Research On Advanced Pre-Reinforced Technology Of Working Face For Liuyang River Tunnel

Liuyang River tunnel is the key control engineering of the Wuhan-Guangzhou passenger transport special line. It is 10.115km, undercrossing Liuyang river at DIIK1568+666-DIIK1569+028.This is a strong～weak weathering silty mudstones area. Joints and fissures are developing, filled with local gypsum rock. Across from the yellow syncline core part beneath the river, so working face is not steady and blocks out during construction. There will be the devil to pay if the working face collapsed, so whether the working face is steady is the key point of the engineering.For the complex geological and hydrogeological conditions of Liuyang River,this thesis studies advanced pre-reinforcement technology of working face with engineering analogy, numerical simulation, field testing and other means. The following are main conclusions:1,Definite these concepts such as ahead of the core soil, tunnel working face extrusion deformation, pre-tunnel convergence; Point out the methods of pre-reinforcing design and content of construction system; Offer the construction process of advanced pre-reinforcement of working face.2,Applying numerical simulation to study the merit and demerit of three-step excavation, two-step excavation, full face excavation method based on geological conditions and related construction machinery. The conclusion is excavation of two steps is the best. Working face is pre-reinforced with advanced small pipe from the arch whose parameter isΦ42 and 3.5m long and glass fiber anchor which is 5m long every 4m2;3,The key point of advanced pre-reinforcement technology for working face is to keep the stability of ahead of the core soil. Besides conventional measurements, this method pays much attention to the extrusion of ahead of the core soil, pre-convergence measure, and measurement method for ahead of the core soil is put forward clearly.4,Combining with the geological conditions surrounding the Liuyang River tunnel,the study on adaptability of pre-reinforcing method, facilities of glass fiber anchor and machinery equipment model of construction system was made; The conclusion is the key technology of glass fiber anchor construction is drilling and grouting anchor; C6 multi-function rig is the main machinery equipment and efficient highly.5,By the study on advance advanced pre-reinforcement construction of Liuyang River tunnel beneath the river,a system of advanced pre-reinforcement technology is formed, that gives a solid technical foundation to the promotion and application for advanced pre-reinforcing method for working face.