Recently, with the completion of the last truck of concrete pouring, the first floor of the first section of Nanjing Underground Space Phase I Project has been successfully poured, marking that the deepest part of the ultra-deep foundation pit of Nanjing Underground Space Phase I Project, 50.8 meters, has begun to be sealed.
It is reported that the first phase of the underground space project in Nanjing Jiangbei New Area is developed and constructed by China Gezhouba, with a total investment of & nbsp; 13.12 billion yuan, with a land area of about 29.66 hectares and a total construction area of about 857000 square meters. There are totally 12 plots in the area, which are divided into 10 sections and 12 foundation pits for construction by stages and in sequence. Among them, the deepest foundation pit is Binjiang Station of Metro Line 4. The excavation of the foundation pit is 50.8 meters underground, which is equivalent to inserting 17 floors into the underground. It is the deepest subway station under construction in Asia.
Usually, the foundation pit deeper than 5 meters is defined as "deep foundation pit", which is usually difficult to construct, and the surrounding soil layer needs to be supported in the process of excavation. The excavation depth of the deep foundation pit of this project is 50.8 meters, which is 10 times deeper than ordinary deep foundation pit. In addition, it is located in the Yangtze River floodplain landform area which is only 600 meters away from the Yangtze River, so the geological conditions are very complex. "It is equivalent to building a palace in water tofu, and there is no precedent to follow so far." Song Hongwei, secretary of the Party branch and project manager of Nanjing Underground Space Project Department of China Gezhouba No.1 Company, said. It is not easy to build underground space
in such a rare depth, and it is even more difficult to set up subway platforms. The thickness of the slab poured this time is 2.6 meters, and the steel bars of the slab in the subway section are dense, so the concrete pouring is very difficult. Before the pouring, the Nanjing Underground Space Project of China Gezhouba No.1 Company organized a special meeting on the pouring of the bottom slab. Hundreds of people discussed it for three hours, and finally determined the pouring plan, and put forward the strict requirement that all the bottom slabs must be poured in 30 hours.
After 29 hours of hard work day and night, more than 2600 cubic meters of concrete were successfully poured on the bottom plate of the 1-4 axis of the foundation pit, and cheers were heard from the scene. The successful pouring of the first warehouse floor ensures the safety of the foundation pit, and further strengthens the confidence of the participating units in the smooth closure of the floor.
According to Song Hongwei, the project started in September 2017, adhering to the four core concepts of "integrated development, human activities as the core, transportation as the key, and municipal administration as the basis", and plans to build underground comprehensive corridors, underground commerce, underground parking lots, underground public space, underground treasure houses, and so on. As well as the sections and transfer stations of Metro Line 4, Line 13, Line 11 and Line 15, they have large scale, tight construction period, heavy tasks and many technical problems, especially in terms of scale, concept, depth of foundation pit and complexity of engineering projects.
In order to stabilize the space of 857000 square meters, the new technology and technology of this project account for 70%, and many technologies have reached the leading domestic and international advanced level. For example, the construction team designed 1500 pieces of the largest, thickest, deepest and heaviest diaphragm wall in the municipal field with a depth of 75.06 meters and a thickness of 1.5 meters and 93 meters deep holes (grooves) to solidify the "tofu" structure; 68 ultra-deep steel pipe columns with a diameter of 1.1 meters and a length of 47.59 to 53.38 meters are used, and the ultra-high precision of 1/1000 is maintained to ensure that each piece of "small tofu" is stable and accurate when it is cut; Ultra-deep and ultra-high pressure large-diameter jet grouting, centralized disposal of large-scale mud solidification, high-strength steel bars, glass fiber steel bars, digitalization, informatization and other key new technologies, new technologies, new materials.. Together, they ensure that the whole project is impregnable. The successful pouring of the
large floor provides favorable preconditions for the construction of Binjiang Station of Nanjing Metro Line 4 and the opening of Metro Line 4. In the future, Nanjing Underground Space Project, as the largest underground space complex under construction in China and even in Asia, will further strengthen the rail transit links between Jiangbei and Jiangnan in Nanjing, support the urban renewal and construction of Nanjing Yangtze River Economic Belt and Jiangbei New Area, and build a national "three districts and one platform" and enhance the construction of "two cities and one center" in Jiangbei New Area. At the same time, this "reflection of the city" will also serve as a "milestone" to open a new page in the history of the development of modern underground space in Asia.
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