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The p-y method as a simplified analysis tool has been widely used to analyze the behavior of laterally loaded piles. This paper develops a novel cyclic p-y elastoplastic model within the framework of the single-surface bounding surface theory. The model can capture the soil stiffness degradation during cyclic loading by incorporating the cumulative plastic displacement to an interpolation function of the elastoplastic resistance coefficient. The model is relatively simple with only four parameters that can be determined from standard soil properties and stress-strain responses measured in direct simple shear tests. The performance of developed model is validated by predicting the cyclic lateral response of piles installed in soft clay during field and centrifuge tests published in the literature. The model can reliably simulate monotonic and cyclic responses of piles under different lateral loading patterns, and capture main characteristics of the pile-head load-displacement curve, such as nonlinearity, hysteresis, displacement accumulation, and stiffness degradation. It can also predict the evolution of the lateral deflection and sectional bending moment along the pile during cyclic loading. Key words: p-y curve, pile, lateral loading, bounding surface model, cyclic loading, 1. Introduction In harsh offshore environmental conditions, offshore platforms and wind turbines supported by pile foundations are subjected to cyclic lateral loads due to wind, sea waves, and currents. Consequently, [...]

The concept of disaster prevention and mitigation is vital for the safe development of urban underground space. Considering the coexistence of natural and engineering safety risks, the concept needs to be improved for further development of the urban underground space, and it is imperative to follow a disaster-adaptation-oriented concept that emphasizes post-disaster recovery resilience of the urban underground space. This study analyzes the implications and influencing factors of recovery resilience and summarizes the research on recovery resilience from the engineering and non-engineering perspectives. Moreover, the development status of recovery resilience research is analyzed from the aspects of structural system, evaluation method, management mechanism, space planning, and emergency plan. On this basis, a strategy that consists of three stages and an evaluation system is proposed; it categorizes post-disaster recovery into three stages—emergency rescue, recovery, and plan adaptation—and proposes recovery goals for each stage, providing a basis for the establishment of a recovery resilience evaluation system for the urban underground space.Furthermore, we suggest that the management regulations and emergency plans of the urban underground space should be optimized, the resilience planning improved, and intelligent management promoted, thereby realizing the orderliness and high efficiency of urban underground space recovery.

The urban underground infrastructure is a vital part of urban construction. In the context of resilient city, sponge city, and urban renewal, the low-carbon, safe, and coordinated development of urban underground infrastructure is crucial for promoting the high-quality development of cities and helping China achieve its carbon reduction goals. This study summarizes the development status and problems of low-carbon development of urban underground infrastructure and proposes carbon development paths and strategies for new and existing urban underground infrastructures. For new urban underground infrastructure, a low-carbon development strategy that considers the whole lifecycle of the infrastructure is proposed from the perspective of the source, consumer, and carbon fixation sides. For existing urban underground infrastructure, a green transformation strategy that features electrification, intelligence, and practicality is proposed alongside with a green expansion principle of harmony in diversity. To further promote the low-carbon development of China’s urban underground infrastructure, the following measures are suggested: figuring out the greenhouse gas emission status, improving the top-level design, strengthening the research and development of low-carbon technologies, and promoting policy incentives.

Fine-grained marine sediments often contain gas bubbles that can cause many geotechnical problems. This soil has a composite structure with gas bubbles fitting within the saturated soil matrix. The gas cavity has a detrimental effect on the soil stiffness and strength when they are filled with undissolved gas only. The gas cavity can be filled with gas and pore water due to 'bubble flooding'. Bubble flooding has a beneficial effect on the soil stiffness and undrained shear strength because it makes the saturated soil matrix partially drained under a globally undrained condition. A critical state constitutive model for gassy clay is presented that accounts for the composite structure of the soil and bubble flooding. The gas cavity is assumed to have a detrimental effect on the plastic hardening of the saturated soil matrix. Some of the bubbles can be flooded by pore water from the saturated soil matrix, which leads to higher mean effective stress of the saturated soil matrix. Consequently, both soil stiffness and strength increase. Only one new parameter is introduced to model the detrimental effect of gas bubbles on plastic hardening. The model has been validated by the results of three gassy clays. Key words: gassy clay, critical state, constitutive model, undrained shear strength, pore pressure. Les sediments marins a grain fin contiennent souvent des bulles de gaz qui peuvent causer de nombreux problemes geotechniques. Ce sol a une structure composite avec des bulles de gaz s'inserant dans la matrice du sol sature. La cavite gazeuse a un effet nefaste sur la rigidite et la resistance du sol lorsqu'elle est remplie uniquement de gaz non dissous. La cavite gazeuse peut etre remplie de gaz et d'eau interstitielle en raison de l'inondation des bulles. L'inondation par bulles a un effet benefique sur la rigidite du sol et la resistance au cisaillement sans drainage, car elle permet a la matrice de sol saturee d'etre partiellement drainee dans une condition globalement non drainee. Un modele constitutif d'etat critique pour l'argile gazeuse est presente, qui tient compte de la structure composite du sol et de l'inondation des bulles. La cavite gazeuse est supposee avoir un effet nefaste sur le durcissement plastique de la matrice du sol sature. Certaines des bulles peuvent etre inondees par l'eau interstitielle de la matrice du sol sature, ce qui entraine une augmentation de la contrainte effective moyenne de la matrice du sol sature. Par consequent, la rigidite et la resistance du sol augmentent. Un seul nouveau parametre est introduit pour modeliser l'effet nefaste des bulles de gaz sur le durcissement plastique. Le modele a ete valide par les resultats de trois argiles gazeuses. [Traduit par la Redaction] Mots-cles : argile gazeuse, etat critique, modele constitutif, resistance au cisaillement sans drainage, pression interstitielle., 1. Introduction Submarine soils with free gas bubbles are widely seen in the seabed throughout the world (Hong et al. 2017; Gao et al. 2020; Sultan and Garziglia 2014). Gas [...]

In the construction process of construction engineering, there exist a complex construction site layout and multiequipment collaborative work. If a reasonable construction plan cannot be made quickly and accurately, the investment in construction costs will be increased. Aiming at the construction material distribution, this study proposed a construction plan planning method under the multinode and multivehicle scene. Firstly, a mathematical model of the material distribution planning problem in the multinode multivehicle scene was established. The basic assumptions, objective functions, and constraints were proposed. The triangular scalar variables and 'unitization' processing methods were incorporated into the mathematical model. In order to solve the problem of material distribution planning, a heuristic neural network algorithm was designed. A 'gene-chromosome-individual' representation method and a 'two-step' calculation concept were defined. The specific implementation steps of the algorithm were given. Fully considering the type and quantity of vehicles and the length of the path, a method of establishing the mapping relationship between the construction scheme and the construction cost was proposed. The feasibility of the proposed theoretical method was verified by a cable truss structure model experiment. A calculation method with high fitting degree and fast running speed was established. According to the experiment model, the best construction scheme was formed. The results showed that the optimal construction scheme had a high vehicle loading rate and a clear distribution path, which effectively saved the construction cost under the premise of ensuring smooth construction. [ABSTRACT FROM AUTHOR]