Abstract: To quantitatively study the influence of pre-drilled borehole parameters on the soil squeezing effect of pipe piles in peaty soils, field tests were conducted on the driving of of pipe piles in soft soils in a trail site at the bridge abutment area of Hailing Island Bridge to investigate the effect of pre-drilled pipe piles on the soil squeezing deformation around the piles. The results showed that pre-drilling measures caused the soil to shift towards the center of the borehole, while pipe pile driving caused the soil to shift significantly in the opposite direction. The impact range of soil squeezing was greater than 3D (D is the pile diameter). After a sharp linear increase in the pressure of excess pore water pressure in peaty soils, it maintains a relatively stable value in the short term. On this basis, a discrete element model was established, and the calculated values of lateral horizontal displacement were in good agreement with the on-site monitoring results. The displacement field can be divided into three parts. The area below the pile top and 2/3 of the pile body is the uplift displacement zone, the area above the pile end and 1/3 of the pile shaft is the horizontal displacement zone, and the area below the pile end is the subsidence displacement zone. The displacement field is distributed in an inverted cone shape and has a strip-shaped characteristic in the horizontal direction. When the pre-drilling rate and pre-drilling depth are above 0.5, the reduction effect on soil squeezing is more significant. It is recommended to set the pre-drilling rate and pre-drilling depth between 0.5 and 0.8 in the project, respectively.

Key words: Roadway Engineering, Horizontal Displacement of Soil Mass, Discrete Element, Squeezing Effect, Thick Peaty Soils