Highlights: deep foundation pit design
Height 34 floors, 2 basements. Total floor area: 52,100m2
Type: High-rise mixed-use
Designed in 2007. Completed and put into use.
Actual situation
The project is located on Tran Phu Street – Ha Dong, the tallest building in the district at the time of construction. With a height of 120m to the top. The load-bearing structure chosen for the building is a reinforced concrete frame with a column and core wall structure system to ensure the rigidity of the building, along with a diagonal bracing system at the top and base.
The foundation solution of the project mainly uses bored piles with a diameter of 1.2m. The pile depth is 51m, leaning on the gravel layer. The pile raft foundation is the largest foundation block under the core system, with the largest load of the structure transmitted down.
A challenge when excavating the basement is the very weak clay layer that is more than 7m thick within the depth of 2 basement floors. Due to economic requirements, the method of supporting the excavation pit is to use Larssen piles combined with steel props to support the excavation pit nearly 5m deep. The disadvantage is that the groundwater level appears within the foundation pit, making construction difficult and increasing the horizontal displacement of the piles when excavating the soil. Therefore, the pile – prop system needs to ensure the safety of the foundation pit, avoiding subsidence of adjacent structures.
Therefore, the geotechnical problem of the excavation pit is an iterative problem, testing many options to decide the depth of the piles, the number of prop floors, the location and size of the props.
Excavation analysis model in Plaxis
Basement construction method orientation.
…
🎁Attached is the explanation of the excavation calculation.
