New global sign tower – Africa's highest reinforced concrete building starts ground construction

On October 29, the main tower of T01 bid section of the ultra-high complex project of Alamein new city in Egypt starts ground construction.

This project is the largest spot exchange project signed by Chinese enterprises in the Egyptian market, and it is also the starting point and center of the construction of Alamein new city.

Among them, the symbolic tower built by China Construction First Group Construction & Development CO. LTD is about 300 meters high, with a building area of about 400 thousand square meters. After completion, it will become one of the highest ten residential buildings in the world, and is the largest single building constructed by CSCEC overseas.

Construction speed of 8 pile foundations per day

In the early stage of construction, the temporary construction and earth excavation of the project have become the biggest problem faced by the project team. In order to carry out the excavation of super large deep foundation pit in the desert of about 150000 square meters, the project team coordinated the allocation of more than 30 muck trucks and 20 excavators. In two months, it successfully completed 80 offices and living houses that can accommodate about 1000 workers.

Since the height of the main tower is about 300 meters, it needs strong pile foundation support. After careful calculation, a total of 375 post-grouting rotary drilling bored piles with a diameter of 1.2 meters and a pile length of 45 meters need to be completed, the overall number and volume are enormous. The T01 Iconic tower team actively researched construction arrangements with local subcontractors, and optimized the construction route, resulting in improving construction efficiency. Ultimately, the construction speed of the pile foundation in the T01 iconic tower reached 8 roots per day, which is the package with the largest number of working piles completed in a single day and the largest amount of concrete pouring in a single day among the five packages of the entire Alamein Downtown Towers project. It only took 75 days to complete the construction of all 375 rotary drilling bored piles, demonstrating the high-standard Chinese construction speed in Egypt.

Solve the dewatering problem of super deep foundation pit in desert

The total excavation area of foundation pit in T01 bid section is about 107000 square meters, and the underground water level needs to be lowered by at least 4.72 meters to meet the construction requirements. At the same time, the region is adjacent to the Mediterranean Sea, and the hydrogeological environment is complex. The project is connected with the offshore water system, so the water supply is fast and the precipitation is very difficult.

How to solve the rare "unclosed precipitation of super large deep foundation pit in the near Mediterranean desert area" has become another big problem in the construction process. This is the first dewatering project implemented by CSCEC in Egypt. The project team without local precipitation experience can only grope forward. Through two deep well and shallow well dewatering tests, the important parameters such as precipitation influence radius, unit time precipitation of different pump depths are obtained.

Zhang Xiuchuan, project manager of T01 bid section, introduced: "We adopted non closed dewatering technology, arranged dewatering wells inside and outside the foundation pit respectively, and set 27 dewatering well pipes with diameter of 300 mm, and set 3 standby dewatering wells with observation function at the most central part of the foundation pit to ensure the effect of unclosed dewatering."

At the last step of earth excavation, the project team suddenly found that there was a subsurface flow or karst cave on the south side of the foundation pit. The water system was rich and the water output was large, and obvious water flow could be seen. The project team skillfully put forward the technical scheme of setting blind ditch around the foundation pit and using gasoline pump to discharge the open water, which perfectly overcame the difficulty of water lowering and drainage, ensured the smooth construction of earth excavation and foundation slab, and completed the pouring of the largest foundation slab in Africa on August 17 this year.

Provide sustainable and intelligent construction scheme for desert

The project takes 'designed & built' mode. In the design stage, the project team uses BIM Technology to achieve node optimization and joint design of various disciplines, and promotes the process of scheme preparation. In the construction stage, the BIM Technology is integrated with the site operation. The construction site layout model and 3D room model are established to achieve interactive simulation between BIM Technology and B6 software, which improves the building energy efficiency level and promotes green construction.

At the same time, the project successfully used the highly information management cooperation system, which aiming to better apply to international project management. The project team applied Aconex document control system to realize paperless office between the construction unit, the supervision unit and the general contractor, which greatly improved the work efficiency. Application of remote video monitoring system to ensure on-site security and personnel attendance. Through the office WI-FI system, the problems of imperfect and underdeveloped network in Africa are solved, and the real-time updating and sharing of drawings and scheme changes are realized.

At present, the project has officially entered the construction stage of the main structure above ground, and the coordinated construction and alternate operation of various disciplines will begin soon. The project will continue to show the speed and wisdom of Chinese builders in the African continent, and contribute to the construction of Egypt's "Summer Nation" and the high-quality development of the " One belt and one road".