# Model Tests on Jacked Pile Penetration Characteristics Considering a Static Press-in Piling Machine
## 1 Introduction  
With the increasing advancement of jacked pile technology and the rapid development of pile machinery, jacked pile is widely used in soft soil areas. In order to meet various construction conditions, the weight of the static press-in piling machine is increasing, leading to frequent accidents during the pile jacking process. Hence, it is imperative not to overlook the impact of the piling machine on the pile penetration characteristics and soil squeezing effect during construction. Effective estimation of pile jacking resistance before pile foundation construction is essential for guiding the selection of static press-in piling machines, improving jacked pile techniques, and ultimately making the pile jacking process go smoothly [1; 2; 3; 4; 5]. A substantial number of scholars have conducted various studies on the penetration characteristics of piles. In field tests, [PERSON] and [PERSON] [6] studied the penetration characteristics of jacked piles in layered cohesive soil and examined how different pile jacking methods affect the development and alteration of pile side friction resistance. [PERSON] et al. [7] measured the strain distribution of the pile body and evaluated the influence of the pile depth and soil resistance on the axial force and lateral friction resistance of the pile body through the strain distribution. Some scholars have studied the different mechanical characteristics of the open and closed PHC pipe piles through field tests and revealed the distribution law of soil pressure at the pile-soil interface [8; 9; 10]. In terms of numerical simulation, [PERSON] et al. [11] conducted a friction analysis on the penetration process of large diameter steel using the discrete element method (DEM) and studied the impact of the contact parameters on side friction. [PERSON] et al. [12] used the numerical platform to establish the nonlinear relationship between pile resistance and sand density to guide thereasonable design of a pile foundation in sand. [PERSON] et al. [13] independently developed a noncircular particle numerical simulation program to analyze the interaction between soil and piles during pile penetration in sand. [PERSON] et al. [14] proposed the displacement penetration method, which uses the boundary displacement condition to facilitate pile penetration, rendering it more in line with the actual situation of pile jacking. It can be seen that a series of field tests and numerical simulation research studies have been carried out to study the pile penetration characteristics. However, neither of them has taken into account the influence of the static press-in piling machine on the research results, making them not entirely suitable for engineering practice. The model test is of low cost and fleeting period, prompting many scholars to study the problem of pile jacking through model tests. [PERSON] and [PERSON] [15] obtained the stress characteristics of piles in sand with different compactness through the model box test of steel pipe piles. [PERSON] et al. [16] analyzed the critical depth of pile end resistance in the model pile test. [PERSON] and [PERSON] [17] studied the influence of soil stress, diameter, and wall thickness on the characteristics of pipe pile jacking in sand by a test. It can be found that many studies on the penetration mechanism of jacked piles have focused on sand soil. However, viscous soil can more accurately replicate the actual engineering conditions of jacked piles in coastal soft areas [18]. Hence, investigating the penetration characteristics of jacked piles in soft clay soil through model tests is meaningful. Through many traditional pile jacking model tests, scholars have acquired the variation law of pile end resistance, pile side resistance, and pile jacking force in the process of pile pressing in different foundation soils and proposed the phenomenon of \"side resistance degradation\" to correct the results and finally summed up the relevant laws about the penetration characteristics of jacked pile [19; 20; 21; 22].