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The reliability calculation model of grouting pile foundation under eccentric load was studied. JC method was used to calculate its single reliability. Considering the correlation of failure modes, the narrow limit of the reliability of grouting pile foundation was obtained.

In dense urban building environments, various adjacent construction projects will inevitably occur during the large-scale construction of urban underground transportation projects. Based on an actual project, this paper conducted a practical study on the construction control technology of a four-hole shield tunnel passing through existing bridge-pile foundations over a short distance and proposed a micro-disturbed control technology system of “two-stage analysis method theoretical prediction + active control and passive protection”. The core content of the technology system included the following: 1) By introducing an additional ground loss ratio, a theoretical calculation method for predicting the deformation of pile foundations during the adjacent construction of a multi-line tunnel was established, which enabled the preconstruction prediction of the influence of construction on the adjacent structures. 2) A multi-coupled numerical model, which included tunnels, strata, and pile foundations, was developed to analyze the mechanical behavior of the pile foundations during the entire construction process. 3) Combined with practical engineering experience, the control measures of this project were implemented in terms of active control and passive protection. The deformation of the pile foundations was effectively controlled during the construction process, which certified that the proposed micro-disturbed control technology was reasonable and feasible.

Inclined pile foundations with high inclination angles, subjected to both vertical and horizontal load, are increasingly used due to the advancement in installation technology. This study aimed to characterize the bearing capacities and deformation behavior of inclined pile foundations subjected to vertical and horizontal loads in laboratory-scaled testing. In a series of pile-modeled tests, the stainless-steel pile as a model pile, the single pile and the symmetrical 2 × 1 pile group were installed in dense sand at 0°, 10°, 20°, and 30° of inclination angles. The experiment in an inclined single pile subjected to vertical load aimed to minimize the eccentricity effect. The results showed that the optimal pile inclinations for vertical load were 10° and 20° for single pile and pile group, respectively. For optimal pile inclinations of horizontal load, they were between −10° to −20° and 20° for single pile and pile group, respectively. The ratios of the ultimate horizontal load to the ultimate vertical load ( Q uh / Q uv ) ranged from 0.02 to 0.19 and 0.15 to 0.23 for the single pile and the pile group tests, respectively. The group efficiencies for vertically loaded pile groups ranged from 58%–139% and 107%–130% for horizontal loading.

Offshore pile foundations are essential for supporting structures, such as wind turbines, oil platforms, and bridges. Important factors influencing soil-pile interactions and assessing the impact of various environmental loads, including axial, lateral, and moment loads. This study begins with a comprehensive review of the analytical and numerical methods used for pile analysis. This research aims to analyze the behavior of piles in the offshore seabed environment, taking into account various factors, such as soil-pile interactions, environmental load conditions, and the design of a sturdy pile foundation. This research method exploits the importance of accurate modelling to ensure the stability and longevity of offshore structures. The strength and performance of offshore structures, such as wind turbines, oil platforms, and bridges, are highly dependent on the integrity of the pile foundations. This research will provide a detailed analysis of piles in offshore seabed environments, emphasizing the importance of soil-pile interactions, varying loading conditions, and robust pile designs. These findings underscore the need for an integrated approach that combines geotechnical data, advanced modelling, and ongoing monitoring to ensure the stability and longevity of offshore pile foundations. This research produces a foundational analysis of pile behavior in offshore environments, considering factors such as soil-pile interactions, environmental load conditions, and variations in pile diameter. Piles with a diameter of 1.067 m demonstrate the highest axial and lateral capacities, making them ideal for more extreme environmental load conditions, such as strong ocean currents and high wind loads.

An unconnected pile foundation allows separation between the lower pile and the pile cap, and it has been proposed as an effective foundation type for reducing the seismic load during strong earthquakes. However, previous quantitative evaluations of unconnected piles with various foundation types and earthquake intensities are inadequate. In this study, the influence of base shaking level and the material of the interposed layer between pile and pile cap on the seismic behaviour of unconnected piles were evaluated using a centrifuge model test to reproduce the field stress conditions. A dynamic centrifuge model test was completed on an experimental model consisting of dry sandy soil, a foundation and a single degree-of-freedom structure. The acceleration of the structure and the settlement of the foundation system were measured during base shaking. For the unconnected pile system, the structural seismic load reduction effect due to rocking behaviour was confirmed, and the unconnected pile foundation with the interposed layer with large stiffness had less vertical settlement than the conventional shallow foundation. Finally, the rotational stiffness and damping ratio for the foundation system used in the centrifuge model tests were derived and discussed.

To study the dynamic response rules of pile foundations of mega-bridges over faults in strong seismic areas, a finite element model of the pile foundation-soil-fault interaction of the Haiwen Bridge is established. The 0.2–0.6 g peak acceleration of the 5010 seismic waves is input to study the effect of the seismic wave of different intensities and the distance changes between the fault and the pile foundation on the dynamic response of the pile body. The results show that the soil layer covering the bedrock amplifies the peak pile acceleration, and the amplifying effect decreases with increasing seismic wave intensity. However, bedrock has less of an effect on peak acceleration. The relative pile displacement shows the mechanical properties of elastic long piles. The pile foundation generates a large bending moment at the bedrock face and the upper soil layer interface, and a large shear force at the pile top and the soft-hard soil body interface. The relative displacement, bending, and shear bearing characteristics of the pile foundations on the upper and lower plates of the fault are significantly different. The deformation characteristics are affected by faults in a region ten times the pile diameter. Analysis of the dynamic p-y curves shows that the soil resistance on the pile side of the lower plate at the same depth is greater than that of the upper plate. Sensitivity of the dynamic response of pile foundations on either side of the fault to the effects of seismic intensity and distance between the pile foundation and the fault: distance l > seismic intensity q.

In extreme marine environments, the interaction between offshore wind turbine pile foundations (OWTPFs) is critical, and the associated hydrodynamic loads are complex. This study focused on fixed OWTPFs and used computational fluid dynamics (CFD) to numerically simulate the flow field around pile foundations under the combined action of focusing waves and current. The objective was to investigate the influence of different focusing wave and current parameters on the hydrodynamic properties of the pile foundations. The findings indicate the following: (1) When the wave and current directions are opposite, the maximum wave force on the pile foundations is greater than when they are aligned. (2) Large-amplitude focusing waves around pile foundations generate secondary loads, which are nonlinear and lead to a rapid increase in the wave force. These secondary loads are short-lived and particularly prominent near the front row of pile foundations. (3) The influence of the group pile effect diminishes under high-amplitude waves, where the wave component dominates the generation of the dimensionless wave force, and the impact of the current on this force decreases.

This paper addresses the issue of reduced lifespan of coastal concrete piles due to chloride ion corrosion. A combination of concrete mix optimization and pile geometry improvement measures is proposed. Based on the diffusion coefficient optimization of Fick’s second law, the service life prediction of concrete piles in corrosive environments is completed. The results show that, compared to single slag incorporation and the “slag-fly ash” dual-component mix, the “slag-fly ash-corrosion inhibitor” triple-component concrete achieves a 28-day compressive strength of 67.4 MPa, and the chloride ion diffusion coefficient is reduced to 1.14 × 10−12 m2/s, significantly improving overall performance. Finite element simulations reveal that, compared to ordinary square piles, cut-corner square piles can effectively alleviate stress concentration at the pile tip and reduce settlement. The maximum stress is 3.94 MPa, and the settlement is 22.64 mm, representing reductions of about 16.3% and 15.5%, respectively, compared to ordinary square piles. Concrete service life prediction confirms that the concrete with corrosion inhibitors has a predicted service life of 31.5 years, extending 7.4 years and 13.3 years longer than the single slag and the “slag-fly ash” dual-component groups, respectively. The “material-structure” optimization theory proposed in this study provides a theoretical basis and technical path for the long-life design of coastal engineering pile foundations.

It is particularly important to find out the pile foundation of existing buildings for building safety protection and engineering construction safety during the development and utilization of urban underground space. As a non-destructive, efficient and economic method, the borehole geophysical techniques such as magnetic gradient method, ground penetrating radar method and parallel seismic test method are used to detect the pile foundation of existing buildings, which have obvious advantages. According to the combined abnormal characteristics such as \"strong magnetic anomaly, electromagnetic wave in-phase axis change and diffraction wave anomaly at the pile end, P-wave velocity variation\", the pile foundation length can be judged.

In soft soil or karst areas, several problems exist, such as the poor properties of the pile tip bearing layer or difficulties in cutting the rock. Using multi-tooth piles, end-bearing piles can be turned into friction piles to solve these problems. Through the scale model device, three variables: the bearing layer, tooth length, and tooth number, are designed to experimentally explore the load-bearing behaviour of multi-tooth piles under different bearing layer conditions. The test results show that the model pile has better anti-settlement performance in the sand bearing layer than in the red clay bearing layer. Compared with smooth piles, multi-tooth piles can greatly improve the bearing capacity of pile foundations in bearing layers with poor stiffness. The tooth length and tooth number greatly impact the compressive bearing capacity and the pile-side resistance of the multi-tooth pile, respectively. The concept of roughness is innovatively introduced to quantify the roughness of pile surfaces, which provides an effective method for the subsequent experimental and theoretical research of multi-tooth piles and other similar piles with small cross-section modifications. This study can enrich the research field of small, modified cross-section piles and provide a reference for innovative research on pile foundations.