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1
Li, Zheming, Malcolm D. Bolton i Stuart K. Haigh. "Cyclic axial behaviour of piles and pile groups in sand". Canadian Geotechnical Journal 49, nr 9 (wrzesień 2012): 1074–87. http://dx.doi.org/10.1139/t2012-070.
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Piled foundations are often subjected to cyclic axial loads. This is particularly true for the piles of offshore structures, which are subjected to rocking motions caused by wind or wave actions, and for those of transport structures, which are subjected to traffic loads. As a result of these cyclic loads, excessive differential or absolute settlements may be induced during the piles’ service life. In the research presented here, centrifuge modelling of single piles and pile groups was conducted to investigate the influence of cyclic axial loads on the performance of piled foundations. The influence of installation method was investigated and it was found that the cyclic response of a pile whose jacked installation was modelled correctly is much stiffer than that of a bored pile. During displacement-controlled axial load cycling, the pile head stiffness reduces with an increasing number of cycles, but at a decreasing rate; during force-controlled axial load cycling, more permanent settlement is accumulated for a bored pile than for a jacked pile. The performance of individual piles in a pile group subjected to cyclic axial loads is similar to that of a single pile, without any evident group effect. Finally, a numerical analysis of axially loaded piles was validated by centrifuge test results. Cyclic stiffness of soil at the base of pre-jacked piles increases dramatically, while at base of jacked piles it remains almost constant.
2
Mahmood, Aseel Kahlan, i Jasim M. Abbas. "The Effect of Vertical Loads and the Pile Shape on Pile Group Response under Lateral Two-Way Cyclic Loading". Civil Engineering Journal 5, nr 11 (3.11.2019): 2377–91. http://dx.doi.org/10.28991/cej-2019-03091418.
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This paper is presented the lateral dynamic response of pile groups embedded in dry sand under influence of vertical loads and the pile shape in-group, which are subjected to the lateral two-way cyclic loads. The laboratory typical tests with pile groups (2×1) have an aluminum-pipe (i.e. circular, square) pile, embedded length to diameter of pile ratio (L/D=40) and spacing to diameter ratio (S/D) of 3, 5, 7 and 9 are used with different cyclic-load ratio (CLR) 0.4, 0.6 and 0.8. The experimental results are revealed that both the vertical and lateral pile capacity and displacement is significantly affected by the cyclic-loading factors i.e. (number of cycles, cyclic load ratio, and shape of pile) .In this study, important design references are presented. Which are explained that the response of the pile groups under cyclic lateral loading are clear affected by the attendance of vertical load and pile shape. Where, it is reduction the lateral displacement of group piles head and increase lateral capacity about (50) % compared without vertical loads. On the other side, the pile shape is a well affected to the pile response where the level of decline in lateral displacement at the pile groups head in the square pile is more than circular pile about 20 % at the same load intensity.
3
Briaud, Jean-Louis, i Guy Y. Felio. "Cyclic axial loads on piles: Analysis of existing data". Canadian Geotechnical Journal 23, nr 3 (1.08.1986): 362–71. http://dx.doi.org/10.1139/t86-051.
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A data base is collected to study the behavior of piles in clay under cyclic axial loads generated by ocean waves. The data base includes 9 studies on the cyclic behavior of clay samples in laboratory tests, 10 studies on cyclic model pile load tests in clay, and 16 studies on cyclic full-scale pile load tests in clay of which 4 studies are proprietary. First, general conclusions are drawn from inspection of these studies. Then a power law model is used to quantify the soil stiffness degradation as the number of cycles increases. The parameter for the model is back-figured for each case of the data base and general trends are observed. Key words: pile load tests, cyclic loads, laboratory tests, clay.
4
Liang, Haian, Hao Zeng, Kaiwei Cao, Chao Liu i Xinjun Cheng. "Analysis of Cumulative Damage Characteristics of Long Spiral Belled Pile under Horizontal Cyclic Loading at Sea". Shock and Vibration 2021 (9.11.2021): 1–20. http://dx.doi.org/10.1155/2021/2667545.
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In order to study the cumulative damage and failure characteristics of long spiral belled pile under horizontal cyclic loading of offshore wind and waves, a series of indoor experiments on single piles under horizontal cyclic load were carried out. The cycle times as well as load amplitude at the same frequency were considered during the horizontal pseudo-static cyclic tests. On the basis of the distribution of pile deflection, bending moment, and Earth pressure around the pile, the pile-soil interaction was comprehensively discussed. The cumulative energy dissipation characteristics were introduced to describe the damage of test piles. Meanwhile, the effects of load amplitude and cycle times on the cumulative damage of long spiral belled piles were discussed. A power function model for energy dissipation coefficient prediction under multi-stage cyclic load was proposed. The results show that the horizontal peak bearing capacity of long spiral belled pile is increased by 57.2% and 40.4%, respectively, as compared with the straight pile and belled pile under the same conditions. The horizontal displacement mainly occurs at the upper part of the pile. Under the condition of limited cyclic times, the load amplitude has more significant effect on the bearing characteristics of the long spiral belled pile. In contrast to the straight pile and belled pile, the long spiral belled pile has better energy dissipation capacity, and the rank of the energy dissipation capacity of these three piles is long spiral belled pile > belled pile > straight pile. The power function model can well reflect the cumulative damage characteristics of long spiral belled pile under horizontal cyclic loading, and there is a good linear relationship between power function model parameters and load amplitude. The energy dissipation coefficient of long spiral belled pile with diverse cycle times at different mechanical stages of test pile is analysed. Then, the recommended power function model parameters according to different failure stages are proposed. The verification example indicates that the prediction results are close to the measured values with a calculation error of 22%. The prediction model can provide a certain reference for the application of long spiral belled pile in marine structures.
5
Prasad, Y. V. S. N., i S. Narasimha Rao. "Pullout behaviour of model pile and helical pile anchors Subjected to lateral cyclic loading". Canadian Geotechnical Journal 31, nr 1 (1.02.1994): 110–19. http://dx.doi.org/10.1139/t94-012.
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This paper presents the effect of lateral cyclic loading on the pullout capacity of model and helical piles in clayey soil. The tests were conducted on short rigid model piles in the laboratory in three phases, namely lateral static load tests, lateral cyclic load tests, and vertical pullout tests. From the test results it was found that the lateral cyclic loading affects the pullout capacity of piles substantially. Reduction in pullout capacity mainly depends upon the lateral deflection of the pile during cyclic loading and the embedment ratio of the pile. This reduction in the pullout capacity of model piles is presented in terms of nondimensional parameters, viz., degradation factor, lateral deflection ratio, and embedment ratio of pile. However, in the case of helical piles under similar conditions, it was found that the lateral cyclic loading has very little influence on the pullout capacity. The reasons for the better performance of helical piles over ordinary piles are explained. Key words : clay, degradation factor, helical pile, lateral cyclic loading, lateral deflection, Joading level, pile, pullout capacity.
6
Satar, M. H. Mohd, A. Marto i B. A. Othman. "Settlement behaviour of geothermal energy pile under cyclic thermo-axial loads". IOP Conference Series: Earth and Environmental Science 1103, nr 1 (1.11.2022): 012030. http://dx.doi.org/10.1088/1755-1315/1103/1/012030.
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Geothermal energy pile (GEP) foundation is a new type of sustainable geostructure that can be used as an alternative solution to the energy demand for heating and cooling of built structures. However, due to limited information of this system, the installed piles have generally been over-designed to lower the risk of the system failing. This paper presents the findings of the research carried out to evaluate the performance of laboratory scaled GEP model (model pile) under the effects of the cyclic thermal loads on the settlement behaviour of the model pile with and without the application of axial load. A small-scale model pile of 19 mm diameter and 300 mm length (150 mm embedded length) was used in the experimental work while kaolin was chosen as the model soil. The model soil was compacted at 90% maximum dry density (1.4625 Mg/m3) with optimum moisture content (17%) to obtain ‘firm’ consistency, in a container of 450 mm height and 270 mm diameter. Strain gauges were installed along the pile to monitor the temperature. The ultimate load, Qu of model pile was determined as 480 N. It is found that two cycles of thermal load decreased the settlement; the higher the values, the lower the settlement due to pile expansion and soil heaves. For thermo-axially loaded pile with two cycles of thermal load, the reduction was not significant as the effect of settlement due to axial load had caused much more settlement. For the thermo-axial loads of 50°C-100 N, 17% of the settlement at failure, sf occurred after the application of axial load. When two cycles of thermal load were applied from 29°C to 50°C, the settlement occurred reduced to 16%sf. From this study it can be concluded that the effect of two cycles of cyclic thermal loads from 29°C to 50°C on pile subjected to 21% of Qu in firm clay, is negligible. The pile could function satisfactorily as designed. However, the application of higher axial loads and cycles of thermal load may need to be studied as it could potentially cause hazard to the building due to the excessive pile settlement.
7
El Sharnouby, M. M., i M. H. El Naggar. "Field investigation of axial monotonic and cyclic performance of reinforced helical pulldown micropiles". Canadian Geotechnical Journal 49, nr 5 (maj 2012): 560–73. http://dx.doi.org/10.1139/t2012-017.
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Helical piles are used increasingly to support new and existing foundations. This paper presents a field study on the axial monotonic and cyclic behaviour of steel fibre–reinforced helical pulldown micropiles. Test piles consisted of a round corner square helical pile with three helices attached to it, and a steel fibre–reinforced grout shaft. To assess the grout shaft contribution, one helical pile without a grout shaft was tested. Piles were instrumented with strain gauges to evaluate the load-transfer mechanism. This paper discusses the load–displacement response of this pile system, and load-sharing mechanism between the grout shaft and lead section. The study shows that the grout shaft significantly improves the helical pile axial performance. It was found that the load-transfer mechanism within the lead section is through individual bearing of each helix. Also, the findings demonstrate that the behaviour of this pile system is satisfactory under one-way cyclic loading conditions. The results suggest that the reinforced helical pulldown micropile is a viable deep foundation option for axial monotonic and one-way cyclic loading applications.
8
Lu, Yiwei, Hanlong Liu, Changjie Zheng i Xuanming Ding. "Experimental Study on the Behavior of X-Section Pile Subjected to Cyclic Axial Load in Sand". Shock and Vibration 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/2431813.
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X-section cast-in-place concrete pile is a new type of foundation reinforcement technique featured by the X-shaped cross-section. Compared with a traditional circular pile, an X-section pile with the same cross-sectional area has larger side resistance due to its larger cross-sectional perimeter. The behavior of static loaded X-section pile has been extensively reported, while little attention has been paid to the dynamic characteristics of X-section pile. This paper introduced a large-scale model test for an X-section pile and a circular pile with the same cross-sectional area subjected to cyclic axial load in sand. The experimental results demonstrated that cyclic axial load contributed to the degradation of shaft friction and pile head stiffness. The dynamic responses of X-section pile were determined by loading frequency and loading amplitude. Furthermore, comparative analysis between the X-section pile and the circular pile revealed that the X-section pile can improve the shaft friction and reduce the cumulative settlement under cyclic loading. Static load test was carried out prior to the vibration tests to investigate the ultimate bearing capacity of test piles. This study was expected to provide a reasonable reference for further studies on the dynamic responses of X-section piles in practical engineering.
9
Zhu, Zhao-rong, Wei Guan, Kan Han, Hong-gang Wu, Shou-quan Zhao i Xu Liu. "Experimental Study on the Dynamic Characteristics of a New Long-Short Pile Composite Foundation under Long-Term Train Load". Shock and Vibration 2023 (30.01.2023): 1–16. http://dx.doi.org/10.1155/2023/7032053.
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Long-short pile composite foundation (PC-LSPCF) composed of part-screw pile and cement-soil compaction pile is a new railway foundation treatment method, which has been widely used in high-speed railway construction projects in China. To explore the dynamic characteristics and deformation characteristics of railway PC-LSPCF under long-term train loads, the dynamic characteristics of long piles, short piles, and soil between piles under long-term train loads are tested by an indoor dynamic model test. The dynamic amplification of pile and soil under dynamic load and the temporal and spatial distribution of peak response are analyzed, and the stress and deformation development mechanism of PC-LSPCF under cyclic loading of large-cycle trains is revealed. The results show that the neutral point of the long pile is at 1/2 of the pile length and that of the short pile is at 3/8 of the pile length. The part-screw pile has a certain absorption effect on vibration energy. The deformation of a long-short pile composite foundation under long-term train loads can be divided into three stages: extreme growth, transition, and stability. The train speed is negatively correlated with the cumulative settlement of the long-short pile composite foundation. The higher the train speed, the smaller the cumulative settlement, and the smaller the number of cycles of the N-S curve entering the gentle period. As the number of train cyclic loads increases, the load-sharing relationship of the long pile-short pile-soil system will be redistributed. The research results have important reference significance for the optimization design of high-speed railway foundation treatment.
10
Liu, Kaifu, Yiguo Yang, Lei Wang, Jiapei Xu i Xinyu Xie. "Experimental Investigation of Geosynthetic-Reinforced Pile-Supported Composite Foundations under Cyclic Loading". Advances in Civil Engineering 2020 (17.12.2020): 1–11. http://dx.doi.org/10.1155/2020/8886131.
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A series of model tests were conducted in this study to investigate the deformation characteristics of geosynthetic-reinforced pile-supported (GRPS) composite foundations under cyclic loading. The effects of the applied load, the number of geogrid layers, and types of piles on the performance of the GRPS composite foundation were studied through 1g physical models of composite foundation with well-planned instrumentation. Furthermore, a numerical fitting method was used to assess the relationship between the foundation settlement and the number of load cycles. The results show that with the increase in the magnitude of cyclic load and the number of load cycles, the settlement of GRPS composite foundations and the strain of the pile and geogrid increased accordingly. Adding rigid piles and increasing the number of geogrid layers both could reduce the settlement of GRPS composite foundations, while adding rigid piles was more effective. The relationship between the foundation settlement and the number of load cycles can be expressed by an exponential regression function. The pile strain varied from place to place that the strain of the upper part of the pile was greater than that of the lower part. The geogrid showed a significant impact on the load transfer mechanism of the composite foundation as the geogrid closer to piles endured larger strain. It is critical to consider the variation of the pile strain and the geogrid strain under cyclic loading in the geotechnical practice of composite foundation. The model test results also suggest that the use of GRPS system can effectively reduce the composite foundation settlement. This paper can provide useful references for developing the theoretical framework and design guides for GRPS composite foundations under cyclic loading.
11
Swinianski, Jerzy, i Andrzej Sawicki. "A model of soil–pile interaction owing to cyclic loading". Canadian Geotechnical Journal 28, nr 1 (1.02.1991): 11–19. http://dx.doi.org/10.1139/t91-002.
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A model of a pile–soil system subjected to vertical cyclic loading is proposed. The model is based on the classical t–z concept and on the compaction theory of granular materials to study the reduction of shearing resistance around a shaft owing to cyclic loading and the redistribution of loads carried by the shaft and tip of a pile. The model is applied to predict the behaviour of cyclically loaded piles in experimental conditions. Theoretical predictions against experimental data are presented. The model gives realistic predictions from a qualitative view point. Quantitative agreement is obtained for large-scale tests. Key words: piles, theoretical model, cyclic loading, compaction theory, redistribution of load transfer.
12
Liu, Chunhui, Liang Tang i Xianzhang Ling. "Investigation of piles behavior under lateral cyclic load". Engineering review 39, nr 3 (17.06.2019): 213–20. http://dx.doi.org/10.30765/er.39.3.01.
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In this paper, the capability of 3D nonlinear finite element models is validated by single pile and 5x3 pile group filed experiments that is subjected to cyclic lateral loading. Then, a series 3D finite elements models are built to analyze the effect of the number of cycles of lateral loading, pile spacing, and pile group arrangement. The results have shown that the number of cycles affected the pile-soil system stiffness seriously, and the pile group effect became insignificant as the increase of pile spacing, while this effect became more significant with the increase of the pile group arrangement. In practical engineering, the pile spacing and pile group arrangement should be considered and chosen carefully.
13
Massad, Faiçal. "Theoretical and Experimental Studies on the Resilience of Driven Piles". Soils and Rocks 37, nr 2 (1.05.2014): 113–32. http://dx.doi.org/10.28927/sr.372113.
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This paper deals with the resilient condition that may be reached by driven piles, during its installation as well as under static cyclic and monotonic loading tests. During the 1950’s Van Weele observed its effect in the context of a method for the separation of the toe and shaft loads at failure using the results of static cyclic loading tests on driven piles. Under this condition and based on a mathematical model that uses Cambefort’s Relations and takes into account pile compressibility and residual loads, this paper shows that there is a homothetic relation between the loading and the unloading-movement curves at pile head. A graphical construction is presented along with a numerical procedure allowing to improve the understanding of pile behavior and to determine significant parameters of pile-soil interaction under static or driving loadings. Application of the homothetic relations is made to several piles and particularly a new procedure was developed to analyze dynamic loading tests with a single blow record, considering the residual load at the toe.
14
Wang, Feng, Ji Feng Liang i Guo Bao. "Grid Service Behavior in Geogrid-Reinforced and Pile-Supported Composite Foundations". Applied Mechanics and Materials 204-208 (październik 2012): 751–54. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.751.
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In geogrid-reinforced and pile-supported composite foundations, the piles, grids and soil compose a complex system in which the three parties perform in coordination to bear the loads. The service behavior and functional mechanism of the geogrids are explored through static and cyclic load tests.
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Zhuang, Yan, Xiangwei Song i Kangyu Wang. "Ground Reaction of Lightly Overconsolidated Subsoil in Reinforced Piled Embankment under Cyclic Loads". Sustainability 15, nr 1 (29.12.2022): 619. http://dx.doi.org/10.3390/su15010619.
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Subsoil support is generally ignored in the design of reinforced piled embankments, resulting in a very conservative design for settlement control. This design philosophy may lead to an unnecessary increase in construction costs, especially for embankments constructed over subsoil of medium and high compressibility (i.e., compression index of subsoil larger than 0.2). This paper presents the ground reaction of lightly overconsolidated subsoil in a reinforced piled embankment subjected to cyclic loads for the purpose of investigating the general behavior of lightly overconsolidated subsoil, and it promotes the sustainable development of piled embankment technology. The ground reaction of subsoil under both static and cyclic loads was comprehensively analyzed in terms of settlement and incremental vertical stress, which exhibited approximately the same profile. However, the settlement of lightly overconsolidated subsoil under a cyclic load was 23% larger than that under a static load. A parametric study was then performed under cyclic loads, and the results showed that the vertical stress carried by the subsoil was the most sensitive to the pile spacing amongst all the parameters considered in this paper. The analysis demonstrated an approximately 88% increase in stress when spacing was enlarged from 2.0 to 3.0 m. Finally, a modified analytical method for the ground reaction of lightly overconsolidated subsoil under cyclic loads was presented, and it showed reasonable agreement with the numerical simulation, particularly for relatively low geogrid stiffnesses, low embankment height (<6.5 m), and small pile spacing (e.g., 2–3 m center to center).
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Buckley, R. M., R. J. Jardine, S. Kontoe i B. M. Lehane. "Effective stress regime around a jacked steel pile during installation ageing and load testing in chalk". Canadian Geotechnical Journal 55, nr 11 (listopad 2018): 1577–91. http://dx.doi.org/10.1139/cgj-2017-0145.
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This paper reports experiments with 102 mm diameter closed-ended instrumented Imperial College piles (ICPs) jacked into low- to medium-density chalk at a well-characterized UK test site. The “ICP” instruments allowed the effective stress regime surrounding the pile shaft to be tracked during pile installation, equalization periods of up to 2.5 months, and load testing under static tension and one-way axial cyclic loading. Installation resistances are shown to be dominated by the pile tip loads. Low installation shaft stresses and radial effective stresses were measured that correlated with local cone penetration test (CPT) tip resistances. Marked shaft total stress reductions and steep stress gradients are demonstrated in the vicinity of the pile tip. The local interface shaft effective stress paths developed during static and cyclic loading displayed trends that resemble those seen in comparable tests in sands. Shaft failure followed the Coulomb law and constrained interface dilation was apparent as the pile experienced drained loading to failure, although with a lesser degree of radial expansion than with sands. Radial effective stresses were also found to fall with time after installation, leading to reductions in shaft capacity as proven by subsequent static tension testing. The jacked, closed-ended, piles’ ageing trends contrast sharply with those found with open piles driven at the same site, indicating that ageing is affected by pile tip geometry and (or) installation method.
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Zhou, Shengquan, Haojin Zhang, Rui Wang i Dongwei Li. "Model Test of Bearing Characteristics of Fly Ash Foundation under Cyclic Loading". Processes 10, nr 6 (2.06.2022): 1117. http://dx.doi.org/10.3390/pr10061117.
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Based on the vertical cyclic model test of the cement-fly ash mixing pile (CFMP) composite foundation, the effects of different dynamic load ratios on the long-term bearing characteristics of the composite foundation were studied. From the perspectives of foundation cumulative settlement, dynamic stiffness, pile axial force, and pile lateral friction, etc., the bearing mechanism of the CFMP fly ash composite foundation under cyclic load was investigated. By virtue of the assay herein, the authors discovered that the cumulative settlement under different load ratios exhibited the “threshold effect”, which could be divided into the attenuation type and destruction type. When the peak value of the cyclic load was close to the ultimate bearing capacity, the dynamic failure of the pile foundation occurred. The cyclic displacement ratio ranged from 1.05 to 1.23, satisfying the relation of quadratic equation. The cyclic load settlement could be predicted by the static load displacement. During cyclic loading, the proportion of the pile side sharing the upper load decreased persistently, and the fatigue degradation of side friction resistance occurred. The degradation could be alleviated by reducing the water content of fly ash and taking waterproof measures during construction.
18
Jalbi, Saleh, Joseph Hilton i Luke Jacques. "Assessment of Practical Methods to Predict Accumulated Rotations of Monopile-Supported Offshore Wind Turbines in Cohesionless Ground Profiles". Energies 13, nr 15 (31.07.2020): 3915. http://dx.doi.org/10.3390/en13153915.
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Monopiles supporting offshore wind turbines can experience permanent non-recoverable rotations (or displacements) during their lifetime due to the cyclic nature of hydrodynamic and aerodynamic loading exerted on them. Recent studies in the literature have demonstrated that conventional cyclic p–y curves recommended in different codes of practice (API-RP-2GEO and DNVGL-RP-C212) may not capture the effects of long-term cyclic loads as they are independent of the loading profile and the number of applied cycles. Several published methodologies based on laboratory scaled model tests (on sands) exist to determine the effect of cyclic lateral loads on the long-term behaviour of piles. The tests vary in terms of the pile behaviour (rigid or flexible pile), number of applied loading cycles, and the load profile (one-way or two-way loading). The best-fit curves provided by these tests offer practical and cost-efficient methods to quantify the accumulated rotations when compared to Finite Element Method. It is therefore desirable that such methods are further developed to take into account different soil types and the complex nature of the loading. The objective of this paper is to compare the performance of the available formulations under the actions of a typical 35-h (hour) storm as per the Bundesamt für Seeschifffahrt und Hydrographie (BSH) recommendations. Using classical rain flow counting, the loading time-history is discretized into load packets where each packet has a loading profile and number of cycles, which then enables the computation of an equivalent number of cycles of the largest load packet. The results show that the loading profile plays a detrimental role in the result of the accumulated rotation. Furthermore, flexibility of the pile also has an important effect on the response of the pile where predictions obtained from formulations based on flexible piles resulted in a much lower accumulated rotation than tests based on rigid piles. Finally, the findings of this paper are expected to contribute in the design and interpretation of future experimental frameworks for Offshore Wind Turbine (OWT) monopiles in sands, which will include a more realistic loading profile, number of cycles, and relative soil to pile stiffness.
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Baek, Sung-Ha, i Joonyoung Kim. "Investigation of p-y Behaviors of a Cyclic Laterally Loaded Pile in Saturated Silty Sand". Advances in Civil Engineering 2022 (5.12.2022): 1–16. http://dx.doi.org/10.1155/2022/1811795.
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This study aimed to evaluate the p-y behavior of pile foundations installed in saturated silty sand subject to cyclic lateral loading. Model piles were installed in saturated silty sand with three relative densities (40%, 70%, 90%), and lateral loads of three magnitudes were repeatedly applied. The model test results revealed that as the cyclic lateral loading was applied to the piles, the soil around the piles became densified in the loose soil (relative density of 40%), and the stiffness of the p-y curve increased. In contrast, in dense soil (relative density of 70% and 90%), the stiffness of the p-y curve decreased as the soil around the piles was disturbed. Special attention was devoted to the development of static and cyclic p-y curves for assessing the lateral behavior of offshore pile foundations installed in saturated silty sand. A comparison between the p-y curves derived in this study and the existing p-y curves for silica sand revealed that the existing p-y curves were more likely to overestimate the lateral load capacity of a pile installed in silty sand.
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Heidari, Mehdi, Mojtaba Jahanandish, Hesham El Naggar i Arsalan Ghahramani. "Nonlinear cyclic behavior of laterally loaded pile in cohesive soil". Canadian Geotechnical Journal 51, nr 2 (luty 2014): 129–43. http://dx.doi.org/10.1139/cgj-2013-0099.
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Pile foundations may be subjected to lateral dynamic loads due to different hazards, such as impact of ships on bridge piers or jetties during berthing, wave and wind actions on offshore structures, and seismic wave motion on different buildings. The beam on nonlinear Winkler foundation (BNWF) approach is widely employed for predicting the response of piles under lateral loading because of its simplicity and practical accuracy. p–y curves are employed to represent the nonlinear soil reactions within the framework of the BNWF approach. However, they are empirically obtained from limited full-scale field tests and are not unique, accounting only for the pile width and not its mechanical properties. On the other hand, the strain wedge (SW) method allows the assessment of three-dimensional (3-D) soil–pile interaction of laterally loaded piles by incorporating soil continuity and pile properties as well as soil properties. In this study, the nonlinear p–y curves generated by the SW model are implemented as the backbone curve of developed BNWF model to effectively account for different response features of the pile–soil system. These features include the soil and pile nonlinear behavior, cyclic degradation of soil stiffness and strength, formation of soil–pile gap, and radiation damping. Two case studies of cyclic lateral load tests for single piles are investigated to examine the effects of soil degradation and gap formation on the response of laterally loaded piles embedded in cohesive soil. The developed model is shown to be capable of representing different soil–pile interaction features observed in experiments. The predictions of the developed BNWF model are in good agreement with experimental results. Finally, a comprehensive parametric study is performed to compare the predictions of the SWM-based model of the pile response under cyclic loading with that obtained from the conventional p–y curve–based model for different pile cross-section configurations, mechanical properties (strength and stiffness), and soil strength–stiffness.
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Yuan, Bingxiang, Zhijie Li, Weijie Chen, Jin Zhao, Jianbing Lv, Jie Song i Xudong Cao. "Influence of Groundwater Depth on Pile–Soil Mechanical Properties and Fractal Characteristics under Cyclic Loading". Fractal and Fractional 6, nr 4 (1.04.2022): 198. http://dx.doi.org/10.3390/fractalfract6040198.
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The analysis of the behavior of soil and foundations when the piles in offshore areas are subjected to long-term lateral loading (wind) is one of the major problems associated with the smooth operation of superstructure. The strength of the pile-soil system is influenced by variations in the water content of the soil. At present, there are no studies carried out analyzing the mechanical and deformational behavior of both the material of the laterally loaded piles and soil with groundwater level as a variable. In this paper, a series of 1-g model tests were conducted to explore the lateral behavior of both soil and monopile under unidirectional cyclic loading, based on the foundation of an offshore wind turbine near the island. The influence of underground water level and cyclic load magnitude on the performance of the pile–soil system was analyzed. To visualize the movements of soil particles during the experimental process, particle image velocimetry (PIV) was used to record the soil displacement field under various cyclic loading conditions. The relationship curves between pile top displacement and cyclic steps, as well as the relationship curves between cyclic stiffness and cyclic steps, were displayed. Combined with fractal theory, the fractal dimension of each curve was calculated to evaluate the sensitivity of the pile–soil interaction system. The results showed that cyclic loading conditions and groundwater depth are the main factors affecting the pile–soil interaction. The cyclic stiffness of the soil increased in all test groups as loading progressed; however, an increase in the cyclic load magnitude decreased the initial and cyclic stiffness. The initial and cyclic stiffness of dry soil was higher than that of saturated soil, but less than that of unsaturated soil. The ability of the unsaturated soil to limit the lateral displacement of the pile decreased as the depth of the groundwater level dropped. The greater the fluctuation of the pile top displacement, the larger the fractal dimension of each relationship curve, with a variation interval of roughly 1.24–1.38. The average increment of the cumulative pile top displacement between each cycle step following the cyclic loading was positively correlated with fractal dimension. Based on the PIV results, the changes in the pile–soil system were predominantly focused in the early stages of the experiment, and the short-term effects of lateral cyclic loading are greater than the long-term effects. In addition, this research was limited to a single soil layer. The pile–soil interaction under layered soil is investigated, and the results will be used in more complex ground conditions in the future.
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Ali, Ahmed S., Nahla M. Salim i Husam H. Baqir. "The Performance of Taper Helical Pile Embedded in Loose Sand Under Uplift Static and Cyclic Load Using 3D-Finite Element Analysis". IOP Conference Series: Earth and Environmental Science 961, nr 1 (1.01.2022): 012033. http://dx.doi.org/10.1088/1755-1315/961/1/012033.
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Abstract Piles with helices are a kind of foundation that is capable of withstanding compression, tension, and lateral loads. However, for almost 25 years, this kind of Pile was widely used across the world. Its behaviour is unpredictable and terrifying, especially in Iraq. The present study analysed this kind of Pile using the finite element method. It was recommended that the helical pile geometry be modeled by numerical model technique and the computer program Plaxis 3D. The plaxis 3D software is a well-known geotechnical engineering tool that numerically analyses soil and simulates experimental work in terms of curve matching and outcomes. Furthermore, an analysis of variables was conducted. The primary variable research investigates the influence of the number of helices and the tapered helix distance under static and cyclic load. The final finding is that the more helices in a pile, the smaller the displacement (or amplitude) in comparison to one helix under the effect of uplift static and cyclic load. As a result that the effect of helix number on soil behaviour is more than the effect of changing the distances between helix.
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Salman, Alaa Dawood, i Ali Hamoudi. "Analytical Approach for Load Capacity of Large Diameter Bored Piles Using Field Data". Journal of Engineering 21, nr 8 (1.08.2015): 40–54. http://dx.doi.org/10.31026/j.eng.2015.08.03.
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An analytical approach based on field data was used to determine the strength capacity of large diameter bored type piles. Also the deformations and settlements were evaluated for both vertical and lateral loadings. The analytical predictions are compared to field data obtained from a proto-type test pile used at Tharthar –Tigris canal Bridge. They were found to be with acceptable agreement of 12% deviation.
Following ASTM standards D1143M-07e1,2010, a test schedule of five loading cycles were proposed for vertical loads and series of cyclic loads to simulate horizontal loading .The load test results and analytical data of 1.95m in diameter test pile proved efficiently to carry a working load of 450 tons. The calculated lateral displacements based on a specified coefficient of subgrade reaction are compared to the measured values from dial gauges and strain gauges placed at various locations along the length of the pile.
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Song, Junnan, i Martin Achmus. "Cyclic overlay model of p–y curves for laterally loaded monopiles in cohesionless soil". Wind Energy Science 8, nr 3 (8.03.2023): 327–39. http://dx.doi.org/10.5194/wes-8-327-2023.
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Abstract. The bearing behaviour of large-diameter monopile foundations for offshore wind turbines under lateral cyclic loads in cohesionless soil is an issue of ongoing research. In practice, mostly the p–y approach is applied in the design of monopiles. Recently, modifications of the original p–y approach for monotonic loading stated in the API regulations have been proposed to account for the special bearing behaviour of large-diameter piles with small length-to-diameter ratios. However, cyclic loading for horizontally loaded piles predominates the serviceability of the offshore wind converters, and the actual number of load cycles cannot be considered by the cyclic p–y approach of the API regulations. This research therefore focuses on the effects of cyclic loading on the p–y curves along the pile shaft and aims to develop a cyclic overlay model to determine the cyclic p–y curves valid for a lateral load with a given number of load cycles. A stiffness degradation method (SDM) is applied in a three-dimensional finite element model to determine the effect of the cyclic loading by degrading the secant soil stiffness according to the magnitude of cyclic loading and number of load cycles based on the results of cyclic triaxial tests. Thereby, the numerical simulation results are used to develop a cyclic overlay model, i.e. an analytical approach to adapt the monotonic (or static) p–y curve to the number of load cycles. The new model is applied to a reference system and compared to the API approach for cyclic loads.
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Silva, Matías, Orianne Jenck, Fabrice Emeriault i Jean Benoit Toni. "Experimental study of shear-key equipped pile to grout connection under cyclic loading". E3S Web of Conferences 92 (2019): 13005. http://dx.doi.org/10.1051/e3sconf/20199213005.
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A technical solution for tidal turbine foundation in granite seabed consists of grouted steel piles. The piles would be subjected to cyclic loading due to the severe service conditions. The mechanical behaviour at the interface between the pile and the surrounding media is one of the key points that determine the bearing capacity of the foundation system. Experimental research work has been carried out in the laboratory to study the grouted pile-to-rock connection (GPRC) and focused more precisely on the pile to grout connection when the pile is equipped with shear-keys that enhance the interface capacity. Monotonic and cyclic shear tests were performed using a specific direct shear test device (BCR3D), allowing application of sample confining conditions close to the in-situ conditions, namely constant normal stiffness conditions. Cyclic tests - either under one way or two-way shear loading application - were performed on several samples, under both constant volume and various constant stiffness boundary conditions. This study has shown that the strength of the interface is highly dependent on the combination of mean load, cyclic amplitudes and number of cycles applied to the interface. Cyclic failure was observed with less than 30 cycles for two-way and one-way cyclic loading.
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Sani, Abubakar Kawuwa, i Rao Martand Singh. "Long-Term Thermal Performance of Group of Energy Piles in Unsaturated Soils under Cyclic Thermal Loading". Energies 14, nr 14 (8.07.2021): 4122. http://dx.doi.org/10.3390/en14144122.
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Geothermal energy piles (GEPs) are an environmentally friendly heat exchange technology that dualizes the role of the structural foundation pile for load support and in meeting the building heating/cooling need. Energy loops made from high-density polyethylene, which allow heat carrier fluid circulation, are fitted into the pile foundation elements to extract or inject and store heat energy in the soil surrounding the pile. This paper reports the results of a numerical study investigating the long-term behaviour of a group of energy piles embedded in unsaturated soils (sand and clay) under continuous cyclic heating and cooling load. Additionally, two scenarios were investigated where: (1) the whole GEPs were heated and cooled collectively; (2) alternate piles were heated and cooled. It was found that the trend of temperature magnitude at all the observed locations decreases with time as a result of the continuous heating and cooling cycles. Furthermore, subjecting alternate GEPs to the heating and cooling cycles result in lower temperature development in comparison to thermally activating all the GEPs in the group. This is attributed to the applied thermal load, which is 0.5 times that considered in the first case. However, this might not be the case where equal thermal load is applied on the GEPs in the two cases investigated.
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Liu, Junwei, Zhipeng Wan, Xingke Dai, Dongsheng Jeng i Yanping Zhao. "Experimental Study on Whole Wind Power Structure with Innovative Open-Ended Pile Foundation under Long-Term Horizontal Loading". Sensors 20, nr 18 (18.09.2020): 5348. http://dx.doi.org/10.3390/s20185348.
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The offshore wind energy (OWE) pile foundation is mainly a large diameter open-ended single pile in shallow water, which has to bear long-term horizontal cyclic loads such as wind and waves during OWE project lifetime. Under the complex cyclic loads, the stress and displacement fields of the pile-soil system change continuously, which affects the dynamic characteristics of the pile foundation. Within the service life of the pile foundation, the pile-soil system has irreversible cumulative deformation, which further causes damage to the whole structure. Therefore, it is important to examine the overall dynamic characteristics of wind power foundation under high cycle. In this paper, in the dry sand foundation, taking the Burbo Bank 3.6 MW offshore turbine-foundation structure as the prototype, the horizontal cyclic loading model tests of the wind power pile foundation with the scale of 1:50 were carried out. Considering the factors such as loading frequency and cyclic load ratio, the horizontal dynamic characteristics of the whole OWE pile foundation are studied. The comparison results between the maximum bending moment of pile and the fitting formula are discussed. In conclusion, moment of OWE pile shaft is corresponding to the loading frequency (f = 9 HZ) and loading cycles by fitting formulas. The fatigue damage of the OWE pile does not occurs with low frequencies in high cycles.
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Guner, Serhan, i Sundar Chiluwal. "Cyclic load behavior of helical pile-to-pile cap connections subjected to uplift loads". Engineering Structures 243 (wrzesień 2021): 112667. http://dx.doi.org/10.1016/j.engstruct.2021.112667.
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Cui, Xiaoyan, Yajun Cao i Yanli Jin. "Three-Dimensional Analysis of Load Transfer Mechanism for Deep Cement Mixing Piled Embankment under Static and Cyclic Load". Sustainability 15, nr 8 (12.04.2023): 6532. http://dx.doi.org/10.3390/su15086532.
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Piles have been widely used to improve the bearing capacity of the soft foundation. The existing research obtains significant findings on the load transfer mechanism for rigid piled embankments. However, limited studies have been focused on the deep cement mixing (DCM) piled embankment. To grasp the load transfer characteristics of DCM piled embankments, a three-dimensional numerical simulation was conducted in this study, which was validated by the measurements from the field case. It was found that the effect of soil arching was reduced compared with the rigid piled embankment. This induced approximately 61.5% larger vertical stress transferred to the subsoil surface and approximately 83–150% larger settlement of the embankment in DCM piled foundation system. To further understand the working mechanism of this system, the factors which influence the load transfer mechanism were investigated. It is found that the area replacement ratio is the most influential factor affecting the settlement at the top of the embankment, whereas the elastic modulus of the DCM pile influences most the vertical stress and the earth pressure coefficient. The cyclic load with vehicle speeds of 90 km/h will lead to approximately 34% growth of embankment settlement and about 11% reduction in the maximum earth pressure coefficient. Based on the numerical simulation results, the analytical equation of the normalized vertical stress acting on the subsoil surface for the DCM piled foundation was proposed and validated by two field cases, with the difference in the range of 13.8~16.7%.
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Peng, Wenzhe, Minghua Zhao, Chaowei Yang i Shuai Zhou. "Experimental and Theoretical Study of One-Way Cyclic Lateral Responses of Piles in Sloping Ground". Applied Sciences 12, nr 16 (16.08.2022): 8169. http://dx.doi.org/10.3390/app12168169.
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This study aims to investigate the one-way cyclic lateral responses of piles in sloping ground by means of experimental and theoretical analyses. For this purpose, a series of laboratory model experiments were performed for different cases of cycle number, load amplitude, and slope angle, and lateral static loading tests on both level ground and sloping ground were conducted for comparison. Based on these experimental observations, the effects of cycle number, load amplitude, and slope angle on the pile head deflection and the profiles of bending moment and subgrade reaction are discussed. The pile deflection profile is difficult to measure directly owing to the restriction of experimental conditions, and thus a supplementary finite beam element method (FBEM) is provided to compensate for this deficiency. The comparisons between experimental and theoretical results demonstrate that the FBEM can well predict the pile responses in sloping ground, either under one-way cyclic lateral loading or lateral static loading.
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Nadilla, Saskia, i Widjojo Adi Prakoso. "Pile lateral subgrade reaction modulus for Jakarta". MATEC Web of Conferences 270 (2019): 02002. http://dx.doi.org/10.1051/matecconf/201927002002.
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The behavior of laterally loaded piles could be simulated by the subgrade reaction model. The primary soil parameter for this model is the subgrade reaction modulus, and in this paper, the correlation between the subgrade reaction modulus and the soil N-SPT value is examined by conducting numerical analyses of 34 pile cyclic lateral load tests in Jakarta. In each analysis, the pile is modeled as a series of beam elements, while the surrounding soil is modeled as a series of linear elastic springs. The moduli are varied according to the N-SPT values recorded in the associated deep boring data. In each load cycle, a trial and error process is conducted to match the resulting pile head lateral deflection to the measured value. The resulting correlation between the subgrade reaction modulus and the pile lateral deflection is presented for the 34 case studies and compared to a correlation in the literature. Furthermore, the analyses reveal that subgrade reaction modulus is affected by the magnitude of measured deflection, by the applied lateral loads, as well as by the construction methods.
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Yang, Yuzhe, Xiaodong Gao, Wenbing Wu i Kangyu Xing. "A Simplified Method for Analysis of Laterally Loaded Piles considering Cyclic Soil Degradation". Advances in Civil Engineering 2021 (3.07.2021): 1–10. http://dx.doi.org/10.1155/2021/9096540.
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This paper proposes a simplified method to analyze the bearing behavior of pile undergoing cyclic lateral load. Firstly, a modified strain model is proposed by utilizing the Duncan–Chang model to describe the stress-strain behavior of soils in the strain wedge. Then, a cyclic degradation model of soft clay considering the accumulation of plastic strain and pore water pressure is presented based on the cyclic triaxial test. Combining with the modified strain wedge model and degradation model of soil, a simplified method is established for the cyclic laterally loaded pile. The accuracy of the present method is verified by comparing it with existing model tests. The results show that the pile lateral displacement and strain wedge depth increase with the number of cycles and cyclic load amplitude. It is necessary to consider the effect of cumulative pore water pressure during the analysis of cyclic laterally loaded pile embedded in soft clay.
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Zhang, Ben-jiao, Bin Huang, Can Mei, Xu-dong Fu, Gang Luo i Zhi-jun Yang. "Dynamic Behaviours of a Single Soft Rock-Socketed Shaft Subjected to Axial Cyclic Loading". Advances in Materials Science and Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/7457086.
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The soft rock was simulated by cement, plaster, sand, water, and concrete hardening accelerator in this paper. Meanwhile, uniaxial compressive strength tests and triaxial compression tests were conducted to study the mechanical properties of simulated soft rock samples. Model tests on a single pile socketed in simulated soft rock under axial cyclic loading were conducted by using a device which combined test apparatus with a GCTS dynamic triaxial system. Test results show that the optimal mix ratio is cement : plaster : medium sand : water : concrete hardening accelerator = 4.5% : 5.0% : 84.71% : 4.75% : 1.04%. The static load ratio (SLR), cyclic load ratio (CLR), and the number of cycles affect the accumulated deformation and cyclic secant modulus of the pile head. The accumulated deformation increases with increasing numbers of cycles. However, the cyclic secant modulus of pile head increases and then decreases with the growth in the number of cycles and finally remains stable after 50 cycles. According to the test results, the development of accumulated settlement was analysed. Finally, an empirical formula for accumulated settlement, considering the effects of the number of cycles, the static load ratio, the cyclic load ratio, and the uniaxial compressive strength, is proposed which can be used for feasibility studies or preliminary design of pile foundations on soft rock subjected to traffic loading.
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Hu, Juan, Yi Fan Song i Zuo Long Luo. "Research Status of Modeling Test on Pile Foundation of Existed Bridge". Applied Mechanics and Materials 488-489 (styczeń 2014): 377–80. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.377.
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The pile-soil dynamics is an interdisciplinary studies of structural, geotechnical and vibration engineering in the existing bridge. Traffic load model, the developments and status in the existing bridge were reviewed and introduced. The main content and characteristic of pile were summarized in clay, sand, silt and red clay. Main problems existed in the study of cyclic loaders on the piles were discussed. The prospect of future research trend in this field was also examined.
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Huang, FY, L. Li, F. Zhang i YW Lin. "Study on Calculation Method of Internal Force of Integral Abutment-Pile-Soil Interaction". Journal of Physics: Conference Series 2158, nr 1 (1.01.2022): 012005. http://dx.doi.org/10.1088/1742-6596/2158/1/012005.
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Abstract Integral abutment jointless bridge (iajb) has the advantages of long service life, convenient construction and low construction and maintenance cost. At present, it has been widely used at home and abroad. Based on an actual iajb, an experimental model of integral abutment pile structure is designed and made. The quasi-static test is carried out under low cyclic displacement load, and the interaction between integral abutment, H-steel pile and soil is studied, with emphasis on the strain and bending moment of abutment and pile foundation. The test results show that the strain distribution of pile body is “Cup” shape when the abutment moves forward and “olive” shape when the abutment moves negatively. The maximum compressive stress and tensile stress under positive displacement load are greater than those under negative displacement load. Therefore, when the temperature increases, the internal force of pile foundation is greater than that when the temperature decreases, which means that H-shaped steel foundation pile is more unfavorable when the temperature increases in summer. In order to reduce the adverse effect of temperature on foundation piles, it is suggested that the overall closure temperature of the bridge should be slightly higher than the annual average temperature. In addition, the calculation also shows that when negative load is adopted, the pile bending moment calculated by these methods is not different from the test results, and the distribution law is similar to that of traditional foundation piles. However, under normal load, the pile bending moment calculated by classical theory or bridge code is quite different from the test results, and the distribution law is also different. In this paper, the moment of integral abutment pile-soil interaction is calculated accurately by polynomial fitting method and huanglin method, which can be used in practical engineering and provide reference for the design and application of iajbs.
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Gavin, Kenneth, David Gallagher, Paul Doherty i Bryan McCabe. "Field investigation of the effect of installation method on the shaft resistance of piles in clay". Canadian Geotechnical Journal 47, nr 7 (lipiec 2010): 730–41. http://dx.doi.org/10.1139/t09-146.
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This paper presents the results of a series of field experiments performed to study the effect of installation method on the shaft resistance developed by a pile installed in soft clayey silt. Tests were performed on piles that experienced different levels of cyclic loading during installation. The test results indicate that the radial total stress, pore-water pressure, and shear stress on the pile shaft during installation were strongly affected by the installation procedure; all three were found to increase when the jacking stroke length used during installation increased (or the number of cyclic load applications decreased). However, equalized radial effective stresses that control the long-term pile shaft capacity were found to be insensitive to the installation method. A simple expression that requires the results of a cone penetration test, laboratory measurements of the interface friction angle, and the pile geometry is proposed to calculate the shaft resistance.
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Mostafa, Yasser E., i M. Hesham El Naggar. "Dynamic analysis of laterally loaded pile groups in sand and clay". Canadian Geotechnical Journal 39, nr 6 (1.12.2002): 1358–83. http://dx.doi.org/10.1139/t02-102.
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Pile foundations supporting bridge piers, offshore platforms, and marine structures are required to resist not only static loading but also lateral dynamic loading. The static py curves are widely used to relate pile deflections to nonlinear soil reactions. The p-multiplier concept is used to account for the group effect by relating the load transfer curves of a pile in a group to the load transfer curves of a single pile. Some studies have examined the validity of the p-multiplier concept for the static and cyclic loading cases. However, the concept of the p-multiplier has not yet been considered for the dynamic loading case, and hence it is undertaken in the current study. An analysis of the dynamic lateral response of pile groups is described. The proposed analysis incorporates the static py curve approach and the plane strain assumptions to represent the soil reactions within the framework of a Winkler model. The model accounts for the nonlinear behaviour of the soil, the energy dissipation through the soil, and the pile group effect. The model was validated by analyzing the response of pile groups subjected to lateral Statnamic loading and comparing the results with field measured values. An intensive parametric study was performed employing the proposed analysis, and the results were used to establish dynamic soil reactions for single piles and pile groups for different types of sand and clay under harmonic loading with varying frequencies applied at the pile head. "Dynamic" p-multipliers were established to relate the dynamic load transfer curves of a pile in a group to the dynamic load transfer curves for a single pile. The dynamic p-multipliers were found to vary with the spacing between piles, soil type, peak amplitude of loading, and the angle between the line connecting any two piles and the direction of loading. The study indicated the effect of pile material and geometry, pile installation method, and pile head conditions on the p-multipliers. The calculated p-multipliers compared well with p-multipliers back-calculated from full scale field tests.Key words: lateral, transient loading, nonlinear, pilesoilpile interaction, py curves, Statnamic.
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Wheeler, Lisa N., Michael T. Hendry, W. Andy Take i Neil A. Hoult. "Field performance of a peat railway subgrade reinforced with helical screw piles". Canadian Geotechnical Journal 55, nr 12 (grudzień 2018): 1888–99. http://dx.doi.org/10.1139/cgj-2017-0594.
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Rail tracks on peat subgrades can experience significant deflections, some of which have led to derailments. A potential ground stabilization strategy is to use screw piles to reduce rail displacements; however, limited research has been undertaken to investigate the effect of these piles and their performance under cyclic train loading. A field site was instrumented and monitored before and after screw pile installation. The piles were instrumented with strain gauges, piezometers were installed in the peat, and high-speed cameras were used to measure track and subgrade displacements. The load carried by each instrumented pile was approximately 50–60 kN 3 weeks after installation, but reduced to approximately 30 kN after 6 months. Although 1 year’s worth of piezometric data were collected before installation of the piles, it is difficult to conclusively attribute the changes in pore pressures to the piles, particularly because the piezometric data collected after the pile installation were only available for the 7 months that exhibit the period of greatest seasonal fluctuations. The track support system deformations showed no significant difference pre- and post-pile installation. Therefore, based on the monitoring data at this site, it appears that the designed transfer of load from the ties to the piles through arching within the ballast layer was not realized.
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Basack, Sudip. "Design Recommendations for Pile Subjected to Cyclic Load". Marine Georesources & Geotechnology 33, nr 4 (4.01.2015): 356–60. http://dx.doi.org/10.1080/1064119x.2013.778378.
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Basack, Sudip, i Abhik Kumar Banerjee. "Offshore Pile Foundation Subjected to Lateral Cyclic Load in Layered Soil". Advanced Materials Research 891-892 (marzec 2014): 24–29. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.24.
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The pile foundations supporting offshore structures are required to be designed against cyclic load, moments and torques initiated by a combined action of waves, wind, tides, currents, etc. Such a complex loading condition produces progressive degradation in the pile-soil interactive performance which is likely to introduce significant reduction in bearing capacity with increased settlement and displacements. This paper is based on a numerical model developed by the Authors to study the response of pile foundation under lateral cyclic load in layered soil. The model is validated with a field test data and thereafter, parametric studies have been carried out. A brief description of the works conducted and the major conclusions drawn are highlighted in this paper.
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Cheng, Junfeng, Xiaoyong Luo, Yizhou Zhuang, Liang Xu i Xiaoye Luo. "Experimental Study on Dynamic Response Characteristics of RPC and RC Micro Piles in SAJBs". Applied Sciences 9, nr 13 (29.06.2019): 2644. http://dx.doi.org/10.3390/app9132644.
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The pile foundations below approach slab in a semi-integral abutment jointless bridge (SAJB) that requires high flexibility to accommodate the horizontal cyclic deformation of approach slab generated by the girder’s thermal expansion and contraction as well as earthquake action. In this paper, reactive powder concrete (RPC) and reinforce concrete (RC) micro piles were designed and fabricated. The shaking table tests on dynamic response of micro piles-soil interaction were conducted to investigate the dynamic response characteristics such as the strain time history of pile-soil system, the bending moment, and the deformation of piles. The maximum strain response of piles was observed at the buried depth of 4.2 D (D is the diameter of pile). Meanwhile, the maximum bending moments of RPC and RC piles appear at the depth of 0.64 D and 0.42 D, respectively, under the dynamic load excitation, and the peak horizontal deformation of piles were observed at pile head. It is found that the bending moment and the strain response of the RPC pile are larger than that of the RC micro pile, and increased by 40% and 98%, respectively. The RPC micro pile has better crack resistance, higher ductility, and flexural rigidity than that of the RC pile, and it can be widely used as pile foundations in SAJBs for the earthquake area.
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Jenck, Orianne, Armita Obaei, Fabrice Emeriault i Christophe Dano. "Effect of Horizontal Multidirectional Cyclic Loading on Piles in Sand: A Numerical Analysis". Journal of Marine Science and Engineering 9, nr 2 (23.02.2021): 235. http://dx.doi.org/10.3390/jmse9020235.
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Foundations of offshore and nearshore wind energy production systems are subjected to multidirectional and cyclic loads, due to the combined action of wind and waves and in the particular case of mutualized anchor foundations for floating wind turbines, to the phase shift between the loads generated in the adjacent anchored turbines. This article presents a three-dimensional numerical model developed with FLAC3D to analyse the impact of the change in direction of the horizontal load during the cycles. The typical case of a 1.7 m diameter and 10 m-long pile founded in a dense homogeneous sand is considered. A specific procedure has been implemented to apply force-controlled cycles with a change in lateral load direction. The results are compared to mono-directional lateral cyclic loads with the same average and cyclic forces. The results of the parametric study highlight the effect of the average value and amplitude of the cyclic loading on the accumulation of pile head horizontal displacements during the cycles. When a multidirectional cyclic loading is applied, it also leads to an accumulation of the deviated horizontal displacements, and the resulting accumulated horizontal displacements are larger than for a mono-directional cyclic loading of the same amplitude.
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Fu, Qiang. "Experimental Analysis on Dynamic Response of X-Section Piled Raft Composite Foundation under Cyclic Axial Load for Ballastless Track in Soft Soil". Shock and Vibration 2021 (19.10.2021): 1–17. http://dx.doi.org/10.1155/2021/4561806.
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Large-scale model tests were established at a scale of 1/5 using a 7 m deep model tank with cross-sectional dimension of 5 m × 4 m, to study the vibration response characteristics of ballastless track, embankment, and X-section piled raft foundation under cyclic axial load, including the vibration displacement, velocity, dynamic soil, and pile stress. Cyclic dynamic loading can be achieved by controlling the loading frequency and cycles through the vibration servo control loading system. The test results are presented in the variation of dynamic displacement, velocity, and stress of X-section piled raft composite foundation. The vibration displacement, velocity, and stress of the track, embankment, and pile foundation follow a pattern of vibration characteristics of loading sine wave. The vibration characteristics of loading waves can be identified easily from the peaks and troughs in the dynamic response of displacement, velocity, and stress at many locations of track slab, embankment, cushion, and underlying soil, at which the vibration response presents almost monotonically increasing tendency with the loading frequencies. With the increase of loading frequency, the vibration responses at the track structure and embankment have higher increasing rates than those at substructure (raft, cushion, and subsoil). The piled raft bears more dynamic load than cushion and subsoils, to ensure long-term dynamic stability and safety of the foundation soils. The model testing results provide a better understanding of the dynamic response characteristics of ballastless track, embankment, and X-section piled raft foundation under cyclic axial load in soft soil.
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Rui, Yi, i Mei Yin. "Investigations of pile–soil interaction under thermo-mechanical loading". Canadian Geotechnical Journal 55, nr 7 (lipiec 2018): 1016–28. http://dx.doi.org/10.1139/cgj-2017-0091.
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Thermo-active piles that couple load bearing with ground source heat pump systems are one of the new technologies in geotechnical engineering. This paper investigates the pile–soil interaction behaviour of a thermo-active pile in overconsolidated London clay by conducting a thermo-hydro-mechanical finite element analysis using an advanced soil constitutive model. Negative and positive excess pore pressures are computed around the pile during cooling and heating, respectively. However, the difference in the radial effective stress acting on the pile–soil interface between the cooling and heating stages is small, and the pile–soil interaction is governed by the shear mobilization associated with thermally induced cyclic movements of pile expansion and contraction. During the first cooling stage, the shear stress at a small portion in the upper part of the pile reaches close to the yield values, which leads to an additional settlement about 3 mm from the original mechanical load–induced settlement of 2 mm. The shear stresses in subsequent heating and cooling cycles are much smaller than the ultimate shear stress values, because of the heavily overconsolidated nature of the London clay.
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Sun, Yong-Xin, Zhi-Peng Wang, Hong-Qiang Dou, Zhan-Fei Qu, Bing-Lei Xue i Ling-Yun Feng. "Influence of Horizontal Loading in Changing the Ultimate Uplift Bearing Capacity of Monopile Foundation of Offshore Wind Turbine". Journal of Marine Science and Engineering 11, nr 6 (31.05.2023): 1150. http://dx.doi.org/10.3390/jmse11061150.
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Throughout their lifespan, monopile foundations supporting offshore wind turbines inevitably experience horizontal loads from waves, winds, and currents, resulting in cumulative deformation. It has been believed that deformation caused by horizontal loading weakens the interaction between the pile and the soil, leading to a reduction in the ultimate uplift bearing capacity of the pile foundation. However, there is a scarcity of literature investigating this issue, particularly regarding monopiles used in offshore wind turbine installations. Therefore, this study aims to explore the impact of horizontal cyclic loads on the ultimate uplift bearing capacity of monopile, focusing on the pile–soil interaction. To achieve this, a series of 1 g model tests were conducted on a rigid model pile embedded in silt with varying relative compaction. The test results indicate that the ultimate uplift bearing capacity of the pile is significantly diminished after experiencing horizontal cyclic loading, and the extent of reduction is closely linked to the amplitude of the horizontal deformation. A semi-empirical model is developed to predict the ultimate uplift bearing capacity of the pile foundation following horizontal cyclic loading. The key findings of this study are as follows: (1) The earth pressure in the active zone gradually decreases with an increasing number of cycles, while the earth pressure in the passive zone experiences a slight increase under horizontal cyclic loading. (2) The position of the pile rotation center under horizontal cyclic loading is approximately 0.84 times the depth at which the pile is buried, and this relationship appears to be independent of soil density and cyclic load ratio. (3) The variation of earth pressure corresponding to the horizontal deformation of the pile in the active zone can be divided into three phases: a rapid decline phase, a slow decline phase, and a stable phase. (4) The reduction in the ultimate uplift capacity is influenced by the cyclic ratio and number of cycles but does not appear to have a significant relationship with soil density.
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Ding, Ming Bo, i Xing Chong Chen. "Research in Testing of Loess Foundation Pile Hysteretic Property under Horizontal Cyclic Load". Advanced Materials Research 433-440 (styczeń 2012): 202–6. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.202.
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In this paper, by the large scale model test of pile-soil in remodeling loess foundation, authors research the basic discipline of pile-soil interaction plastic hysteretic property of pile foundation in loess area under horizontal cyclic load and obtain hysteretic curves, skeleton curves and relationship between equivalent viscous damping coefficient and displacement under pile-soil interaction. The paper also discusses the intensity components, plastic and other energy and equivalent viscous damping coefficient cycles occur with varying degrees of degradation of the variation.
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David, Thevaneyan K., i John P. Forth. "Integral Pile-Backfill Soil Relationship in Stub-Type Integral Abutment Bridge". Applied Mechanics and Materials 699 (listopad 2014): 388–94. http://dx.doi.org/10.4028/www.scientific.net/amm.699.388.
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Temperature effects are significant to the sustainability of integral abutment bridges with the elimination of expansion joints. The thermally induced lateral movement of the structural components is opposed by the backfill soil supporting the components of integral abutment bridges. A 2D finite element analysis was performed on a typical integral abutment bridge using OASYS SAFE to investigate the complex interactions that exist between the pile supporting stub-type integral abutment and the backfill soil. The primary objective of this paper is to compare the effect of various soil types on the displacement of the piles when subjected to lateral loading and secondly to identify the significance of cyclic lateral load on the behaviour of the piles for various foundation soil types. The results suggest similar effect on the integral pile displacements for investigated soil types, especially for non-cyclic lateral loading.
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Kim, Keunju, Boo Hyun Nam i Heejung Youn. "Effect of Cyclic Loading on the Lateral Behavior of Offshore Monopiles Using the Strain Wedge Model". Mathematical Problems in Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/485319.
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This paper presents the effect of cyclic loading on the lateral behavior of monopiles in terms of load-displacement curves, deflection curves, andp-ycurves along the pile. A commercial software, Strain Wedge Model (SWM), was employed, simulating a 7.5 m in diameter and 60 m long steel monopile embedded into quartz sands. In order to account for the effect of cyclic loading, accumulated strains were calculated based on the results of drained cyclic triaxial compression tests, and the accumulated strains were combined with static strains representing input strains into the SWM. The input strains were estimated for different numbers of cycles ranging from 1 to 105and 3 different cyclic lateral loads (25%, 50%, and 75% of static capacity). The lateral displacement at pile head was found to increase with increasing number of cycles and increasing cyclic lateral loads. In order to model these deformations resulting from cyclic loading, the initial stiffness of thep-ycurves has to be significantly reduced.
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Kahribt, Muqdad Abdallah, i Jasim M. Abbas. "Lateral Response of a Single Pile under Combined Axial and Lateral Cyclic Loading in Sandy Soil". Civil Engineering Journal 4, nr 9 (24.09.2018): 1996. http://dx.doi.org/10.28991/cej-03091133.
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According to practical situation, there have been limited investigations on the response of piles subjected to combined loadings especially when subjected to cyclic lateral loads. Those few studies led to contradictory results with regard to the effects of vertical loads on the lateral response of piles. Therefore, a series of experimental investigation into piles in dense sand subjected to combination of static vertical and cyclic lateral loading were conducted with instrumented model piles. The effect of the slenderness ratio (L/D) was also considered in this study (i.e. L/D= 25 and 40). In addition, a variety of two-way cyclic lateral loading conditions were applied to model piles using a mechanical loading system. One hundred cycles were used in each test to represent environmental loading such as offshore structures. It was found that under combined vertical and cyclic lateral loads the lateral displacement of piles decreased with an increase in vertical load whereas it causes large vertical displacements at all slenderness ratios. In addition, for all loading conditions the lateral, vertical (settlement and upward) displacements and bending moments increased as either the magnitude of cyclic load or the number of cycles increases.
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Lehane, Barry M., i David J. White. "Lateral stress changes and shaft friction for model displacement piles in sand". Canadian Geotechnical Journal 42, nr 4 (1.08.2005): 1039–52. http://dx.doi.org/10.1139/t05-023.
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The paper describes a series of tests performed in a drum centrifuge on instrumented model displacement piles in normally consolidated sand. These tests examined the influence of the pile installation method, the stress level, and the pile aspect ratio on the increase in lateral effective stress on the pile shaft during static load testing to failure. A parallel series of constant normal load and constant normal stiffness (CNS) laboratory interface shear experiments was performed to assist interpretation of the centrifuge tests. It is shown that although the cycling associated with pile installation results in a progressive reduction in the stationary horizontal effective stress acting on a pile shaft and densification of the sand in a shear band close to the pile shaft, this sand dilates strongly during subsequent shearing to failure in a static load test. The dilation (the amount of which depends on the cyclic history) is constrained by the surrounding soil and therefore leads to large increases in lateral effective stresses and hence to large increases in mobilized shaft friction. The increase in lateral stress is shown to be related to the radial stiffness of the soil mass constraining dilation of the shear band and to be consistent with measurements made in appropriate CNS interface shear tests. The paper's findings assist in the extrapolation of model-scale pile test results to full-scale conditions.Key words: sand, displacement pile, centrifuge tests, shaft friction.