The North Cross Channel is a "horizontal" road of Shanghai’s "three vertical and three horizontal" skeleton network. In the early 1990s, constructing highway for the whole line was the plan. However, the huge size of the highway would tear apart the precious city ground space permanently, occupy public space and impact the surrounding community while the underground tunnel scheme had been stalled for years due to too many construction difficulties. In 2014, thanks to the continuous technological innovation in the field of construction, STEC succeeded in making the North Cross Channel an underground one. After commanding the use of large diameter shield and overcoming the building settlement challenge in Yangtze River and the Bund Tunnel, STEC now has the ability to ensure the safety and quality of the tunnel construction with the highest degree of difficulty and risk in the world. During the construction, STEC will push 15.59 meters’ diameter super large shield excavating from downtown Weining Road, continuously crossing the six metro tunnels in operation and 92 buildings in 6.4 kilometers, turning directions with minimum 500 meters’ radius, overcoming the tunnel lining structure, seal, construction risk and many other challenges.  STEC conquered the challenging underground traffic queue in spite of heavy underground traffics and buildings.

Shanghai Yangtze River Tunnel epitomizes the highest technical standard of shield method tunnel construction in the world. The overall length of the tunnel is 8.95 kilometers. We used a slurry balance shield, which is 15.43 meters in diameter, developed and manufactured by STEC and German Herrenknecht AG together, to excavate 7.45 kilometers in the tunnel, 55 meters deep at the bottom of the Yangtze River. This project broke three world records at that time, the largest shield diameter, the longest distance with single excavation, and the deepest buried depth. During the construction of Yangtze River Tunnel, the three major challenges STEC faced were “length, width and depth”. In accordance to the design, construction and disaster prevention of oversize-diameter and extra-long distance shield tunnel under the condition of complicated soft soil stratum, STEC mastered the stability of oversize-diameter shield tunneling and the accuracy of extra-long distance shield tunneling, resolving seven world-class technical difficulties including the synchronous construction technology which prevents the tunnel from floating, overcoming 50 crucial construction problems and furthermore, creating the global standard of extra-large tunnel construction in future cities. Yangtze River Tunnel is also the first shield tunnel adopting all-around stagger assembling craft in our country. STEC manufactured 74,710 pieces of large reinforced concrete segment for its production, and the precise fault margin of which is lowered under 0.5 millimeter, which ensured the quality of the tunnel form.

At present, the Shanghai Yangtze River tunnel has won various domestic tunnel construction awards, including China Civil Engineering Jeme Tien Yow Award, Gold Medal of National Quality projects and others. It also became the first Chinese tunnel project to win "The Tunnel Award" from International Tunneling Association.

Project introduction: Qinwang Tunnel is the first shield tunnel for both highway and railway purposes in Zhejiang Province. The tunnel section, with a total length of 2,868 m, crosses the Fuchun River and connects the Qinwang Square, the "City Eye" of Qinwang, and the Zhongsha district. It works as a crucial infrastructure that improves the cross-rive traffic system in Fuyang. The shield section of left line contracted by STEC is as long as 1,254 m. The outer diameter of tunnel segment is as long as 15.2 m and the inner diameter is 13.9 m. simultaneously, STEC also constructs the underground complex of Qinwang Square, the Qinwang Square Station of rail transit and the relevant ancillary works. The project, upon its completion, will open up the North-South traffic artery of Fuchun Bay in Fuyang, Hangzhou, connect the golden axis of Fuyang rail transit, and thus accelerate the high-quality development in urban integration.

The river-crossing tunnel under West Jianning Road, Nanjing begins at the intersection of Xingpu Road and Jiangbei Avenue in Jiangbei New District; its main line, constructed with a bridge over Jiangbei Avenue, ends near the intersection of Jianning West Road and Rehe Road. The route has a total length of about 6,801 m, of which the tunnel section is as long as about 3,550 m (Including opening section), the subgrade section is as long as about 336 m, and the elevated section is as long as about 2,915 m. “Jianning” slurry balance shield tunneling machine with a super large diameter of 15.07 m was adopted for tunnel construction. The shield tunneling machine will penetrate through the Yangtze River levee, Nanjing Metro Line 5 and other sensitive buildings in succession. The construction of river-crossing tunnel under West Jianning Road is of great significance for Nanjing to speed up the construction of Jiangbei New District, improve the capacity of Yangtze River trunk, relieve the traffic pressure of the main city across the Yangtze River, and keeps promoting the regional road network system.

Apart from resolving the construction difficulties in road tunnels, STEC is also dedicated to reserving space for city transportation system via pre-design. Guangdong Zhuhai Maliuzhou Traffic Tunnel is an exclusive underwater tunnel connecting Zhuhai city center and Hengqin New District, which is also the first 14-meter diameter massive shied tunnel in southern China. As the weaver of “intelligent transportation system plan” in Zhuhai, STEC has a more profound understanding in the design and construction of Zhuhai-Hengqin tunnel.

Due to the influences of three to four typhoons in Zhuhai every year, two bridge passageways in Hengqin will be totally blocked when the typhoons come. Therefore, STEC helped the island to maintain contact under severe weather by enhancing the design of flood prevention platform in tunnels thereby resolving the problem. Meanwhile, STEC also connects the tunnel, with surrounding city transportation and tube systems, taking into account transportation function and city planning development. The move to combine the tunnel and the surrounding municipal road network, pipeline network, municipal pipelines into the underwater shield tunnel reduce the expenses of underwater cables and specified pipes and provides a multi-functional tunnel so as to free up space for Hengqin’s further development.

Besides its function, STEC also considered the important harbor as the city’s image. Tunnel designers adopt the “Chinese zither” as the model to make the surrounding system composed in the shape of Chinese zither. It also adopts the form of earth-covered construction, making the vegetation appear like the elaborate decoration patterns on Chinese zithers. With the premise of satisfying transport demand, the project not only presents the characteristic culture of Zhuhai Hengqin but also emphasizes the ecological meaning which perfectly displayed the geographical scenery traits of Hengqin Island.

Zhengzhou Zhongzhou Avenue Tunnel is the longitudinal axis of the city’s downtown expressway system. It has the biggest section of a rectangular pipe jacking tunnel in the world. Since 1999, STEC has put rectangular pipe jacking technology into tunnel construction. The conduit jacking construction technology has a higher utilization rate of space with shallow overburden and low construction cost. These advantages make conduit jacking construction technology favorable for underground construction in big cities.

The construction of Zhengzhou Zhongzhou Avenue Tunnel consists of four rectangular pipe jacking tunnels through the use of a large section pipe jacking machine (10.4 m * 7.5 M). STEC managed to finish the first 110 meters long extra large section rectangular pipe jacking in China without disturbing the ground transportation, underground lines or pipes. The land subsidence was controlled in less than 3 centimeters. At the same time, in view of the special section structure of conduit jacking, the tunnel has a 35% higher utilization rate of space than a round section tunnel, reducing the depth of tunnel burial.

Till dare, among the finished rectangular pipe jacking tunnels, the biggest width is 6 meters like a pavement. STEC’s domestically designed 10 meters’ width tunnel is the first example in the world. It subverted the concept of city road design and construction. It is poised to become one of the best options of city’s underground transportation and tunnel net construction.

Shanghai City Sewage Treatment Line in Bailonggang Trunk Improvement Project is the last massive-scale sewage treatment line in the sewage treatment system’s professional plan in the city center. Manufacturing models, hoisting equipment and fabrication craft are all innovated to specialize in a disposable pouring-made drain pipe which has the largest diameter of 4,000 millimeters in China for the trunk improvement project SST 2.1, SST 2.3, SST 2.4. To ensure the smooth process of pipe-jacking, we utilized the jacking parameters and applied the digitalized information feedback technology to manipulate the construction quality, execute calibration system and control the center and height of jacking center. To guarantee the pipe-jacking’s successful crossing the maglev foundation and aviation tubes in Pudong International Airport, we carried out in time detection, feedback and rectification. This project is honored “four star” in National Site-Management Evaluation Assessment and Shanghai Magnolia Construction Project. After the construction, this project will effectively resolve the sewage treatment from Puxi in Shanghai, enabling a match between sewage treatment system line in Bailonggang and the ongoing project of enlarging the Bailonggang sewage treatment factory, which embodies strong meaning for improving the water quality in Huangpu River and protecting the water environment in Shanghai.

As the established enterprise in domestic tunnel construction field, STEC participated in constructing the first tunnel in China, Shanghai Dapu Road Tunnel, which was the first underwater tunnel as well as the first tunnel using shield method in China. During the construction, STEC applied the 10.2-meter diameter long grid extrusion shield which is an unprecedented invention fully conceived by our own country for tunnel construction. We have made a construction miracle, which is “digging a hole in the toufu”, building the first-ever cross-river tunnel and unfolding a new era of shield method in tunnel building. Dapu Road Tunnel ends the isolation between Puxi and Pudong in Shanghai, also accelerating the development in Pudong. This project was given the National Science Award in 1978.

As the sole vital transportation tunnel beneath the HuangPu River during the World EXPO, South Xizang Road Tunnel is 5,319.5 meters in length. During the construction, the first national large-scale slurry shield” Xiong Ying Second” designed by STEC was put into use, changing the dilemma of our thorough dependence of large-scale tunnel shield machinery on foreign countries, opening up a brand new way of nationalization in this field, filling the void of domestic large-scale slurry manufacture. Meanwhile, the large-diameter slurry shield also successfully conquered the global difficulty of passing through small-diameter metro tunnel, Shanghai Metro Line 8, which is in operation. This achievement has accomplished the new record of construction in rail transport, and is honored as the model project of the appliance of new technologies in national architecture industry.

Shanghai Outer Ring Tunnel is the key link crossing the Huangpu River as the northern part of Shanghai Outer Ring Road. It is also the first cross-river tunnel in Shanghai which is constructed by immersed tunneling method and is the largest scale in Asia. The immersed tunneling method was introduced to China in 1980s, so it marked the first time that STEC constructed immersed tunnel in such a big scale. The location of the construction is near the Yangtze River estuary. The tide variation brought high construction risk and difficulty. During the construction, STEC managed to sink enormous tabulation (9.55 meters high, 43 meters wide, 100 - 108 meters, weight of 45000 tons of each). We skillfully grasped the axis, elevation and mileage changes. We ensured that the construction quality reach the design precision under harsh conditions of high wind flow, ferocious back silting. By using satellite positioning system and 3D bathymetry technology, we overcame the water displacement difficulty of the pipe sinking construction and promoted immersed tunnel construction level in our country to an international advanced level.

Qianjiang Channel is constructed by STEC through BOT investment with 3.884 billion yuan. It is China's first large diameter shield tunnel project, integrating "investment, construction, operation and maintenance”.

In terms of investment and financing, STEC determined the financial services program and partners through bank bidding for the first time. By cooperating with the Bank of China, China Merchants Bank and Shanghai Pudong Development Bank, STEC raised comprehensive credit of 25.4 billion yuan in total, effectively reducing the overall cost of financing, distributing the pressure of funds from tight monetary policy to different banks. We avoided capital risk and ensured the capital is secured.

In terms of the construction, we successfully pushed 15.43 meters’ diameter large shield machine crossing the embankment foundation of the Ming Dynasty Qianjiang Levee for 4 times, overcoming the world-class difficulty to build express way tunnel in the special hydrological conditions of Qiantang River. In addition, Qianjiang Channel is the first batch of model construction project subsidized by the national budget from the central government which funds semiconductor lighting products application. The whole tunnel was equipped with LED light source illumination. It can save 2.47 million kwh each year compared to ordinary fluorescent lamp system. After the opening of the tunnel, STEC, as its operation and maintenance agent has formulated safety regulations, management system, and operation manual for the tunnel, thereby establishing a management system fitting for local project operation.

A city’s culture and footprints lie in its history. STEC dedicates itself to providing more continual construction blueprints for the city; in ensuring the project’s smooth development, STEC will perpetuate the city culture and protect the cultural environment.

The Shanghai Bund Tunnel is known as the major project in solving the transportation problems in city center. It extends 3.3 kilometers in total length. STEC needs to first guarantee the transportation system in the Bund and the stability of the surrounding erections; then we try to push 14.27-meter diameter long earth pressure balance shield crossing the historic architecture groups along the Bund with precision. Since most of these buildings are over hundred years, there exists uneven degrees of subsidence, leaning and structure aging, which indicates that large-scale shield method for them is a major operation.

During the whole construction, STEC views the protection of historic constructions as the first priority; “FCEC shelter pile and slip casting reinforcement” protection method has been established after several negotiations and experiments on site. Finally, FECE shelter pie technology which takes more working periods is applied to crossing the Astor House Hotel, the minor distance of which is only 1.7 meters. As for other regions, specialized slip casting reinforcement technology is put into use. After the whole project, the subsidence of historic constructions is merely 5.3 millimeters at most and the upheaval of which is just 3.7 millimeters at most, which are far lower than the expected control index.

It is STEC’s advanced construction skills that bring about more options for the exploitation of underground space in city core areas and the improvement of city transportation. Just like the stable, secure and convenient projects we have completed in suburban areas, we can also successfully construct tunnel projects in the prosperous city center.

Hubei Wuhan Sanyang Road Tunnel will become the first massive-diameter cross river tunnel in the upper middle stream of Yangtze River and also the largest-diameter “railway and road co-construction” shield tunnel in China. The total length of the tunnel is 4.6 kilometers and STEC contracted two shield working wells, 2,590-meter long tunnel in the middle of the river and Wuchang working shield wells which are the hidden part of Xujiapeng Station and tunnels as well as major cables working as power substation and construction missions as ventilator room in Xujiapeng.

Wuhan Hubei Sanyang Road Tunnel is renowned as the largest diameter, the largest shield tunneling machine and the largest wind foundation nationwide. We employ two combined type 15.76-meter-long diameter slurry balance shield machines, which are the largest in China, in the middle of river as well as big tunnel part in the process of erection. The outer diameter will reach 15.2 meters after its completion; as for the subway part of the whole tunneling erection, we adopt an earth pressure balance shield machine to excavate. During the entire construction process, we succeeded in the nearly 2.6-meter long distance excavation and the shortest distance of 0.5-meter minor distance construction and shooting construction by virtue of accumulated rich experience in massive-diameter shield constructing. What’s more, we even bypassed the barriers of changing the working tools under the circumstances of shield machines in high-water pressure tunnels. With the rapid development of our city construction, the method of “railway and road co-construction” has gradually become an efficient way to make the best use of underground space resources. STEC’s working performance in the first ever largest-diameter “railway and road co-construction” has proved our technical strength again and also offered a model example for the coming “railway and road co-construction” in China.