It is briefly introduced that when passing over or crossing rivers, lakes and seas, underwater tunnel construction method is preferred to be adopted for its summed advantages. The survey of design and construction, key construction technology and frequently-used construction method of underwater tunnel are also discussed in this article.
Wuhan Changjiang tunnel is the first tunnel under Changjiang River. The geological condition is very complicated with high hydraulic permeability, high water pressure, big-diameter shield, long driven distance and complicated ground and underground environment. The paper introduced the process of design and research of the project, the construction model, the overall design and general situation of the construction. Shield type select method and protection measure of the adjacent structure are emphasized.
Combined with some underwater shield tunnels such as Wuhan Changjiang tunnel, the determination of reasonable cover thickness, the shield type and key parameter selection are analyzed. The key technology of stabilizing working face, preventing muddy water eruption, preventing tunnel floating, controlling shield direction, excavating long distance, abutting joint underwater, shield launching and arriving are generalized.
A comparison of the bridge programs and the tunnel programs for the project of across the sea in Chinese Xiamen Xiang'an was given in this paper. And there is a preliminary and brief conclusion for the construction of the Chinese first subsea tunnel, which contains the characteristics and difficulties and disadvantages of the construction.
Xiamen Xiang'an subsea tunnel is the first subsea tunnel in China, whose geological conditions in the land are strongly weathered granite with enriched groundwater, shallow-buried excavation method is adopted. During the tunnel construction, the deformation of tunnel support is great. It is important to seek for a reasonable countermeasure to restrict the large deformation to ensure safety construction and advance through trials in locale. The arch crown settlement and level convergence are controlled effectively. Its subsea geological condition is granite.Drilling hole and blasting parameters trials are carried out through construction, and better blasting plan and parameters are gained. The ranges of rock crash of the tunnels are measured by using ultrasonic instrument and displacement record.
Xiang'an sub-sea tunnel is the first large section sub-sea tunnel in China, and will cross the weak stratum with abundant water. As the low stabilizing capacity of the surrounding rocks, water inrush is the maximal risk during the sub-sea tunnel construction. In this paper, based on analyzing the excavation method of the tunnel and results of on site monitoring measurement, we studied the excavation method,drainage technique and pre-reinforcement method of the tunnel when crossing the weak stratum with abundant water, and offer technological support for construction.
The construction of the Qiongzhou strait tunnel will not only meet the requirements of the straits' passenger and cargo traffic,but also the needs of national defense, and the constructed tunnel will play a huge pulling role in Hainan´s economic development.Comparing with the similar projects abroad, the preliminary work of Qiongzhou strait tunnel was very urgent and needed a long time, because of enormous workload of research, complex technology and difficulties. Based on the study of meteorological, hydrological, geological data and other information of Qiongzhou strait tunnel, the bridge and tunnel schemes are simply compared, which indicate that the tunnel scheme is suitable, moreover, the shield tunnel scheme for line Ⅱ is better than others. After compared the shallow tunnel with deep tunnel schemes of line Ⅱ, the shallow tunnel using shield method scheme is proposed. As highway tunnel had many technical problems, and project costs and operating costs are very high, therefore, the railway tunnel plan as the preferred option is feasible, and cars could pass through the tunnel by shuttle trains.
Qingdao Jiaozhouwan tunnel is 7 800 m, and subsea tunnel is 3 950 m. There are 2 main traffic tunnels and 1 serving tunnel. Accessorial tunnel passing in or out the main traffic tunnel is founded at 2 000 m part from gate in Qingdao. Space between the center lines of the 2 main traffic subsea tunnesl is 55 m. The section is oblong, width is 16 m, and height is 12 m. The tunnel is through slightly weathering granite, dolerite and andesite. Its vertical section is "V" slope. The maximum seawater depth is 42 m and the minimal rock cover depth is 30 m.The key tunneling technology and configuring big machines of drilling and blast for constructing Qingdao Jiaozhouwan subsea tunnel were discussed in this thesis.
Shiziyang subaqueous tunnel, a part of Guangzhou-Shenzhen-Hongkong dedicated passenger high-speed railway, is the very first underwater railway tunnel of China, also the first extra-long underwater tunnel of our country. Its design speed reaches 350 km/h. The tunnle is a key project of Guangzhou-Shenzhen-Hongkong dedicated passenger high-speed railway. Basing on the engineering geology environment and adopted tunneling technology of Shiziyang tunnel construction, the thesis introduces comprehensively design and tunneling technology of the tunnel, also puts forward corresponding technical measures. In the project, tunneling is going to be carried out by shield machine from both portals, which is also the first practice of its kind in our country.
Based on the construction of Baojiashan tunnel,the authors used numerical simulation and field test to analyze lining force,deformation and safety in the conditions of setting deformation joint and not. Studies suggest that:a. whether deformation joint is set or not,tunnel's vertical safety can meet the security requirements;b. if we do not set deformation joint for tunnel structure of the horizontal safety,the safety factor increases in V grade rock side,decreases in IV class rock side and reinforcement is needed at this time; when deformation joint is set,IV and V grade-level department of dome rock safety factors are smaller and can not meet the safety requirements,then reinforcement is needed.
Based on the conformal mapping of the complex variable methods, analytical solutions for water inflow into an underwater tunnel are derived for a constant hydraulic head, constant water pressure and constant hydraulic head as well as grouting ring boundary condition at the tunnel perimeter. According to the proposed formula, relation between water inflow and h/2r, as well as grouting ring thickness, some valuable conclusions are proposed.
The waterproof and drainage principle for subsea tunnel is clarified. Based on Xiamen subsea tunnel, the suitable discharge is discussed. Different waterproof and drainage schemes for various grounds are put up, and the main problems that must be paid attention to and questions that must be studied further during subsea tunnel design and construction are put forward. The design method of waterproof and drainage system for subsea tunnel is a reference for other subsea tunnels.
Combined with the built immersed tube tunnel, comparison and selection of dry-dock scheme, waterproof design of tube sections and joints are analyzed. The key technologys such as tube prefabrication, tube floating, tube sinking, jointing underwater and foundation treatment method are generalized.
Based on the similarity theory and simulation experiment, main construction parameters of immersed tunnel are researched. The following items related with the simulation experiment are introduced, which include the model design, experiment process, important points for attention and the technical requirements. A large of the immediate data is obtained by the experiment. On the basis of analyzing test results, the main original parameters on construction of the immersed tunnel are verified and analyzed. The achievement of the experiment can be used to provide reference for the future engineering construction of immersed tunnel.
In this paper, the characteristics of underground works and constructive guidelines for risk assessment of underground works were intro.The results of the research were successfully applied to the study of the Beijing Municipal City Planning and Design of the underground road system.
Squeezed pile with plates (being DX pile) is a new type pile that has been developed in recent years. Based on common cast-in-place pile, it adequately avails itself of the bearing capacity of each soil hard layer. According to the difference of design bearing capacity and engineering geological condition, it consists of plates by the squeezing equipment of hydraulic pressure in the different parts of DX pile. DX pile is a sort of change-section pile and is priority to shaft resistance between friction pile and shaft pile. Making use of the tip resistance of breaches and plates and shaft resistance around the branches is in order to add the shaft resistance and tip resistance. In situ test has shown that it can sharply improve the bearing capacity of pile. DX squeezed pile cannot only be applied in clay, silt, sand, weathering rock mass and residual deposits of soil, but also can be used in interactive layers of gravel,clay,and sand. The diameter of DX squeezed pile can be 400~2 000 mm,and the length of it can be more than 60 m. It is a new type of pile which has a bright future for application. Now it has got the extensive application in high building, bridge,civil engineering and high structure. Due to it's good bearing capacity and low settlements,it can an be applied and promoted to different foundation engineering of railway bridge engineering,and would get a good prospect of application and extension.