The effects and vertical bearing capacity of two jacked piles in sand are still not well understood, and the mechanism of the adjacent pile’s uplift caused by the jacking pile in a double pile system is especially unclear, but these facets are important to the stability of the jacked pile. In this paper, a series of tests is performed on jacked model piles in sand, where in the influences of the pile length and the driving pile’s speed on the effects and vertical bearing capacity of two jacked piles were studied. The results revealed that the effects and vertical bearing capacity of the two jacked piles were mainly in relation to pile length and influenced by the driving speed. The horizontal displacement of the top of the first jacking pile during the installation of the post-jacking pile was caused by the difference in the stress state of the first jacking pile between the side of the pile’s face and its back side, in which the uplift displacement of the first jacking pile was also involved. The radial stress of the pile increased nonlinearly with the depth under different pile lengths and gradually converged to the passive earth pressure. The ultimate capacity of the double pile is approximately twice that of a single pile, and the ratio of the ultimate capacity of a single pile to the final jacking pressure was approximately 1.04.

This study aims to clarify the relationship between surface hardness and the peak interfacial frictional coefficient under different particle sizes. The relationship between particle size and the peak interfacial frictional coefficient with different surface hardness values has not been addressed in previous literature. A pile-soil interfacial shear test was conducted using a multifunctional interfacial shear instrument was developed in the laboratory. The influences of surface hardness and particle size on the shear characteristics of pile-soil interfaces and the peak interface friction coefficient were studied. The test results revealed that the interfacial shear stress-shear displacement curves showed typical softening behavior when the surface of the model pile was smooth. The difference in curve characteristics for different particle sizes gradually cleared as the surface hardness decreased. The initial shear stiffness of the interface increased with increasing surface hardness and decreased with increasing particle size. The peak interfacial friction coefficient decreased with increasing surface hardness for different particle sizes. Furthermore, the peak interface friction coefficient increased with increasing particle size when the surface was hard. However, when the surface was soft, the peak interfacial friction coefficient decreased with increasing particle size. The linear relationship between the peak interfacial friction coefficient and particle size for different surface hardness values was established.

The excavation of pits will induce the vertical displacement of tunnels and lead to engineering problems. The shape as well as size of a pit, and the complex spatial position relationship between the pit and tunnel will induce different deformation responses of tunnel structures; however, the degree to which each factor influences tunnel structure deformation is still unclear. This paper studied the impact of excavation on the deformation of tunnels via a combination of numerical simulation and orthogonal tests. The deformation of tunnels induced by excavation was studied using a numerical method, after which the sensitivity of influencing factors to tunnel deformation was studied by means of range and variance analyses through a four-factor and three-level orthogonal test. The results show that, for a foundation pit with a long side perpendicular to the tunnel longitude, the excavation has the least influence on tunnel deformation. Tunnel deformation increased with an increase in the excavation depth and decreased with an increase in tunnel–pit vertical and horizontal distance. As the plane shape of the foundation pit is 20 m × 45 m, the depth of excavation is 4 m, the pit tunnel vertical distance is 13 m, and the pit tunnel horizontal distance is 28 m, the tunnel has the least deformation. Based on the results of this study, the position relationship between the pit and the tunnel can be optimized in terms of design and construction, and the aim of controlling tunnel deformation can be achieved.

As a new type of offshore wind foundation, the wide‐shallow bucket foundation with honeycomb bulkheads mainly bears vertical, horizontal, and moment loads. As yet, no systematic study has been conducted regarding the effects of honeycomb bulkheads on the undrained bearing capacities of the wide‐shallow bucket foundation. In this study, a large number of three‐dimensional (3D) finite element (FE) analyses were performed to investigate the undrained bearing capacities of the wide‐shallow bucket foundations with and without honeycomb bulkheads, thereby evaluating the influence of honeycomb bulkheads on the bearing capacities under different conditions. The results show that under uniaxial loading, the uniaxial bearing capacities of the wide‐shallow bucket foundation are basically unaffected by the honeycomb bulkheads in homogeneous clay. For nonhomogeneous clay, the moment bearing capacity will be considerably enhanced with the increase in soil shear strength heterogeneity. Under combined loading, the honeycomb bulkheads will enhance the combined bearing capacities only in nonhomogeneous clay. The enhancement effects will increase with the increase in soil shear strength heterogeneity but decrease with the increase in vertical load. Besides, the simplified equations for calculating the uniaxial bearing capacities of the wide‐shallow bucket foundation with honeycomb bulkheads are also proposed considering the influence of embedment ratio and soil shear strength heterogeneity. At last, the parameters of an approximating expression are fitted to predict the failure envelopes of this foundation under combined loading.

The quality of grouting in pre-stressed pipelines plays a critical role in ensuring the safety and durability of pre-stressed concrete bridges. In this study, the transmission wave method was proposed as a means to assess the quality of grouting in pre-stressed pipelines. The ABAQUS finite element simulation (FE simulation) method was used to study the propagation of hammer stress waves in pre-stressed pipes. A full-scale test was conducted to verify the numerical simulation using the AGI-BWG instrument system developed to detect the quality of grouting. The results show that the propagation speed of transmitted waves increases and the frequency shifts towards higher frequencies with an increase in void length within pre-stressed pipelines. This research suggests that the propagation velocity of elastic waves in pre-stressed pipelines serves as a key indicator of grouting quality. The transmission wave method, based on hammer signals, proves to be an effective tool for detecting the quality of grouting in pre-stressed pipelines.

In order to study the effect of honeycomb bulkheads on uniaxial undrained bearing capacities of wide-shallow bucket foundation, the finite element models of bucket foundations with and without bulkheads on soft ground were established respectively. A large number of 3D finite element analyses have been performed to obtain uniaxial bearing capacities of the two foundations with different embedment ratios and soil shear strength heterogeneity by using displacement control method. The results show that, for homogenous clay, all the vertical, horizontal and moment bearing capacities of the wide-shallow bucket foundation are not affected by the honeycomb bulkheads. For non-homogenous clay, the moment bearing capacity of the wide-shallow bucket foundation is obviously affected by the honeycomb bulkheads, while the effect for improving the vertical and horizontal bearing capacity of the bucket foundation can be neglected. For the convenience of designers reference, simplified calculation equations for undrained bearing capacities are fitted according to the finite element results.