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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]

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]

AbstractThis paper presents the results of numerical predictions for an instrumented piled raft foundation of a tall building in tropical soil. The analysis was performed using 3D finite element analysis and included a comparison of foundation settlements, pile loads, skin friction mobilisation, and raft-soil contact pressure. Initially, the geotechnical model was defined based on field and laboratory test data to conduct a Class A geotechnical prediction. Subsequently, the soil parameters used in the numerical model were re-evaluated to match the measured settlements, aiming for a Class C prediction. The study discusses the main factors that affect the accuracy of the computed settlements, providing valuable insights for foundation designers. Additionally, it highlights the significance of considering the pile-soil-pile and raft-soil-pile interactions in the design of the piles beneath the raft, as these interactions impact the mobilisation of the pile skin friction at different depths. [ABSTRACT FROM AUTHOR]

This article investigated the construction conditions of the pile foundation in the Wuxing section of the "Shanghai Suzhou Huzhou" railway bridge project. To test the reliability of large diameter connectors, it has established a finite element model with ABAQUS software for numerical simulation. Based on on-site tests, the reliability of the connection between the pipe pile and the cover steel was studied. According to the simulation results, when the load is P = 900 kN, the displacements of A2 and A3 steel pipe piles are 55.8 mm and 60.1 mm, respectively. The load-displacement relationship shows a high-order curve distribution. According to the results of on-site experiments, the displacements are 77.9 mm and 60.2 mm, respectively. The load-displacement relationship is linear. The results for the simulation and on-site testing are consistent. This study provides a basis to the research on the reliability of the connection between large-diameter steel pipe piles. [ABSTRACT FROM AUTHOR]

The foundation is the lower part of a structure used as a load distributor for the loads generated by the upper structure, which are then transmitted into the hard soil layers. The selection of foundation types in building construction must consider the type and characteristics of the soil at the construction site to avoid construction failures. This analysis is conducted to determine the bearing capacity of pile foundations using analytical and finite element methods. The type of foundation used in this analysis is a pile foundation with a pile length of 8 meters and a pile diameter of 0.4 meters. For the analytical calculation, Standard Penetration Test (SPT) data obtained from PT. Adhi Karya (Persero) for the Infrastructure Green House Biodiversity LIPI Cibinong-Bogor project are used, employing the analytical method (Alpha Method) and the finite element method with the assistance of Plaxis 2D V.8 software. The results of the analysis show that the bearing capacity of the group pile foundation (Qg) for a pile diameter of 0.4 meters and a pile length of 8 meters on clayey soil, based on SPT data using the analytical method (Alpha Method), is 60.432 tons. Meanwhile, the bearing capacity of the horizontal pile foundation using the Broms method is 6.03 tons. The bearing capacity obtained using the Finite Element Method yields an ultimate load on the group pile (Qq) of 57.89 tons. The bearing capacity of the group pile foundation (Qg) from both sets of data, with a difference of 2.5%, meets the requirement, being greater than the axial load (P) of 42.6 tons that must be supported. [ABSTRACT FROM AUTHOR]

Designing tunnels in urban areas necessitates an accurate estimation of their construction effects on adjacent structures. This study explores tunnelling impacts beneath raft foundations, focusing on settlement and bending moment variations due to different tunnel depths and soil densities. A verification model validated tunnel modelling with field data, employing a 2D finite element model to assess raft foundation performance above tunnels. It also examines the influence of tunnel depth, soil consistency, and spacing of two tunnels. Key results show raft settlement increasing by over 250% when tunnels are directly below at a 7.5 m depth, regardless of soil density. Soil cover thickness above the tunnel significantly affects the raft's bending moment, with an increase of up to 400% and 300% for 5 m and 7.5 m cover depths, respectively. Final tunnel construction stage settlements varied with soil density. The study also reveals that increasing the spacing between closely spaced tunnels beyond 1.2 diameters reduces both raft settlements and bending moments. These findings emphasize the importance of careful tunnel placement and soil cover management to minimize negative impacts on raft foundations. [ABSTRACT FROM AUTHOR]

This study investigates the ultimate bearing capacity (UBC) of an eccentrically loaded strip footing of width, B, resting above circular dual cavities in the rock mass using the Generalized Hoek–Brown (GHB) yield criteria for the rock mass. The stability number (Ns) is determined using upper and lower-bound finite element limit analysis (FELA), incorporating an adaptive meshing technique. The study considers two configurations: symmetrical and parallel outlines based on the relative positions of the dual cavities and the footing. The effects of the numerous governing parameters, including the load eccentricity (e/B), the vertical distance of dual cavities from the ground surface (δ/B), the spacing between dual cavities (β/B), the uniaxial compressive strength of intact rock, ( σ ci /γB), geological strength index (GSI), and material constant for intact rock (mi) on the Ns are studied. The study finds that the magnitude of e/B significantly affects Ns. For symmetrical outline, Ns improves with increasing δ/B, and the effect of δ/B is insignificant when δ/B ≥ 3, corresponding to β/B = 4 irrespective of e/B. Moreover, Ns increases with β/B for δ/B ≤ 3 and e/B ≤ 0.2. However, the effect of β/B on Ns is insignificant beyond δ/B > 3, irrespective of e/B. For the parallel outline case, the strip footing achieves maximum Ns under centrally placed load (i.e., e/B = 0), regardless of β/B and δ/B values. The study presents potential failure envelopes that might include all representative cases to provide insights into the possible failure mechanism of such foundation systems. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of the dynamic responses of machine foundations, both block and pile foundations, on stratified residual soils in Duri and Ulubelu, Indonesia. The evaluation was conducted using two widely recognized methods: the lumped mass method (LMM) and the finite element method (FEM). LMM and FEM were performed by utilizing DYNA and ABAQUS, respectively. The analysis results showed that LMM generally predicted more conservative displacements compared to FEM. This conservatism in predicted displacement was more pronounced for pile group foundations, which are inherently more flexible than block foundations. Additionally, this study found that the resonance frequencies obtained through both analysis methods were not the same. Furthermore, this paper includes a parametric study and presents its results to assess the influence of key factors, i.e., pile cap thickness, pile diameter, number of piles, and vertical dynamic loads, on displacement. [ABSTRACT FROM AUTHOR]

To assess the sensitivity of impulse response testing to potential poor support zones or voids beneath the foundation slabs, numerical simulations were performed using the finite element method. These simulations covered a range of scenarios, including soil-loosening zones, sub-slab cavities, and slab cracks. The analysis of the simulation results employed two distinct techniques: the normalized acoustic response method and the ASTM C1740 mobility spectrum approach. These methods allowed the parameters and attributes derived from changes in input signals to be described in relation to the specifications within the synthetic models. [ABSTRACT FROM AUTHOR]

This study is focused on the effect of vibration induced by moving trains in tunnels on the surrounding ground and structures. A three-dimensional finite element model is established for a one-track railway tunnel and an adjacent twelve-storey building frame by using commercial software Midas GTS-NX (2019) and Midas Gen. This study considered the moving load effect of a complete train, which varies with space as well as with time. The effect of factors such as train speed, overburden pressure on the tunnel and variation in soil properties are studied in the time domain. As a result, the variations in horizontal and vertical acceleration for two different sites, i.e., the free ground surface (without structure) and the area containing the structure, are compared. Also, the displacement pattern of the raft foundation is plotted for different train velocities. At lower speeds, the heaving phenomenon is negligible, but as the speed increases, both the heaving and differential settlement increase in the foundation. This study demonstrates that the effect of moving train vibrations should be considered in the design of new nearby structures and proper ground improvement should be considered for existing structures. [ABSTRACT FROM AUTHOR]

With the slowdown of urban incremental construction in China, reinforcement and renovation of existing buildings have become a hot topic in the fields of engineering and theoretical research. Underpinning pile foundations and underground excavation are commonly used methods for foundation renovation and reinforcement in existing buildings reinforcement and renovation projects. Nevertheless, there remains a dearth of relevant research concerning the effects of different excavation methods on the stability of existing structures during foundation reinforcement and underground space excavation. In the context of existing building pile foundation underpinning and underground excavation, this paper adopts a numerical simulation research method based on the modification of experimental model parameters, and it compares the overall stress changes and settlement of the underpinning pile foundation and the building under two modes of lateral and vertical excavation. The results indicate that there is a good agreement between the stress and settlement changes of the components in the indoor model experiment and the finite element simulation. Both excavation methods show that lateral and vertical excavation will generate maximum stress on the bottom components of the upper structure and the upper part of the pile. In terms of differences, vertical excavation will cause greater overall settlement of the building, but the settlement in different areas is basically the same. On the other hand, lateral excavation will have smaller overall settlement but may cause the structure to tilt. At the same time, lateral excavation will cause greater stress changes in the columns in the structure. Based on these findings, relevant engineering suggestions are provided to choose different excavation methods and strengthen existing buildings. [ABSTRACT FROM AUTHOR]

In view of the complexity of the pile foundation underpinning structure system and the stringent requirements of the construction process, this paper briefly describes the necessity of introducing epoxy resin reinforcing adhesive of planting rebar in the design of pile foundation underpinning beam structure to improve the mechanical properties of the reinforced beam new and old concrete joint surfaces and proposes a new type of pile foundation replacement beam system construction method by "chiseling + prestressed reinforcement + epoxy resin reinforcing adhesive". This paper uses an actual pile foundation underpinning project of an urban overpass as a prototype, designs and creates a model structure with a similarity ratio of 1/6, and performs repeated progressive static loading tests to study the load carrying capacity, displacement change, and other properties of the strengthened replacement structure, as well as analyses and distorts the overall working performance and failure mode of them. On this basis, the prototype structure's finite element analysis model was built, and the finite element analysis results were compared with the test results to obtain the mechanical properties and deformation characters of the actual pile foundation underpinning structure system corresponding to the actual underpinning beam load. This paper's study can lay the theoretical and experimental foundation for the smooth development of similar projects. [ABSTRACT FROM AUTHOR]

In piled raft foundations, the bearing capacity is the result of the combination of the resistance of the pile group and the contribution of the contact between the pile cap and the soil. Although this contact contribution is still neglected, studies show that in certain cases, the load capacity directly absorbed by the pile cap can exceed the load absorbed by the pile group. Among the various factors that influence the behavior of piled raft foundations, the effect of contact geometry on the foundation has been inadequately researched. In this study, three-dimensional numerical analyses were conducted using the finite element method with the LCPC-CESAR software to investigate how pile cap–soil contact geometries affect the behavior of piled raft foundations. The net contact area, diameter, length, and number of piles were kept constant in all cases analyzed. Despite the complex interface of the LCPC-CESAR software, which hinders problem remodeling, validation securely demonstrated that this tool could replicate the behavior of piled raft foundations. The study results showed that, regardless of the spacing between the piles, the contact geometry does not affect the load–settlement curve of the system but significantly alters the distribution of loads among the foundation elements and the transfer of loads from the piles to the surrounding soil. When comparing pile cap geometries, it was observed that the square geometry supports a larger portion of the load compared to other geometries, likely due to better coverage of the pile inside the pile cap provided by this square configuration. [ABSTRACT FROM AUTHOR]

This paper used finite element modeling to evaluate the consolidation effect on the performance of existing rafts underpinned with micropiles under combined vertical and lateral loads. For this purpose, a real-life case study was discussed, in which micropile underpinning was used to stop the continuous tilt of a 13-floor residential building supported by a surface raft. It was found that the building tilted towards the northeast direction because of the consolidation of a deep soft clay layer under the northeast building corner. After discussing the as-built micropiling system, a 3D numerical model, developed using the PLAXIS software, was used to conduct the numerical research. The time-dependent behavior of the raft with and without the consideration of micropiles was assessed. Moreover, the variation of load-sharing ratios with time was investigated. The numerical results emphasize that the underpinning process was effective and reduced the final raft rotation and maximum settlement by 79.9% and 73.9%, respectively, compared to the case of the absence of micropiles. The consolidation process under a steady level of vertical loads enhanced the performance of the micropiled and unmicropiled rafts against upcoming lateral loads. The vertical load-sharing ratio increased during a life span of 20 years by 10.4% due to the consolidation process, but the increase was at a decreasing rate. Comparing all the four directions in which the lateral load was applied, the micropiles carried (57.4–76.6%) of the lateral load. [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]

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]

Urbanization and population concentration in China's major cities drive high land utilization demands, affecting nearby bridges during underground construction. Foundation pit construction alters the internal forces, deformation, and displacement of bridge piles. To understand these impacts and assess excavation support rationality, a case study was conducted on an ultra-deep foundation pit near an elevated ring road bridge in Wuhan. Considering the engineering geological conditions of the project site, construction sequence, and traffic load on the bridge, a three-dimensional finite element model was established to simulate the impact of foundation pit excavation on the elevated structure. And through an analysis of tracked monitoring data from the construction site, comparisons were also made with the simulation results. The findings of this case study indicated that throughout the entire construction phase of the foundation pit, the maximum horizontal and vertical displacements of the bridge foundation structure caused by the construction are 2.98 mm and −1.75 mm, respectively; the maximum change rate of the bending moment in the bridge structure due to the foundation pit construction is 6.3%, while the change in the axial forces is small, and completely within the safety control standards for bridge structure displacement. By analyzing the monitoring data over three stages within one year after the completion of the foundation pit, it is shown that the bridge structure gradually tends to stabilize. Additionally, due to soil consolidation, its displacement shows uniform rebound and tends to stabilize. The research findings provide valuable reference points for the design and construction of similar deep foundation pit projects. [ABSTRACT FROM AUTHOR]

Due to the limitations of planar mode wharfs, this paper proposes a new type of wharf—the three-dimensional cantilevered wharf. The proposed wharf is defined as an improvement of the traditional wharf, extending the traditional wharf upward and cantilevering out to the sea. The three-dimensional cantilevered wharf is a composite truss structure that meets structural and functional requirements. The composite truss structure is formed by connecting the beams of frame structures as a whole. The material consumption of the three-dimensional cantilevered wharf is decreased by controlling stresses and optimizing components. A finite element model of the proposed wharf, with a length of 200 m, width of 105 m, and cantilever length of 80 m, was established to analyze the basic mechanical performance. In this paper, the force distribution of the pile foundation, the vertical force transfer efficiency of web members, the structural stiffness, and the natural frequencies of the proposed wharf are analyzed. Tests regarding the stress and stiffness of different plane cantilever trusses are carried out, and finite element analysis is used for comparison. The test results show that the high-rise cantilever truss has a great in-plane stiffness and a reasonable component stress distribution. Additionally, the three-dimensional cantilevered wharf significantly improves the utilization efficiency of the wharf. [ABSTRACT FROM AUTHOR]

Engineers pay more and more attention to the economic benefits of foundation pit engineering. At present, the optimal design of the foundation pit supporting structure mainly focuses on strength and functional design, and there is no mature theoretical design method for deformation control. In this paper, a method for calculating the overall deformation of a foundation pit supporting structure based on the principle of minimum potential energy is proposed. Based on this method, the optimal design of the foundation pit of Guangzhou Baiyun District Comprehensive Transportation Hub Metro Station is realized. The deformation calculation results and optimization design scheme are validated by finite element numerical simulation and field monitoring data. The results show that the proposed theoretical algorithm predicts the pile deformation curves better than the finite element method, suggesting the proposed theoretical method is reasonable and the optimization scheme of the retaining pile is feasible. In the optimized design, the deformation of the foundation pit retaining pile is controlled by its push-back effect. The proposed deformation calculation method can realize the overall deformation calculation of the foundation pit supporting structure. [ABSTRACT FROM AUTHOR]

Nonlinear soil–pile–structure interaction (SPSI) phenomena are known to play a vital role in the response of bottom-fixed marine structures. For such structures, these phenomena are commonly considered by the imposition of p-y, τ-z, and q-z springs, representing the lateral and axial shaft and axial base soil resistances, respectively. The importance of each resistance mechanism depends on the type of foundation system, with only very limited studies investigating their roles in the response of piled marine structures, such as jetties. Within this context, this study presents numerical three-dimensional pushover analysis results for two marine jetties, a smaller model with four piles and a larger model supported by twenty-four piles. SPSI effects are considered through p-y, τ-z, and q-z springs, the behaviours of which are determined by following commonly employed procedures. The structures' responses are investigated under the influence of various assumptions regarding the behaviours of springs, as well as steel plasticity. The current investigation underscores the substantial influence of the axial soil–pile interaction on the response of the jetty, particularly in terms of its failure mode. Moreover, it demonstrates the importance of incorporating p-y springs, even though the choice between their linear or nonlinear constitutive behaviour is found to be less critical. Finally, the study concludes that the behaviours of the springs significantly affect the system's ductility and the degree of steel yielding in the piles, while also highlighting the unconservative influence of neglecting SPSI phenomena. [ABSTRACT FROM AUTHOR]

This paper examines the effects of soil–structure and structure–soil–structure interactions in the design of foundations for adjacent concrete buildings, which are located on soft soils. The study employs an elasto-plastic model through static (quasi-dynamic) analysis using the direct finite element method by applying earthquake loads in one time step. Two concrete buildings, one with 6 stories and another with 12 stories, were modelled and numerically analysed using ANSYS. The foundations of these two buildings were analysed separately and compared when they were assumed to be adjacent to each other. The designs of the buildings' foundations were evaluated independently and in comparison with each other to determine the impact of these interactions. The results indicated that accounting for the effects of both interactions increases the total deformation of the foundations. Additionally, the study found that adjusting the subgrade reaction modulus values (Ks) for different sections of the foundation can be a practical method to address both interaction effects simultaneously. This method also optimizes the weight of reinforcement material (Wr) by reducing it by 15% and modifying the positions and quantities of reinforcements used and considering various subgrade reaction modulus values in foundation design. [ABSTRACT FROM AUTHOR]

Composite plate shear walls/concrete-filled (C-PSW/CFs), also known as SpeedCore systems, are a relatively new structural member in American codes and standards. Prior research has focused primarily on C-PSW/CF walls with either flange/closure plates or filled composite members as boundary elements. Walls without boundary elements have also been studied, but they are no longer permitted by the American Institute of Steel Construction (AISC 341-22). The reason is that composite walls without boundary elements do not provide adequate ductility for seismic design. This paper presents the results of experimental and numerical studies conducted to evaluate the cyclic lateral load behavior of C-PSW/CFs using hot-rolled structural steel members as boundary elements. The steel web plates of the C-PSW/CF specimens were connected to each other using threaded tie bars with double nut connections. Composite interaction between the steel and concrete infill was achieved using the tie bars and additional shear studs welded to the boundary elements. The composite walls were embedded and anchored to reinforced concrete foundation blocks using welded deformed bar anchors. The experimental investigations focused on the cyclic lateral load-drift responses including test observations and limit states, moment-rotation response of the plastic hinge and the section moment-curvature relationship, overall lateral stiffness, strength, and displacement ductility. The experimental results show that the specimens exceeded their nominal flexural capacities calculated using the plastic stress distribution method or fiber-based section modeling using measured material properties. The specimens had plastic hinge rotation capacity greater than 0.028 rad. and displacement ductility ratio greater than 5.2. Detailed 3D nonlinear inelastic finite element models and simpler fiber-based macro models of the tested specimens were developed and benchmarked using experimental results. The detailed 3D finite element models can reasonably simulate the global and local behavior of the specimens, and are recommended for conducting further parametric studies of composite wall design details. Simpler fiber-based macro models can efficiently simulate the cyclic lateral load behavior of the specimens, and are recommended for modeling C-PSW/CFs while simulating the behavior of multi-story building structures. [ABSTRACT FROM AUTHOR]

When significant deformation occurs in a foundation pit, it is critical to have an accurate method for predicting this deformation. This is necessary for enacting timely safety measures. Unfortunately, finite element simulations, which are strongly aff ected by soil parameters, fail to reflect the dynamic deformation of foundation pits during excavation. To address this, we used the actual soil parameters of a deep foundation pit to design 64 representative combinations of soil parameters through orthogonal testing. Using a three-dimensional (3D) finite element model of the foundation pit, we obtained displacement values for each parameter combination. These included the maximum horizontal displacement of the support structure and the surface settlement value. Subsequently, we developed a backpropagation (BP) neural network model. We trained this model using the soil parameters of each combination as input and the deformation values obtained from the 3D finite element model as output. Once the model was trained, we inverted the soil parameters, reflecting the dynamic deformation of the foundation pit by using actual monitoring data. This process allowed us to obtain the deformation data for the next excavation stage. Results showed that the soil parameters obtained via the BP neural network model eff ectively reflected the stress state of the deep foundation pit. Moreover, the prediction of the foundation pit deformation aligned well with the monitoring data, which validates the accuracy and feasibility of our method. [ABSTRACT FROM AUTHOR]

Existing projects indicate that a large number of pile boreholes formed via cement fly ash gravel (CFG) pile construction in soft soil could produce a borehole group effect in the absence of timely backfilling. The borehole group effect could cause ground settlement and threaten the safety of adjacent buildings, tunnels, and pipelines. However, the mechanism of the borehole group effect, causing serious deformation in surrounding soil, has seldom been studied, and there exists no simple simulation method to predict the borehole group effect. In this study, a case involving CFG pile boreholes in a soft soil area causing a significant settlement of surrounding buildings was introduced. Based on this case, a centrifuge test was designed to simulate the influence of a single borehole and multiple boreholes on the surrounding soft soil. The mechanism of the borehole group effect was investigated via centrifuge tests and the finite-element method. In the case of a single borehole, a horizontal circumferential stress arch and vertical stress transfer arch were formed in the soil, which effectively limited the shrinking deformation of the borehole wall. In the case of a large number of boreholes with a small spacing, the horizontal and vertical stress arches around the boreholes affected and weakened each other. As a result, the shrinking deformation of the borehole group was greater than that of the single borehole. In other words, the borehole group effect was found to cause serious deformation in the surrounding soil. To overcome the difficulty in the simulation of a large number of pile boreholes in engineering, the borehole-type conversion and multihole merging method was proposed. The simulation results indicated that the simplified method was reasonable. [ABSTRACT FROM AUTHOR]

With the increasing utilization of urban underground space in densely populated cities, it is crucial to understand the interactive impact of the excavation sequence on the excavation group of foundation pits. The foundation pit of Tianta Station of Tianjin Metro Line 7 was adjacent to a deep foundation pit of an apartment, which provided a good case for the study of simultaneous excavation of foundation pits. In this paper, based on two deep foundation pit excavation projects, a finite element model was established to better understand the mutual influence of simultaneous foundation pit excavation. The responses of the two deep foundation pits under five different excavation sequences were investigated, including the horizontal displacement of the ground‐connected wall and the displacement of the top of the wall, the settlement of the ground surface, and the supporting axial force of the basement floor slab. The position of the maximum horizontal displacement in different modes is the same, and the shape of the deformation curve was fish‐bellied. When both pits B and C were excavated simultaneously, the surface settlement between adjacent pits was smaller than in other working conditions. Mode 5 is optimal among these five modes, in which not only the construction progress is the fastest but also the underground wall deformation and the ground settlement are relatively small. The findings and lessons learned from these two adjacent pits, both of which were constructed using the cap‐and‐reverse method, can help professionals optimize excavation design and construction, as well as performance prediction and control. [ABSTRACT FROM AUTHOR]

The ongoing refinement of bearing capacity equations remains pivotal in soil mechanics and foundation engineering, reflecting its critical role in ensuring design efficacy and construction safety. This study conducts a thorough evaluation of classical bearing capacity methods—Terzaghi, Meyerhof, Vesic, and Hansen—and methods included in various design standards, such as EN1997:2004, prEN1997:2023, GEO, AASHTO, FHWA, and API. It explores the performance and applicability of these approaches, identifying areas for potential improvement. In response to identified challenges, the paper proposes the integration of a unified depth factor. This new factor is designed to be applicable across all N-terms, providing a more versatile and accurate tool for bearing capacity predictions. Unlike the original depth factors unique to each method, which may not fully address complex soil and footing conditions, the unified depth factor is developed to enhance prediction accuracy for a wide range of conditions, including both flexible and rigid footings under varying flow rules (ψ = 0 and ψ = φ). This depth factor corrects for modeling errors, emphasizing the importance of pairing the correct set of N-factors with their corresponding depth factor. By offering a singular depth factor that aligns with the outcomes of finite element analysis, this paper not only simplifies the computational process but also enhances the accuracy of bearing capacity predictions across a diverse range of soil conditions and footing types. The comparative analysis, based on finite element analysis, validates the proposed method's effectiveness, showcasing its potential to significantly refine foundation design practices by comparing it with both traditional and newly developed depth factors. [ABSTRACT FROM AUTHOR]

This paper aims to analyze and describe the geotechnical behavior of a piled raft foundation of a tall building (53 floors, 172.4 m high) through the monitoring of strains in the building's columns and piles, the stresses at the raft–soil interface, and the foundation settlements. Field and laboratory tests were performed, and associated with axisymmetric and three-dimensional finite element analysis to the assessment of the measured data. The monitoring of the pile strains suggests the occurrence of soil expansion, caused by the raft excavation process, up to approximately 6 months after the excavation was completed. The presence of different soil profiles under the raft, with different mechanical properties, affected the distribution of the foundation settlements and the pile loads. Initially, the average pile loads were concentrated in the perimeter elements, but, as the construction of the building evolved, they tended to become more uniform. The effect of the superstructure stiffness caused successive load redistributions in the columns, which contributed to the maintenance of the maximum angular distortion of the building within the allowable values and reduced the load difference between the piles positioned in opposite soil profiles. [ABSTRACT FROM AUTHOR]

In response to land use challenges, major urban centers have started implementing over-track building constructions above metro lines as a means of accommodating residents and workers. However, the continuous operation of trains can generate excessive vibrations that may negatively impact the overall living conditions for occupants residing in these structures. In this paper, vibration measurements were conducted on the soil and within a three-story frame structure building. Additionally, a three-dimensional finite element model of the track–soil–building was established. The wheel–rail contact force was incorporated as a dynamic load that varies with time to accurately simulate the vibration response induced by trains. According to the construction process of the over-track building, four construction stages were set up using the finite element model to study the impact of the construction stages on the vibration propagation from the soil to building structure. The results indicate that the presence of existing structures exerts a mitigating influence on soil vibrations. Pile foundation construction can effectively mitigate soil vibration to a significant extent. The findings provide references for the future development and design of over-track buildings. [ABSTRACT FROM AUTHOR]

Application of systems for passive vibration control is an efficient way for seismic protection of structures. Systems for passive vibration control consist of seismic isolation devices and energy dissipation devices. Base isolation of structures is a concept where devices for passive vibration control are placed in foundations of buildings. Various energy dissipation devices have been developed and tested so far, while metallic dampers represent a significant class. Those devices dissipate energy through the yield of metal material which they are made of. The metallic dampers have often been used because of their main advantages reflected in stable hysteretic behavior and well-known models for analytical prediction of the dissipated energy and structural response. Most of the metallic dampers have been developed for application in the beam-column joints or in the bracing system. The innovative energy dissipation device named multi-gap multi-level multi-directional seismic energy absorber, intended for the application in the horizontal seismic dilatation in the system of base isolation, has been developed recently by the group of the authors among whom is one of the authors of this paper. The main parts of the absorber are vertical components with linearly changeable circular cross-section. Due to the lateral displacements of the isolated structure the vertical components bend and energy dissipation is provided by yielding of the steel material they are made of. According to the previous experimental and numerical study of the absorber's vertical components, three-dimensional finite element model of the absorber has been developed and presented in this paper. The aim of the numerical analysis is to determine mechanical properties of the absorber based on the lateral force-displacement diagram. Furthermore, a simplified numerical model using one-dimensional beam finite elements has been proposed. The performance of the absorber has been determined using the available semianalytical solution for elastoplastic deflection of non-prismatic cantilever beams previously developed by the first author as well. The obtained results have been compared and it has been concluded that all three modelling approaches provide reliable mechanical properties of the absorber necessary for dynamic analysis of structures in engineering practice. [ABSTRACT FROM AUTHOR]

In order to reduce the influence of underground space development on the surrounding environment, deformation of supports should be strictly controlled in the construction of deep foundation pits in soft soil area. Based on the excavation of a deep foundation pit in the soft soil area of the Changjiang River floodplain, typical stress path tests considering the foundation pit's excavation process were carried out for undisturbed soil samples. The law of stress deformation of soil during excavation is analyzed, and the calculation parameters of Ohta-Sekiguchi constitutive model are determined. A three-dimensional finite element model that takes into account the construction process is built to numerically simulate of the bottom-up construction method, the top -down construction method and the integration of bottom -up and top -down construction method. The displacement of the foundation pit cut with the method integrating bottom-up and top-down construction is analyzed, and the calculated deformation of the supporting structure and the foundation pit soil with the method integrating bottom-up and top down construction is compared to the observed values. The influence of the three different construction methods on the horizontal displacement of diaphragm walls, deformation and displacement of soil around the foundation pit and the constructionduration is analyzed and compared. Compared with the bottom-up construction method and the top-down construction method,the integration of bottom-up and top-down construction method can control the deformation of a foundation pit in the soft soilarea of the Changjiang River floodplain, and has the advantage of construction period and cost. [ABSTRACT FROM AUTHOR]

Building foundations using pile groups generally assume that the piles absorb the entire load of the structure. However, it is known that pile caps rest not only on the piles but also on the surrounding soil. These foundations involve great complexity in the phenomenon of load sharing, especially when they are situated on unconventional soils, such as tropical climate soils. To study this behavior, static load tests were conducted on real foundations. These tests were also used to calibrate a three-dimensional finite element numerical model (FEA-3D) using Rocscience's RS3 software. The results showed that the settlement corresponding to the allowable load of the pile groups was significantly lower, ranging from 22 % to 73 %, compared to pile caps that exert contact pressure on the soil. For pile groups, the efficiency ranged between 92 % and 109 %, while for pile caps with contact, it ranged from 132 % to 178 %. In this sense, it becomes evident that estimating the settlement of the pile group based on the conventional design, which does not consider the contact between the cap and the soil, can significantly underestimate the settlement, and provide an overly optimistic analysis of the soil-structure interaction. ● The main contribution of this article lies in the experimental soil and numerical analyses of the peculiarities of piled foundations behavior in unconventional conditions, highlighting the differences between the conception of these foundations in design and their effective performance as supporting elements for the structure. ● It was found that the piles played a role in reducing the load transmitted by the raft to the subsoil, resulting in a decrease in the overall stiffness of the raft. ● This indicates that the majority of the load is supported by the piles, and subsequently, the proportion of the load on the raft increases. ● These findings experimentally corroborate results made by other works. [ABSTRACT FROM AUTHOR]

The foundations of particular engineering structures, including marine and jetty structures, mooring systems for submerged platforms or those on the ocean surface, and transmission towers, are subjected to various external loads including compression, uplift, and lateral loads. In such cases, to improve the soil resistance below foundations, pile foundations such as helical piles, anchored piles, and batter piles are commonly preferred, depending on the in situ conditions. Helical piles, increasingly used as an alternative foundation to conventional piles, are placed in the soil body by rotating with torque. This paper deals with the contribution of a helical pile in improving loose sandy soil, and the main purpose is to study the effect of the helix-buried depth on the load-bearing capacity and failure mechanism. The investigated variables include the distance between helixes, the number of helixes, and the diameter of the upper helix. Physical model tests were conducted, and two- and three-dimensional numerical analyses were performed by using the finite element method with an advanced soil model to illustrate the failure mechanisms of helical piles. The aim was to reveal the efficiency of the finite element method in modelling helical piles placed in weak sandy soil. A simplified linear geometry for helixes was established in a two-dimensional finite element model whereas a real geometry for helixes, which was a more realistic approach, was created in a three-dimensional finite element model. The results show that the three-dimensional model indicates better agreement with the physical model compared to the two-dimensional model, and all investigated variables highly affect the load-bearing capacity of helical piles. [ABSTRACT FROM AUTHOR]

In recent years, the detection of offshore pile foundations has received wide attention in engineering. Compared with traditional methods, the O-cell test has unique advantages in offshore pile foundation detection. To study the load transfer characteristics of the O-cell method for pile testing in coastal soft soil foundation, this paper established the pile–soil numerical model to simulate the O-cell and traditional testing processes. The finite element method and equal displacement method are combined to calculate the conversion coefficient and ultimate bearing capacity, and the distribution forms of axial force, side friction resistance, and tip resistance are discussed. The research results show that the O-cell test method and the traditional method have different load transfer forms. By introducing the equal displacement method into the O-cell pile–soil model, the error between the equivalent conversion ultimate bearing capacity and the calculation result of the surcharge method is less than 0.5%, and the O-cell conversion coefficient can be accurately calculated. [ABSTRACT FROM AUTHOR]

The advantages of the piled raft foundations system over conventional pile group foundations have been demonstrated in previous studies. In a pile raft foundation, the raft load capacity is extensively investigated in level ground conditions; its behaviour in a soil slope is limited. In the present study, three-dimensional finite element analyses using PLAXIS 3D software were performed to examine the effect of the soil slope on the lateral response of the piled raft foundation. The study showed that the lateral capacity of piled raft foundations decreases when installed within a certain distance (less than 8 times the pile diameter) from a slope. Furthermore, the enormous effect of slope occurs at distances nearer than 4D. Despite a decrease in lateral capacity when installed near slopes, the effect on the piles is insignificant, especially the rear piles. As a result, the distance between the piled raft foundations and the slope is a key factor that needs to be considered to improve design guidance to reduce construction costs. [ABSTRACT FROM AUTHOR]

This study examines the performance of mat foundations in 13 blocks of eight-story concrete-walled residential buildings. Topographic monitoring bolts were used to monitor the slab's construction, which was 0.35 m thick and comprised an area of 225 m2. Using the collected data, a retro-analysis of the modulus of elasticity was conducted to obtain the geotechnical parameters for forecasting the settlement using the elasticity theory. A nonlinear approach for construction modeling and soil–structure interactions showed that the earthworks at the start of construction had a significant role in settling. Blocks in landfills settled faster than those in land-cut zones. The partial execution of building levels was found to be critical in terms of angular distortions and stresses in the concrete slab. The partial lifting of the foundation plate was confirmed in blocks with partial building floor execution, demonstrating the importance of assessing the foundation's behavior at this stage. The modulus of elasticity dropped as construction progressed, with landfill parts being particularly vulnerable. Creep settlements contributed significantly, accounting for about 20% of the total settlements in some blocks. The numerical staged construction model accurately replicated the behaviors observed in the monitoring data, confirming the hypothesis of the partial raising of the foundation during the building process, which resulted in higher angular distortions. Based on the results obtained, the authors strongly recommend that the simultaneous consideration of soil–structure interactions and construction effects be commonly used in foundation designs. [ABSTRACT FROM AUTHOR]

This work uses the Yematan Bridge as an example to explore the seismic damage mechanism of simply supported girder bridges at near‐fault liquefaction site. It analyzes the bridge from the local portion to the complete bridge, considering the effects of the near‐fault and liquefied soil layers. First, a three‐dimensional model of the pile‐soil seismic action of Pier No.17 was created using simulated near‐field ground motion, and analysis was performed to simulate the action of the liquefied soil layers on the pile foundation, getting pile‐soil dynamic p‐y curves. After that, the accuracy of the pile spring parameters was verification by doing an equivalent static analysis. Finally, to identify the seismic damage mechanism of high‐damping rubber (HDR) bearings and the dynamic unseating process of the Yematan Bridge, a finite element model of the complete bridge was developed. During this procedure, the near‐field ground motion amplitude and soil spring parameters were iterated and optimized continually, such that the simulated earthquake damage was identical to the real one. The findings suggest that the bridge was destroyed by significant structural vibration. The near‐fault impulse effect and lack of equivalent limiting measures induced the entire collapsing girders to move consistently and destroyed the HDR bearings. Liquefied soil can cause some damage to pile foundations, and lateral spreading can cause the piers of the same span to perform differently. [ABSTRACT FROM AUTHOR]

Background: The estimation of the natural frequency is a key step in the design of an offshore wind turbine (OWT). In the literature, the natural frequency can be evaluated through two steps, the first one is the estimation of the fixed base natural frequency using formulas from the literature, and the second one is the estimation of the foundation system effect. These formulas are efficient for simple shapes of OWTs but become hard to use for recent OWTs. Method: The finite element method and the Fourier series have been used to develop a computer code under the name of "TurbiSoft" to compute the natural frequency of the OWT with the foundation system. Each of the linear, the quadratic volume elements, and the joint element was employed in TurbiSoft to model the whole system to examine the influence of the element type, the soil profile, and the interaction soil–pile state on the natural frequency. Results: The outcomes of TurbiSoft for several OWTs were compared with the measured frequencies to define the range error of each parameter. The results show that the quadratic elements are more suitable for the natural frequency calculation. Also, this study demonstrates that the natural frequency value is strongly related to the interaction soil–pile state, and is slightly affected by the soil profile variation. [ABSTRACT FROM AUTHOR]

To investigate the pipeline deformation pattern caused by the excavation of deep foundation pits in composite soil–rock strata, a comprehensive study integrating on-site monitoring and numerical simulation was conducted. This study centered on a deep foundation excavation project in the soft soil in Nanjing's floodplain region. The analyses of pipeline settlement and deformation were performed based on field-measured data. This study investigated the impact of excavation on the mechanical properties of the surrounding soil that resulted in the progressive deformation of adjacent pipelines. Furthermore, numerical simulations were conducted using Plaxis 3D CONNECT Edition v22 finite element analysis software. This study elucidated the influence of factors such as pipeline–pit distance and burial depth on pipeline deformation, conducting a quantitative analysis of their effects. The results indicated that deformation primarily occurs unevenly near pit corners and is less pronounced in soil–rock strata than in single-type soil layers. This study established correlations between pipeline displacements and various factors, offering valuable insights for future excavation projects conducted under similar conditions. [ABSTRACT FROM AUTHOR]

Pile-soil interaction is one of the most critical factors in evaluating foundations' static and seismic responses. During an earthquake, piles can become subject to stress caused by the surrounding soil and structure movement. To design a suitable seismic pile foundation, in addition to considering the effect of the structure on the pile (inertial interaction), the impact of the soil that applies to the pile (kinematic interaction) must be considered. Therefore, dynamic analysis of piles simultaneously exposed to both vertical and horizontal loads is one of the most essential subjects in geotechnical engineering. The present study evaluated various approaches proposed in the literature to determine the inertial and kinematic loads applied to the pile. Also, based on the results of the centrifuge test, the best method that could correctly predict the combined effect of these two loads on the pile response was presented. The results indicated that precise determination of the maximum lateral force exerted on the pile-soil-superstructure system plays a crucial role in the reliability of the theoretical methods employed to calculate the maximum bending moment of the pile. Also, if the appropriate theoretical approach is used, the accuracy can be similar to the 3D finite element analysis results. [ABSTRACT FROM AUTHOR]

In recent years, double-wall steel boxed cofferdams with bottom structures have been applied in the construction of deepwater caps for bridges. However, their mechanical properties are affected by many factors. To elucidate the mechanics influencing such double-wall steel boxed cofferdam configurations, an analytical and computational model was proposed. Through the three-dimensional finite element software midas civil, calculations and analyses were executed on a steel boxed cofferdam design example from the 10# pier pile foundation of the Xinjiang Kalasuke Reservoir's extra-large bridge and its platform construction. The alterations in mechanical states triggered by adjustments to the influential parameters, such as wall plate thickness, water injection height between double walls, and support rod spacing within the double walls of the steel boxed cofferdam, were discussed. Results show that, the optimal wall thickness for this cofferdam variant is between 5 and 6 mm, the controllable water injection height ranges from 3.4 m to 4.5 m, and consistently low-stress states occur across the bottom skeleton, secondary beam, and bottom plate throughout the construction process. The spacing between double-wall horizontal components greatly influences the stress and deformation of the inner and outer wall plates. The obtained conclusions provide a significantly reference value for the design theory and practical application of doublewall steel boxed cofferdam structures. [ABSTRACT FROM AUTHOR]

As urbanization accelerates, deep excavation projects have become increasingly vital in the construction of high-rise buildings and underground facilities. However, the potential risks to the surrounding environment and the inherent complexities involved necessitate thorough research to ensure the safety of those engineering projects with deep foundation pit excavation and to minimize their impact on adjacent structures. This study introduces a multi-stage and multi-parameter numerical simulation method to scrutinize the construction process of deep foundation pits. This approach not only investigates the influence of excavation activities on nearby buildings and roads but also enhances the fidelity of simulation models by establishing a three-dimensional finite element model integrated with on-site investigated geological information. Therefore, the proposed method can provide a more holistic and accurate analysis of the overall impacts of the pit excavation process. To examine the feasibility and effectiveness of the proposed method, this study adopts the multi-stage and multi-parameter influence analysis approach for a real practical engineering case to explore the impact of excavation on the foundation pit support structure, nearby buildings, and surrounding roads. The foundation pit support's maximum displacement was 8.64 mm, well under the 25 mm standard limit. Anchor rod forces were about 10% below the standard limit. Building and road settlements were also minimal, at 10.33 mm and 16.44 mm, respectively, far below their respective limits of 200 mm and 300 mm. This study not only validates the feasibility of design and construction stability of deep foundation pits but also contributes theoretical and practical insights, serving as a valuable reference for future engineering projects of a similar scope. [ABSTRACT FROM AUTHOR]

It is important to predict the future behavior of historic buildings to avoid potential problems. Wat Khao Sukim Pagoda is situated on a hill slope and has different types of foundations. These foundations include both shallow and pile foundations representing different stages of construction and having different loadings. Although the structure meets the design criteria for the current loading, in the future overloading may occur. Therefore, an analysis of additional loading was undertaken using the 3D finite element method (FEM). In particular, the effects of differential settlement and its mitigation were investigated. Changes in the groundwater level were simulated after major rain events and compared to dry conditions. Overall, the concept of staged construction (preloading) is a useful technique to minimize the risk of differential settlement associated with different types of foundations. In addition, the current results showed that the average differential settlement value at each stage was lower than in previous work. Furthermore, the new model reduced the differential settlement value by more than 50%. These results showed that the concept of preloading can better solve the differential settlement problem in this type of construction. The PLAXIS 3D model showed that the groundwater level increase did not affect Pagoda settlement, indicating that the Pagoda was stable and could withstand a large load without undergoing any major structural deformations and that it was suitable structurally for a variety of applications, even in wet conditions. [ABSTRACT FROM AUTHOR]

Major structures like offshore platforms, wind turbines, transport infrastructure, tall buildings, etc., resting on soft compressible clays, are often supported by pile foundations. Apart from usual vertical loading (dead load, live load, etc.), these piles are subjected to significant cyclic loads arising from actions of waves, ship impacts, winds or moving vehicles. Under such circumstances, the lateral mode of cyclic loading is predominant and affects the overall foundation stability. Such repetitive loading leads to stress reversal in adjacent soft clay initiating progressive degradation in soil strength and stiffness, deteriorating the pile capacity with unacceptable displacements. Although several past studies investigated the response of single pile under lateral cyclic loading, a detailed investigation on pile group in clay subjected to cyclic lateral loading, which is of immense practical interest to field engineers, is yet to be carried out. In this paper, in-depth study has been carried out by developing a three-dimensional dynamic finite element model. Comparison of the computed results with available test data validates the numerical model. Extensive parametric studies with field data indicate that both the axial and lateral pile capacities and displacements have been significantly influenced by the cyclic loading parameters. Relevant design curves are also constructed. [ABSTRACT FROM AUTHOR]