Visualization Study on Construction Disturbance of Drainage Board Sleeve Pile Shoes

One of the key indicators of the foundation soil consolidation is the smear effect brought on by the insertion of a Prefabricated vertical drain (PVD), which also smears the extent of disturbance. Prior research primarily examined the impact of the diameter of the Prefabricated vertical drain sleeves, ignoring the impact of pile shoe size on smear effect. The penetration process of pile shoes of varying sizes in layered soils was simulated using transparent soil model experiments, and Particle Image Velocimetry (PIV) technology was used to visualize and assess the soil disturbance caused by the pile shoes. Theoretical and experimental data are used to suggest and analyze the correction coefficients for the geometric characteristics of pile shoes using the Mohr–Coulomb criterion and reaming theory. The study’s findings demonstrate that transparent soil and the PIV method can successfully capture the dynamic evolution of the “inverted cone” in the smeared area, which is consistent with the theory of cylindrical pore expansion’s prediction. The horizontal disturbance range will increase as the equivalent radius of the pile shoes increases, and it is 4.5d for pile shoes with an equivalent radius of 1.5 mm and 5d for pile shoes with an equivalent radius of 2.0 mm. The discontinuity of the soil layer interface will be made worse by pile shoes with a high equivalent radius, making the phenomenon of stress concentration more noticeable. Its quantitative analysis demonstrates the reasonableness of the correction factor λ, which offers a trustworthy tool to quantify the perturbation effect of the pile shoe size. A correction factor λ is proposed so that the error between the corrected theoretical value and the test value is less than 5%.