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As an important infrastructure, the floating platform plays a significant role in coastal and oceanic development. The single‐point mooring system anchored by piles has been widely used to support floating offshore platforms. However, few studies in the field of floating structures focused on the dynamic reliability and mechanical analysis of the mooring pile foundation under wind and wave vibration. A Monte Carlo‐based mooring pile reliability analysis method was introduced in this paper, which could consume the calculation source significantly. Based on the Monte Carlo simulation, the dynamic reliability of the mooring pile system of the floating platform was analyzed and discussed. Finally, considering the material cost, the design of the mooring pile of floating platform was optimized. The simulation work presented here also will contribute to a deeper understanding of civil engineering works' pile foundation. [ABSTRACT FROM AUTHOR]

This work presents an analytical method for determining vertical dynamic impedance and displacement response factor of a rigid cylindrical foundation embedded in unsaturated poroelastic soils. The foundation is assumed to be perfectly boned to its surrounding soil and its overlying half-space of unsaturated poroelastic soil, subjected to harmonic vertical loadings. The soil surrounding the circumference of the cylinder is modeled as a number of infinitely thin horizontal soil layers. Based on the Biot-type soil constitutive model, the equations governing the interaction of unsaturated soils with the cylindrical foundation are derived. Solutions are obtained by solving ordinary differential equations transformed from partial differential governing equations using the Hankel transform. The proposed solutions are verified against existing solutions of benchmark elastodynamic problems for embedded cylindrical foundations in dry and saturated soils. Using the derived solutions, several influencing parameters defining the stiffness and mass of the foundation system are examined to investigate the dynamics of the foundation interacting with it adjacent soils. It is concluded that the dynamic displacement response factor is sensitive to soil saturation. It is believed that the proposed solution should be beneficial to dynamic design with cylindrical foundations embedded in unsaturated soils. [ABSTRACT FROM AUTHOR]

In soft soil layers, piles are frequently loaded laterally by horizontal soil movements. In many cases, the lateral pressure acting on piles due to horizontal soil movements is calculated with empirically or analytically based approaches, respectively. However, most of these design approaches do not consider possible influences on the resulting pile loads. This paper presents the results of model tests and numerical simulations on single piles and pile groups in cohesive soil subjected to lateral loads which were carried out to overcome limitations of available design approaches. Based on extensive small-scale 1 × g-model tests and numerical investigations with the finite element method, influencing factors on the lateral pressure, such as the roughness of the pile–soil interface, the pile size, the pile shape and the pile spacing were identified. A parametric study with the numerical model quantified the most relevant factors influencing the development of lateral pressure on piles due to adjacent surface loads and lead to the development of a simplified analysis approach. [ABSTRACT FROM AUTHOR]

In the realm of constructing urban underground spaces, it is imperative to address the impact of tunnel leakage on the surrounding environment. This paper introduced a theoretical analysis to investigate the localized water leakage's influence on adjacent pile foundations. A pore pressure distribution function, accounting for localized leakage water, was formulated. Integrated with the seepage control equation, this function facilitated the calculation of additional stress imposed on piles due to tunnel localized water leakage. Employing the Pasternak foundation model, an analytical solution was developed to assess the lateral performance of adjacent piles under localized water leakage conditions. This approach was compared with numerical simulations to validate the reliability of soil seepage fields and pile lateral performance resulting from localized tunnel leakage at different positions. Through comprehensive parameter analysis, it was observed that the width of the leakage joint significantly influenced pile lateral responses, manifesting in three distinct stages: linear increase, nonlinear gradual augmentation, and stabilization. Different positions of the lining leakage joint yielded varying effects on adjacent piles' lateral responses, with closer proximity intensifying the impact on the pile. When leakage joints were situated near the pile toe, a pronounced negative bending moment was generated. Furthermore, this study summarized the influence range of tunnel localized leakage adjacent to piles. It established that the maximum pile-tunnel horizontal distance inducing lateral pile responses due to tunnel localized leakage was set at 8 times the pile diameter (8 Dp). Additionally, tunnel leakage influences should be considered when the pile length exceeded 0.6 times the depth of the tunnel axis. [ABSTRACT FROM AUTHOR]

The hydration heat generated during the concreting of cast-in-place piles causes thermal disturbance to the surrounding permafrost, leading to its thawing. This further affects the stability of the pile foundation and degrades the construction progress. To explore the influence mechanisms of the concrete hydration heat on the permafrost temperature field around the pile, as well as that of different construction seasons on the pile-side boundary conditions and permafrost temperature field, monitoring results of on-site tests and numerical simulation were used to analyze the distribution law of the pile soil temperature field in space and time, and the pile-side boundary conditions and permafrost temperature field during construction seasons. The results show that the temperature trend of the pile foundation can be divided into three stages: a rapid rise phase (0∼2 d), a rapid decline phase (2∼10 d), and a slow decline and stabilization phase (10∼90 d). As the radial distance from the pile center decreases, there occur a corresponding acceleration in temperature increase and an elevated maximum temperature rise (MTR). The influence range of the molding temperature and the hydration heat is about 1∼2 times the pile diameter and less than 1.5 m in the depth direction. Compared to the atmospheric temperature, there is a lag in the change in the permafrost temperature caused by accumulation of ground temperature, and the significant difference between the two leads to an increased rate of heat exchange at the boundary condition. Conducting drilling operation and cast-in-place pile construction in the cold seasons is conducive to reducing the thermal disturbance to the permafrost around the pile in permafrost areas. [ABSTRACT FROM AUTHOR]

Seasonal freeze–thaw (F–T) cycles significantly affect the mechanical properties of soils and the behavior of pile foundations in soils subjected to F–T cycles under different loading conditions. Soils exposed to F–T cycles can impact the performance of pile foundations. Consequently, the effects of F–T cycles should be taken into account when designing piles, particularly in cold regions such as Canada. In recent years, climatic conditions in Canada have changed due to global warming, increasing the number of F–T cycles in many regions each year. This study aimed to investigate the influence of different numbers of F–T cycles on the behavior of piles in sandy soils. Laboratory experiments were conducted on physical models of piles subjected to axial (uplift) and lateral loads combined with F–T cycles. The model was scaled using standard scaling principles, and the test apparatus was equipped with various sensors to measure temperatures, forces, and displacements. The results showed that as the number of F–T cycles increased, the lateral capacities of the piles under individual and combined loads increased steadily. The lateral load capacity increased from 350 to 430 N after five F–T cycles under individual loading and from 225 to 455 N after five F–T cycles under combined loading. However, the pile's uplift load capacity remained constant under individual and combined loads and there was no change due to F–T cycles. The results of this experimental study will be useful for understanding the behavior of piles subjected to seasonal F–T cycles and for improving the design of pile foundations in cold regions. [ABSTRACT FROM AUTHOR]

In general, pile foundations are utilized to support structures like tall buildings, bridges, and transmission towers, which are frequently subjected to lateral stresses initiated by wind, action of waves, earthquakes, or traffic loads. Several high-rise structures, highway and railroad overpasses, as well as transmission towers, are constructed near slopes and rely on pile foundations for support. Due to the effects of wind and waves, pile foundations are continuously subjected to cyclic loads. For piles supporting tall buildings, transmission towers, offshore structures, or infrastructure in seismic zones, 1-way or 2-way cyclic lateral loads are commonly applied. Therefore, while designing pile foundations, it is essential to understand how piles behave laterally when they are located near a sloping crest. One of the primary challenges in ensuring the efficient functioning of the superstructure is analyzing how the soil and foundations respond when exposed to long-term lateral loads, such as wind, over an extended period on the piles of offshore platforms. Because of the presence of slope, the pile's lateral load capacity decreased due to the reduced ability of the soil to provide passive resistance. This paper presents small-scale 1-g model tests conducted on the sand to assess the loss of pile's lateral capacity when subjected to 100 cycles under 1 and 2-way cyclic loading. The Relative Density (60%) and varying slopes (Horizontal ground, 1V:3H) with varying spacing (5D and 7D) and aspect ratios (L/D) of 25 and 40 were implemented in this study. Cyclic lateral load tests were performed for sloping as well as horizontal ground. A major reduction in lateral capacity, exceeding 60%, was observed due to the application of cyclic loading. Moreover, the transition from horizontal ground (HG) to sloping ground (SG) decreased the maximum bending moment by 25–40%. This study exemplifies the piles' behaviour when subjected to cyclic lateral loading while resting on a sloping crest, which represents a critical scenario in pile foundation design. [ABSTRACT FROM AUTHOR]

Under various stress paths, the deformation characteristics represented great differences. In this paper, a series of cyclic triaxial tests have been conducted with Fujian standard sand. By comparing the constant deviatoric (CDS) and constant axial stress paths (CAS), the influence mechanism of the cyclic amplitude of the deviatoric stress was discussed. The test results showed that the stress path significantly influenced the volumetric and shear strains. The increasing and decreasing trend in the volumetric strain (ɛv) was consistent with the spherical stress (lnp). Compared with the two stress paths, the slope of the ɛv−lnp curve during the loading and unloading stages was larger under the CAS path. In the CDS path, qc almost did not affect the cumulative volumetric strain, and in the CAS path, the effect was obvious. The shear strain curve was in accordance with the direction of the stress path. As the cyclic number increased, the shear strain gradually accumulated. The shear strain accumulation under the CAS path was larger. The shear strain largely depended on the relative position between the critical state line (CSL) and the stress state of the soil during cyclic loading and unloading. Practical Applications: In practical engineering, the soil will experience various stress paths. For example, in slope or earth–rock dam engineering, where the water level rises and falls repeatedly, the soil often goes through the stress path of constant deviational stress with the cyclic increase and decrease in the spherical stress. In foundation pit engineering, the soil often experiences the stress path of the constant axial stress (CAS) with cyclic loading and unloading of the lateral stress. The stress path greatly influences the deformation and strength of soil. Therefore, the previous two stress paths are compared in this paper to discuss the influence of the cyclic amplitude of deviatoric stress. Under three different consolidation states, the cyclic amplitude of the deviatoric stress significantly influenced the volumetric and shear strains. The shear strain largely depended on the relative position between the critical state line (CSL) and the stress state of the soil during cyclic loading and unloading. Therefore, in practical engineering, if the stress path in the experiment differs from the actual value, the influence of the stress path should be properly considered. The results should be modified according to the degree of influence of each stress condition. [ABSTRACT FROM AUTHOR]

Collapsibility significantly impacts the bearing capacity of pile foundations in loess areas. To improve the load-bearing capacity of piles, the pile-base postgrouting technique is widely used worldwide. However, there are still several related issues to be solved: the impact of loess collapsibility on the bearing capacity; the effectiveness of the pile-base postgrouting technique in enhancing the bearing capacity; and the diffusion pattern of the grout during the grouting process. To investigate these issues, this experiment utilizes a visual static pressure device combined with numerical simulation. According to the experiment, the maximum axial force and neutral point appeared to shift downward after grouting, resulting in a 17.5% increase in the bearing capacity of the pile foundation. Additionally, an increase in grouting pressure leads to a rise in both the number of shear cracks and the diffusion radius. As the permeability of the grout improves, the number of shear cracks and diffusion radii tend to stabilize after an initial increase. These discoveries enable a thorough analysis of the changes in side friction and base resistance of postgrouted piles in collapsible loess. Furthermore, they provide valuable references and guidance for the implementation of the pile-base postgrouting technique in loess areas. [ABSTRACT FROM AUTHOR]

The prevailing design methodology for foundation pit support structures conventionally treats the pit cross section as a two-dimensional plane, facilitating the computation of soil and water pressures acting upon the retaining structure. Regrettably, this conventional approach tends to overlook the critical corner effect, particularly when the foundation pit is in proximity to a subway tunnel, where the nuanced nature of this corner effect remains indeterminate. Consequently, this research is directed toward an in-depth investigation of a deep foundation pit contiguous to a subway tunnel. A systematic evaluation and optimization of the corner effect pertaining to the deep foundation pit are undertaken through a combination of comprehensive field monitoring and simulation methodologies. The results show that a substantial mitigation in the deformation of the supporting structure, settlements of the ground surface and adjacent buildings, as well as the displacement of the subway tunnel, were achieved through a consideration of the corner effect. Notably, the ameliorative impact of adjacent buildings on the corner effect is observed. Further scrutiny reveals that the supporting structure within a distance of 12 m from the pit corner is most susceptible to the corner effect, as evidenced by a plane strain ratio (PSR) falling below 0.8. Beyond a spatial threshold of 20 m, the PSR attains a value of 1.0, indicative of a negligible corner effect and the foundation pit section existing in a plane strain state. The adjustment of pile length or diameter based on the PSR emerges as a viable strategy that can realize the construction cost optimization on the premise of ensuring the stability of the foundation pit. The impact of pile diameter variation is paramount, corresponding to a reduction in the range of PSR values below 0.8 from 12 m to 9.8 m. The corner effect is significantly diminished. [ABSTRACT FROM AUTHOR]

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The seepage field of a suspended waterproof curtain strip foundation pit in a deep phreatic aquifer is theoretically analyzed, and a calculation method for the foundation pit water inflow and water level outside the curtain is derived. In this paper, it is assumed that the horizontal hydraulic gradient of the seepage field above the aquiclude below the bottom of the waterproof curtain decreases linearly. The separation variable method is used to solve the seepage field in the regular area inside the foundation pit, and the hydraulic head distribution function inside the foundation pit is obtained. According to the hydraulic head distribution function inside the foundation pit, the calculation expression of the water inflow of the foundation pit is further deduced theoretically. On this basis, the improved resistance coefficient method is applied to link the water level outside the pit with the solved hydraulic head inside the pit and solved. In addition, the calculation results presented in this study are compared with the calculation results of the existing model and the measured data of the foundation pit project of Yangwan Station, which proves that the analytical method can effectively meet the requirements of engineering applications. [ABSTRACT FROM AUTHOR]

The primary objective of this case study is to evaluate the effectiveness of drone-based ground penetrating radar (GPR) in detecting and mapping underground water levels and soil-to-rock boundaries. This knowledge is crucial for accurate structural engineering analyses, including foundation engineering and site-specific response evaluations. The paper also considers drone-based GPR to overcome common urban obstacles, topographic variations, and environmental factors by simply flying over them, offering a promising solution to these challenges. The research utilized drone-based GPR equipped with an unshielded 150 MHz dipole antenna and employed filtering procedures to diminish the effect of above-ground obstacles on the interpretation of our results. The study unequivocally demonstrated the feasibility and effectiveness of drone-based GPR in these applications, reassuring the civil engineering community. The findings of this study significantly advance our understanding of drone-based GPR technology for mapping disturbed soil boundaries and water table levels in foundation engineering and site response applications and provide valuable recommendations for optimizing its performance in complicated terrains, thereby inspiring and guiding future research and practice in this field. [ABSTRACT FROM AUTHOR]

To ensure the long-term safety and stability of bridge pile foundations in permafrost regions, it is necessary to investigate the rheological effects on the pile tip and pile side bearing capacities. The creep characteristics of the pile-frozen soil interface are critical for determining the long-term stability of permafrost pile foundations. This study utilized a self-developed large stress-controlled shear apparatus to investigate the shear creep characteristics of the frozen silt-concrete interface, and examined the influence of freezing temperatures (−1, −2, and −5°C), contact surface roughness (0, 0.60, 0.75, and 1.15 mm), normal stress (50, 100, and 150 kPa), and shear stress on the creep characteristics of the contact surface. By incorporating the contact surface's creep behavior and development trends, we established a creep constitutive model for the frozen silt-concrete interface based on the Nishihara model, introducing nonlinear elements and a damage factor. The results revealed significant creep effects on the frozen silt-concrete interface under constant load, with creep displacement at approximately 2–15 times the instantaneous displacement and a failure creep displacement ranging from 6 to 8 mm. Under different experimental conditions, the creep characteristics of the frozen silt-concrete interface varied. A larger roughness, lower freezing temperatures, and higher normal stresses resulted in a longer sample attenuation creep time, a lower steady-state creep rate, higher long-term creep strength, and stronger creep stability. Building upon the Nishihara model, we considered the influence of shear stress and time on the viscoelastic viscosity coefficient and introduced a damage factor to the viscoplasticity. The improved model effectively described the entire creep process of the frozen silt-concrete interface. The results provide theoretical support for the interaction between pile and soil in permafrost regions. [ABSTRACT FROM AUTHOR]

Lateral spreading has historically caused extensive pile failure in liquefaction‐prone areas during strong earthquakes. A critical design scenario involves piles embedded in lateral spreading ground composed of a nonliquefied soil crust overlying a liquefied layer; it is critical because both layers can exert loads on the piles. Different thicknesses of the liquefied soil and the upper nonliquefied crust may engender different pile response patterns. Accordingly, to investigate factors influencing the lateral responses of a single pile embedded in liquefied ground with a nonliquefied crust, we conduct parametric analyses. The effects of liquefied and nonliquefied soil thicknesses are analyzed first, followed by those of pile‐head rotational restraint, pile diameter, and lateral spreading displacement. We observe two main pile response patterns for various liquefied soil thicknesses. The ground can be categorized into thin or thick liquefied ground depending on whether its liquefied soil thickness is less or greater than a critical value, namely, critical liquefied soil thickness; this critical thickness is dependent on the pile‐head rotational restraint, pile diameter, and lateral spreading displacement. The difference in the patterns stems from the varying roles of the upper nonliquefied soil layer during lateral spreading. For the thin liquefied ground, the nonliquefied layer contributes to adding lateral spreading force; therefore, the displacement, moment, and shear force responses of the pile increase with the nonliquefied soil thickness. However, for the thick liquefied ground, the nonliquefied layer provides resistance to lateral spreading; therefore, the maximum displacement, moment, and shear force of the pile initially decreases and then gradually increases with the nonliquefied soil thickness. [ABSTRACT FROM AUTHOR]

Urbanization can pose water management challenges in cities while overlooking the possibilities of residents' lived experience and collaborative action learning. We show how the conceptual model of the Lived Experience of Sustainable Urban Groundwater Level identifies several aspects of local knowledge development through an ex-post case study in Rotterdam's Flower Neighbourhood (The Netherlands), where too low groundwater levels threaten house foundations. Three types of local knowledge development emerged: (i) performing and monitoring well measurements by residents, (ii) environment-specific insights collected by residents and shared with civil servants, and (iii) collaboration on groundwater management experiments, resulting in empirical groundwater data. Overcoming communication barriers, trust issues, and power dynamics are crucial for effectively retrieving and integrating lived experience into collective learning for urban sustainable development. [ABSTRACT FROM AUTHOR]

In recent years, foundation pit construction has been rapidly developing in the direction of deep and large-scale, leading to the frequent occurrence of construction accidents. The pit construction process is characterised by a complex environment, high construction risk, and numerous coupling effects between the construction risk factors. In this paper, 23 main accident-causing factors in foundation pit construction are determined based on the six major risk accident types. In addition, the Grey-DEMATEL-Fuzzy comprehensive evaluation method of the risk evaluation model is introduced for better prediction and judgment of risk level, which combines the grey system theory with the method of decision-making experimental analysis, and in the case of inaccurate or incomplete information, the use of less data can achieve the evaluation results with a high degree of reliability, and it will effectively avoid the impact of the lack of information as well as the subjectivity in the process of risk evaluation. Through the Grey-DEMATEL method, the central degree value for each risk indicator factor is calculated, the coupling role and importance of each risk indicator are analysed, and the indicator weights are calculated. Based on the calculated weights, the fuzzy comprehensive evaluation method is used to evaluate the overall risk level. The empirical research on the deep foundation pit construction project of Haitangxi subway station in Chongqing reveals that the excessive lateral earth pressure on the pile wall is the most prominent risk factor. The overall risk level of the construction process is medium, and the risk is within the controllable range. On this basis, corresponding preventive measures can be formulated, providing a basis for risk prevention in the construction of deep foundation pit projects. [ABSTRACT FROM AUTHOR]

Translation abstract Induced vibrations of structures on piled or shallow foundations – a comparison using numeric calculationsWhen predicting structural vibrations due to vibration sources in the neighbourhood, e. g. from traffic, construction work or machine vibrations, the question sometimes arises as to what influence the foundation of the structure has on the amplitude and frequency content of the resulting vibrations. This article systematically compares the so‐called induced vibrations of structures on pile foundations and on shallow foundations on the basis of numerical calculations. After a description of the calculation method using the “Thin Layer Method” (TLM) in the frequency domain, individual piles in a homogeneous half‐space and those in a soil layer on a stiffer subsoil are first considered. Excited by horizontal and vertical forces on the ground surface at some distance, the amplitudes of the vibration velocity (Schwingschnelle) at the level of the pile head before and after installation of the pile are determined and compared. Frequencies between 1 Hz and 40 Hz are considered. The influence of soil stratification is discussed. In the second part of the work, the vibration velocities of shallow and pile foundations under the same excitation are calculated and compared. Characteristic differences can be recognized from the comparison. In this analysis the rising building structures are modelled as rigid masses in a highly simplified manner. The calculation results contribute to the introductory question. [ABSTRACT FROM AUTHOR]

AbstractNowadays, the use of deep foundations in various civil engineering projects, especially in marine and coastal structures, has been increasing. One type of deep foundations are helical pile foundations, which have gained significant attention in recent decades. This research investigates the load–displacement behavior of different helical pile configurations regarding geometry, i.e., helix diameter and spacing ratio (S/D) in two different soil densities under pullout and compressive loading conditions via the FCV-AUT device. Babolsar sand from the southern coast of the Caspian Sea was utilized for advancing this study. Additionally, four full-scale pile tests were conducted on the Caspian Sea coast under both grouted and non-grouted conditions for pullout and compressive loading. The results indicate that increasing the helix diameter, soil density, and S/D ratio enhances the compressive load-bearing capacity. However, in tensile loading, the ultimate load decreases with an increase in the spacing ratio. Furthermore, the grouting process in the three-helix pile exhibits better performance compared to the two-helix pile, potentially increasing the pile capacity up to 30%. In conclusion, the results obtained from the FCV device, utilizing scale theory, have been generalized to the large-scale pile test results in the field, are representative of in agreement and compatible. [ABSTRACT FROM AUTHOR]

Translation abstract Innovative foundation for noise barriers – a Deutsche Bahn pilot project with ground screwsIn geotechnical engineering, ground screws are often associated with lightweight constructions and are established worldwide as a foundation for solar power plants. Larger ground screw designs are currently being developed and tested as part of pilot projects. At approx. 406 mm, these ground screws have around four times the tube diameter of the above mentioned and are therefore to be classified and dimensioned as pile foundations. In contrast to conventional driven steel piles, the ground screws are driven into the ground without vibration. It is obvious that the foundation elements should be used where particular attention must be paid to noise and vibration emissions. For example, as a foundation element for noise barriers as part of the special noise remediation program for the Middle Rhine Valley. This article presents the Deutsche Bahn pilot project, provides information on the design of the large ground screws and highlights the advantages of the innovative foundation system. [ABSTRACT FROM AUTHOR]

Prestressed spun high-strength concrete (PHC) piles are commonly used in various types of structures, including bridges, buildings and marine infrastructures. However, piles installed in aggressive environments are vulnerable to corrosion of the steel, which can lead to rapid degradation of the piles. As a corrosion-resistant material, carbon fiber-reinforced polymer (CFRP) is considered an alternative to steel tendons for durability enhancement. In this study, a new pile system with CFRP was proposed. Experimental tests of three full-scale piles and a numerical analysis of eight piles with various parameters were performed to investigate the flexural performance of CFRP prestressed spun high-strength concrete pile. The proposed piles were loaded under four-point bending after prestressing. The experimental and numerical results verified the feasibility of the proposed system, and the CFRP pile exhibited twice of flexural capacity of that of steel-reinforced piles. The flexural performance of the CFRP PHC pile was significantly affected by the reinforcement ratio, prestressing level and modulus of the CFRP. An analytical approach predicting the flexural capacity of the CFRP PHC pile was proposed based on the parametric study. Ninety percent accuracy was achieved for the proposed analytical approach. The presented study can significantly promote the application of CFRP in pile foundations and improve the durability of PHC piles. [ABSTRACT FROM AUTHOR]

Based on field hydro-meteorological observations and sediment sampling data, this study analyzes sediment transport under normal conditions in the Fanshi offshore wind farm project area in Yangjiang, China. It was found that sediment transport in the engineering sea area is relatively stable, and seabed sediments are not easily mobilized. By building a tidal current–sediment mathematical model, the impact of wind farm construction on the erosion and deposition environment in the surrounding sea areas was studied. It was found that areas with significant accumulation are mainly located near the pile foundations of wind turbines. Furthermore, considering ocean dynamics, geological conditions, and wave–current interactions, different local erosion empirical formulas were used to calculate local erosion depth and range. The results show that Han Haiqian's formula and the HEC-18 formula, which consider wave velocity, are very close and more suitable for the actual conditions of this project. As turbine pile diameters increase, local scour depths and ranges also increase. This study preliminarily analyzes the basic scour characteristics of deep-sea wind turbines off the western coast of Guangdong Province, offering important design parameters for the construction of this project, and also providing a systematic and scientific method for studying local scour at turbine pile foundations. This has great reference value for deep-sea wind farm construction projects. [ABSTRACT FROM AUTHOR]

This paper presents a thorough reliability assessment of cavity foundation systems involving the generation of 272 datasets using Plaxis 2D automation. The parameters were systematically varied across feasible ranges, and Sobol‐based sensitivity analysis identified the negligible influence of the soil modulus of elasticity (E) on subsequent reliability analyses. A robust 1D‐CNN surrogate model was developed to predict the critical foundation responses by integrating Gaussian white noise to simulate real‐world uncertainties. A log transformation with 1,000 bootstrap samples was chosen for resampling non‐normally distributed data. This study employed a novel approach utilising 1D‐CNN regressor models for bearing capacity (BC) prediction, achieving promising results with R2 values of 0.953 and 0.945 for BC in the training and testing phases, respectively. Bootstrapping resampling facilitates reliability analysis preparation and ensures robustness in handling complex data. Simulated noise varied with specific variance (p) from 0.01 to 0.5, allowing the examination of model efficacy under varying noise levels. Both the Monte Carlo Simulation (MCS) and first‐order reliability method (FORM) were employed, revealing a reliability index (β) of 2.046 for FORM and 2.066 for MCS. This indicates a 0.976% increase in β and a 75% increase in the probability of failure transitioning from FORM to MCS, underscoring the model's sensitivity to analytical methods. [ABSTRACT FROM AUTHOR]

The joints between precast reinforced concrete pile segments in deep foundations are typically mechanically lockable. They include anchor bars embedded inside the ends of each segment, forming lap splices with the main bars. Because of their particular technology, these lap splices are somewhat different from traditional lap splices, as shown in the first part of this paper, where the impact of their specific characteristics on the tensile behavior of the joints is discussed. The experimental section presents the results of 19 tensile tests on these lap splices and compares them with established theoretical models. The roles of various parameters (lap length, type and amount of confining reinforcement, type of anchor bars, and concrete cover thickness) are investigated. One of the major findings indicates a significantly lower lap capacity when using plain‐bar spirals compared to closed‐ribbed stirrups. Additionally, at low stress levels, the models tend to be unconservative. Building on this insight, a modified model is proposed for lap splices provided with plain‐bar spirals. [ABSTRACT FROM AUTHOR]

In this study, numerical analyses of connected and disconnected piled-raft foundations (PRFs) comprising a single pile, 2 × 1, 3 × 1, 2 × 2, 3 × 2, 3 × 3 and 5 × 5 pile groups subjected to different lateral loads, with a constant vertical load, have been carried out by three-dimensional finite-element analysis. Results from the analysis have been validated with reported field studies considering vertical load and reported experimental studies considering lateral load. The reported multilayered sub-soil profile has been considered for the analysis. Parametric studies in terms of the effect of variation in pile length (L/d = 20, 30, 39), spacing of piles in the pile group (S/d = 3, 5, 6), number of piles, thickness of raft (0.5, 1.2 and 2 m), variation of axial force, excess pore water pressure, bending moment and shear force along the depth of the piles for connected and disconnected PRFs have been discussed for a time period of 20 years. The horizontal connected piled-raft coefficients have been determined corresponding to the lateral deflections. A generalised equation has been predicted for the horizontal connected PRF coefficient. [ABSTRACT FROM AUTHOR]

Local scour is prone to occur around offshore wind turbine pile foundation. The solidified soil protection has widely used in the field of subgrade treatment, bridge pier protection, etc., and the pilot research is gradually carried out in offshore wind turbine projects. Based on an offshore wind power project in a sand ridge sea area in the eastern part of Jiangsu Province, the numerical simulations are carried out by using Flow -3D to establish the models of offshore wind turbine monopile foundation under constant flow. Comparing with classical tests and empirical formulas, simulation results demonstrate that the model of offshore wind turbine monopile foundation without solidified soil protection can accurately simulate the flow field and predict the maximum scour depth. Also, there is a good agreement between the simulation results of monopile foundation model protected by solidified soil and the scanning pictures around the monopile. By comparing the retention rates and the maximum scour depths of solidified soil, the optimum protection radius of solidified soil is considered as 2 times of the pile diameter. Solidified soil protection is less effective in protecting the seabed where the flow velocity is over 4 m/s, which verifies that the solidified soil is generally designed to resist scouring by flow velocity of 4 m/s in practical engineering construction. [ABSTRACT FROM AUTHOR]

Pile foundations may be exposed to torsional loads caused by horizontal eccentric loads brought on waves, wind and earthquakes, as well as axial load brought on by supporting superstructures. This paper highlights a recent strategy to modify piles known as the finned pile. A series of experimental tests were conducted to increase the torsional capacity of a single pile with/without fins in sand under the influence of vertical loads (V), torsional loads (T) and combined loads (T → V), these experiments involved altering fins' length, width, shape, and number and knowing the effect of these variables on the piles' maximum torsional capacity. The vertical load-displacement response and the torsion-rotation response have been observed. The results showed that fins improve piles' torsional capacity. It also showed that on piles' maximum vertical capacity for independent vertical or torsional loads is different from that of piles under combined loading. It was found that fins' optimum geometry is that their length equal to 0.6 of the embedded pile's length and their width equal to the pile's diameter, where piles' maximum torsional capacity was (4.12 and 7.36) N.m for regular and finned piles, respectively. Fins increased piles' maximum torsional capacity by about 79%. [ABSTRACT FROM AUTHOR]

The PHC (pre-stressed high-strength concrete) pile foundation, serving as an innovative supporting structure for solar power stations, is subjected to complex loading conditions in engineering scenarios. In this study, field tests of the full-scale PHC Pile foundation were conducted in sand layer, loess layer, and double-layer sites to investigate its operational behavior under different load conditions. The study assessed the inclination of the column top, ground displacement, and torsion to analyze the stress and deformation characteristics of PHC pile foundations. The deformation of PHC short pile foundations exhibited distinct phases. Torsional load reduced the column crack load by 30%. The pile cap effectively controlled plastic deformation, minimizing foundation deformation, while torsional load increased lateral deformation. Under cyclic load, the PHC pile behaved with an approximate elasticity characteristic within the test load range. The deformation increased by approximately 10%. Furthermore, three-dimensional numerical simulations analyzed the effects of foundation dimension, bending-moment-to-lateral-load ratio, torque-to-lateral-load ratio, and pile cap size on internal forces and deformation. Simulations indicated that increasing the pile cap length was more advantageous for reducing deformation and internal forces. The bending-moment-to-lateral-load ratio was significant in design, while the torque-to-lateral-load ratio had a negligible impact. A comprehensive design program is proposed based on field tests and numerical simulations, considering deformation and bearing capacity. The study confirms the reliability of the PHC pile foundation as a support structure for heliostats, aiming to offer valuable insights for practical applications. [ABSTRACT FROM AUTHOR]

Piled raft foundations (PRFs) below stepped high rise towers are often subjected to non-uniform loads with eccentricities. In this study, twenty five cases of rectangular rafts with different pile configurations and orientations embedded in sand are analyzed using nonlinear three-dimensional finite element analysis. These PRFs are subjected to different triangularly distributed loads and uniformly distributed loads with and without eccentricities. The piled raft responses investigated are the maximum and differential settlements, angular distortion, tilt, load sharing between the raft and the piles, the load carried by the individual piles, and the subgrade modulus (spring constant) at the raft-soil and pile-soil interfaces. The PRF responses are greatly influenced by the distribution of the applied loads and the magnitudes of the load eccentricities. The study provides insights into the PRF behavior under nonuniform and eccentric loads and may help practitioners in making informed design decisions. [ABSTRACT FROM AUTHOR]

Pile foundations supporting wind turbines, silos, elevated water tanks or bridge piers are frequently subjected to multi-component loads, which may lead to significant rotations and settlements compromising the safe operation of the structure. The prediction of these displacements is of major concern and can be easily carried out using force-resultants plasticity models, also referred to as 'macro-elements', stemming from the idea of describing the foundation behaviour by a single upscaled constitutive relationship between generalized forces and displacements. When properly formulated, they can reproduce key aspects of the mechanical response of the foundation at low computational cost as compared to numerical analysis. To this end, a new macro-element for pile groups formulated in the classical framework of strain-hardening elasto-plasticity is presented and discussed. The required model parameters can be calibrated by closed-form equations and additional few data of numerical and/or experimental nature. The proposed mathematical framework is finally validated against the results of centrifuge tests and 3D finite element analyses. [ABSTRACT FROM AUTHOR]

Records of pile lengths are not available for several hundred high-mast light towers (HMLTs) throughout the state of Minnesota. The foundation systems, typically steel H-piles or concrete-filled steel pipe piles connected to a triangular concrete pile cap, risk overturning in the event of peak wind loadings if the foundation piles are not sufficiently deep to provide the designed uplift capacity. Without prior knowledge of the in situ pile lengths, an expensive tower foundation retrofit or replacement effort would need to be undertaken. However, the development of a nondestructive screening tool to determine the in situ pile length—compared with replacing or retrofitting all towers with unknown foundation geometries—would potentially provide significant cost savings. The main goal of the research is the development of nondestructive evaluation testing techniques for determining in situ pile lengths using steady-state vibration and hammer-impact seismic testing. The foundation testing protocol involves (1) a preliminary site investigation to determine the shallow subsurface geometry and orientation of the foundation pile cap, (2) the use of seismic cone penetrometer (SCP) attached to a cone penetration test rig to capture the induced steady-state and impact waveforms, and (3) data-driven analysis of field testing results to determine the pile lengths. [ABSTRACT FROM AUTHOR]

In order to solve the problem of poor accuracy of blasting vibration prediction by the traditional Sadowski empirical formula and BP neural network, a model based on the mind evolutionary algorithm (MEA) is proposed for the first time to optimize the BP neural network. The blasting demolition of a raft slab foundation of an underground garage in Shenyang City, Liaoning Province, China, is taken as a research object, and the effects of the horizontal distance between different monitoring points, demolition area, elevation difference, the maximum amount of a single section of the charge, and the horizontal angle between the measurement point and the minimum resistance line on the peak velocity of vibration are taken into account. The empirical Sadowski formula, the MEA-BP algorithm, and the GA-BP algorithm were introduced to randomly train the 40 sets of data monitored at the site and to predict the eight sets of data outside the training, respectively. The results showed that the maximum relative errors of the results predicted by the MEA-BP model, the GA-BP model, and the empirical Sadowski formula were 14.94%, 19.36%, and 22.81%, respectively, and the average relative errors were 8.88%, 10.79%, and 16.84%, respectively. The prediction results corroborate that the MEA-BP algorithm has high adaptability in blasting vibration prediction for raft foundation demolition and provides reference for the prediction of vibration peak velocity in similar blasting projects. [ABSTRACT FROM AUTHOR]

Piled rafts and pile groups are the common types of deep foundations for tall buildings subjected to combined loading. Their complex behavior made their design and analysis very complex and sometimes uneconomical. This paper explores the distribution of lateral load on piles within a piled raft and pile group under a constant vertical load. The study utilized experiments with small-scale models of piles and rafts to observe the behavior. The response of each pile was recorded and analyzed with respect to lateral displacement. The results indicated that in the case of piled rafts under lateral load, the rear piles are resisting more load than the front piles, unlike in pile groups where front piles carry more load than rear piles. This behavior continued until the number of piles reaches nine, thereafter the load-carrying behavior shifted, and front piles began to carry more lateral load. The reason behind this shift is that as the number of piles increases, the raft contact pressure decreases and subsequently decreases the stiffness of soil below raft and hence the piled raft starts behaving as a pile group, where front piles carry more lateral load. [ABSTRACT FROM AUTHOR]

Cracks develop in concrete piles under lateral static loading as the tensile stress exceeds the concrete strength, causing a decrease in the pile's flexural rigidity and influencing the load–deflection behavior. This paper presents a three-dimensional finite-element analysis (FEA) performed by PLAXIS 3D (version 2021) to investigate the impact of concrete cracking on the load–deflection behavior of laterally loaded piles in rock mass. Two FEA models were established to assess the influence of concrete cracking on load–deflection behavior. In the first model, nonlinear rock mass behavior was coupled with linear pile behavior (FEANL), while in the second model, nonlinear rock mass behavior was coupled with nonlinear pile behavior (FEANN). The three-dimensional (3D) FEA models were verified with a full-scale test case study for a deep-water pile foundation. The FEANN yields a more accurate simulation of measured deflection than the FEANL. A single run of the FEANN typically requires an entire day of computational time. Thus, a simplified approach was proposed to minimize the computational time process by incorporating the relationship of the change in pile flexural rigidity versus the bending moment (EI–M) into FEANL. In addition, the available EI–M relationships in the literature, such as the American Concrete Institute (ACI) method and beam theory, were evaluated by the EI–M relationship derived from the FEANN. The beam theory yields a lower estimate of pile flexural rigidity than the ACI method. The predicted deflection obtained through the simplified approach exhibits good agreement with the measured deflection utilizing the EI–M relationship derived from the FEANN. On the other hand, the EI–M relationship obtained from the beam theory overestimates the deflection compared to those obtained from the EI–M relationships of the ACI method and FEANN. [ABSTRACT FROM AUTHOR]

Previous earthquake events indicate that pile foundations in liquefiable soils are vulnerable to damage due to the coupling of inertial and kinematic effects. Inclined piles are widely applied in structures located in liquefiable soils, but few investigations of the coupling of the superstructure–pile inertial and soil–pile kinematic effects have been conducted. To address this gap, this study adopted a three-dimensional (3D) numerical model to investigate the coupling of inertial and kinematic effects in pile foundations with different inclination angles. The pile head bending moment was employed to represent the pile response, while the soil surface displacement and structure acceleration were utilized to quantify the kinematic and inertial effects. The role of the inclination angle on the interactions between inertial and kinematic effects is herein considered for pile groups. In particular, the inertial effect significantly influences the behavior of pile groups with larger inclination angles, whereas the kinematic effect predominates the pile head moment in vertical pile groups. In this paper, the influence of the pile inclination angle, superstructure configuration, and earthquake intensity on the interactions was investigated. The principal findings revealed that the kinematic effect dominates in the vertical pile group irrespective of the properties of the superstructure, while the inertial effect plays a significant role in the response of the inclined pile groups, especially for superstructures with considerable heights. Practical Applications: Inclined piles are vulnerable to damage due to the interaction of inertial and kinematic effects during earthquakes. This study conducted a series of three-dimensional (3D) finite-element simulations to investigate the interaction of inertial and kinematic effects in pile foundations with different inclination angles. The influence of pile inclination angle, superstructure height, and earthquake characteristics was investigated. In current practices, various codes and pseudostatic methods have been adopted to sum a percentage of the inertia-induced bending moment and another percentage of the kinematic-induced bending moment. This study indicates that under certain conditions, the simple summing of the bending moment induced by the inertial and kinematic effects could be inaccurate. The present study identified several factors that influence the interaction of inertial and kinematic effects on piles with different inclination angles. The inclined piles in liquefied soil, especially for supporting tall and heavy superstructure, attention should be given to the influence of inertial effect on the pile head bending moment. [ABSTRACT FROM AUTHOR]

For the significant energy consumption and environmental impact, it is crucial to identify the carbon emission characteristics of building foundations construction during the design phase. This study would like to establish a process-based carbon evaluating model, by adopting Building Information Modeling (BIM), and calculated the materialization-stage carbon emissions of building foundations without basement space in China, and identifying factors influencing the emissions through correlation analysis. These five factors include the building function type, building structure type, foundation area, foundation treatment method, and foundation depth. Additionally, this study develops several machine learning-based predictive models, including Decision Tree, Random Forest, XGBoost, and Neural Network. Among these models, XGBoost demonstrates a relatively higher degree of accuracy and minimal errors, can achieve the RMSE of 206.62 and R 2 of 0.88 based on testing group feedback. The study reveals a substantial variability carbon emissions per building's floor area of foundations, ranging from 100 to 2000 kgCO 2 e/m2, demonstrating the potential for optimizing carbon emissions during the design phase of buildings. Besides, materials contribute significantly to total carbon emissions, accounting for 78%–97%, suggesting a significant opportunity for using BIM technology in the design phase to optimize carbon reduction efforts. [ABSTRACT FROM AUTHOR]

The earthquake that occurred in Palu-Sulawesi Indonesia in 2018 has caused many problems to infrastructure buildings. One of the impacts of the earthquake was the reduction the level of hardness includes the level of stiffness saturated sandy and condition makes the foundation structure experience greater lateral deformation, which can lead to the collapse of the building above it. This phenomenon is called liquefaction. This article describes the results of laboratory simulations using a one-way shaking table. It aims to obtain the lateral resistance of a group of short pile foundations. The lateral resistance is investigated from the amount of lateral deformation of the pile cap. Laboratory modeling used field and laboratory comparisons at a scale of 1:10. Pile foundations are used in 2×2 pile groups. To obtain the lateral deformation of the pile, Optic Flow is used which is placed on top of the pile cap as high as 30cm. Meanwhile, to obtain the increase in pore water pressure, a PWP sensor was used which was inserted at a certain soil depth of 30cm from the ground surface. The test results show that the lateral deformation of the pile cap due to liquefaction can be observed well. The phenomenon of liquefaction can be observed the excess the pressure of pore water into the soil is caused by loading of seismic. Furthermore, observation results were compared through analysis using the Plaxis 3D program, which showed a good agreement. [ABSTRACT FROM AUTHOR]

Structural foundation integrity is crucial for sustaining diverse constructions, but in Qatar, the prevalent rapid penetration of chloride ions and sulfate in soil and groundwater poses a substantial threat. This chemical exposure accelerates steel corrosion and induces concrete damage, especially at the foundational level, which is a prevalent concern in the Middle East. This study aimed to identify the most durable concrete foundation by evaluating its compressive strength at 7 and 28 days, coupled with various durability tests such as the rapid chloride penetration test, water absorption, chloride penetration, water penetration, and chemical analysis. The emphasis was on achieving a concrete composition capable of enduring for centuries. This research delved into variations in concrete durability, particularly focusing on curing methods, in contrast to previous studies. Samples underwent curing in natural soil, exposing them to chemical attacks such as chloride ion (Cl−=0.12%) and sulfate (SO4 ²- =1.22 g/l) attacks, while others opted for curing in potable water and temperatures controlled as per American Society for Testing and Materials (ASTM). The experimental investigation considered highperformance triple-blend mixtures and control sample concrete compositions, including 70% ordinary Portland cement (OPC), 25% pulverized fuel ash (PFA), and 5% silica fume (MS); 45% ordinary Portland cement (OPC), 50% ground granulated blast furnace slag (GGBS), and 5% silica fume (MS); 100% sulfate resistance cement (SRC); and 100% ordinary Portland cement (OPC). The results indicate that incorporating GGBS enhances both compressive strength and foundation durability. [ABSTRACT FROM AUTHOR]

The open excavation method is a common technique for constructing shallow underground works in foundation pits. The incident of settlement and cracking of resident houses around a 2-basement deep foundation pit of a 26-storey twin tower office building constructed in Hanoi by the open excavation method has been studied. The methods employed were a combination of site investigation and numerical and analytical simulations of a real problem. For the numerical simulation problem, two sections, North-South and East-West, were analyzed using the finite element method, plane strain problem, according to different excavation stages. The simulation results showed that the measures to protect the western slope of the foundation pit by using only bored piles without reinforcing the slope of resident houses adjacent to the excavation pit led to large ground deformation, endangering the stability of the pit and the structure of the adjacent houses. The above-simulated ground settlement results were consistent with those calculated by the method of the beam on an elastic foundation. [ABSTRACT FROM AUTHOR]

Monopile foundations are commonly constructed for offshore wind turbines and installed at depths shallower than 30 m. However, preventing scouring and erosion around the pile foundation due to waves is critical, as this can cause instability of the foundations and supported structures. In this study, model and numerical tests were conducted to investigate wave-induced scour and erosion around a monopile foundation and clarify the fundamental mechanisms involved. Numerical tests were conducted and validated against physical model tests for a bare sea bed, and good reproducibility was obtained. When a monopile foundation was installed in both the numerical and physical tests, the flow velocity on the seabed in the offshore and inshore directions increased on the side of the foundation perpendicular to the direction of the wave motion. In the model test, scouring occurred at the same location, indicating that scouring may have been caused by the flow velocity; however, this scouring occurred locally, suggesting the need for a detailed analysis of the associated factors. [ABSTRACT FROM AUTHOR]

To investigate the effect of in-pit vehicle load on the stability of the pit against overturning, a long tunnel foundation pit project in Suzhou is used as a case. In-pit vehicle load effects are modelled using the improved equivalent soil thickness method. Through the utilization of the upper limit theory of limit analysis of finite soils and considering the spatial distribution of suction force in the matrix of unsaturated soils, a deduced method for calculating the stability coefficient of the unsaturated finite soil pit against overturning under vehicle load is established. The results indicate that in-pit vehicle load favours pit stability against overturning relative to conventional outside-pit vehicle load. The change in pit stability is more significant when the soil rupture angle is corrected by using the improved equivalent soil thickness method. The increased suction in the unsaturated soil matrix contributes to the pit's stability against overturning. When calculating the stability coefficient against overturning, the finite earth pressure theory proves to be more realistic than the classical earth pressure theory. The results of this study can provide a valuable reference for similar types of pits to prevent overturning. [ABSTRACT FROM AUTHOR]

The piles are structural elements in a foundation that transfer weight from the superstructure to the soil. The behaviour of pile foundations under lateral loading is critical. The pile needs to have enhanced tensile strength and ductility by adding supplementary material to withstand the lateral loads. There were many research studies done to improve these properties in concrete, and the addition of fibre to the concrete is one among them. Fibre-reinforced concrete is classified into numerous categories depending on the type of fibre used. This study is to use the combination of Basalt and E-glass fibre i.e., hybrid in the full-scale pile foundation under combined axial and lateral cyclic loadings. The experimental investigation was conducted on the full-scaled Conventional Concrete (CC) and Hybrid Fibre Reinforced Concrete (HFRC) piles to understand the behaviour under static and cyclic lateral loads. The lateral displacement on the piles was measured at each level of loadings using a Linear Variable Differential Transformer (LVDT). The load–displacement behaviour of CC and HFRC piles was compared under different loading conditions. The HFRC pile exhibits a 40% reduction in displacement and a 10% increase in ultimate carrying capacity compared to the CC pile. HFRC piles tend to have more load-carrying capacity than the CC piles under all types of loadings. [ABSTRACT FROM AUTHOR]

This paper provides universal structural design criteria for heavy industrial projects. Structural design requirements for pipe racks, steel modules, modularized equipment skids, vertical and horizontal vessel supports, and vibrating equipment foundations are discussed. An overview of loading mechanisms of various systems is provided for operational, testing, and lifting conditions. Design recommendations are provided for permanent and removable structures. Several structural idealization concepts are also proposed to ensure accurate load transfer. The theoretical basis and the merits of various methods used in the practice are also discussed. Industrial design examples are provided including multilevel pipe rack and pump foundations. The paper overviews and pieces together the engineering requirements for critical structures that are encountered in heavy industry. [ABSTRACT FROM AUTHOR]

Excavation of foundation pits can cause deformation and differential settlement to nearby pipe gallery structures, potentially resulting in significant issues such as seepage and structural damage. Based on a deep foundation pit construction project for a residential building plot adjacent to the Wuhan-Jiujiang utility tunnel, a three-dimensional finite element analysis model with cement-soil mixed wall (SMW) and trench cutting remixing deep wall (TRD)-drilled pile is established to study the impact of the excavation process on the utility tunnel. The results indicate that as the foundation pit excavation depth increases, the lateral deformation of the drilled pile support structure shows an initial increase followed by a subsequent decrease, and the maximum lateral deformation occurs at the point approximately one-third from the bottom of the foundation pit. Besides, the surface settlement exhibits an initial increase, followed by a subsequent decrease and eventual stabilization. The deformation of the utility tunnel structure causing by excavation is always within specified limit of 15 mm. Compared to the structure before excavation, the maximum values of axial force, shear force, and bending moment of the utility tunnel increases by 0.09%, 0.14%, and 4.88%, respectively. The stress variation is small, which satisfies the safety requirements for its usage, the feasibility of the TRD-drilled pile support structure is demonstrated. This study can serve as a reference for safety assessment of comparable engineering projects. [ABSTRACT FROM AUTHOR]

Flooding occurrences have become increasingly severe, posing a serious danger to end-user safety and bridge resilience. As flood fragility assessment is a valuable tool for promoting the resilience of bridges to climate change, it is of great importance to push the development of such methods. However, flood fragility has not received as much attention as seismic fragility despite the significant amount of damage and costs resulting from flood hazards. There has been little effort to estimate the flood fragility of bridges considering various flood-related factors and the corresponding failure modes. To this end, a fragility-based approach that can explicitly address the scour-hole geometry and flood-induced lateral load is presented. First, a three-dimensional finite-element model with pile foundations and surrounding soil was established to estimate the failure mode under various flood scenarios. The loadings on pile foundations were characterized by vertical loading from the superstructure, horizontal loading from the flood-induced lateral load, and the scour effect simulated through a time-history analysis. Then, all potential failure modes of bridge pile foundations in various flood scenarios were summarized. Based on extensive parameter investigations using the deterministic method, the dominant failure mode of penetration failure was determined, and a failure envelope was fitted to guide the design of the pile foundation. Upon establishing the failure mode, a probabilistic fragility analysis considering uncertainties in hydraulic, structural, and geological parameters was finally conducted using the Latin hypercube sampling (LHS) method. The results showed the effects of variation on the fragility of the pile foundation, highlighting that the deterministic analysis without considering the uncertainties in model parameters leads to underestimating the risk due to the penetration failure and the significant influence region. [ABSTRACT FROM AUTHOR]

In order to study the dynamic response of high-speed railway bridge under flood, a two-span high-speed railway simple-supported beam bridge with unequal 32-meter pier height is studied. A three-dimensional hydrodynamic model of the substructure and a finite element model of the bridge under flooding are built up to analyze the law of flow field distribution around and the hydrodynamic pressure. The influences of the change of velocity and height of flood and the foundation scour depth on the dynamic response of bridge and internal force of pile foundation are revealed. The study shows that: (1) The law of flow field distribution is basically the same when the bridge substructure is impacted by the flood with different velocities; (2) When the flood velocity exceeds 3 meters per second, the influence of the hydrodynamic pressure on the substructure cannot be ignored, and the pressure is positively correlated with velocity and height of the flood; (3) The depth of foundation scour has a significant influence on the hydrodynamic pressure. But when the depth of foundation scour is increased after the bearing platform is exposed, the increase of the pressure is not obvious; (4) When the bridge is impacted by the flood, the overall law of the dynamic response of the bridge with time is basically the same. The response is as follows: When t = 1.06 s, the lateral vibration acceleration of pier top reaches the peak value; When t = 1.16 s, the lateral displacement of pier top reaches the peak value. After the lateral displacement and vibration acceleration reach their peak values, they both tend to attenuate decay rapidly and periodically. With the velocity and height of flood increasing, the peak values and final stable values of displacement and acceleration at prier top as well as the pile bending moment increase; (5) With the increase of foundation scour depth, both the dynamic response and the pile bending moment increase, but the negative bending moment area of pile foundation is more sensitive to the impact of foundation scour depth. [ABSTRACT FROM AUTHOR]