Broken Wall Rock In The Pipe Roof Advance Care Deals With Applied Research

Along with the accelerating construction pace in China, highways, railways, hydropower, mining and other mountain tunnel projects are entering a new era. Gradually weak and broken rocks are met with in the tunnel buliding of urban construction,transportation,utilities mining. Sometimes, the layer ground of the tunnel is thin and the loading is big.In some cases the tunnels should go through some bad ground or exsiting structure.In these cases,the pre-support technologies are applied to the soil reinforcement before excaving for the following goals:support the loading, contorl the settlements of ground and exsiting structures and also fasten the ground. The paper selected barrel vault advanced support technologiy which is popular applied in tunnel excavtion as an auxiliary technique carried out but whose theory lags behind the practice,the main content of this disseration is as following:1. The pre-support technology and the diversified pre-brace method were systematically analyzed. The research status of domestic and abroad were systematically summarized.2. The elastic foundation beam was selected as the model.The basic equations of elastic foundation beam were described. Double parameter theory for solving differential equations of elastic foundation beams and the theoretical solution were derived.3. The deflection curve of pipe roof was solved based on the actual project.The depth of tunnel,the steps of excavation,the diameter and spacing of pipe roof were changed.The reasonable parameters were got by the corresponded deflection curves.4.The design theory of forepoling bolt were introduced and the design of forepoling bolt was analyzed based on the actual project.5.The flac3d was systematically introduced and compared with the software of finite element.And the support in tunnel construction was numerical simulated with flac3d.The author analysed the stress,displacement of surrounding rock in different form of advance support and thus made the role of control surface subsidence and the level convergence of tunnel are made clearly.