Numerical simulation of deformation control during excavation of deep foundation pit in soft soil with newly filled soil

Under the overburden of newly filled soil, the deformation law of ground caused by excavation of foundation pits needs attention. Based on a linear deep foundation pit in the coastal Shenzhen-Hong Kong cooperation zone, the influences of different reinforcement plans and insertion ratios of retaining piles on the rebound deformation and surface settlement of the foundation pit are investigated through the finite element simulation. The conclusions can be drawn as follows: in the coastal soft soil areas with poor soil quality and newly filled soil, as the resistance to deformation in the passive areas is poor, the relevant measures should be taken to reduce the bottom uplift of pit and surface settlement deformation. Increasing the insertion ratio of retaining piles is not a useful way to control the uplift of pit bottom, but can significantly reduce the surface settlement outside the pit. Using the mixing piles to reinforce the passive areas of soil at the bottom of the pit can significantly reduce the uplift of the pit bottom and the surface settlement, and when the depth of reinforcement is 9 m, the uplift and surface settlement can be reduced by more than 75%. © 2021, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.