Top-down construction technology (from top to bottom), English is Top-down construction method, is the technology of constructing the underground part of the house, according to the top-down method, different from the traditional method: construction bottom up. In Top-down construction technology, one can simultaneously construct the underground floors (below the core ± 0.00 (the core ± 0.00 ie the height of the completed ground floor of the building's ground floor). is the zero core)) and the foundation of the work, just constructed a limited number of floors, belonging to the body, above the zero core (on the ground).
Construction of Topdown underground part of Vincom 2 building at Doan Tran Nghiep street, Hai Ba Trung district, Hanoi
In the Top-down technology, the basements are constructed by constructing the diaphragm wall with the barrette pile system around the house (later the top part of the diaphragm wall is used as the surrounding wall of the entire basement) and the pile system. bored drilling (located at the foot of the column foundation) inside the house plan. The diaphragm wall is constructed according to the technology of concrete-filled piles to the natural ground reinforcement or ground floor reinforcement (zero reinforcement).
In case the diaphragm wall system is built to the natural ground lower than the ground floor foundation, instead of Top-down construction right from the ground floor, top-down construction can be started from the ground floor of the first basement. (first basement floor), below ground level. At that time, the first basement was constructed by the traditional bottom-up method, the diaphragm wall at the top had the same function as the piling system to keep the wall of the dug hole. This case can also be called selling Top-down or "Shirt" top-down (semi-top-down).