Structural Selection And Design Analysis Of A Kind Of Cable Tunnels In Urban Rail System

With the development of economy and the construction of city, traditional buried and cobweb overhead cables in urban area do not meet the requirements of sustainable development. In order to keep the city clean and beautiful, power cable and high-voltage power cable laying have been developed under ground. The cable tunnel construction in city becomes an important aspect of the municipal building, so its selection and design are essential tasks.Based on the extensive research in domestic and foreign cable tunnel design, the structural selection and design analysis of the Innovation Road’s cable tunnel of Hefei rail system are studied in this thesis. The main work and research results are in the following.1. Based on the 1.65 kilometers long cable tunnel in Innovation Road of Hefei rail system whose geological conditions are deep buried soil with underground water, three-dimensional solid model of lining and covering-soil have been set up in this thesis, while the project cost, safety and construction factors are considered to propose different forms of section of the tunnel. Afterwards, the finite-element software MIDAS/GTS is used to analyze the stress and the deformation distribution of the tunnel structure for selecting the most suitable cross-section form, comparing with the merits and demerits of the scheme as well as the stress state.2. Considering the laying requirement of the cable as well as the convenience of construction, operation, management etc., the cross-sectional size of the tunnel is determined. Meanwhile, subjected to the depth, work condition and security level, the tunnels with three thicknesses are designed by the mechanical analysis and strength assessment. Then the more appropriate cross-section thickness is determined according to lower cost.3. Because of smaller section and more shallow buried depth, the cable tunnel in cities have some particularity in its design and construction compared with the ones in railway, road and subway engineering, so the calculation method of the pressure load of the cable tunnel is different. In this thesis, through synthetically contrasting various calculation methods of pressure load, the earth pressure is calculated based on the soil case surrounding the cable tunnel, whose results could be the reference for the tunnel reinforcement calculation.4. According to the type and circuit number of the tunnel, the suitable material and advantageous type of cable bracket have been chosen out. Furthermore, the stress and deformation results for different cable bracket in the tunnel are carried out by the finite element software MIDAS/CIVIL so that it could meet the usage requirements.In the thesis, the research results for the section shape and wall thickness, load calculation, structural reinforcement and design of cable bracket for the present cable tunnel in urban rail system can be used for the same cable tunnel constructions.