In order to study the squeezing effect of static press large-diameter single pile and piles group in layered soil, field tests of static press large-diameter pipe piles were carried out based on a project under construction, and numerical simulations of the squeezing effect of single piles and piles group were conducted using finite element software. It is shown that during the process of pile penetration, the pore water pressure in the soil surrounding the pile rapidly increases to a higher initial value. Subsequently, the excess pore pressure will rapidly dissipate and gradually stabilize. The simulated and measured values of pile top displacement show a pattern of larger displacement at the pile top when the pile is first penetrated, and smaller displacement at the pile top when the pile is penetrated later. The measured horizontal displacement of the soil layer at each observation point of the group of 7 piles showed a turning point at a depth of about 2.5 m and fluctuated with increasing depth. The measured displacement reached its maximum value between 25 and 30 m and then rapidly decreased. The finite element simulation results of squeezing effect of the group of 20 piles show that the squeezing effect around the pile is very obvious within the depth range of the pile length. The horizontal displacement of the soil below the pile length rapidly decreases, and the maximum horizontal displacement of the soil at different depths around the pile mainly occurs at the surface. In addition, the reasons for the errors between the finite element simulation values and the measured values were analyzed.

Large-diameter pipe piles are widely applied in various civil engineering fields due to their outstanding load- bearing capability. The unsaturated characteristics, anisotropy, and heterogeneity of the soil jointly affect the dynamic response of the pipe pile. However, most previous studies were limited to single-phase or two-phase soil. This paper develops an analytical model for the torsional vibration of a pipe pile in transversely isotropic unsaturated soils considering construction disturbance. Based on transversely isotropic unsaturated soil theory, a pipe pile-soil interaction model has been developed, while the effect of construction disturbance is simulated by the radial heterogeneity of the soil. The general solution for the unsaturated soil is obtained using the separation of variables method with the boundary conditions. Then, the solution for the whole pipe pile-soil system is derived by considering the pile-soil interface conditions. The accuracy of the proposed solution is verified through comparisons with previous research results. The results show that unsaturated characteristics, construction disturbance, and transverse isotropy of the soil have significant effects on the impedance of large- diameter pipe piles. Specifically, with a low degree of saturation, there will be significant prediction errors when using previous works based on single-phase or two-phase soil theory to predict the dynamic response of large-diameter pipe piles.

Buried cast iron pipelines are susceptible to damage at joints under fault movements. In this paper, a new three-dimensional soil-pipe continuum model for segmented pipelines undergoing fault rupture is introduced, in which both the nonlinear behavior of lead-caulked joints and post-peak softening behavior of dense sand are properly characterized. The rationality of the developed numerical model is validated against experimental results reported in the literature. Parametric analyses indicate that ignoring the strain softening behavior of soil would underestimate the maximum joint rotations, and the parameters of fault-pipe inter angle, cast iron-lead adhesion, and burial depth play a notable role on the magnitude of joint kinematics. Numerical fault rupture analyses are then conducted for cast iron pipelines with nominal diameters ranging from 900 to 1500 mm. Based on the numerical results, predictive solutions are developed for estimating the maximum axial translations and joint rotations under fault movements. The residuals of the proposed solutions are generally unbiased. The proposed solutions can be used to evaluate the maximum joint kinematics in terms of axial translations and joint rotations for largediameter cast iron pipelines with lead-caulked joints undergoing strike-slip fault ruptures.