The batter piles of a pile-supported wharf are severely damaged under excessive lateral loads, and effective reinforcement strategies are of great concern. In this paper, the effect of different reinforcement strategies on the lateral bearing performance of the wharf, taking into account the pile-soil interaction, was investigated using centrifuge test and numerical simulation. The results showed that both reinforcement strategies were effective in improving performance, with results generally aligning with those of the intact wharf in terms of load-displacement relationships, and significantly reduced the magnitudes of pile lateral deflection, soil pressure, bending moment, and shear force compared to the broken wharf. However, the concrete jacketing method resulted in larger lateral deflections in the middle sections of the retrofitted batter piles, and then abruptly reduced to match those of the steel-bonding method in the cap-pile regions. The degree of abrupt changes of bending moment in retrofitted batter piles was more distinct in the concrete jacketing wharf than that in the steel-bonding wharf. The steel-bonding method distributed the lateral load more evenly than the concrete jacketing, which involved more abrupt changes in shear forces. Overall, although the performance of both retrofitting methods was slightly better than that of the intact wharf at component level, the steel-bonding method appeared to prove superior due to the smaller change in stiffness and the more even distribution of lateral loads.

The approach bridge of the pile-supported wharf is an important structure that connects the pile foundation platform and the land, and it has a significant impact on the safety of the high-pile wharf. However, the influence of an approach bridge on the seismic dynamic response of a pile-supported wharf has often been neglected in previous studies. Besides, the excess pore water pressure (Delta u) generated under combined vertical and horizontal seismic components is typically greater than that induced by unidirectional excitations, which may further impact the dynamic response of pile-supported wharf. Firstly, this study developed a numerical method for simulating the approach bridge of a pile-supported wharf. Secondly, the three-dimensional finite element model of a pile-supported wharf with an approach bridge is established to investigate the dynamic response during horizontal and vertical seismic components. Additionally, the effects of seismic frequency and relative density of liquefied layer on the dynamic response of pile-supported wharf were also studied. By comparing with the experimental results, the numerical model effectively simulated the overall response of the pile-supported wharf and the liquefaction behavior of the surrounding soil. During high-frequency earthquakes, the influence of the approach bridge on the dynamic response of the pile-supported wharf is minimal, whereas it has a more significant impact during low-frequency earthquakes. Furthermore, vertical seismic components significantly amplify the effect of approach bridge on the lateral displacement and internal forces of piles. The effect of the approach bridge on the lateral displacement and internal force of the pile decreases with the increase of the relative density of the liquefaction layer.

Seismic fragility analysis is an effective method to evaluate the seismic performance of retrofitted wharf systems affected by the uncertainty of soil-cement strength. Nevertheless, fragility analysis usually consumes a large consumption of computational power. In this study, seismic fragility analysis using the artificial neural network (ANN) for the retrofitted wharf, considering the aleatory uncertainty of soil-cement strength and the epistemic uncertainty of the ANN, is carried out; On this basis, the fragility surface for two types of damage limit states considering the uncertainty of soil-cement strength is obtained. It was found that: (1) overall, the soil-cement strengthening strategy is effective for improving the seismic safety of wharf systems, however, the strengthening effect is limited, especially under strong earthquakes, will be further weakened; (2) ANN can effectively predict the maximum seismic response of retrofitted pile-supported wharves, so as to quickly carry out seismic fragility analysis. Examples show that the prediction method has good generalization; and (3) the fragility surface model considers the aleatory uncertainty of soil-cement strength and the epistemic uncertainty of the ANN, which makes the performance-based evaluation of retrofitted pile-supported wharves more comprehensive.