In order to study the mechanism of bearing behavior at the tip of a pile embedded in rock, the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems w...In order to study the mechanism of bearing behavior at the tip of a pile embedded in rock, the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems which govern the stress field were applied to derive the ultimate end beating capacity based on some reasonable hypothesis and failure plane model. Both numerical simulation and test results were compared with the theoretic solution. The results show good consistency with each other and verify the validity of the present approach. The depth effect with respective to embedment ratio and other influence factors like geological strength index, intermediate principal stress, overburden factor, and damage on end bearing capacity were discussed in the analytical solution. The results show that the proposed yield criterion can be much better for investigating the ultimate end bearing performance of rock-socketed pile. The end bearing capacity increases with embedment ratio and the increasing degree is influenced intensely by the above parameters. Furthermore, ignoring intermediate stress effect would underestimate the strength properties of the rock material and lead to a very conservative estimation value.展开更多
Based on the fictitious soil pile model, the effect of sediment on the vertical dynamic impedance of rock-socketed pile with large diameter was theoretically studied by means of Laplace transform technique and impedan...Based on the fictitious soil pile model, the effect of sediment on the vertical dynamic impedance of rock-socketed pile with large diameter was theoretically studied by means of Laplace transform technique and impedance function transfer method. Firstly, the sediment under rock-socketed pile was assumed to be fictitious soil pile with the same sectional area. The Rayleigh-Love rode model was used to simulate the rock-socketed pile and the fictitious soil pile with the consideration of the lateral inertial effect of large-diameter pile. The layered surrounding soils and bedrock were modeled by the plane strain model. Then, by virtue of the initial conditions and boundary conditions of the soil pile system, the analytical solution of the vertical dynamic impedance at the head of rock-socketed pile was derived for the arbitrary excitation acting on the pile head. Lastly, based on the presented analytical solution, the effect of sediment properties, bedrock property and lateral inertial effect on the vertical dynamic impedance at rock-socketed pile head were investigated in detail. It is shown that the sediment properties have significant effect on the vertical dynamic impedance at the rock-socketed pile head. The ability of soil-pile system to resist dynamic vertical deformation is weakened with the increase of sediment thickness, but amplified with the increase of shear wave velocity of sediment. The ability of soil pile system to resist dynamic vertical deformation is amplified with the bedrock property improving, but the ability of soil-pile system to resist vertical vibration is weakened with the improvement of bedrock property.展开更多
In the past two decades, numerous large-diameter rock-socketed piles were constructed in China to support foundations of skyscrapers, great bridges or to retain soil in potential geological hazard areas. However, dril...In the past two decades, numerous large-diameter rock-socketed piles were constructed in China to support foundations of skyscrapers, great bridges or to retain soil in potential geological hazard areas. However, drilling large-diameter rock-socketed pile holes with conventional drilling method such as rotary drilling or cable tool drilling is time-consuming and the cost is usually very high. In order to drill large-diameter rocksocketed pile holes faster at relatively low cost, the FGC15A large-diameter DTH air hammer drilling system was developed in 1987 and was given the second-clasa award by Ministry of Geology and Mineral Resources in 1991. Since it was innovated the drilling system has been used in more than twenty important and tough pro- jects on land, and wonderful results were acquired. At the same time the large-diameter DTH air hammer drilling system was improved continuously. The FGC15D is the latest version of the technique.展开更多
A centrifuge modeling test and a three-dimensional finite element analysis（FEA）of super-long rock-socketed bored pile groups of the Tianxingzhou Bridge are proposed.Based on the similarity theory,different prototypi...A centrifuge modeling test and a three-dimensional finite element analysis（FEA）of super-long rock-socketed bored pile groups of the Tianxingzhou Bridge are proposed.Based on the similarity theory,different prototypical materials are simulated using different indicators in the centrifuge model.The silver sand,the shaft and the pile cap are simulated according to the natural density,the compressive stiffness and the bending stiffness,respectively.The finite element method（FEM）is implemented and analyzed in ANSYS,in which the stress field during the undisturbed soil stage,the boring stage,the concrete-casting stage and the curing stage are discussed in detail.Comparisons in terms of load-settlement,shaft axial force distribution and lateral friction between the numerical results and the test data are carried out to investigate the bearing behaviors of super-long rock-socketed bored pile groups under loading and unloading conditions.Results show that there is a good agreement between the centrifuge modeling tests and the FEM.In addition,the load distribution at the pile top is complicated,which is related to the stiffness of the cap,the corresponding assumptions and the analysis method.The shaft axial force first increases slightly with depth then decreases sharply,and the rate of decrease in rock is greater than that in sand and soil.展开更多
In order to discuss the buckling stability of super-long rock-socketed filling piles widely used in bridge engineering in soft soil area such as Dongting Lake, the second stability type was adopted instead of traditio...In order to discuss the buckling stability of super-long rock-socketed filling piles widely used in bridge engineering in soft soil area such as Dongting Lake, the second stability type was adopted instead of traditional first type, and a newly invented numerical analysis method, i.e. the element-free Galerkin method (EFGM), was introduced to consider the non-concordant deformation and nonlinearity of the pile-soil interface. Then, based on the nonlinear elastic-ideal plastic pile-soil interface model, a nonlinear iterative algorithm was given to analyze the pile-soil interaction, and a program for buckling analysis of piles by the EFGM (PBAP-EFGM) and arc length method was worked out as well. The application results in an engineering example show that, the shape of pile top load-settlement curve obtained by the program agrees well with the measured one, of which the difference may be caused mainly by those uncertain factors such as possible initial defects of pile shaft and the eccentric loading during the test process. However, the calculated critical load is very close with the measured ultimate load of the test pile, and the corresponding relative error is only 5.6%, far better than the calculated values by linear and nonlinear incremental buckling analysis (with a greater relative error of 37.0% and 15.4% respectively), which also verifies the rationality and feasibility of the present method.展开更多
Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experim...Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experiment on a three-spiral-pile jacket foundation under deep-buried sandy soil conditions.During the experiment,horizontal displacement was applied to the structure to thoroughly investigate the bearing characteristics of the three-spiral-pile jacket foundation.This study also focused on analyzing the bearing mechanisms of conventional piles compared with spiral piles with different numbers of blades.Three different working conditions were set up and compared,and key data,such as the horizontal bearing capacity,pile shaft axial force,and spiral blade soil pressure,were measured and analyzed.The results show the distinct impacts of the spiral blades on the compressed and tensioned sides of the foundation.Specifically,on the compressed side,the spiral blades effectively enhance the restraint of the soil on the pile foundation,whereas on the tensioned side,an excessive number of spiral blades can negatively affect the structural tensile performance to some extent.This study also emphasizes that the addition of blades to the side of a single pile is the most effective method for increasing the bearing capacity of the foundation.This research aims to provide design insights into improving the bearing capacity of the foundation.展开更多
Precast driven piles are extensively used for infrastructure on soft soils,but the buildup of excess pore water pressure associated with pile driving is a challenging issue.The process of soil consolidation could take...Precast driven piles are extensively used for infrastructure on soft soils,but the buildup of excess pore water pressure associated with pile driving is a challenging issue.The process of soil consolidation could take several months.Measures are sought to shorten the drainage path in the ground,and permeable pipe pile is a concept that involves drainage channels at the peak pore pressure locations around the pile circumference.Centrifuge tests were conducted to understand the responses of permeable pipe pile treated ground,experiencing the whole pile driving,soil consolidating,and axially loading process.Results show that the dissipation rate of pore pressures can be improved,especially at a greater depth or at a shorter distance from the pile,since the local hydraulic gradient was higher.Less significant buildup of pore pressures can be anticipated with the use of permeable pipe pile.For this,the bearing capacity of composite foundation with permeable pipe pile can be increased by over 36.9%,compared to the case with normal pipe pile at a specific time period.All these demonstrate the ability of permeable pipe pile in accelerating the consolidation process,mobilizing the bearing capacity of treated ground at an early stage,and minimizing the set-up effect.展开更多
Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration...Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration and freeze–thaw(FT) cycles is a significant factor causing slope failure. This study aims to investigate the transmedia seepage characteristics at slope–concrete stabilizing pile interface systems by using silty clay and concrete with varying microstructure characteristics under FT cycles. To this end, a self-developed indoor test device for transmedia water migration, combined with a macro-meso-micro multiscale testing approach, was used to analyze the laws and mechanisms of transmedia seepage at the interface systems. The effect of the medium's microstructure characteristics on the transmedia seepage behavior at the interface systems under FT cycles was also assessed. Results indicated that the transmedia water migration exhibited particularity due to the migration of soil particles and the low permeability characteristics of concrete. The water content in the media increased significantly within the range of 1/3–2/3 of the height from the interface for soil and within 5 mm from the interface for concrete.FT cycles promoted the increase and penetration of cracks within the medium, enhancing the permeability of the slope-concrete stabilizing pile interface systems.With the increase in FT cycles, the porosity inside the medium first decreased and then increased, and the porosity reached the minimum after 25 FT cycles and the maximum after 75 FT cycles, and the water content of the medium after water migration was positively correlated with the porosity. FT cycles also significantly influenced the temporal variation characteristics of soil moisture and the migration path of water in concrete. The study results could serve as a reference for related research on slope stability assessment.展开更多
A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influen...A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.展开更多
In order to effectively improve the horizontal bearing capacity of pile foundations,this study proposes post-expanded arm grouting technology and associated pile foundations.The horizontal bearing characteristic of th...In order to effectively improve the horizontal bearing capacity of pile foundations,this study proposes post-expanded arm grouting technology and associated pile foundations.The horizontal bearing characteristic of the post-expanded arm grouting pile was explored through model tests.The test results indicate that the post-expanded arm grouting pile can increase the contact area between the pile and soil,and can improve the strength of the soil.The horizontal bearing capacity of the post-expanded arm grouting pile was approximately 3 times that of the conventional pile.It also shows that the larger the plate diameter ratio or grouting volume,the higher the horizontal bearing capacity of the post-expanded arm grouting pile.The maximum bending moment of the post-expanded arm grouting pile was located at the pile plate,and the displacement zero point of the new pile was higher than that of the conventional pile.The soil resistance at the pile plate was significantly higher than that of conventional piles,indicating that the pile plate effectively enhances the soil resistance.The improved p-y curve model and horizontal bearing capacity calculation method for the post-expanded arm grouting pile were proposed by considering the pile plate diameter factor.This method was finally verified by experimental results.The results of this study can provide a reference for calculating the horizontal bearing capacity of the post-expanded arm grouting pile.展开更多
Reliability analysis of soil slopes under rainfall is an important task for landslide risk assessment.Previous studies rarely contribute to the probabilistic analysis of slope stability under rainfall with reinforceme...Reliability analysis of soil slopes under rainfall is an important task for landslide risk assessment.Previous studies rarely contribute to the probabilistic analysis of slope stability under rainfall with reinforcement.A new method is suggested for reliability analysis of soil slopes stabilized with piles under rainfall.First,an efficient numerical model is exploited for slope stability analysis,where two types of slope failure modes,i.e.,plastic flow and local failure are considered.To address the blocking effect of piles during seepage analysis,the equivalent hydraulic conductivity of the pile area is estimated according to the effective medium theory.The stabilizing force of piles is investigated by an analytical approach.For saving computational effort,the response surface is established based on a multi-class classification model to predict two types of slope failure modes.Finally,uncertainties in soil parameters and rainfall events are both modelled,and the failure probability of soil slopes within a given time period is assessed through Monte Carlo simulation.An illustrative example is used to demonstrate the performance of the suggested method.It is found that the slope is mainly controlled by local failure.As the pile spacing increases,the likelihood of plastic flow significantly increases.As the piles are located near the slope crest,plastic flow is effectively prevented and the slope is better stabilized against rainfall.If rainfall uncertainties are not considered,the slope failure probability is significantly overestimated.Overall,this study can provide a useful guidance for the design of pile-stabilized slopes against rainfall infiltration.展开更多
With the increasing construction of port facilities,cross-sea bridges,and offshore engineering projects,uplift piles embedded in marine sedimentary soft soil are becoming increasingly necessary.The load-displacement c...With the increasing construction of port facilities,cross-sea bridges,and offshore engineering projects,uplift piles embedded in marine sedimentary soft soil are becoming increasingly necessary.The load-displacement curve of uplift piles is crucial for evaluating their uplift bearing characteristics,which facilitates the risk evaluation,design,and construction of large infrastructural supports.In this study,a load-displacement curve model based on piezocone penetration test(CPTU)data is proposed via the load transfer method.Experimental tests are conducted to analyze the uplift bearing characteristics and establish a correlation between the proposed model and CPTU data.The results of the proposed load-displacement curve are compared with the results from numerical simulations and those calculated by previous methods.The results show that the proposed curves appropriately evaluated the uplift bearing characteristics and improved the accuracy in comparison with previous methods.展开更多
This study investigates the load-bearing capacity of open-ended pipe piles in sandy soil, with a specific focus on the impact of soil plug constraints at four levels(no plug, 25% plug, 50% plug, and full plug). Levera...This study investigates the load-bearing capacity of open-ended pipe piles in sandy soil, with a specific focus on the impact of soil plug constraints at four levels(no plug, 25% plug, 50% plug, and full plug). Leveraging a dataset comprising open-ended pipe piles with varying geometrical and geotechnical properties, this research employs shallow neural network(SNN) and deep neural network(DNN) models to predict plugging conditions for both driven and pressed installation types. This paper underscores the importance of key parameters such as the settlement value,applied load, installation type, and soil configuration(loose, medium, and dense) in accurately predicting pile settlement. These findings offer valuable insights for optimizing pile design and construction in geotechnical engineering,addressing a longstanding challenge in the field. The study demonstrates the potential of the SNN and DNN models in precisely identifying plugging conditions before pile driving, with the SNN achieving R2 values ranging from0.444 to 0.711 and RMSPE values ranging from 24.621% to 48.663%, whereas the DNN exhibits superior performance, with R2 values ranging from 0.815 to 0.942 and RMSPE values ranging from 4.419% to 10.325%. These results have significant implications for enhancing construction practices and reducing uncertainties associated with pile foundation projects in addition to leveraging artificial intelligence tools to avoid long experimental procedures.展开更多
The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation...The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.展开更多
A full-scale research study was conducted during the bored tunnelling of the Klang Valley Mass Rapid Transit-Putrajaya Line beneath an existing building structure in Kuala Lumpur,Malaysia.The primary objective was to ...A full-scale research study was conducted during the bored tunnelling of the Klang Valley Mass Rapid Transit-Putrajaya Line beneath an existing building structure in Kuala Lumpur,Malaysia.The primary objective was to investigate the tunnel-soil-pile interaction at various stages of tunnel excavation.This study combined field measurements and three-dimensional(3D)numerical analysis to understand the transient effects of TBM tunnelling on a loaded pile.An experimental pile was instrumented with vibrating wire strain gauges,an inclinometer,and distributed fibre optic sensors using Brillouin optical time domain analysis.The pile was pre-loaded and continuously monitored in real-time throughout the tunnel construction process.The 3D finite element modelling was used to simulate the pile’s transient responses based on actual tunnel boring machine(TBM)driving data.The study revealed that the zone of influence due to tunnelling effects extended from y¼2D to y¼4D,with the peak effect observed at y¼1D to 1.5D,where D represents the tunnel diameter.The analysis of axial load patterns highlighted transient responses,including tensile loads below the tunnel invert,which propagated upward and subsided due to negative skin friction.The maximum downdrag load observed reached 56%e71%of the pile’s working load.Additionally,pile movement patterns indicated outward deflections as the TBM approached and a return toward the tunnel post-passage,aligning with the predicted behaviour in a negative face loss scenario.This validated numerical framework provides a solid foundation for further parametric studies and enhances the understanding of tunnel-soil-pile interactions.展开更多
Bridge pier failures from granular flow impacts are common.Installing defense piles upstream is an effective mitigation strategy,yet their protective mechanisms and standardized design guidelines are unclear.This stud...Bridge pier failures from granular flow impacts are common.Installing defense piles upstream is an effective mitigation strategy,yet their protective mechanisms and standardized design guidelines are unclear.This study employed 3D discrete element method to analyze the influence of defense pile size and placement on its performance across 219 scenarios,providing a detailed examination of their protective mechanisms.Results show that optimizing these factors can reduce the maximum impact force on bridge piers by up to 94%.In terms of size,a critical height threshold is identified,beyond which increasing pile height does not enhance protection.This threshold depends on the movement height of granular particles at the slope base.Protection effectiveness varies with pile size:when H≤0.05 h(H is the height of defense piles,h is the height of bridge),protection marginally improves with increasing height and diameter;for 0.05 h<H<0.15 h,protection strongly correlates with both parameters;for H≥0.15 h,diameter becomes the dominant factor.In terms of placement,an optimal longitudinal distance exists between the defense pile and the bridge pier.The larger the diameter,the greater the optimal longitudinal distance.However,the transverse distance is inversely related to protection effectiveness.Mechanistic analysis shows that defense piles are more effective at redirecting particles to prevent direct collisions with the pier(contributing 100%impact energy reduction before the non-dimensional travel time t*=7.01 and 63%–100%afterward)than at reducing particle velocity.This study provides insights into the protective mechanisms of defense piles and informs strategies for optimizing bridge pier protection in granular flow-prone regions.展开更多
Seismic-induced landslides critically threaten infrastructure and human safety,especially in sandy slopes where conventional stabilization methods often fail under dynamic loading.This study evaluates circular open-en...Seismic-induced landslides critically threaten infrastructure and human safety,especially in sandy slopes where conventional stabilization methods often fail under dynamic loading.This study evaluates circular open-ended anti-slide pipe piles embedded in a two-layer sandy slope with differing geotechnical properties.Ten physical models,including five freefield and five pile-reinforced slopes,were tested on a shaking table.Key seismic responses—acceleration,soil displacement,and bending moments—were monitored using accelerometers,strain gauges,and Digital Image Correlation(DIC).Complementary numerical simulations using Abaqus with a Mohr–Coulomb model validated experimental results.Soil displacement in free-field models under 0.25g shaking was about 3.5 times greater than in reinforced slopes.Bending moments increased with seismic intensity,peaking at depths around five times the pile diameter.Limitations including simplified two-layer soil representation,idealized seismic inputs,and boundary effects inherent to laboratory models restrict direct field application but enable controlled analysis.By combining physical experiments with numerical modeling,the study provides a robust and validated framework for seismic slope stabilization.This integrated approach enhances understanding of soil–pile interaction under seismic loads and offers targeted insights for developing safer and more reliable geotechnical design strategies in earthquake-prone areas.展开更多
During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile str...During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.展开更多
Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experi...Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation.Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed.Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter.Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.展开更多
The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,...The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,experience one-way cyclic tensile loads at inclinations ranging from 0°(horizontal)to 90°(vertical).However,the combined effects of cyclic loading and load inclination remain inadequately understood.This study presents findings from centrifuge tests conducted on rough rigid piles installed in dense sand samples.The results demonstrate that load inclinations significantly influence both cyclic response and ultimate capacity of the piles.Based on the observed cyclic response characteristics,the vertical cyclic load amplitude should not exceed 25%of the ultimate bearing capacity to maintain pile stability.A power expression(with exponent m values ranging from 0.055 to 0.065)is proposed for predicting cumulative pile displacement under unidirectional cyclic loading at inclinations from 0°to 60°.The cyclic response exhibits reduced sensitivity to horizontal cyclic load magnitude,with m-value increasing from 0.06 to 0.14 as load magnitude increases from 0.3 to 0.9.For piles maintaining stability under oblique cyclic loading,the average normalized secant stiffness exceeds 1 and increases with decreasing inclination,indicating enhanced pile stiffness under cyclic loading.For load inclinations below 30°,pile stiffness can be determined using logarithmic function.展开更多
基金Project(2007AA11Z134) supported by the National High-tech Research and Development Program of ChinaProject(10JJ4035) supported by Hunan Provincial Natural Science Foundation of ChinaProject(04SK2008) supported by Hunan Provincial Science and Technology Department,China
文摘In order to study the mechanism of bearing behavior at the tip of a pile embedded in rock, the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems which govern the stress field were applied to derive the ultimate end beating capacity based on some reasonable hypothesis and failure plane model. Both numerical simulation and test results were compared with the theoretic solution. The results show good consistency with each other and verify the validity of the present approach. The depth effect with respective to embedment ratio and other influence factors like geological strength index, intermediate principal stress, overburden factor, and damage on end bearing capacity were discussed in the analytical solution. The results show that the proposed yield criterion can be much better for investigating the ultimate end bearing performance of rock-socketed pile. The end bearing capacity increases with embedment ratio and the increasing degree is influenced intensely by the above parameters. Furthermore, ignoring intermediate stress effect would underestimate the strength properties of the rock material and lead to a very conservative estimation value.
基金Projects(51109084/E09070151308234/E08061) supported by the National Natural Science Foundation of China+1 种基金Project(2013J05079) supported by the Natural Science Foundation of Fujian Province,ChinaProject(Z012002) supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering(Institute of Rock and Soil Mechanics,Chinese Academy of Sciences),China
文摘Based on the fictitious soil pile model, the effect of sediment on the vertical dynamic impedance of rock-socketed pile with large diameter was theoretically studied by means of Laplace transform technique and impedance function transfer method. Firstly, the sediment under rock-socketed pile was assumed to be fictitious soil pile with the same sectional area. The Rayleigh-Love rode model was used to simulate the rock-socketed pile and the fictitious soil pile with the consideration of the lateral inertial effect of large-diameter pile. The layered surrounding soils and bedrock were modeled by the plane strain model. Then, by virtue of the initial conditions and boundary conditions of the soil pile system, the analytical solution of the vertical dynamic impedance at the head of rock-socketed pile was derived for the arbitrary excitation acting on the pile head. Lastly, based on the presented analytical solution, the effect of sediment properties, bedrock property and lateral inertial effect on the vertical dynamic impedance at rock-socketed pile head were investigated in detail. It is shown that the sediment properties have significant effect on the vertical dynamic impedance at the rock-socketed pile head. The ability of soil-pile system to resist dynamic vertical deformation is weakened with the increase of sediment thickness, but amplified with the increase of shear wave velocity of sediment. The ability of soil pile system to resist dynamic vertical deformation is amplified with the bedrock property improving, but the ability of soil-pile system to resist vertical vibration is weakened with the improvement of bedrock property.
文摘In the past two decades, numerous large-diameter rock-socketed piles were constructed in China to support foundations of skyscrapers, great bridges or to retain soil in potential geological hazard areas. However, drilling large-diameter rock-socketed pile holes with conventional drilling method such as rotary drilling or cable tool drilling is time-consuming and the cost is usually very high. In order to drill large-diameter rocksocketed pile holes faster at relatively low cost, the FGC15A large-diameter DTH air hammer drilling system was developed in 1987 and was given the second-clasa award by Ministry of Geology and Mineral Resources in 1991. Since it was innovated the drilling system has been used in more than twenty important and tough pro- jects on land, and wonderful results were acquired. At the same time the large-diameter DTH air hammer drilling system was improved continuously. The FGC15D is the latest version of the technique.
基金The Natural Science Foundation of Hubei Province(No.2007ABA094)
文摘A centrifuge modeling test and a three-dimensional finite element analysis（FEA）of super-long rock-socketed bored pile groups of the Tianxingzhou Bridge are proposed.Based on the similarity theory,different prototypical materials are simulated using different indicators in the centrifuge model.The silver sand,the shaft and the pile cap are simulated according to the natural density,the compressive stiffness and the bending stiffness,respectively.The finite element method（FEM）is implemented and analyzed in ANSYS,in which the stress field during the undisturbed soil stage,the boring stage,the concrete-casting stage and the curing stage are discussed in detail.Comparisons in terms of load-settlement,shaft axial force distribution and lateral friction between the numerical results and the test data are carried out to investigate the bearing behaviors of super-long rock-socketed bored pile groups under loading and unloading conditions.Results show that there is a good agreement between the centrifuge modeling tests and the FEM.In addition,the load distribution at the pile top is complicated,which is related to the stiffness of the cap,the corresponding assumptions and the analysis method.The shaft axial force first increases slightly with depth then decreases sharply,and the rate of decrease in rock is greater than that in sand and soil.
基金Project(50378036) supported by the National Natural Science Foundation of China
文摘In order to discuss the buckling stability of super-long rock-socketed filling piles widely used in bridge engineering in soft soil area such as Dongting Lake, the second stability type was adopted instead of traditional first type, and a newly invented numerical analysis method, i.e. the element-free Galerkin method (EFGM), was introduced to consider the non-concordant deformation and nonlinearity of the pile-soil interface. Then, based on the nonlinear elastic-ideal plastic pile-soil interface model, a nonlinear iterative algorithm was given to analyze the pile-soil interaction, and a program for buckling analysis of piles by the EFGM (PBAP-EFGM) and arc length method was worked out as well. The application results in an engineering example show that, the shape of pile top load-settlement curve obtained by the program agrees well with the measured one, of which the difference may be caused mainly by those uncertain factors such as possible initial defects of pile shaft and the eccentric loading during the test process. However, the calculated critical load is very close with the measured ultimate load of the test pile, and the corresponding relative error is only 5.6%, far better than the calculated values by linear and nonlinear incremental buckling analysis (with a greater relative error of 37.0% and 15.4% respectively), which also verifies the rationality and feasibility of the present method.
基金The National Natural Science Foundation of China(No.52171274).
文摘Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experiment on a three-spiral-pile jacket foundation under deep-buried sandy soil conditions.During the experiment,horizontal displacement was applied to the structure to thoroughly investigate the bearing characteristics of the three-spiral-pile jacket foundation.This study also focused on analyzing the bearing mechanisms of conventional piles compared with spiral piles with different numbers of blades.Three different working conditions were set up and compared,and key data,such as the horizontal bearing capacity,pile shaft axial force,and spiral blade soil pressure,were measured and analyzed.The results show the distinct impacts of the spiral blades on the compressed and tensioned sides of the foundation.Specifically,on the compressed side,the spiral blades effectively enhance the restraint of the soil on the pile foundation,whereas on the tensioned side,an excessive number of spiral blades can negatively affect the structural tensile performance to some extent.This study also emphasizes that the addition of blades to the side of a single pile is the most effective method for increasing the bearing capacity of the foundation.This research aims to provide design insights into improving the bearing capacity of the foundation.
基金supported by the National Natural Science Foundation of China(Grant Nos.52168046 and 52178321)the Natural Science Foundation of Guangxi Province,China(Grant No.2021AC18019).
文摘Precast driven piles are extensively used for infrastructure on soft soils,but the buildup of excess pore water pressure associated with pile driving is a challenging issue.The process of soil consolidation could take several months.Measures are sought to shorten the drainage path in the ground,and permeable pipe pile is a concept that involves drainage channels at the peak pore pressure locations around the pile circumference.Centrifuge tests were conducted to understand the responses of permeable pipe pile treated ground,experiencing the whole pile driving,soil consolidating,and axially loading process.Results show that the dissipation rate of pore pressures can be improved,especially at a greater depth or at a shorter distance from the pile,since the local hydraulic gradient was higher.Less significant buildup of pore pressures can be anticipated with the use of permeable pipe pile.For this,the bearing capacity of composite foundation with permeable pipe pile can be increased by over 36.9%,compared to the case with normal pipe pile at a specific time period.All these demonstrate the ability of permeable pipe pile in accelerating the consolidation process,mobilizing the bearing capacity of treated ground at an early stage,and minimizing the set-up effect.
基金financially supported by Jilin Provincial Natural Science Foundation (No.20220101164JC)。
文摘Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration and freeze–thaw(FT) cycles is a significant factor causing slope failure. This study aims to investigate the transmedia seepage characteristics at slope–concrete stabilizing pile interface systems by using silty clay and concrete with varying microstructure characteristics under FT cycles. To this end, a self-developed indoor test device for transmedia water migration, combined with a macro-meso-micro multiscale testing approach, was used to analyze the laws and mechanisms of transmedia seepage at the interface systems. The effect of the medium's microstructure characteristics on the transmedia seepage behavior at the interface systems under FT cycles was also assessed. Results indicated that the transmedia water migration exhibited particularity due to the migration of soil particles and the low permeability characteristics of concrete. The water content in the media increased significantly within the range of 1/3–2/3 of the height from the interface for soil and within 5 mm from the interface for concrete.FT cycles promoted the increase and penetration of cracks within the medium, enhancing the permeability of the slope-concrete stabilizing pile interface systems.With the increase in FT cycles, the porosity inside the medium first decreased and then increased, and the porosity reached the minimum after 25 FT cycles and the maximum after 75 FT cycles, and the water content of the medium after water migration was positively correlated with the porosity. FT cycles also significantly influenced the temporal variation characteristics of soil moisture and the migration path of water in concrete. The study results could serve as a reference for related research on slope stability assessment.
基金financially supported by NSERC,CanadaDiscovery Grant 2020(Grant No.5808).
文摘A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.
基金supported by the National Natural Science Foundation of China(Grant Nos.52208333 and 52378328)China Communications Construction Company Ltd.(Grant No.2023-ZJKJ-01).
文摘In order to effectively improve the horizontal bearing capacity of pile foundations,this study proposes post-expanded arm grouting technology and associated pile foundations.The horizontal bearing characteristic of the post-expanded arm grouting pile was explored through model tests.The test results indicate that the post-expanded arm grouting pile can increase the contact area between the pile and soil,and can improve the strength of the soil.The horizontal bearing capacity of the post-expanded arm grouting pile was approximately 3 times that of the conventional pile.It also shows that the larger the plate diameter ratio or grouting volume,the higher the horizontal bearing capacity of the post-expanded arm grouting pile.The maximum bending moment of the post-expanded arm grouting pile was located at the pile plate,and the displacement zero point of the new pile was higher than that of the conventional pile.The soil resistance at the pile plate was significantly higher than that of conventional piles,indicating that the pile plate effectively enhances the soil resistance.The improved p-y curve model and horizontal bearing capacity calculation method for the post-expanded arm grouting pile were proposed by considering the pile plate diameter factor.This method was finally verified by experimental results.The results of this study can provide a reference for calculating the horizontal bearing capacity of the post-expanded arm grouting pile.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB2600504)the National Natural Science Foundation of China(Grant No.42072302)the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20240533).
文摘Reliability analysis of soil slopes under rainfall is an important task for landslide risk assessment.Previous studies rarely contribute to the probabilistic analysis of slope stability under rainfall with reinforcement.A new method is suggested for reliability analysis of soil slopes stabilized with piles under rainfall.First,an efficient numerical model is exploited for slope stability analysis,where two types of slope failure modes,i.e.,plastic flow and local failure are considered.To address the blocking effect of piles during seepage analysis,the equivalent hydraulic conductivity of the pile area is estimated according to the effective medium theory.The stabilizing force of piles is investigated by an analytical approach.For saving computational effort,the response surface is established based on a multi-class classification model to predict two types of slope failure modes.Finally,uncertainties in soil parameters and rainfall events are both modelled,and the failure probability of soil slopes within a given time period is assessed through Monte Carlo simulation.An illustrative example is used to demonstrate the performance of the suggested method.It is found that the slope is mainly controlled by local failure.As the pile spacing increases,the likelihood of plastic flow significantly increases.As the piles are located near the slope crest,plastic flow is effectively prevented and the slope is better stabilized against rainfall.If rainfall uncertainties are not considered,the slope failure probability is significantly overestimated.Overall,this study can provide a useful guidance for the design of pile-stabilized slopes against rainfall infiltration.
基金supported by the China Postdoctoral Science Foundation(Grant No.2024M760734)National Science Fund for Distinguished Young Scholars(Grant No.42225206)the National Natural Science Foundation of China(Grant Nos.41877231 and 42072299).
文摘With the increasing construction of port facilities,cross-sea bridges,and offshore engineering projects,uplift piles embedded in marine sedimentary soft soil are becoming increasingly necessary.The load-displacement curve of uplift piles is crucial for evaluating their uplift bearing characteristics,which facilitates the risk evaluation,design,and construction of large infrastructural supports.In this study,a load-displacement curve model based on piezocone penetration test(CPTU)data is proposed via the load transfer method.Experimental tests are conducted to analyze the uplift bearing characteristics and establish a correlation between the proposed model and CPTU data.The results of the proposed load-displacement curve are compared with the results from numerical simulations and those calculated by previous methods.The results show that the proposed curves appropriately evaluated the uplift bearing characteristics and improved the accuracy in comparison with previous methods.
文摘This study investigates the load-bearing capacity of open-ended pipe piles in sandy soil, with a specific focus on the impact of soil plug constraints at four levels(no plug, 25% plug, 50% plug, and full plug). Leveraging a dataset comprising open-ended pipe piles with varying geometrical and geotechnical properties, this research employs shallow neural network(SNN) and deep neural network(DNN) models to predict plugging conditions for both driven and pressed installation types. This paper underscores the importance of key parameters such as the settlement value,applied load, installation type, and soil configuration(loose, medium, and dense) in accurately predicting pile settlement. These findings offer valuable insights for optimizing pile design and construction in geotechnical engineering,addressing a longstanding challenge in the field. The study demonstrates the potential of the SNN and DNN models in precisely identifying plugging conditions before pile driving, with the SNN achieving R2 values ranging from0.444 to 0.711 and RMSPE values ranging from 24.621% to 48.663%, whereas the DNN exhibits superior performance, with R2 values ranging from 0.815 to 0.942 and RMSPE values ranging from 4.419% to 10.325%. These results have significant implications for enhancing construction practices and reducing uncertainties associated with pile foundation projects in addition to leveraging artificial intelligence tools to avoid long experimental procedures.
文摘The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.
文摘A full-scale research study was conducted during the bored tunnelling of the Klang Valley Mass Rapid Transit-Putrajaya Line beneath an existing building structure in Kuala Lumpur,Malaysia.The primary objective was to investigate the tunnel-soil-pile interaction at various stages of tunnel excavation.This study combined field measurements and three-dimensional(3D)numerical analysis to understand the transient effects of TBM tunnelling on a loaded pile.An experimental pile was instrumented with vibrating wire strain gauges,an inclinometer,and distributed fibre optic sensors using Brillouin optical time domain analysis.The pile was pre-loaded and continuously monitored in real-time throughout the tunnel construction process.The 3D finite element modelling was used to simulate the pile’s transient responses based on actual tunnel boring machine(TBM)driving data.The study revealed that the zone of influence due to tunnelling effects extended from y¼2D to y¼4D,with the peak effect observed at y¼1D to 1.5D,where D represents the tunnel diameter.The analysis of axial load patterns highlighted transient responses,including tensile loads below the tunnel invert,which propagated upward and subsided due to negative skin friction.The maximum downdrag load observed reached 56%e71%of the pile’s working load.Additionally,pile movement patterns indicated outward deflections as the TBM approached and a return toward the tunnel post-passage,aligning with the predicted behaviour in a negative face loss scenario.This validated numerical framework provides a solid foundation for further parametric studies and enhances the understanding of tunnel-soil-pile interactions.
基金supported by the National Natural Science Foundation of China(Grant numbers 41977233)。
文摘Bridge pier failures from granular flow impacts are common.Installing defense piles upstream is an effective mitigation strategy,yet their protective mechanisms and standardized design guidelines are unclear.This study employed 3D discrete element method to analyze the influence of defense pile size and placement on its performance across 219 scenarios,providing a detailed examination of their protective mechanisms.Results show that optimizing these factors can reduce the maximum impact force on bridge piers by up to 94%.In terms of size,a critical height threshold is identified,beyond which increasing pile height does not enhance protection.This threshold depends on the movement height of granular particles at the slope base.Protection effectiveness varies with pile size:when H≤0.05 h(H is the height of defense piles,h is the height of bridge),protection marginally improves with increasing height and diameter;for 0.05 h<H<0.15 h,protection strongly correlates with both parameters;for H≥0.15 h,diameter becomes the dominant factor.In terms of placement,an optimal longitudinal distance exists between the defense pile and the bridge pier.The larger the diameter,the greater the optimal longitudinal distance.However,the transverse distance is inversely related to protection effectiveness.Mechanistic analysis shows that defense piles are more effective at redirecting particles to prevent direct collisions with the pier(contributing 100%impact energy reduction before the non-dimensional travel time t*=7.01 and 63%–100%afterward)than at reducing particle velocity.This study provides insights into the protective mechanisms of defense piles and informs strategies for optimizing bridge pier protection in granular flow-prone regions.
基金the support from the Outstanding Youth Foundation of Shandong Province(ZR2021YQ31)the National Natural Science Foundation of China(42277135)+5 种基金National Foreign Experts Individual Program(Category Y)(Grant No.Y20240084)the National Natural Science Foundation of China Joint Fund Key Project(U2006225)Special Fund for Taishan Scholar Projectthe Youth Project of Open Funding from Engineering Research Center of Concrete Technology under Marine Environment,Ministry of Education(Grant No.TMduracon202217)the funding from Key Laboratory of Ministry of Education for Coastal Disaster and Protection,Hohai University(Grant No.202206)Shandong Provincial Overseas High-Level Talent Workstation,China。
文摘Seismic-induced landslides critically threaten infrastructure and human safety,especially in sandy slopes where conventional stabilization methods often fail under dynamic loading.This study evaluates circular open-ended anti-slide pipe piles embedded in a two-layer sandy slope with differing geotechnical properties.Ten physical models,including five freefield and five pile-reinforced slopes,were tested on a shaking table.Key seismic responses—acceleration,soil displacement,and bending moments—were monitored using accelerometers,strain gauges,and Digital Image Correlation(DIC).Complementary numerical simulations using Abaqus with a Mohr–Coulomb model validated experimental results.Soil displacement in free-field models under 0.25g shaking was about 3.5 times greater than in reinforced slopes.Bending moments increased with seismic intensity,peaking at depths around five times the pile diameter.Limitations including simplified two-layer soil representation,idealized seismic inputs,and boundary effects inherent to laboratory models restrict direct field application but enable controlled analysis.By combining physical experiments with numerical modeling,the study provides a robust and validated framework for seismic slope stabilization.This integrated approach enhances understanding of soil–pile interaction under seismic loads and offers targeted insights for developing safer and more reliable geotechnical design strategies in earthquake-prone areas.
基金sponsored by Natural Science Research Project of Anhui Educational Committee(GrantNo.2022AH050810),NationalNatural Science Foundation of China(GrantNos.42402276,41972286,42072309,42102329)State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,Jianghan University(No.PBSKL2023A1)the Open Fund of National Center for International Research on Deep Earth Drilling and Resource Development(No.DEDRD-2023-02).
文摘During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2021YFB2601100)the National Natural Science Foundation of China (Grant No. 51979190)。
文摘Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation.Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed.Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter.Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.
基金supported by Fundamental Research Funds for the Central Universities(Grant No.B200202050)Open Funds of Key Laboratory of Navigation Structure。
文摘The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,experience one-way cyclic tensile loads at inclinations ranging from 0°(horizontal)to 90°(vertical).However,the combined effects of cyclic loading and load inclination remain inadequately understood.This study presents findings from centrifuge tests conducted on rough rigid piles installed in dense sand samples.The results demonstrate that load inclinations significantly influence both cyclic response and ultimate capacity of the piles.Based on the observed cyclic response characteristics,the vertical cyclic load amplitude should not exceed 25%of the ultimate bearing capacity to maintain pile stability.A power expression(with exponent m values ranging from 0.055 to 0.065)is proposed for predicting cumulative pile displacement under unidirectional cyclic loading at inclinations from 0°to 60°.The cyclic response exhibits reduced sensitivity to horizontal cyclic load magnitude,with m-value increasing from 0.06 to 0.14 as load magnitude increases from 0.3 to 0.9.For piles maintaining stability under oblique cyclic loading,the average normalized secant stiffness exceeds 1 and increases with decreasing inclination,indicating enhanced pile stiffness under cyclic loading.For load inclinations below 30°,pile stiffness can be determined using logarithmic function.
