect pre-reinforcement, and forming a scaffolding support system to support the rock pressure from the outside eventually.As a supplementary method for tunnel construction safety, advanced small pipe technology in the construction process of the poor area which plays an increasingly important role, especially when dealing with the issues of tunnel construction collapse,because of its good economic as well as the flexibility. But this technology has been widely used in tunnel excavation process of practice for more reason of its reinforcing effect. Therefore, it is necessary to explore the mechanism of the small pipe grouting technology.This paper mainly talks about the analysis and research on the support mechanism of advanced small pipe technology, and investigates the interaction mechanism between the upper part soil or surrounding rock of the tunnel and the archstructure which is formed through the way of grouting. Through the research on the arch structure’s stress mode and the role of small pipes in this support process, we need to learn that small pipes’ stress transmission is how to achieve during the support process. We also need to know that the grouting area is how to ensure the stability of the working face of the tunnel excavation, and investigate the effect of changes in the angle of the catheter reinforcement effect. Ensure this technology in actual engineering can achieve the desired supporting effect, and thus playing a very important role on the tunnel excavation, the continuity of the lining and the safety of construction.