PURPOSE OF WORKS
Alpha City apartment project with the old name of Golden Hill, was licensed by the HCM City People's Committee in 2008 but due to the old investor financial difficulties, the project was suspended for long time. Project owns the most prime location in District 1 at 87 Cong Quynh Street, right at the intersection with Tran Hung Dao and Nguyen Cu Trinh. The construction scale consists of 8,320m2 area. The project includes 2 blocks of 49-storey apartments, in which 8-storey high-end commercial area of Alpha shopping mall.
CONCEPT AND DESIGN
The project was originally invested by Ngan Binh Investment & Construction Co., Ltd. Diaphragm wall for phase 1 and phase 2 was with depth of 23m and 30m was completed including 375 nos of bored piles were installed as per original design. After acquiring the project, the investor decided to increase the number of basements and building height as compared to the original plan. This requires installation of secant pile wall from B2 level to the depth of 35m to support additional excavation depth. Moreover, 277 bored piles of diameter 1500mm are designed to support additional loads generated by increased height of the structure. 152 nos of kingposts are installed to facilitate semi-top-down construction.
OIL / ROCK CONDITION
The soil conditions consist of medium dense sandy clay from the working platform down to the toe of piles and secant pile wall.
CONSTRUCTION WORKS & SPECIAL FEATURES
Construction of secant pile wall with cut-off level approx. 9m below existing ground level and at distance of 40cm from existing diaphragm wall and construction of bored piles in very limited areas between existing 375 piles were great challenge.
In such particular cases, works need to be carried out with extensive care and diligence. Taking into consideration the tight schedule, Bauer Vietnam decided to construct secant pile wall and bored piles simultaneously. Despite of traffic restrictions in the heart of District 1, bored piles and secant pile wall were completed within agreed time frame by deployment of four BG type drilling rigs with sufficient number of service cranes for operations.