A series of large-scale (1:13) model tests of multi-stage loading and unidirectional multi-cycle loading were conducted on semi-rigid piles before and after cement-soil reinforcement in clay. The difference of ultimate bearing capacity between unreinforced and reinforced piles under different criterions is discussed, and their bending moment and displacement distribution rules are revealed. Meanwhile, the cyclic bearing behaviour of the unreinforced and reinforced piles are compared and analyzed, including cyclic load-displacement response, unloading stiffness, cumulative peak & residual displacement, peak & locked in moment. The test results show that the ultimate bearing capacity of the large diameter pile is increased by 34.4 % and the initial stiffness is increased by 56.8 % (reinforced width is 3D and depth is 1D) in the multistage loading test. Comparing the monotonic and cyclic load-displacement curves of unreinforced and reinforced piles obtained by multi-stage loading test and unidirectional multi-cycle loading test respectively, it is found that when the applied load is small, the curve obtained from multistage loading test is almost coincident with the first cycle envelope of all load levels in 1-way multi-cycle loading test, indicating that the cyclic effect is not significant. As the load increases, the difference between the curves becomes larger, indicating that the cyclic loading of higher amplitude causes greater soil disturbance. In addition, after applying cement-soil to the shallow soil around monopile, cement-soil reinforced pile exhibits a more rigid response, specifically manifested as an initial unloading stiffness of 1.76 times that of unreinforced pile, and a slower stiffness degradation rate. Meanwhile, the cyclic peak displacement & residual displacement accumulation of reinforced piles are smaller than that of the unreinforced pile, thereby reducing the development of the locked in moment.

With the increasing capacity of offshore wind turbines, the diameter of wind power monopiles has been continuously growing, leading to a significant decrease in the length-to-diameter ratio (L/D). Existing methods primarily focus on correcting the p-y curve due to increased pile diameter but fail to adequately consider the impact of changes in resistance components distribution resulting from a decreased L/D. This study aims to analyse the pile-soil interaction of large-diameter horizontally loaded monopiles by examining the distributed resistance components. Through finite element analysis and verification via engineering pile testing, the paper explores the resistance composition, deformation characteristics, and changes in resistance components of large-diameter monopiles. The findings reveal that the pile-soil horizontal resistance primarily governs the lateral bearing capacity of large-diameter monopiles for small range of length-to-diameter ratios (4 similar to 10). It is found that the deformation mode of monopiles is controlled by the pile-soil relative stiffness. A p-y resistance component curve for large-diameter horizontally loaded monopiles under various interlayer states of sand and clay was proposed as a function of pile-soil relative stiffness. For engineering practice, a simple but useful method for evaluating and correcting the lateral bearing capacity of monopiles was demonstrated based on the proposed resistance component curve.

A pile group under lateral loading is a complex pile-soil-pile interaction problem. In this study, numerical analysis was used to investigate the lateral behavior of pile groups arranged in a 3 x 3 configuration with varying piles spacings. The hypoplastic constitutive model embedded into ABAQUS software through the UMAT subroutine was used to characterize the stress-strain relationship of Toyoura sand. The effects of the pile spacing on the load-displacement relationship of the pile group, the bending moment-depth relationship of each pile in the pile group, the deflection-depth relationship, and the soil resistance distribution were investigated. The results indicate that the lateral bearing capacity of the pile group decreases by more than 50% when the pile spacing is reduced from 7D to 3D. When the pile spacing is greater than 5D, the edge effect of the laterally loaded pile group gradually decreases, and when the pile spacing is greater than 7D, the shadowing effect can be negligible, and the wedge-shaped failure zone of the pile group occurs within a depth of 5D below the mud surface.

Rammed earth building has garnered attention from researchers due to its low energy consumption and excellent thermal performance. However, addressing the issue of low seismic performance in rammed earth buildings still lacks effective solutions. This study investigated the influence of embedded steel wire mesh and bamboo reinforcement mesh on the in-plane seismic performance of rammed earth walls through pseudo-static tests. Four half-scale models of rammed earth walls were constructed, each with dimensions of 1900 mm in length, 1200 mm in width, and 250 mm in height. The experimental results were compared in terms of failure mode, hysteresis response, lateral bearing capacity, displacement, ductility, stiffness degradation, damage index, and energy dissipation capability. The peak ground acceleration (PGA) for each specimen was calculated using the N2 method to assess their seismic performance. The results indicated that both steel wire mesh and bamboo reinforcement mesh can significantly enhance the seismic performance of rammed earth walls. Finally, based on the hysteresis curves of the specimens and the strain test results of the steel wire mesh or bamboo reinforcement mesh, this study proposed a hysteretic model and lateral bearing capacity calculation formula for rammed earth walls.

Precisely estimating the lateral capacity of the large-diameter monopile is essential for securing the stability of the fixed wind turbine of high power generation. Conventional standards relying on p-y curves often underestimate the monopile-soil interaction due to their failure to account for pile shaft rotations and base effects, leading to overly cautious lateral capacity designs. This paper introduces the three-spring soil reaction model that comprehensively considers lateral soil resistance, shaft frictional resistance, base shear force, and base moment. The analytical expressions for three springs are established considering the self-similarity between soil stress-strain relationships and load-displacement responses. The bearing capacity calculation method of monopiles with varying rigidity is developed based on the combinations of three springs. The results reveal that the modified p-y curve for lateral capacity predictions achieves over 80% accuracy. The contributions of base effects and shaft frictional resistance to bearing capacity gradually increase with the increases in pile rigidity, and the correction of monopile ultimate lateral displacement prediction is also enhanced.

Liquefaction can lead to structural failure as it reduces the bearing capacity of building foundations. This phenomenon occurs in saturated sandy soils where pore water pressure increases, significantly decreasing effective soil stress. Evaluating the axial and lateral bearing capacity of bored piles affected by liquefaction is crucial to ensure the stability and performance of foundation systems. This study focuses on assessing the capabilities of bored piles in the Governor's Office of Sulawesi Barat Province, which are influenced by liquefaction phenomena. The empirical approach applied the O'Neill and Reese 1989 method, while the numerical approach used RS Pile. The calculation results revealed decreased axial bearing capacity under liquefaction conditions. In non-liquefaction, PC. 4 can withstand up to 24946 kN, with displacements of 0.94 cm (x), 0.39 cm (y), and 1.12 cm in settlement. In liquefaction, it decreases to 2876.78 kN, with displacements of 1.32 cm (x), 0.86 cm (y), and 1.68 cm in settlement. In non-liquefaction, PC.3 can withstand up to 17407.93 kN with displacements of 0.02 cm (x), 0.04 cm (y), and 0.06 cm in settlement. In liquefaction, it decreases to 1713.05 kN, with displacements of 0.02 cm (x), 0.05 cm (y), and 0.07 cm in settlement.