At present, China has become the world's fastest developing urban rail transit country。The rapid development of rail transit construction in our country，Many problems and weak links have also been exposed in the construction of rail transit projects around the country，For example, extensive installation and construction of equipment, facilities and components，The damage to the civil structure of subway tunnel is very serious，Corrosion of parts is very common，The service life of the project is greatly reduced，At the same time, it also increases the difficulty and cost of daily operation and maintenance。This problem has increasingly aroused high attention in the industry, and began to explore and practice relevant technical measures and methods on the basis of the successful experience of foreign developed countries。

　　Various types of installation equipment The electromechanical installation of the subway 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 and so on，There are many equipment pipelines to be installed and laid in subway tunnels and their layout is complicated。In the construction of subway engineering, the civil construction period is long, the construction period of mechanical and electrical installation engineering is short, and the construction space is extremely narrow, which causes huge pressure on the mechanical and electrical installation contractor, and also causes great physiological impact on the construction personnel on the site。There are many pipelines of mechanical and electrical installation equipment in subway, which are cross-crossed and complicated. How to make a comprehensive balance of pipeline layout, reasonable design and application is related to the construction progress of the entire mechanical and electrical installation project, and also restricts whether the subway can be opened and operated as scheduled。

Concrete segment breakage caused by drilling construction

Concrete segment breakage caused by drilling construction

　　Taking shield subway tunnel as an example, at present, most of the cables, pipelines and equipment need to drill holes in the pipe segments。This operation method has the following three disadvantages: first, the construction efficiency and quality are low, and the quality of installation can not be guaranteed, leaving hidden dangers for the future use and operation of equipment;Second, the noise and dust pollution during the construction operation are serious, which affects the health of the operators。If the drilling equipment has less impact on the environment and the safety and health of construction personnel，The construction cost is greatly increased;Third, the drilling operation will cause permanent damage to the segment structure，It leads to quality problems such as breakage, cracking, leakage and so on，Thus, the service life of the project is greatly reduced，The current situation of subway tunnel equipment installation in our country is worrying。

　　Hafen groove/Huadun groove, Tiandun groove embedding technology: Hafen groove embedding technology originated in Germany in the early 20th century, is a embedded part technology developed and applied with the rapid development of concrete engineering, and is widely used in reinforced concrete structures of tunnel and bridge engineering。In rail transit engineering, it is the best choice for the fixed installation of overhead contact lines, communication signals and power equipment, and it is also suitable for all fixed devices that will have dynamic load, such as lifting rails or mechanical fixed devices。Hafen Groove is a kind of embedment device suitable for all kinds of concrete structures. Its basic working principle is: first, C-channel steel is embedded in concrete, then the big head of T-bolt is fastened into the C-channel, and then the equipment component to be installed is fixed with T-bolt。Domestic research and production of Hafen trough similar products are Huadun trough, Tiandun trough and so on。

All kinds of line facilities are densely arranged in the subway shield tunnel

All kinds of line facilities are densely arranged in the subway shield tunnel

　　Hafen tank 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 minimum can reach 5 cm。4) Convenient installation, easy to adjust。5) No noise and dust during installation。6) The use of stainless steel or anti-corrosion treatment of steel, good anti-corrosion performance。

　　As a very mature concrete embedment technology, Hafen trough/Huadun trough has the following significant advantages when applied to the installation of various equipment in subway tunnel: 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 the embedded parts increases, the operation and maintenance cost of the equipment is reduced in the long run, and the overall cost of equipment installation and maintenance is reduced。3) The installation environment is greatly improved, the installation efficiency of the equipment is significantly improved, and the average construction period can be shortened by 1 month per 10 km。4) Facilitate the replacement and addition of various equipment during the operation period。

　　In order to verify the construction efficiency, accuracy and applicability of the embedded parts of Hafen trough/Huadun trough and Tiandun trough, Shenzhen Metro Group Co., Ltd. carried out relevant installation process tests。The model is 1:1, 5 rings, 7.5 m长。The model installation test proves that the technology of Hafen/Huadun groove embedded parts is feasible and suitable for the installation of any component in shield tunnel。

Corrosion of subway components

Corrosion of subway components

　　The comprehensive promotion of embedded parts technology can improve the installation efficiency of equipment, improve the installation environment, facilitate the daily maintenance of equipment, but also greatly reduce the damage caused by installation and construction of the tunnel structure, and effectively extend the project life。

　　Shenzhen Metro on the basis of summarizing the successful experience of pilot projects，The comprehensive promotion of embedded parts technology is intended to be the starting point，Promote the standardization and standardized management of subway equipment installation，The embedded parts design manual was submitted in June 2013 as planned，Large-scale drilling is not allowed for all new projects in 2014，In order to fully achieve the quality target of the 150-year life of the project。

　　Insulated nylon sleeve embedding technology Insulated nylon sleeve embedding technology is to facilitate the installation of various types of equipment through the pipe through the brick wall, concrete beam, concrete wall and other components, in the concrete pouring in the form of embedded sleeve holes in the concrete components。The technology is suitable for air defense, underground engineering, chemical industry, steel, tap water, sewage treatment and other pipelines through the wall requires strict waterproof。

　　The comparative advantage of embedded parts technology: the embedded technology such as Halfen groove/Huadun groove and insulated nylon casing is compared with the traditional drilling technology，The embedded parts technology has shown remarkable advantages in standardization, comprehensive efficiency and protection of concrete structures，The drilling technology of the drilling rig is equally low in terms of the upfront engineering cost，However, factors such as the investment of maintenance costs and project life in the later stage of the project are considered comprehensively，On the whole, the embedded part technology has absolute comparative advantages over the traditional drilling technology。

The rust of steel parts after 5 years of use is compared to the hot dip zinc treatment on the left and the zinc-nickel infiltration layer on the right

The rust of steel parts after 5 years of use is compared to the hot dip zinc treatment on the left and the zinc-nickel infiltration layer on the right

　　In many subway operation system equipment, there are a large number of steel parts, such as various equipment parts, fasteners, etc。These equipment components and fasteners, due to the lack of appropriate anti-corrosion measures during manufacturing, coupled with the application of poor environmental conditions, there are often serious oxidation rust phenomenon during use, which has an adverse impact on the normal use of equipment, but also caused a lot of equipment safety risks。The corrosion of subway equipment and installation parts is a common quality problem that needs to be solved urgently。

　　Solution -- promoting the anticorrosion technology of zinc-nickel infiltration layer

　　Zinc-nickel infiltration layer anticorrosion technology is a chemical heat treatment technology, the technology is based on zinc infiltration technology, in order to enhance the wear resistance and corrosion resistance of the infiltration layer, the addition of nickel and aluminum in the formula and developed black metal anticorrosion technology。The principle of the technology is that under certain temperature conditions, steel parts and zinc, aluminum, nickel, rare earth and other elements are fully heated, so that zinc, aluminum, nickel and other multiple metal atoms are uniformly diffused into the surface of steel products, and an intermetallic compound - alloy layer with different proportions of zinc, aluminum, nickel and iron is formed on the surface of the product。Its potential is lower than that of iron and higher than that of zinc, and as an anode protective layer, its anti-corrosion life is naturally longer than that of pure zinc anti-corrosion layer of the same thickness。The physical and mechanical properties, such as tensile strength, yield point, corrosion resistance and surface hardness are superior to those of stainless steel。

　　The engineering practice has proved that the popularization of zinc-nickel coating anticorrosion technology is an effective measure to solve the corrosion problem of subway equipment and installation parts。The comprehensive promotion of zinc-nickel coating anticorrosion technology to prevent corrosion of equipment and installed parts can effectively reduce operating costs and improve equipment integrity and safety。