At present, China has become the country with the fastest development of urban rail transit in the world. With the rapid development of rail transit construction in my country, many problems and weaknesses have been exposed in the construction of rail transit projects in various places, such as extensive installation and construction of equipment, facilities, and components, which has caused serious damage to the civil structure of subway tunnels and corrosion of parts. The phenomenon is very common, which has greatly reduced the service life of the project and also increased the difficulty and cost of daily operation and maintenance. This problem has attracted increasing attention in the industry, and began to explore and practice relevant technical measures and methods based on the successful experience of foreign developed countries.
There are many types of installation equipment. Metro electromechanical installation includes many systems, such as ventilation and air conditioning, water supply and drainage, fire water supply, power lighting, fire alarm (FAS), environment and equipment monitoring (BAS), communication, signal, guidance, etc., which need to be in the subway tunnel There are many equipment pipelines installed and laid inside and the layout is complicated. In the subway construction, the civil construction period is long, the construction period of the electromechanical installation project is short, and the construction space is unusually narrow, which puts huge pressure on the construction period of the electromechanical installation contractor, and also has a great physiological impact on the construction personnel on site. Metro electromechanical professional installation equipment has many pipelines, crossing each other, and intricate. How to do a comprehensive balance, reasonable design and application of pipeline layout is related to the construction progress of the entire electromechanical installation project and also restricts whether the subway can be opened and operated on schedule.
Many holes for equipment installation Taking shield-driven subway tunnels as an example, most of the cables, pipelines and equipment installations currently require drilling holes in the pipe segments. This method of operation has the following three disadvantages: first, the construction efficiency and quality are low, and the quality of installation cannot be guaranteed, leaving hidden dangers for future equipment use and operation; second, the noise and dust pollution during construction operations are serious. Affect the health of workers. If drilling equipment that has less impact on the environment, the safety and health of the construction personnel is used, the construction cost will be greatly increased; thirdly, the drilling operation will cause permanent damage to the segment structure, resulting in damage, cracking and seepage of the segment structure. Quality problems such as water leakage have greatly reduced the service life of the project. The current status of the installation of subway tunnel equipment in my country is worrying.
Embedded technology of HALFEN trough/huadun trough and skydun trough: The embedded technology of HALFEN trough originated in Germany at the beginning of the 20th century. It is a kind of embedded technology developed and applied with the rapid development of concrete engineering. It is widely used Reinforced concrete structures for tunnels and bridges. In rail transit engineering, it is the best choice for fixed installations such as catenary, communication signals and power equipment. The Hafen trough is also suitable for all fixed installations that are subject to dynamic load, such as lifting rails or mechanical fixed installations. The Hafen trough is a kind of pre-embedded device suitable for various concrete structures. Its basic working principle is: first embed the C-shaped channel steel in the concrete, and then buckle the big end of the T-bolt into the C-shaped groove, and then Fix the equipment components to be fixed with T-bolts. Similar products of Hafen trough developed and produced in China include Huadun trough and Tiandun trough.
Halfen trough has the following excellent quality characteristics: 1) High load capacity, up to 32 kN/m or 128 kN/m. 2) Can be used for static and dynamic load. 3) The installation margin is small, the smallest can reach 5 cm. 4) Easy to install and easy to adjust. 5) No noise and dust during installation. 6) The use of stainless steel or anti-corrosion treated steel has good anti-corrosion performance.
As a very mature concrete embedded part technology, the Hafen trough/Hua shield trough has the following significant advantages when applied to the installation of various equipment in subway tunnels: 1) Zero damage to the tunnel structure, which can effectively extend the service life of the project. 2) Although the one-time input cost of embedded parts has increased, in the long run, the operation and maintenance costs of the equipment are reduced, and the overall cost of equipment installation and maintenance is reduced. 3) The installation work environment has been greatly improved, and the equipment installation efficiency has been significantly improved. The construction period can be shortened by 1 month per 10 km on average. 4) It is convenient to replace and add various equipment during the operation period.
In order to verify the construction efficiency, accuracy and applicability of the embedded parts of the Hafen trough/huadun trough and skydun trough, Shenzhen Metro Group Co., Ltd. conducted related installation process tests. The model is 1:1, 5 ring segments, 7.5 m long. The model installation test proves that the technology of the embedded parts of the HALFEN trough/huashidun trough is completely feasible and suitable for the installation of any component in the shield tunnel.
The comprehensive promotion of embedded technology can improve the efficiency of equipment installation, improve the installation working environment, facilitate the daily maintenance of the equipment, and also greatly reduce the tunnel structure damage caused by the installation and construction, and effectively extend the life of the project.
On the basis of summarizing the successful experience of existing pilot projects, Shenzhen Metro intends to promote the standardization and standardized management of subway equipment installation with the comprehensive promotion of embedded parts technology as the starting point, and submit the embedded parts design manual in June 2013 as planned, 2014 Large-scale drilling is not allowed for all newly started projects in 2010, so as to fully realize the quality target of 150 years of project life.
Insulating nylon casing embedded technology Insulated nylon casing embedded technology is to facilitate the pipes to pass through brick walls, concrete beams, concrete walls and other components during the installation of various equipment. When concrete is poured, it is embedded in the concrete components in the form of embedded sleeves. Reserve holes on the top. This technology is suitable for places where the pipelines of civil air defense, underground engineering, chemical industry, steel, tap water, sewage treatment, etc. pass through walls and require tight waterproofing.
The comparative advantages of embedded parts technology: Compared with traditional drilling rig drilling technology, embedded parts technology such as HALFEN slot/huadun slot and insulating nylon casing, the embedded part technology is standardized, comprehensive work efficiency, and protection of concrete structure All aspects have shown significant advantages. The drilling technology of drilling rigs is equally low in the early stage of the project cost. However, considering the investment in repair and maintenance costs and the life of the project in the later stage of the project, the embedded part technology is generally better. The traditional drilling rig drilling technology has absolute comparative advantages.
There are a large number of steel parts and components, such as various equipment parts, fasteners, etc., in numerous subway operation system equipment. These equipment parts and fasteners, due to the lack of appropriate anti-corrosion measures during manufacture, and the harsh application environment conditions, often have serious oxidation and corrosion during use, which will have a negative impact on the normal use of the equipment and cause many equipment Security risks. The widespread presence of corrosion in subway equipment and installation parts is a common quality problem that needs to be resolved urgently in the industry.
Solution Measures--Promote the anticorrosion technology of zinc-nickel infiltration layer
The zinc-nickel coating anticorrosion technology is a chemical heat treatment technology. This technology is a ferrous metal developed by adding nickel and aluminum to the formula to enhance the wear resistance and corrosion resistance of the zinc coating technology on the basis of the zinc coating technology. Anti-corrosion technology. The principle of the technology is: under certain temperature conditions, steel parts are fully contacted and heated with various elements such as zinc, aluminum, nickel, rare earth, etc., so that multi-element metal atoms such as zinc, aluminum, nickel, etc. uniformly diffuse into the surface of the steel product and form on the surface of the product. The intermetallic compound-alloy co-infiltrated layer with different proportions of zinc, aluminum, nickel and iron. Its potential is lower than iron and higher than zinc. As an anode protective layer, its anti-corrosion life is naturally longer than that of a pure zinc anti-corrosion layer of the same thickness. The various physical and mechanical properties of zinc-nickel infiltration coating treatment technology, such as tensile strength, yield point, corrosion resistance and surface hardness, are better than stainless steel materials.
Engineering practice has proved that the promotion of zinc-nickel infiltration coating anti-corrosion technology is an effective countermeasure to solve the corrosion problem of subway equipment and installation components. The comprehensive promotion of zinc-nickel infiltration coating anticorrosion technology to prevent corrosion of equipment and installation parts can effectively reduce operating costs and improve equipment integrity and safety.