The interface mechanical behavior of a monopile is an important component of the overall offshore wind turbine structure design.Understanding the soil-structure interaction,particularly the initial soil-structure stif...The interface mechanical behavior of a monopile is an important component of the overall offshore wind turbine structure design.Understanding the soil-structure interaction,particularly the initial soil-structure stiffness,has a significant impact on the study of natural frequency and dynamic response of the monopile.In this paper,a simplified method for estimating the interface mechanical behavior of monopiles under initial lateral loads is proposed.Depending on the principle of minimum potential energy and virtual work theory,the functions of soil reaction components at the interface of monopiles are derived;MATLAB programming has been used to simplify the functions of the initial stiffness by fitting a large number of examples;then the functions are validated against the field test data and FDM results.This method can modify the modulus of the subgrade reaction in the p-y curve method for the monopile-supported offshore wind turbine system.展开更多
The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plas...The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and considerable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.展开更多
In this paper, the studies on soil-pile interaction behaviors in saturated sands under static, dynamic and cyclic lateral loads by model testing are described. By comparing with the field test results for piles in sof...In this paper, the studies on soil-pile interaction behaviors in saturated sands under static, dynamic and cyclic lateral loads by model testing are described. By comparing with the field test results for piles in soft sandy clay, a formula of p-y curves based on constitutive relationship of soils applicable for both sandy and soft clays is proposed. Good agreements are obtained in comparison with the field test results performed by other investigators abroad. A p-y hysteresis curve formula based on the modified Masing's doubling criterion is also proposed, and the results are in satisfactory agreement with field test results.展开更多
In this paper, several mathmatical models for the pile- soil interaction are outlined. The Boundary Element Method is one of the very effective methods for the reasonable models of elasticity and elastoplasticity. The...In this paper, several mathmatical models for the pile- soil interaction are outlined. The Boundary Element Method is one of the very effective methods for the reasonable models of elasticity and elastoplasticity. The major of this paper is concerned with the Boundary Element Method for the pile-soil interaction, including general methods and calculating formulation of static and dynamic analysis of the pile and pile groups. Some results of analysis are also given.展开更多
This paper describes a shake table test study on the seismic response of low-cap pile groups and a bridge structure in liquefiable ground. The soil profile, contained in a large-scale laminar shear box, consisted of a...This paper describes a shake table test study on the seismic response of low-cap pile groups and a bridge structure in liquefiable ground. The soil profile, contained in a large-scale laminar shear box, consisted of a horizontally saturated sand layer overlaid with a silty clay layer, with the simulated low-cap pile groups embedded. The container was excited in three E1 Centro earthquake events of different levels. Test results indicate that excessive pore pressure （EPP） during slight shaking only slightly accumulated, and the accumulation mainly occurred during strong shaking. The EPP was gradually enhanced as the amplitude and duration of the input acceleration increased. The acceleration response of the sand was remarkably influenced by soil liquefaction. As soil liquefaction occurred, the peak sand displacement gradually lagged behind the input acceleration; meanwhile, the sand displacement exhibited an increasing effect on the bending moment of the pile, and acceleration responses of the pile and the sand layer gradually changed from decreasing to increasing in the vertical direction from the bottom to the top. A jump variation of the bending moment on the pile was observed near the soil interface in all three input earthquake events. It is thought that the shake table tests could provide the groundwork for further seismic performance studies of low-cap pile groups used in bridges located on liquefiable groun.展开更多
An investigation of soil-pile-structure interaction is carried out, based on a large reciprocating compressor installed on an elevated concrete foundation （table top structure）. A practical method is described for t...An investigation of soil-pile-structure interaction is carried out, based on a large reciprocating compressor installed on an elevated concrete foundation （table top structure）. A practical method is described for the dynamic analysis, and compared with a 3D finite element （FE） model. Two commercial software packages are used for dynamic analysis considering the soilpile-structure interaction （SPSI）. Stiffness and damping of the pile foundation are generated from a computer program, and then input into the FE model. To examine the SPSI thoroughly, three cases for the soil, piles and superstructure are considered and compared. In the first case, the interaction is fully taken into account, that is, both the superstructure and soil-pile system are flexible. In the second case, the superstructure is flexible but fixed to a rigid base, with no deformation in the base （no SSI）. In the third case, the dynamic soil-pile interaction is taken into account, but the table top structure is assumed to be rigid. From the comparison beteen the results of these three cases some conclusions are made, which could be helpful for engineering practice.展开更多
Traditionally seismic design of structures supported on piled raft foundation is performed by considering fixed base conditions, while the pile head is also considered to be fixed for the design of the pile foundation...Traditionally seismic design of structures supported on piled raft foundation is performed by considering fixed base conditions, while the pile head is also considered to be fixed for the design of the pile foundation. Major drawback of this assumption is that it cannot capture soil-foundation-structure interaction due to flexibility of soil or the inertial interaction involving heavy foundation masses. Previous studies on this subject addressed mainly the intricacy in modelling of dynamic soil structure interaction (DSSI) but not the implication of such interaction on the distribution of forces at various elements of the pile foundation and supported structure. A recent numerical study by the authors showed significant change in response at different elements of the piled raft supported structure when DSSI effects are considered. The present study is a limited attempt in this direction, and it examines such observations through shake table tests. The effect of DSSI is examined by comparing dynamic responses from fixed base scaled down model structures and the overall systems. This study indicates the possibility of significant underestimation in design forces for both the column and pile if designed under fixed base assumption. Such underestimation in the design forces may have serious implication in the design of a foundation or structural element.展开更多
The seismic behavior of tall buildings can he greatly affected by non-linear soil-pile interaction during strong earthquakes.In this study a 20-storey building is examined as a typical structure supported on a pile fo...The seismic behavior of tall buildings can he greatly affected by non-linear soil-pile interaction during strong earthquakes.In this study a 20-storey building is examined as a typical structure supported on a pile foundation for different conditions:(1) rigid base,i.e.no deformation in the foundation:(2) linear soil-pile system;and (3) nonlinear soil-pile system. The effects of pile foundation displacements on the behavior of tall building are investigated,and compared with the behavior of buildings supported on shallow foundation.With a model of non-reflective boundary between the near field and far field, Novak's method of soil-pile interaction is improved.The computation method for vibration of pile foundations and DYNAN computer program are introduced comprehensively.A series of dynamic experiments have been done on full-scale piles, including single pile and group,linear vibration and nonlinear vibration,to verify the validity of boundary zone model.展开更多
This paper is an attempt to solve the soil-pile interaction problems using the boundary element method（BEM）.A computer package called PGroupN,which deals mainly with the analysis of the pile group problem,is employe...This paper is an attempt to solve the soil-pile interaction problems using the boundary element method（BEM）.A computer package called PGroupN,which deals mainly with the analysis of the pile group problem,is employed in this study.Parametric studies are carried out to assess the impacts of the pile diameter,pile length,ratio of spacing to diameter and the thickness of soil stratum.The external load is applied incrementally and,at each increment,a check is made that the stress state at the pile-soil interfaces does not violate the yield criteria.This is achieved by specifying the limited stresses of the soil for the axial pile shaft capacity and end-bearing resistance.The elements of the pile-soil interface yielded can take no additional load,and any increase in load is therefore redistributed between the remaining elements until all elements have failed.Thus,by successive application of loading increments,the entire load-displacement relationship for the pile group is determined.It is found that as the applied load reaches the ultimate bearing capacity of the pile group,all the piles will share the same amount of load.An exception to this case is for the center pile in a group of 9 piles embedded in clay,which is not consistent with the behaviors of the other piles in the group even if the load reaches the ultimate state.For the 4 piles group embedded in clay,the maximum load carried by the base does not exceed 8% of the load carried by each pile with different diameters.This low percentage ascertains that the piles embedded in cohesive soils carry most of the load throughout their shafts.展开更多
The success of the tuned mass damper (TMD) in reducing wind-induced structural vibrations has been well established. However, from most of the recent numerical studies, it appears that for a structure situated on very...The success of the tuned mass damper (TMD) in reducing wind-induced structural vibrations has been well established. However, from most of the recent numerical studies, it appears that for a structure situated on very soft soil, soil-structure interaction (SSI) could render a damper on the structure totally ineffective. In order to experimentally verify the SSI effect on the seismic performance of TMD, a series of shaking table model tests have been conducted and the results are presented in this paper. It has been shown that the TMD is not as effective in controlling the seismic responses of structures built on soft soil sites due to the SSI effect. Some test results also show that a TMD device might have a negative impact if the SSI effect is neglected and the structure is built on a soft soil site. For structures constructed on a soil foundation, this research verifies that the SSI effect must be carefully understood before a TMD control system is designed to determine if the control is necessary and if the SSI effect must be considered when choosing the optimal parameters of the TMD device.展开更多
This paper proposes an optimum design model for the offshore jacket platform considering multidesign criteria, multi-design constraints and the structure-pile-soil interaction, and gives an optimum design procedure in...This paper proposes an optimum design model for the offshore jacket platform considering multidesign criteria, multi-design constraints and the structure-pile-soil interaction, and gives an optimum design procedure in which the proposed optimum design model is used together with structural analysis software SAP91 and optimum algorithm software OPB1. The Chengbei (#)11 offshore platform, which lies in the Shengli oilfield, is designed by use of the above optimum design model. The results show that the optimum design model is stable, and it depends on neither the optimization algorithm nor initial values of design variables. All values of the objective function converge to the same minimum value, and the speed of convergence is high, showing that the proposed optimum design model is reasonable.展开更多
A rigorous analytical method is presented, which takes into account the pile stiffening effects, using the theory of the transfer matrix-bottom rigidity for calculating the interaction factor between two identical pil...A rigorous analytical method is presented, which takes into account the pile stiffening effects, using the theory of the transfer matrix-bottom rigidity for calculating the interaction factor between two identical piles in multi-layered soils subjected to vertical loads. Following the technique proposed by Muki and Sternberg, the problem is decomposed into extended soil layers and two fictitious piles characterized respectively by Young's moduli of the layered soils and those of the differences between the piles and the layered soils. The unknown axial forces along fictitious piles are determined by solving a Fredholm integral equation of the second kind, which imposes the compatibility condition that the axial strains of the fictitious piles are equal to those corresponding to the centroidal axes of the extended layered soils. The real pile displacements can be calculated based on the determined fictitious pile forces, and finally, the desired pile interaction factors may be obtained. Selected results from parametrical studies are presented to confirm the validity of the proposed approach and portray the influence of the governing parameters on the pile interaction.展开更多
<span style="font-family:Verdana;">This paper proposes a numerical simulation of the mechanical behavior of a reinforced concrete pile foundation under an axial load. In fact, the foundation of a struc...<span style="font-family:Verdana;">This paper proposes a numerical simulation of the mechanical behavior of a reinforced concrete pile foundation under an axial load. In fact, the foundation of a structure represents the essential structural part of it, because it ensures its bearing capacity. Among the types of foundation, </span><span style="font-family:Verdana;">deep</span><span style="font-family:Verdana;"> foundation is the one for which from a mechanical point of view, the justification takes into account the isolated or combined effects of base resistance offered by the soil bed and lateral friction at the soil-pile interface;the latter being the consequence of a large contact surface with the surrounding soil;hence the need to study the interaction between the soil and the pile in service, in order to highlight the characteristics of soil which influence the mechanical behavior of pile and therefore the stability of the structure. In this study,</span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">the reinforced concrete pile is supposed to be </span><span style="font-family:Verdana;">elastic,</span><span style="font-family:Verdana;"> and characterized by a young’s modulus (</span><i><span style="font-family:Verdana;">E</span></i><span style="font-family:Verdana;">) and a Poisson’s ratio (</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">ν</span></i></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">). The soil obeys to a Camclay model characterized by </span><span style="font-family:Verdana;">a cohesion</span><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">c</span></i><span style="font-family:Verdana;">), an initial voids ratio (</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">e</span></i></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><sub><span style="font-family:Verdana;">0</span></sub></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">), shearing resistance angle (</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">φ</span></i></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">) </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> a pre-consolidation pressure (</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">P</span></i></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><sub><span style="font-family:Verdana;">0</span></sub></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">). A joint model with a </span><span style="font-family:Verdana;">Mohr Coulomb</span><span style="font-family:Verdana;"> behavior characterizes the soil-pile interface. The loading is carrying out by imposing a vertical monotonic displacement at the head of </span><span style="font-family:Verdana;">pile</span><span style="font-family:Verdana;">. The results in terms of stress and displacement show that the bearing capacity of the pile is influenced by various soils characteristics, it appears that the vertical stress and the force mobilized at rupture increase when the initial pre_consolidation pressure, the cohesion </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> the internal friction angle of soil increase;and when the initial soil voids index decreases.</span></span></span></span>展开更多
This paper presents a case study on incidents of offshore pile running in layered soils.The study provides a detailed description of the seabed soil data,pile driving records,and field surveillance video observations....This paper presents a case study on incidents of offshore pile running in layered soils.The study provides a detailed description of the seabed soil data,pile driving records,and field surveillance video observations.Three-dimensional large deformation finite element(LDFE)analyses were conducted to retrospectively analyze the incidents,considering the remoulding of seabed soil and degradation of the pile-soil interface in the LDFE modeling.By comparing the field observations with the LDFE analysis,the mechanism of pile running was discussed,with a focus on investigating the pile penetration resistance in each layer.The study revealed that pile running in layered soils primarily resulted from a significant reduction in pile base resistance when transitioning from a strong layer to an adjacent weak layer.To further investigate the pile running mechanism in layered soils,a parametric study on the strength variation of adjacent soil layers and its influence on pile base resistance was conducted.Lastly,a simplified prediction model of pile base resistance,suitable for assessing the risk of pile running in layered soils,was proposed.展开更多
Dynamic soil−pile−superstructure interaction is crucial for understanding pile behavior in earthquake-prone ground.Evaluating the safety of piles requires determining the seismic bending moment caused by combined iner...Dynamic soil−pile−superstructure interaction is crucial for understanding pile behavior in earthquake-prone ground.Evaluating the safety of piles requires determining the seismic bending moment caused by combined inertial and kinematic interactions,which is challenging.This paper addresses this problem through numerical simulations of piles in different soil sites,considering soil nonlinearity.Results reveal that the period of the soil site significantly affects the interaction among soil,piles,and structures.Bending moments in soft and hard soil sites exceed those in medium soil sites by more than twice.Deformation modes of piles exhibit distinct characteristics between hard and soft soil sites.Soft soil sites exhibit a singular inflection point,while hard soil sites show two inflection points.In soft soil sites,pile-soil kinematic interaction gradually increases bending moment from tip to head,with minor influence from superstructure’s inertial interaction.In hard soil sites,significant inertial effects from soil,even surpassing pile-soil kinematic effects near the tip,lead to reversed superposition bending moment.Superstructure’s inertial interaction notably impacts pile head in hard soil sites.A simplified coupling method is proposed using correlation coefficient to represent inertial and kinematic interactions.These findings provide insights into complex seismic interactions among soil,piles,and structures.展开更多
This paper constructs a coupled aero-hydro-elastic-servo simulation framework for a monopile offshore wind turbine(OWT).In this framework,a detailed multi-body dynamics model of the monopile OWT including the gearbox,...This paper constructs a coupled aero-hydro-elastic-servo simulation framework for a monopile offshore wind turbine(OWT).In this framework,a detailed multi-body dynamics model of the monopile OWT including the gearbox,blades,tower and other components(nacelle,hub,bedplate,etc.)has been explicitly established.The effects of pile−soil interaction,controller and operational conditions on the turbine dynamic responses are studied systematically in time domain and frequency domain.The results show that(1)a comprehensive drivetrain model has the capability to provide a more precise representation of the complex dynamic characteristics exhibited by drivetrain components,which can be used as the basis for further study on the dynamic characteristics of the drivetrain.(2)The pile−soil interaction can influence the wind turbine dynamic responses,particularly under the parked condition.(3)The effect of the pile−soil interaction on tower responses is more significant than that on blade responses.(4)The use of the controller can substantially affect the rotor characteristics,which in turn influences the turbine dynamic responses.(5)The tower and blade displacements under the operational condition are much larger than those under the parked condition.The model and methodology presented in this study demonstrate potential for examining complex dynamic behaviors of the monopile OWTs.To ensure accuracy and precision,it is imperative to construct a detailed model of the wind turbine system,while also taking into account simulation efficiency.展开更多
A common design practice for dynamic loading assumes the frame fixed at their bases. In reality, the supporting soil medium allows movement to some extent due to its property to deform. This may decrease the overall s...A common design practice for dynamic loading assumes the frame fixed at their bases. In reality, the supporting soil medium allows movement to some extent due to its property to deform. This may decrease the overall stiffness of the structural system and may increase the natural period of the system. The effect of soil flexibility is suggested to be accounted through consideration of springs which have specified stiffness and soil half space. Results show that the dynamic response of frame structure to vibrations is due to applied dynamic load and is highly dependent on the soil type and the method of modeling soil structure interaction. The response of frame structure under dynamic load is higher in case of linear discrete independent spring as comparing with perfect bond cases. Except the response of frame in case of piles embedded in soft clay, half space are higher than frame with piles and linear elastic spring due to the interaction between the frequencies of applied load and frequencies of frame structure. Also, result showed that it is important to include the soil-structure interaction in the analysis of the system in order to correctly simulate the dynamic problem for controlling on the resonance phenomena.展开更多
The study deals with physical modeling of a typical building frame resting on a pile group embedded in cohesive soil mass using complete three-dimensional finite element analysis. The elements of the superstructure fr...The study deals with physical modeling of a typical building frame resting on a pile group embedded in cohesive soil mass using complete three-dimensional finite element analysis. The elements of the superstructure frame and that of the pile foundation are discretized using twenty node isoparametric continuum elements. The interface between the pile and pile cap is idealized using sixteen node isoparametric surface elements. The more improved finite element mesh is used for modeling soil element as compared to the one used in the study reported in the literature. The soil elements are discretized using eight node, nine node and twelve node continuum elements. Both the elements of superstructure and substructure (i.e., foundation) including soil are assumed to remain in elastic state at all the time. The interaction analysis is carried out using sub-structure approach to attempt a parametric study. The effect of the parameter such as spacing between the piles in a group and diameter of pile is evaluated on the response of superstructure. The response includes the displacement at the top of the frame. The effect of the soil-structure interaction is observed to be significant for the type of foundation and soil considered in the present study.展开更多
This thorough review explores the complexities of geotechnical engineering, emphasizing soil-structure interaction (SSI). The investigation centers on sheet pile design, examining two primary methodologies: Limit Equi...This thorough review explores the complexities of geotechnical engineering, emphasizing soil-structure interaction (SSI). The investigation centers on sheet pile design, examining two primary methodologies: Limit Equilibrium Methods (LEM) and Soil-Structure Interaction Methods (SSIM). While LEM methods, grounded in classical principles, provide valuable insights for preliminary design considerations, they may encounter limitations in addressing real-world complexities. In contrast, SSIM methods, including the SSI-SR approach, introduce precision and depth to the field. By employing numerical techniques such as Finite Element (FE) and Finite Difference (FD) analyses, these methods enable engineers to navigate the dynamics of soil-structure interaction. The exploration extends to SSI-FE, highlighting its essential role in civil engineering. By integrating Finite Element analysis with considerations for soil-structure interaction, the SSI-FE method offers a holistic understanding of how structures dynamically interact with their geotechnical environment. Throughout this exploration, the study dissects critical components governing SSIM methods, providing engineers with tools to navigate the intricate landscape of geotechnical design. The study acknowledges the significance of the Mohr-Coulomb constitutive model while recognizing its limitations, and guiding practitioners toward informed decision-making in geotechnical analyses. As the article concludes, it underscores the importance of continuous learning and innovation for the future of geotechnical engineering. With advancing technology and an evolving understanding of soil-structure interaction, the study remains committed to ensuring the safety, stability, and efficiency of geotechnical structures through cutting-edge design and analysis techniques.展开更多
This paper delves into the critical aspects of sheet pile walls in civil engineering, highlighting their versatility in soil protection, retention, and waterproofing, all while emphasizing sustainability and efficient...This paper delves into the critical aspects of sheet pile walls in civil engineering, highlighting their versatility in soil protection, retention, and waterproofing, all while emphasizing sustainability and efficient construction practices. The paper explores two fundamental approaches to sheet pile design: limit equilibrium methods and numerical techniques, with a particular focus on finite element analysis. Utilizing the robust PLAXIS 2016 calculation code based on the finite element method and employing a simplified elastoplastic model (Mohr-Coulomb), this study meticulously models the interaction between sheet pile walls and surrounding soil. The research offers valuable insights into settlement and deformation patterns that adjacent buildings may experience during various construction phases. The central objective of this paper is to present the study’s findings and recommend potential mitigation measures for settlement effects on nearby structures. By unraveling the intricate interplay between sheet pile wall construction and neighboring buildings, the paper equips engineers and practitioners to make informed decisions that ensure the safety and integrity of the built environment. In the context of the Cotonou East Corniche development, the study addresses the limitations of existing software, such as RIDO, in predicting settlements and deformations affecting nearby buildings due to the substantial load supported by sheet pile walls. This information gap necessitates a comprehensive study to assess potential impacts on adjacent structures and propose suitable mitigation measures. The research underscores the intricate dynamics between sheet pile wall construction and its influence on the local environment. It emphasizes the critical importance of proactive engineering and vigilant monitoring in managing and mitigating potential hazards to nearby buildings. To mitigate these risks, the paper recommends measures such as deep foundations, ground improvement techniques, and retrofitting. The findings presented in this study contribute significantly to the field of civil engineering and offer invaluable insights into the multifaceted dynamics of construction-induced settlement. The study underscores the importance of continuous evaluation and coordination between construction teams and building owners to effectively manage the impacts of sheet pile wall construction on adjacent structures.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52201324,52078128,and52278355)the Natural Science Foundation of the Jiangsu Higher Education Institution of China(Grant No.22KJB560015)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.SJCX21_1794)。
文摘The interface mechanical behavior of a monopile is an important component of the overall offshore wind turbine structure design.Understanding the soil-structure interaction,particularly the initial soil-structure stiffness,has a significant impact on the study of natural frequency and dynamic response of the monopile.In this paper,a simplified method for estimating the interface mechanical behavior of monopiles under initial lateral loads is proposed.Depending on the principle of minimum potential energy and virtual work theory,the functions of soil reaction components at the interface of monopiles are derived;MATLAB programming has been used to simplify the functions of the initial stiffness by fitting a large number of examples;then the functions are validated against the field test data and FDM results.This method can modify the modulus of the subgrade reaction in the p-y curve method for the monopile-supported offshore wind turbine system.
基金Project(50378036) supported by the National Natural Science Foundation of China
文摘The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and considerable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.
文摘In this paper, the studies on soil-pile interaction behaviors in saturated sands under static, dynamic and cyclic lateral loads by model testing are described. By comparing with the field test results for piles in soft sandy clay, a formula of p-y curves based on constitutive relationship of soils applicable for both sandy and soft clays is proposed. Good agreements are obtained in comparison with the field test results performed by other investigators abroad. A p-y hysteresis curve formula based on the modified Masing's doubling criterion is also proposed, and the results are in satisfactory agreement with field test results.
文摘In this paper, several mathmatical models for the pile- soil interaction are outlined. The Boundary Element Method is one of the very effective methods for the reasonable models of elasticity and elastoplasticity. The major of this paper is concerned with the Boundary Element Method for the pile-soil interaction, including general methods and calculating formulation of static and dynamic analysis of the pile and pile groups. Some results of analysis are also given.
基金Major Research Plan of National Natural Science Foundation of China Under Grant No.90815009National Natural Science Foundation of China Under Grant No.50378031 and 50178027Western Transport Construction Technology Projects Under Grant No.2009318000100
文摘This paper describes a shake table test study on the seismic response of low-cap pile groups and a bridge structure in liquefiable ground. The soil profile, contained in a large-scale laminar shear box, consisted of a horizontally saturated sand layer overlaid with a silty clay layer, with the simulated low-cap pile groups embedded. The container was excited in three E1 Centro earthquake events of different levels. Test results indicate that excessive pore pressure （EPP） during slight shaking only slightly accumulated, and the accumulation mainly occurred during strong shaking. The EPP was gradually enhanced as the amplitude and duration of the input acceleration increased. The acceleration response of the sand was remarkably influenced by soil liquefaction. As soil liquefaction occurred, the peak sand displacement gradually lagged behind the input acceleration; meanwhile, the sand displacement exhibited an increasing effect on the bending moment of the pile, and acceleration responses of the pile and the sand layer gradually changed from decreasing to increasing in the vertical direction from the bottom to the top. A jump variation of the bending moment on the pile was observed near the soil interface in all three input earthquake events. It is thought that the shake table tests could provide the groundwork for further seismic performance studies of low-cap pile groups used in bridges located on liquefiable groun.
文摘An investigation of soil-pile-structure interaction is carried out, based on a large reciprocating compressor installed on an elevated concrete foundation （table top structure）. A practical method is described for the dynamic analysis, and compared with a 3D finite element （FE） model. Two commercial software packages are used for dynamic analysis considering the soilpile-structure interaction （SPSI）. Stiffness and damping of the pile foundation are generated from a computer program, and then input into the FE model. To examine the SPSI thoroughly, three cases for the soil, piles and superstructure are considered and compared. In the first case, the interaction is fully taken into account, that is, both the superstructure and soil-pile system are flexible. In the second case, the superstructure is flexible but fixed to a rigid base, with no deformation in the base （no SSI）. In the third case, the dynamic soil-pile interaction is taken into account, but the table top structure is assumed to be rigid. From the comparison beteen the results of these three cases some conclusions are made, which could be helpful for engineering practice.
文摘Traditionally seismic design of structures supported on piled raft foundation is performed by considering fixed base conditions, while the pile head is also considered to be fixed for the design of the pile foundation. Major drawback of this assumption is that it cannot capture soil-foundation-structure interaction due to flexibility of soil or the inertial interaction involving heavy foundation masses. Previous studies on this subject addressed mainly the intricacy in modelling of dynamic soil structure interaction (DSSI) but not the implication of such interaction on the distribution of forces at various elements of the pile foundation and supported structure. A recent numerical study by the authors showed significant change in response at different elements of the piled raft supported structure when DSSI effects are considered. The present study is a limited attempt in this direction, and it examines such observations through shake table tests. The effect of DSSI is examined by comparing dynamic responses from fixed base scaled down model structures and the overall systems. This study indicates the possibility of significant underestimation in design forces for both the column and pile if designed under fixed base assumption. Such underestimation in the design forces may have serious implication in the design of a foundation or structural element.
文摘The seismic behavior of tall buildings can he greatly affected by non-linear soil-pile interaction during strong earthquakes.In this study a 20-storey building is examined as a typical structure supported on a pile foundation for different conditions:(1) rigid base,i.e.no deformation in the foundation:(2) linear soil-pile system;and (3) nonlinear soil-pile system. The effects of pile foundation displacements on the behavior of tall building are investigated,and compared with the behavior of buildings supported on shallow foundation.With a model of non-reflective boundary between the near field and far field, Novak's method of soil-pile interaction is improved.The computation method for vibration of pile foundations and DYNAN computer program are introduced comprehensively.A series of dynamic experiments have been done on full-scale piles, including single pile and group,linear vibration and nonlinear vibration,to verify the validity of boundary zone model.
文摘This paper is an attempt to solve the soil-pile interaction problems using the boundary element method（BEM）.A computer package called PGroupN,which deals mainly with the analysis of the pile group problem,is employed in this study.Parametric studies are carried out to assess the impacts of the pile diameter,pile length,ratio of spacing to diameter and the thickness of soil stratum.The external load is applied incrementally and,at each increment,a check is made that the stress state at the pile-soil interfaces does not violate the yield criteria.This is achieved by specifying the limited stresses of the soil for the axial pile shaft capacity and end-bearing resistance.The elements of the pile-soil interface yielded can take no additional load,and any increase in load is therefore redistributed between the remaining elements until all elements have failed.Thus,by successive application of loading increments,the entire load-displacement relationship for the pile group is determined.It is found that as the applied load reaches the ultimate bearing capacity of the pile group,all the piles will share the same amount of load.An exception to this case is for the center pile in a group of 9 piles embedded in clay,which is not consistent with the behaviors of the other piles in the group even if the load reaches the ultimate state.For the 4 piles group embedded in clay,the maximum load carried by the base does not exceed 8% of the load carried by each pile with different diameters.This low percentage ascertains that the piles embedded in cohesive soils carry most of the load throughout their shafts.
基金National Natural Science Foundation of China Under Grant No.59778027State Key Laboratory of Coastal Offshore EngineeringDalian University of Technology Under Grant No.9702
文摘The success of the tuned mass damper (TMD) in reducing wind-induced structural vibrations has been well established. However, from most of the recent numerical studies, it appears that for a structure situated on very soft soil, soil-structure interaction (SSI) could render a damper on the structure totally ineffective. In order to experimentally verify the SSI effect on the seismic performance of TMD, a series of shaking table model tests have been conducted and the results are presented in this paper. It has been shown that the TMD is not as effective in controlling the seismic responses of structures built on soft soil sites due to the SSI effect. Some test results also show that a TMD device might have a negative impact if the SSI effect is neglected and the structure is built on a soft soil site. For structures constructed on a soil foundation, this research verifies that the SSI effect must be carefully understood before a TMD control system is designed to determine if the control is necessary and if the SSI effect must be considered when choosing the optimal parameters of the TMD device.
基金National Natural Science Foundation of China(Grant No.59895410)
文摘This paper proposes an optimum design model for the offshore jacket platform considering multidesign criteria, multi-design constraints and the structure-pile-soil interaction, and gives an optimum design procedure in which the proposed optimum design model is used together with structural analysis software SAP91 and optimum algorithm software OPB1. The Chengbei (#)11 offshore platform, which lies in the Shengli oilfield, is designed by use of the above optimum design model. The results show that the optimum design model is stable, and it depends on neither the optimization algorithm nor initial values of design variables. All values of the objective function converge to the same minimum value, and the speed of convergence is high, showing that the proposed optimum design model is reasonable.
基金National Natural Science Foundation of China(No.50478022)Research and Innovation Project of Shanghai Education Committee,China(No.10YZ208)Excellent Young Teacher Project of Shanghai Education Committee,China(No.dsd08005)
文摘A rigorous analytical method is presented, which takes into account the pile stiffening effects, using the theory of the transfer matrix-bottom rigidity for calculating the interaction factor between two identical piles in multi-layered soils subjected to vertical loads. Following the technique proposed by Muki and Sternberg, the problem is decomposed into extended soil layers and two fictitious piles characterized respectively by Young's moduli of the layered soils and those of the differences between the piles and the layered soils. The unknown axial forces along fictitious piles are determined by solving a Fredholm integral equation of the second kind, which imposes the compatibility condition that the axial strains of the fictitious piles are equal to those corresponding to the centroidal axes of the extended layered soils. The real pile displacements can be calculated based on the determined fictitious pile forces, and finally, the desired pile interaction factors may be obtained. Selected results from parametrical studies are presented to confirm the validity of the proposed approach and portray the influence of the governing parameters on the pile interaction.
文摘<span style="font-family:Verdana;">This paper proposes a numerical simulation of the mechanical behavior of a reinforced concrete pile foundation under an axial load. In fact, the foundation of a structure represents the essential structural part of it, because it ensures its bearing capacity. Among the types of foundation, </span><span style="font-family:Verdana;">deep</span><span style="font-family:Verdana;"> foundation is the one for which from a mechanical point of view, the justification takes into account the isolated or combined effects of base resistance offered by the soil bed and lateral friction at the soil-pile interface;the latter being the consequence of a large contact surface with the surrounding soil;hence the need to study the interaction between the soil and the pile in service, in order to highlight the characteristics of soil which influence the mechanical behavior of pile and therefore the stability of the structure. In this study,</span><span><span><span style="font-family:""> </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">the reinforced concrete pile is supposed to be </span><span style="font-family:Verdana;">elastic,</span><span style="font-family:Verdana;"> and characterized by a young’s modulus (</span><i><span style="font-family:Verdana;">E</span></i><span style="font-family:Verdana;">) and a Poisson’s ratio (</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">ν</span></i></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">). The soil obeys to a Camclay model characterized by </span><span style="font-family:Verdana;">a cohesion</span><span style="font-family:Verdana;"> (</span><i><span style="font-family:Verdana;">c</span></i><span style="font-family:Verdana;">), an initial voids ratio (</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">e</span></i></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><sub><span style="font-family:Verdana;">0</span></sub></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">), shearing resistance angle (</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">φ</span></i></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">) </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> a pre-consolidation pressure (</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><i><span style="font-family:Verdana;">P</span></i></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><sub><span style="font-family:Verdana;">0</span></sub></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">). A joint model with a </span><span style="font-family:Verdana;">Mohr Coulomb</span><span style="font-family:Verdana;"> behavior characterizes the soil-pile interface. The loading is carrying out by imposing a vertical monotonic displacement at the head of </span><span style="font-family:Verdana;">pile</span><span style="font-family:Verdana;">. The results in terms of stress and displacement show that the bearing capacity of the pile is influenced by various soils characteristics, it appears that the vertical stress and the force mobilized at rupture increase when the initial pre_consolidation pressure, the cohesion </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> the internal friction angle of soil increase;and when the initial soil voids index decreases.</span></span></span></span>
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51879183,51890913)Sino-German Mobility Programme(Grant No.M-0045)。
文摘This paper presents a case study on incidents of offshore pile running in layered soils.The study provides a detailed description of the seabed soil data,pile driving records,and field surveillance video observations.Three-dimensional large deformation finite element(LDFE)analyses were conducted to retrospectively analyze the incidents,considering the remoulding of seabed soil and degradation of the pile-soil interface in the LDFE modeling.By comparing the field observations with the LDFE analysis,the mechanism of pile running was discussed,with a focus on investigating the pile penetration resistance in each layer.The study revealed that pile running in layered soils primarily resulted from a significant reduction in pile base resistance when transitioning from a strong layer to an adjacent weak layer.To further investigate the pile running mechanism in layered soils,a parametric study on the strength variation of adjacent soil layers and its influence on pile base resistance was conducted.Lastly,a simplified prediction model of pile base resistance,suitable for assessing the risk of pile running in layered soils,was proposed.
基金the National Natural Science Foundation of China(Grant No.42277163)for the financial support to this work.
文摘Dynamic soil−pile−superstructure interaction is crucial for understanding pile behavior in earthquake-prone ground.Evaluating the safety of piles requires determining the seismic bending moment caused by combined inertial and kinematic interactions,which is challenging.This paper addresses this problem through numerical simulations of piles in different soil sites,considering soil nonlinearity.Results reveal that the period of the soil site significantly affects the interaction among soil,piles,and structures.Bending moments in soft and hard soil sites exceed those in medium soil sites by more than twice.Deformation modes of piles exhibit distinct characteristics between hard and soft soil sites.Soft soil sites exhibit a singular inflection point,while hard soil sites show two inflection points.In soft soil sites,pile-soil kinematic interaction gradually increases bending moment from tip to head,with minor influence from superstructure’s inertial interaction.In hard soil sites,significant inertial effects from soil,even surpassing pile-soil kinematic effects near the tip,lead to reversed superposition bending moment.Superstructure’s inertial interaction notably impacts pile head in hard soil sites.A simplified coupling method is proposed using correlation coefficient to represent inertial and kinematic interactions.These findings provide insights into complex seismic interactions among soil,piles,and structures.
基金supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant Nos.KJQN202101133 and KJQN202301105)Scientific Research Foundation of Chongqing University of Technology(Grant No.2020ZDZ023).
文摘This paper constructs a coupled aero-hydro-elastic-servo simulation framework for a monopile offshore wind turbine(OWT).In this framework,a detailed multi-body dynamics model of the monopile OWT including the gearbox,blades,tower and other components(nacelle,hub,bedplate,etc.)has been explicitly established.The effects of pile−soil interaction,controller and operational conditions on the turbine dynamic responses are studied systematically in time domain and frequency domain.The results show that(1)a comprehensive drivetrain model has the capability to provide a more precise representation of the complex dynamic characteristics exhibited by drivetrain components,which can be used as the basis for further study on the dynamic characteristics of the drivetrain.(2)The pile−soil interaction can influence the wind turbine dynamic responses,particularly under the parked condition.(3)The effect of the pile−soil interaction on tower responses is more significant than that on blade responses.(4)The use of the controller can substantially affect the rotor characteristics,which in turn influences the turbine dynamic responses.(5)The tower and blade displacements under the operational condition are much larger than those under the parked condition.The model and methodology presented in this study demonstrate potential for examining complex dynamic behaviors of the monopile OWTs.To ensure accuracy and precision,it is imperative to construct a detailed model of the wind turbine system,while also taking into account simulation efficiency.
文摘A common design practice for dynamic loading assumes the frame fixed at their bases. In reality, the supporting soil medium allows movement to some extent due to its property to deform. This may decrease the overall stiffness of the structural system and may increase the natural period of the system. The effect of soil flexibility is suggested to be accounted through consideration of springs which have specified stiffness and soil half space. Results show that the dynamic response of frame structure to vibrations is due to applied dynamic load and is highly dependent on the soil type and the method of modeling soil structure interaction. The response of frame structure under dynamic load is higher in case of linear discrete independent spring as comparing with perfect bond cases. Except the response of frame in case of piles embedded in soft clay, half space are higher than frame with piles and linear elastic spring due to the interaction between the frequencies of applied load and frequencies of frame structure. Also, result showed that it is important to include the soil-structure interaction in the analysis of the system in order to correctly simulate the dynamic problem for controlling on the resonance phenomena.
文摘The study deals with physical modeling of a typical building frame resting on a pile group embedded in cohesive soil mass using complete three-dimensional finite element analysis. The elements of the superstructure frame and that of the pile foundation are discretized using twenty node isoparametric continuum elements. The interface between the pile and pile cap is idealized using sixteen node isoparametric surface elements. The more improved finite element mesh is used for modeling soil element as compared to the one used in the study reported in the literature. The soil elements are discretized using eight node, nine node and twelve node continuum elements. Both the elements of superstructure and substructure (i.e., foundation) including soil are assumed to remain in elastic state at all the time. The interaction analysis is carried out using sub-structure approach to attempt a parametric study. The effect of the parameter such as spacing between the piles in a group and diameter of pile is evaluated on the response of superstructure. The response includes the displacement at the top of the frame. The effect of the soil-structure interaction is observed to be significant for the type of foundation and soil considered in the present study.
文摘This thorough review explores the complexities of geotechnical engineering, emphasizing soil-structure interaction (SSI). The investigation centers on sheet pile design, examining two primary methodologies: Limit Equilibrium Methods (LEM) and Soil-Structure Interaction Methods (SSIM). While LEM methods, grounded in classical principles, provide valuable insights for preliminary design considerations, they may encounter limitations in addressing real-world complexities. In contrast, SSIM methods, including the SSI-SR approach, introduce precision and depth to the field. By employing numerical techniques such as Finite Element (FE) and Finite Difference (FD) analyses, these methods enable engineers to navigate the dynamics of soil-structure interaction. The exploration extends to SSI-FE, highlighting its essential role in civil engineering. By integrating Finite Element analysis with considerations for soil-structure interaction, the SSI-FE method offers a holistic understanding of how structures dynamically interact with their geotechnical environment. Throughout this exploration, the study dissects critical components governing SSIM methods, providing engineers with tools to navigate the intricate landscape of geotechnical design. The study acknowledges the significance of the Mohr-Coulomb constitutive model while recognizing its limitations, and guiding practitioners toward informed decision-making in geotechnical analyses. As the article concludes, it underscores the importance of continuous learning and innovation for the future of geotechnical engineering. With advancing technology and an evolving understanding of soil-structure interaction, the study remains committed to ensuring the safety, stability, and efficiency of geotechnical structures through cutting-edge design and analysis techniques.
文摘This paper delves into the critical aspects of sheet pile walls in civil engineering, highlighting their versatility in soil protection, retention, and waterproofing, all while emphasizing sustainability and efficient construction practices. The paper explores two fundamental approaches to sheet pile design: limit equilibrium methods and numerical techniques, with a particular focus on finite element analysis. Utilizing the robust PLAXIS 2016 calculation code based on the finite element method and employing a simplified elastoplastic model (Mohr-Coulomb), this study meticulously models the interaction between sheet pile walls and surrounding soil. The research offers valuable insights into settlement and deformation patterns that adjacent buildings may experience during various construction phases. The central objective of this paper is to present the study’s findings and recommend potential mitigation measures for settlement effects on nearby structures. By unraveling the intricate interplay between sheet pile wall construction and neighboring buildings, the paper equips engineers and practitioners to make informed decisions that ensure the safety and integrity of the built environment. In the context of the Cotonou East Corniche development, the study addresses the limitations of existing software, such as RIDO, in predicting settlements and deformations affecting nearby buildings due to the substantial load supported by sheet pile walls. This information gap necessitates a comprehensive study to assess potential impacts on adjacent structures and propose suitable mitigation measures. The research underscores the intricate dynamics between sheet pile wall construction and its influence on the local environment. It emphasizes the critical importance of proactive engineering and vigilant monitoring in managing and mitigating potential hazards to nearby buildings. To mitigate these risks, the paper recommends measures such as deep foundations, ground improvement techniques, and retrofitting. The findings presented in this study contribute significantly to the field of civil engineering and offer invaluable insights into the multifaceted dynamics of construction-induced settlement. The study underscores the importance of continuous evaluation and coordination between construction teams and building owners to effectively manage the impacts of sheet pile wall construction on adjacent structures.
