In this study, six rock-socketed bored piles were tested in the field to investigate the bearing characteristics of rock-socketed bored piles in silty clay formations in coastal areas, and the model piles were simulated and optimized using the finite element (FE) method. The results showed that the lateral resistance of the piles in the clay layer is less than 50 kPa, and the lateral resistance of the rock-embedded portion is within 136.2-166.4 kPa. Compared with increasing the rock-embedded depth, increasing the diameter of the test piles can improve their vertical bearing capacity more effectively. The average horizontal critical load (Hcr) increased by 84.54 %, and the average horizontal ultimate load (Hu) increased by 50.3 % for the 800 mm diameter piles compared to the 600 mm diameter piles. Also, at the end of the test, the 600 mm diameter test piles showed severe damage at 6-9.5 D below the mud surface and were more susceptible to instability damage than the 800 mm diameter test piles. In soft clay strata, the 'm' values converged rapidly with increasing horizontal displacement and stabilized when the displacement exceeded 10 mm. The FE simulations confirmed that the horizontal displacement of the pile mainly occurs at 4 m depth below the mud surface, and the displacement of the test pile can be effectively reduced by reinforcing the soil around the pile. The silt at the bottom of the pile is one of the critical factors causing the uneven settlement of the test pile, severely affecting the vertical bearing capacity of the pile foundation.

As an innovative foundation used in the offshore floating platform, the scaled suction caisson (SSC) has a greater advantage in the installation and service than the traditional suction caisson (TSC). To investigate the pull-out capacity of the SSC, the numerical simulations are carried out under static and cyclic loads. The study shows the inclined pull-out capacity of the SSC increases with increasing the loading angle., but firstly increases, then decreases with increasing the padeye depth. Compared with the TSC, the inclined pull-out capacity of the SSC increases by 20 similar to 40% when the loading angles. are in the range of 0 similar to 30 degrees, but its values increase by 100% when the loading angles exceed 60 degrees. Under the combined static and cyclic loads, the vertical cumulative displacement of the SSC decreases, but horizontal cumulative displacement increases. The total cumulative displacement of the SSC decreases by 13% compared with the TSC. It can be concluded that more soils can mobilized by the bio-scale surface to resist the pull-out loads. As a result, the SSC significantly improves inclined pull-out capacity and decreases the cumulative displacement.

Microbiologically Induced Calcite Precipitation (MICP) technology offers a promising method for stiffness reinforcement of offshore wind turbines (OWTs). However, edge scour around microbial reinforcement raises concerns about potential stiffness degradation. This study examines the effects of edge scour on the lateral responses of rigid piles reinforced with precast microbial reinforcement using a low-pH one-phase grouting method. Results from static tests, validated by numerical simulations, demonstrated that MICP technology bonded loose sand grains with the pile, forming a bio-reinforced pile with a larger diameter in the shallow soil layer, which significantly enhanced the original pile's bearing capacity and stiffness. However, edge scour reduced the embedment depth of the bio-reinforced pile, leading to a decrease in its bearing capacity and stiffness. Geometrically, protection width was found to have a relatively greater influence on stiffness and capacity compared to protection thickness. Additionally, symmetric cyclic loading tests were conducted to evaluate the effects of edge scour on backbone curves, secant stiffness, and damping ratio. Although MICP-based reinforcement notably enhanced both the secant stiffness and damping ratio of the piles, its effectiveness was completely lost once the scour depth reached the reinforcement thickness of the bio-reinforced soil block.

The current study addresses the dual challenges of improving the performance of soft soil beds subjected to static and cyclic stresses and managing the environmental impact of waste tire disposal. This research contributes valuable insights into the sustainable use of recycled tire chips in granular pile construction, coupled with the efficacy of combi-grid encasement for improved soft ground under static and cyclic loading conditions. A series of laboratory model tests were carried out on a group of granular piles to examine the principal parameters, such as the selection of geosynthetic materials and cyclic loading characteristics, including cyclic loading amplitude (qca) and cyclic loading frequency (f). The granular pile composition consists of (25% tire chips + 75% aggregates). The performance of granular piles on improved ground is assessed based on the settlement reduction ratio (Sc,r), accumulation of excess pore water pressure (Pexc), and stress concentration ratio (n). The key findings from static model tests are that the load-bearing capacity is significantly increased with installing a group of ordinary granular piles (= 58%) and substantially increased with combi-grid encasement (= 335%). The effectiveness of ordinary granular piles (OGP) in enhancing the performance of a soft soil bed becomes greater when subjected to lower cyclic loading frequencies (f) and smaller cyclic loading amplitudes (qca). The incorporation of combi-grid encasement greatly enhanced the cyclic performance of a group of granular piles by substantially minimizing cyclic-induced settlement (Sc) across both principle parameters f and qca. This study also examines the increased cyclic stresses on the improved soft bed, resulting in the accumulation of excess pore water pressure (Pexc) development, which is reduced to a greater extent with the help of combi-grid encasement across both principle parameters.

The paper presents the evolution of the bearing capacity of a pile model in calibration chamber after the application of a cyclic axial loading at a large number of cycles. This work is a part of the French research project ANR-SOLCYP which aims to understand the mechanisms governing the evolution of the bearing capacity of piles up to a very large number of cycles (105 cycles). The experimental study consists in using a calibration chamber in which axial cyclic loading is applied to pile model jacked into sand under a large number of cycles, up to 105, while measuring the axial shaft capacity before and after the cyclic sequence. Some key parameters have been investigated such as the cyclic displacement amplitude, the level of applied consolidation stress and the density index of the soil. It was found that after a large number of cycles of cyclic axial loading, the post-cyclic bearing capacity of the piles is significantly improved. Results analysis indicated that the mechanism of densification of the soil around the pile led to improve pile capacity.