Technical Study On The Construction Method Applied For Zhong Nanshan Extra-Longer Tunnel In Qinling Mountain

There has been existed two chief construction methods applied to construction of extra-long tunnels, namely Drilling-Blasting Method and Tunnel Boring Machines. The main method utilized mostly in our country takes the precedence of the drilling and blasting method in construction of extra-long tunnel. With the consideration of the actual onstruction conditions of Zhong Nanshan expressway tunnel in Qin Ling Mountain, and based on available experiences obtained from other tunnel construction, this paper chiefly focused on the construction method applied to extra-long tunnel. The probe into the pilot section of tunnel construction in the extra long tunnel has been conducted before the building work was formally undertaken, and we have adjusted something unsuitable in the construction organization. After the formal commencement of the tunnel construction, the chief study on construction organization planning, construction ventilation, optimal arrangement of construction equipments, prediction and prevention of poor geological disasters, the option of construction transport etc. has been carried out in the paper.The perquisites of personnel organization, transport schedule, ventilation, water drainage, design of blasting mode etc have been taken into account during the tunnel construction. Much more attention has been paid to the construction ventilation, geological calamities such as rock fault, rock burst, water inflow and collapse of surrounding rock. The FEM is used to analyze the cause, development of rock burst during tunnel excavation. The comparison between trail haulage and tire haulage has been conducted in order to choose the optimal way to fulfill transport during construction. The aim of discussion presented in this paper will be helpful to the design and construction of extra-long tunnel in the future.From the practice of construction in Zhong Nanshan express way tunnel, I have drawn out a relatively complete construction style about the extra-long tunnel by using the drilling-blasting method, as it is called the mode for construction of Zhong Nanshan tunnel. But the different situation between different tunnels affects the option of construct method according to concrete project, therefore Zhong Nan Shan's construction method only can be regarded as a function of reference for similar extra-long tunnel under similar geological conditions.