Numerical Simulation and Engineering Case Study of Inclined Long-short-pile Support for Excavations

Based on an example of a inclined long and short pile support foundation pit project in the Greater Bay Area of Guangdong, Hong Kong, and Macao, finite element numerical simulation method is used to study its excavation stability. The horizontal displacement of the pile top and the response of the deep horizontal displacement of the soil behind the pile during the excavation process of the foundation pit are analyzed. The comparison and verification analysis are conducted through on-site measured data and numerical calculation results. The results show that the horizontal displacement of the pile top increases with the increase of excavation depth during the excavation process, showing a more obvious cantilever distribution. The measured increase in displacement of the straight pile top is the maximum of 12 mm, followed by 6 mm for short inclined piles, and 3 mm for long inclined piles; The growth rate of displacement varies from large to small, with a relationship between straight piles, short inclined piles, and long inclined piles. The final horizontal displacement of straight piles shows a continuous development trend, while the final horizontal displacement of inclined piles shows a convergence trend; The deep horizontal displacement of the soil behind the pile gradually decreases from the top of the pile to the bottom of the pit. The measured value of the project is affected by the fluctuation of the strata, and the displacement of the short inclined pile in the foundation pit first increases and then decreases. Overall, it still meets the displacement control requirements of the first level foundation pit specified in the specifications.