Construction Technology Of Large Cross-Section Diversion Tunnel Of Shuibuya Water Conservancy

Shuibuya Water Conservancy Project is the "Dragon Head" project which is step-by-step constructed by Qingjiang City. Its pilot tunnel is the most important temporary facilities, whose largest drilling cross-section is 24. 3×20. 9m(W×H), and it is larger than most other similar projects. Because of the short construction schedule, complicated geological conditions, and various large cross-section fashion, the construction of this project is extremely difficult.In the course of construction of this project, not only the drilling and blasting method and shotcrete technology, but also many other methods and technologies have been adopted, such as monitoring survey, geologic advance prediction, very large section tunnel construction method, steel fibre reinforced shotcrete technology, drilling carriage with hydraulic steel module for lining construction, and inverted circular arch plate made by steel pipe rolling method.Integrated with the construction of very large section tunnel of the Shuibuya Water Conservancy Project, this article aims to summarize the above tunnel construction technology and points out the key points and problems in tunnelling.The article mainly summarizes following contents: In the process of monitoring survey, it is important to realize the development of thesurrounding deformation, fixing the support on proper time, inspecting the effect of lining such as deformation and displacement, predicting final displacement, and according to the deformation and displacement evaluating the stability of the surrounding. Meanwhile, it is important to adjust the design parameter of the support in order to ensure the safety of the design and construction.For bad geological conditions such as faultage, cranny and Karst, it should take some measures such as geologic advance prediction, grouting around the working face, rockbolt along the contour line, short-gauge, ripping blasting for excavation, immediate support and grouting, monitoring survey and so on.In the construction of vary large changeable section tunnel, the article emphasizes how to excavate, support, monitoring, and adopt the most proper support method to ensure the safty of the tunnel.In aspect of the steel fibre reinforce shotcrete technology , the article pays much attention to how to adopt the proper shot method, controll tunnelling quality and evaluate the result.The drilling carriage with steel module for full lining is a specialized machine for this tunnel. The article discusses the different characteristics, structure, assembly and disassembly method, operation ,instruction, and maintenance method between this equipment and normal drilling carriage.The Shuibuya Water Conversancy Project adopts the steel pipe rolling. Compared with the traditional pulling mould or covering mould methods, The method applied in this project is easier, cheaper and more efficient.The above mentioned technologies applied in the construction of diversion tunnel of Shuibuya Water Conservancy Project are successful, and can be applied in the similar hydroelectric projects.