Monitoring of internal force characteristics of uplift piles of excavated foundation pit in soft soils

Uplift piles are usually used in the anti-floating design of underground engineering in soft soil areas, but due to the complexity of the site conditions, the play of internal force after construction and the recovery of pore-water pressure are not yet clear. Therefore, the common reinforced meter and fibre grating reinforced meter are used to monitor the long-term internal forces of uplift piles at Fuming Road station, line 1 of Ningbo rail transit traffic, and the tests on the pore-water pressure are also performed. The measured results indicate that the fibre grating reinforced meter is reasonable for monitoring the internal forces of anti-pulled piles because it can remove the produced prestressed effect of temperature changes. The internal force in uplift piles performs as pulling force firstly, then displays as pressure later, and the uplift piles play its anti-pulled role in early, and later as a superstructure of compressive pile to resist pressure. In addition, the pore-water pressure increases with time at the end of the hole, but the rate of growth is slow, and the soil water pressure under all conditions is steady.