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1
Li, Zheming, Malcolm D. Bolton, and Stuart K. Haigh. "Cyclic axial behaviour of piles and pile groups in sand." Canadian Geotechnical Journal 49, no. 9 (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
Lee, Su-Hyung, and Choong-Ki Chung. "An experimental study of the interaction of vertically loaded pile groups in sand." Canadian Geotechnical Journal 42, no. 5 (2005): 1485–93. http://dx.doi.org/10.1139/t05-068.
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The interactions among closely located piles and a cap in a pile group are complex. The current design practice for vertically loaded pile groups roughly estimates their overall behavior and generally yields conservative estimations of the group capacity. For a proper pile group design, factors such as the interaction among piles, the interaction between cap and piles, and the influence of pile installation method all need to be considered. This paper presents the results of the model test, which can be used to better understand the interactions of vertically loaded pile groups in granular soil. Load tests were carried out on the following: an isolated single pile, single-loaded center piles in groups, a footing without any piling, free standing pile groups, and piled footings. The influences of pile driving and the interactions among bearing components on loadsettlement and load transfer characteristics of piles and on the bearing behavior of a cap in a group are investigated separately by comparing their respective test results. The favorable interaction effects that increase pile capacities are identified.Key words: pile group, pile installation, interaction, model test, free standing, piled footing.
3
Bralović, Nemanja, Iva Despotović, and Danijel Kukaras. "Experimental Analysis of the Behaviour of Piled Raft Foundations in Loose Sand." Applied Sciences 13, no. 1 (2022): 546. http://dx.doi.org/10.3390/app13010546.
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This paper presents the experimental analysis that was conducted on small-scale 1g physical models of piled raft foundation structures with a group of 2 × 2 piles in loose sand. The purpose of the piles was to reduce the settlement of the raft. The test program included twelve experiments, three of which were conducted on a raft alone and nine on piled rafts at pile distances of 3d, 4d, and 5d and pile lengths of 10d, 20d, and 40d, where d is pile diameter. The test results show that the current conventional approach to design of piled raft foundations, at a high safety load factor in piles that assume to take the whole external applied load, is very conservative. Instead, it is more economical to apply a low bearing capacity factor for piles as settlement reducers and maximize use of raft bearing capacity to carry part of the external load.
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Alawneh, Ahmed Shlash, Abdallah I. Husein Malkawi, and Husein Al-Deeky. "Tension tests on smooth and rough model piles in dry sand." Canadian Geotechnical Journal 36, no. 4 (1999): 746–53. http://dx.doi.org/10.1139/t98-104.
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In order to delineate the significant variables affecting the ultimate uplift shaft resistance of a pile in dry sand, a testing program comprising 64 pullout tests was conducted on open- and closed-ended rough and smooth model piles of two sizes (41 and 61 mm outside diameter). The model piles were installed in medium dense and dense sand to an embedded depth of 0.8 m using two methods of pile placement, static jacking and driving. A rigid steel box measuring 1.1 × 1.1 × 1.3 m was used as a sand container. The results obtained from this study indicated that pile placement method, initial sand condition, pile surface roughness, and pile end type are all significant variables (given in descending order) affecting the ultimate uplift shaft resistance of a single pile in dry sand. Overall, the closed-ended piles showed a 24% increase in shaft resistance compared with the open-ended piles and the average unit shaft resistance of the driven model pile was 1.33 times that of the jacked model pile in the dense sand condition and 1.52 times that of the jacked model pile in the medium dense sand condition. Depending on the test variables, the rough model piles tested in this study experienced a 12-54% increase in capacity compared with the smooth model piles. Also, the lateral earth pressure coefficient values for the rough model piles were greater than those for the smooth model piles. This suggests that part of the increase in capacity due to pile surface roughness is attributed to an increase in the radial effective stress during tensile loading.Key words: piles, shaft resistance, pile placement method, smooth pile, rough pile.
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Wan, Zhihui, Heng Liu, Feng Zhou, and Guoliang Dai. "Axial Bearing Mechanism of Post-Grouted Piles in Calcareous Sand." Applied Sciences 12, no. 5 (2022): 2731. http://dx.doi.org/10.3390/app12052731.
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Post-grouted piles, as a foundation form for large-span and large-scale structures on calcareous sand, are expected to provide a high bearing capacity, but research on the response of post-grouted piles subjected to axial load in calcareous sand is still in the exploratory stage. In this paper, a model test is constructed for static pressure piles in calcareous sand under axial loading. The response of axial compressive piles, with and without post-grouting, in calcareous sand were investigated, and the test results were compared with those of axial compressive piles, with and without post-grouting, in siliceous sand. The influence of post-side-grouting on the response of a single pile subjected to axial compressive load in calcareous sand and its bearing mechanism were further analyzed. The results show that the change in shaft resistance, caused by the lateral extrusion of calcareous sand, is less than the negative effect caused by particle breakage during pile driving, so single piles without post-grouting in calcareous sand exhibit weaker axial bearing behavior than that in siliceous sand. A single pile with post-side-grouting in calcareous sand can provide a higher bearing capacity by increasing the shaft resistance and tip resistance compared with a single pile without post-side-grouting, and the increased ratio of the bearing capacity of piles, after grouting in calcareous sand, is better than that of piles in siliceous sand. Post-side-grouting can not only strengthen the surrounding soil by the solidification effect of injected cement grout, but it can also have a strengthening effect on the tip resistance. In addition, ideal-geometry grouting has more obvious advantages in improving the bearing behavior of pile foundations than annular point grouting, and higher stability in improving the bearing properties of pile foundations is evident for ideal-geometry grouting. Therefore, it is suggested that a directional grouting device should be adopted in actual projects in the future to form a more stable pile-soil interaction system and to expand the application prospect of pile foundations in calcareous sand.
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Elsawwaf, Mostafa, Marwan Shahien, Ahmed Nasr, and Alaaeldin Magdy. "The behavior of piled rafts in soft clay: Numerical investigation." Journal of the Mechanical Behavior of Materials 31, no. 1 (2022): 426–34. http://dx.doi.org/10.1515/jmbm-2022-0050.
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Abstract This research aims to investigate the applicability and performance of piled rafts in soft clay. This aim has been achieved by studying how the pile length, pile number, raft-soil relative stiffness, and presence of a sand cushion beneath the raft would affect piled raft settlement, differential settlement, and load sharing. Piled rafts have been numerically simulated using PLAXIS 3D software. Experimental testing results were used to verify the numerical simulation. The portion of the load carried by the piles to the total applied load was represented by the load sharing ratio (GPR). The results indicated that with increasing pile length and number, settlement and differential settlement decreased. It was also noticed that with increasing raft-soil relative stiffness, the differential settlement decreased. The GPR decreased with increasing thickness and relative density of the sand cushion, whereas it increased with increasing pile length and number. This increase in GPR was 13.7, 36, and 58% with an increase in pile length to diameter ratio from 10 to 30 for the number of piles 4, 9, and 16, respectively. Additionally, the raft-soil relative stiffness was observed to have a marginal effect on the GPR.
7
Sastry, V. V. R. N., and G. G. Meyerhof. "Behaviour of flexible piles in layered sands under eccentric and inclined loads." Canadian Geotechnical Journal 31, no. 4 (1994): 513–20. http://dx.doi.org/10.1139/t94-060.
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The lateral soil pressures, bending moments, pile displacements at ground surface, and bearing capacity of instrumented vertical single flexible model piles in layered sands consisting of loose sand overlying compact sand under vertical eccentric and central inclined loads have been investigated. The results of these load tests are compared with theoretical estimates based on the concept of an effective embedment depth of equivalent rigid piles. Reasonable agreement has been found between the observed and predicted behaviour of flexible piles. The analyses are also compared with the results of some field case records. Key words : bearing capacity, instrumentation, model test, layered soil, pile, sand.
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Joshi, R. C., Gopal Achari, and Shenbaga R. Kaniraj. "Effect of loading history on the compression and uplift capacity of driven model piles in sand." Canadian Geotechnical Journal 29, no. 2 (1992): 334–41. http://dx.doi.org/10.1139/t92-038.
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Model piles were tested in dry uniform sand to study the effect of loading history on the behaviour of piles in compression and tension. A sand bed was prepared by the raining technique, and a smooth cylindrical instrumented pile was driven into the sand. Load tests on piles were conducted at a constant rate of penetration of 0.5 mm/min. The effects of length to diameter (L/D) ratio and sand density were also investigated. The load transfer along the pile surface was studied for an L/D ratio of 33. The pile tip resistance was measured for model piles with L/D ratios of 20–33 and was generally found to be constant. A significant decrease in the pile capacity both in tension and compression was noted for piles having a loading history. When a pile was loaded in compression after being loaded in tension, the tip load could be mobilized only after a certain movement of the pile. The mobilization of the shaft load, however, started immediately. Key words : load tests, model piles, dry sand, loading history, tip capacity, shaft capacity, compression, tension, load transfer.
9
Al-Neami, Mohammed, and Mariam Wasmi. "Influence of cyclic loading on performance of steel piles in sandy soil." MATEC Web of Conferences 162 (2018): 01012. http://dx.doi.org/10.1051/matecconf/201816201012.
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This paper introduces an experimental study to clarify the response of steel pile models exposed to the cyclic loading. Thirty six models of two types of steel piles are tested (open ended pile and H-pile) with lengths equal to (30, 40, and 50) cm. Three diameters (2.5, 3.5, and 4.1) cm for open ended pipe pile and three flange widths (2.6, 3.6, and 4.4) cm for H-pile are investigated. Jacking technique is employed to installed piles models in dry sandy samples with two different relative densities (60% for medium sand 80% for dense sand). It is found that the pile geometry (diameter and length) with sand density have a high impact on the number of cycles. Analysis of results showed that increasing of pile diameter and relative density cause a reduction in the number of cycles when the length of steel pile models are fixed while variety of diameters of open ended pipe pile has a small effect on the number of cycles. It was found that pipe piles with open ended have more resistance to the cyclic loading compared with H piles under the same geometric conditions (pile diameter, embedded length and sand density) especially in medium sand. Finally, if the testing conditions are the same, number of cycles is decreased with increasing in amplitude loading
10
B., M. Kalbande, I. Dhatrak A., and W. Thakare S. "Experimental Assessment of Performance of XCC Pile in Sand." International Journal of Engineering and Advanced Technology (IJEAT) 9, no. 3 (2020): 4346–51. https://doi.org/10.35940/ijeat.C6244.029320.
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XCC (X-Section Cast in place Concrete) pile is new type of pile developed on the basis of cast-in-place pile from the conventional circular pile and capable of resisting displacement. In this study, an attempt is made to investigate the performance of XCC Pile under different loading conditions viz., vertical loading, lateral loading and uplift loading. Experimental investigation is carried out on small scale model piles embedded in sand, by changing type of loading and distance between arc to diameter ratio of the pile. The relative density of soil, type of soil and spacing between the piles are kept constant during investigations. Ultimate capacities of piles are compared with those of conventional circular pile with same diameter and length. The results show that XCC pile with arc distance to diameter ratio equal to 0.3 provides higher vertical and lateral capacity to the extent of 45 % and 39 % respectively compared to that of conventional pile. XCC Pile with arc distance to diameter ratio equal to 0.4 provides higher uplift load capacity to the extent 29 % compared to conventional circular pile.
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SHAPOVAL, A. B., and M. G. SHNIRMAN. "SAND DENSITY AS SANDPILE DESCRIPTOR." International Journal of Modern Physics C 19, no. 06 (2008): 995–1006. http://dx.doi.org/10.1142/s0129183108012637.
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We investigate a collection of one-parametric families of isotropic sandpile models. The models involve the square lattice slowly accumulating the grains and quickly transferring them as the local piles become over-critical. The paper groups the sand-piles with respect to two features influencing the model dynamics. They are the value of the local transfer's stochasticity and the number of the transferred grains. Every pair generates one-parametric family of the sand-piles. The parameter reflects the relative height of an over-critical pile with respect to the incoming flow of sand. If the stochasticity disappears with the growth of the parameter, the families with the fixed number of the transferred grains have much in common with Bak et al.'s sand-pile [Phys. Rev. Lett.59, 381 (1987)], while the families, whose over-critical piles lose all their grains, tend to the Zhang sand-pile [Phys. Rev. Lett.63, 470 (1989)]. The families with non-disappearing variance give rise to new properties described in terms of the probability distribution of the pile heights.
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Khari, Mahdy, Khairul Anuar Kassim, and Payman Alimohammadi. "Response of Single and Grouped Pile Subjected to Lateral Load in Cohesionless Soil." Applied Mechanics and Materials 773-774 (July 2015): 1397–401. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.1397.
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Piles are generally required to transfer load from a superstructure through weak or compressible strata, or through water, on to stiffer and less compressible soils and rock. The pile behavior is very important in Soil-Pile interaction (as known Kinematic Interaction) so that grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. In this research presents a series of experimental investigations carried out on single and group pile subjected to monotonic lateral loadings. The aluminum model piles were tested in the different relative densities in Johor Bahru sand. The sand samples were prepared by using the newly designed Mobile Pluviator adopted the air pluviation method. The different configurations of model pile groups for embedded length-to-diameter ratio equal to 32 into loose and dense sand spacing from 3 to 6 pile diameter (D) were conducted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. A ratio of s/D more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.
13
Zhu, Fangcai, Zhijia Yang, Qing Liu, et al. "Experimental Study on Pile Load Transfer Considering Rice Stone Filled-In Gaps between Steel Drive Pipe and Pile Casing in Karst Region." Sustainability 15, no. 20 (2023): 14659. http://dx.doi.org/10.3390/su152014659.
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For a guarantee of perpendicularity and stiffness in piles in Karst areas, full rotary cast-in-place piles are often utilized, steel pipes are rotarily driven into a stratum, and inner-steel pile casing is positioned. With the engineering background of the bridge piles of Guinan high-speed railway in Guangxi autonomous region, the space between steel drive pipe is filled with rice stones, the load-transfer mechanism of which was studied. An apparatus was designed for pullout of the drive pipe, rice stones are replaced with coarse stones, a simplified organic glass-pipe model is put forward, another similar indoor stratigraphic model is also pre-cast, and the movement of coarse sands and load transfer is studied with two models. The quantity of sands is calculated using back analysis through reappearance and the Rhino model: the first one is estimated using a reproduction of the pullout procedure, the second is calculated through the Rhino model based on the observation of the shape of sand in caves. When the drive pipe is pulled out, some coarse sand flows into the Karst caves and becomes loose, while load is applied on the top of the pile. The movement of coarse sand develops further, and more coarse sand flows into caves close to the bottom; this leads to a reduction its frictional resistance, and the axial force of the pile increases closer to the upper position of the cave, whereas the axial force of the pile is concentrated almost constantly close to the bottom of the cave. Comparing the end resistance and the frictional resistance, coarse sand can bear pile load to a great extent.
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Gao, Yan, Zixin Guo, and Quan Yuan. "Pile Driving and the Setup Effect and Underlying Mechanism for Different Pile Types in Calcareous Sand Foundations." Journal of Marine Science and Engineering 12, no. 1 (2024): 133. http://dx.doi.org/10.3390/jmse12010133.
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The mechanical response and deformation characteristics in calcareous sand foundations during pile driving and setup were studied using model tests combined with the technical methods of tactile pressure sensors and close-range photogrammetry. Different types of piles were considered, including a pipe pile, square pile and semi-closed steel pipe pile. The test results show that during pile driving, the pile tip resistance of different piles increases with an increase in the pile insertion depth, and an obvious fluctuation is also obtained due to the particle breakage of the calcareous sand and energy dissipation. Different degrees of particle breakage generated by different type piles make the internal stress variations different, as with the pile tip resistance. The pile tip resistance of model pile A, which simulates a pipe pile, is the highest, followed by model pile B, the simulated square pile. Model pile C, which simulates a semi-closed steel pipe pile, has the smallest pile tip resistance because its particle breakage is the most obvious and the pile tip energy cannot be continuously accumulated. The induced deformation such as sag or uplift on the surface and the associated influence range for the calcareous sand foundation are the smallest for model pile C, followed by model pile B and then model pile A. Model pile A has the most obvious pile driving effect. During the pile setup process after piling, the increase in the total internal stress of model pile B is the largest, and the improvement of the potential bearing capacity is the most obvious, followed by model pile A and model pile C. During the pile setup, the induced uplift deformation in pile driving is recovered and the potential bearing capacity increases due the redistribution and uniformity of the vertical and radial stress distributions in the calcareous sand foundation. Considering the potential bearing capacity of different model piles, the influence range of pile driving, foundation deformation and the pile setup effect, it is suggested to use a pointed square pile corresponding to model pile B in pile engineering in calcareous sand foundations.
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Gavin, Kenneth, and Barry Lehane. "Base load – displacement response of piles in sand." Canadian Geotechnical Journal 44, no. 9 (2007): 1053–63. http://dx.doi.org/10.1139/t07-048.
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The paper presents the results of a series of laboratory and field model pile tests performed to study the factors controlling the base pressure – settlement reponse of piles in sand. One series of tests involved the installation and load testing of steel open- and closed-ended piles in loose sand contained in a large pile testing chamber. A second series involved tests on open- and closed-ended steel piles and a concrete bored pile at a dense sand test bed site. The experiments were designed to investigate the effects of pile type, sand consistency, and installation resistance on a pile’s base response during static loading. The tests revealed that both the base capacity and stiffness of piles in sand are controlled by the degree of prestress imposed on the soil below the pile tip. Simple expressions, which require the small strain stiffness and cone penetration test data as the input parameters, are developed to predict the base pressure – settlement response. The final part of the paper employs other field tests on full-scale displacement piles and bored piles to verify the validity of the proposed approach.
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Yalcin, A. S., and G. G. Meyerhof. "Bearing capacity of flexible piles under eccentric and inclined loads in layered soil." Canadian Geotechnical Journal 28, no. 6 (1991): 909–17. http://dx.doi.org/10.1139/t91-108.
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The bearing capacity of flexible model piles and small pile groups under axial, lateral, and various combinations of eccentric and inclined loads in layered soil consisting of clay overlying sand is investigated. Ultimate pile capacity is found to depend on the eccentricity and inclination of the load and, more significantly, on the ratio of the upper layer thickness to pile embedment. Theoretical estimates based on the concept of effective pile embedment ratio and expressed in terms of equivalent rigid piles agree reasonably well with the experimental values. The behaviour of 2 × 2 flexible model pile groups is observed to be similar to that of single piles. Key words: bearing capacity, piles, flexible pile, pile group, layered soil, sand, clay, eccentric load, inclined load, model pile test.
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Hou, Jin Fang, Jian Yu, and Xin Wei Xu. "Research on the Large Size Loading Plate Test of Underwater Sand Compaction Pile Composite Foundation." Applied Mechanics and Materials 744-746 (March 2015): 574–78. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.574.
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Large size loading plate test for sand compaction pile composite foundations with the replacement ratio being up to 60% was carried out to study the deformation and bearing capacity of the sand compaction pile composite foundation. The test was carried out for 53 days with anchor pile, square loading with the side length of 5.4m, 15m-deep water and twice circulation loading mode. The compression deformation, pile-soil stress ratio and deformation modulus of the sand compaction pile composite foundation was analyzed through load test. Test results indicated that, the ultimate bearing capacity of the sand compaction pile composite foundation in this test was larger than 340kPa; sand compaction pile had a drainage consolidation effect on the soft soil between piles; under the load-keeping condition, sand compaction pile composite foundation would also has settlement; pile-soil stress ratio was 6.3 and deformation modulus was about 8kPa. The success of the test may provide experience and reference for load test of underwater sand compaction pile composite foundation carried out at open sea.
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Georgiadis, M., C. Anagnostopoulos, and S. Saflekou. "Centrifugal testing of laterally loaded piles in sand." Canadian Geotechnical Journal 29, no. 2 (1992): 208–16. http://dx.doi.org/10.1139/t92-024.
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Results of an investigation of the response of piles in sand, under lateral loads, are presented. Model piles of three different diameters and flexural stiffnesses were tested in a centrifuge apparatus to determine prototype pile behavior. The experimental results, consisting of pile head displacements and bending moment distributions along the pile length, were interpreted, analyzed, and compared with the results of several numerical analyses. The piles were treated as elastic beams on nonlinear springs, examining several different types of soil reaction relationship (p-y curves). A new p-y relationship was developed for piles in cohesionless soil which provided very satisfactory results. Key words : pile, sand, lateral loading, centrifuge, numerical analysis.
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Fan, Hu, Yan Zhuang, Jinxin Li, and Zhi Chen. "Pile Arrangement for Minimizing Plastic Deformation in Pile-Supported Immersed Tunnel under Seismic Loads." Applied Sciences 13, no. 22 (2023): 12331. http://dx.doi.org/10.3390/app132212331.
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The plastic region of piles under seismic loads is a crucial concern in seafloor improvement design. This paper establishes a physical model of the sand compaction pile-immersed tunnel–water pressure system. This research studies pile arrangements that minimize the sand compaction pile plastic region under seismic loads. The experiments were validated through numerical simulations. The results show that “X-shaped” and rectangular pile groups increase the Energy Residual Index (ERI) due to differences in pile spacing and the instability of the quadrilateral prism damping units formed by piles and soil. In this scenario, piles are limited to heavy and mild plastic regions, with boundary depths at L = 2.25 D and L = 2.08 D (L represents the pile length, and D is the pile diameter). Furthermore, increased water pressure amplifies the structural resonance injury, increasing ERI. In conjunction with the soil, hexagonal pile groups create triangular prism damping units that counteract seismic wavefronts. The total kinetic energy and strain energy of the piled foundation are lower than those of the “X-shaped” and rectangular pile groups. The boundaries between the heavy plastic region, the moderate plastic region, and the mild plastic region are located at depths of L = 4 D and L = 8 D, respectively. This study also reveals that a top-heavy mass distribution in the structure leads to maximum deformation in the heavy plastic region. Pile–soil damping units primarily operate within the moderate plastic region.
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Teji, Biya Degefu, and Argaw Asha Ashango. "Performance Optimization of Piled Raft Foundations in Layered Soil under Uniform Vertical Loading Using Plaxis 3D." Advances in Materials Science and Engineering 2023 (November 20, 2023): 1–11. http://dx.doi.org/10.1155/2023/6693876.
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Piled raft foundations are composite foundations that combine piles and raft to support civil engineering structure and to reduce the settlement. The data were obtained from Addis Ababa, Ethiopia. In this study, the effects of raft thickness, number of piles, pile length, spacing of piles, and pile diameter on the response of piled-raft foundations were investigated using the finite element-based program Plaxis 3D for layered soils (medium to very stiff high plastic silty clay and medium to very dense silty sand soil) subjected to uniform vertical loading. The results showed that increasing the thickness of the raft from 0.7 m to 1.7 m reduced the differential settlement by 78.21% when there were 16 piles. However, the maximum settlement also increased by 2.81%. Increasing the number of piles from 4 to 16 reduced the maximum settlement by 22.09% for a pile spacing of 4D. Moreover, increasing the pile length from 9 m to 15 m contributed to a 19.49% reduction in the total settlement for a pile spacing of 5D. Therefore, the current study provides a useful framework for analyzing and designing large piled-raft foundations.
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Pinto, Paulo, Michael McVay, Marc Hoit, and Peter Lai. "Centrifuge Testing of Plumb and Battered Pile Groups in Sand." Transportation Research Record: Journal of the Transportation Research Board 1569, no. 1 (1997): 8–16. http://dx.doi.org/10.3141/1569-02.
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Pile groups are generally used under structures subject to heavy axial loads or large lateral forces with or without scour. The focus in this paper is only on pile groups subject to large lateral forces. Currently, little, if any, full-scale lateral load data exist on pile groups that vary pile head fixity or batter. Reported here is the summary of a series of centrifuge tests on free- and fixed-head plumb and battered pile groups. Influence of pile head constraint, pile spacing, soil density, and vertical dead load is reported for groups ranging from 3 × 3 to 3 × 7 in size. Results reveal a significant lateral resistance of fixed- over free-head pile groups; fixed-head piles develop significant axial forces; battered piles without vertical dead loads are generally no better than plumb piles; and in the case of plumb piles, the use of multipliers to represent group interaction is valid.
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Spagnoli, Giovanni, and Cristina de Hollanda Cavalcanti Tsuha. "Review of torque models for offshore helical piles." E3S Web of Conferences 205 (2020): 12007. http://dx.doi.org/10.1051/e3sconf/202020512007.
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Helical (or screw) piles, sometimes defined as anchors, are a piled system consisting of one or multiple helices welded along the shaft. Piles are installed by applying a torque to the shaft. The pile is rotated into the soil and the rate of advancement should be an amount equal to the pitch for each rotation in order to minimize the disturbance of the original soil. Torque is maybe the most important parameter to be assessed during pile installation. In fact, torque and uplift capacity are directly proportional. Generally, torque depends on the soil conditions and on the geometrical features of the pile. Torque increases with sand density, installation depth, friction angle of sand, pile shaft and helix diameters. The geometry of the pile has a strong influence on the torque, the larger the helix-to-shaft ratio is, the larger the torque will be. In offshore applications helical piles are being considered as a valid alternative. However, one of the issues is still related to the assessment of the installation torque values. Several torque models have been considered and critical evaluated. Some simple comparisons among selected torque models have been also done and discussed.
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Meyerhof, G. G., and R. D. Purkayastha. "Ultimate pile capacity in layered soil under eccentric and inclined loads." Canadian Geotechnical Journal 22, no. 3 (1985): 399–402. http://dx.doi.org/10.1139/t85-051.
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The ultimate bearing capacity of rigid model piles and pile groups in layered soil consisting of clay overlying sand has been investigated for various combinations of eccentricity and inclination of load and with varying thicknesses of clay layer. The effect of eccentricity and inclination of the load and thickness ratios of clay layer to pile embedment in the sand on the bearing capacity can be represented by simple interaction relationships to estimate the ultimate load. The results of load tests on single model piles and freestanding pile groups are presented in the form of polar bearing capacity diagrams and are compared with the theoretical estimates. The thickness of clay layer on the sand is found to have a significant influence on the bearing capacity of single piles and pile groups. Key words: pile foundation, model test, layered soil, eccentric load, inclined load, sand, clay, analysis, bearing capacity.
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Gavin, Kenneth G., and Barry M. Lehane. "The shaft capacity of pipe piles in sand." Canadian Geotechnical Journal 40, no. 1 (2003): 36–45. http://dx.doi.org/10.1139/t02-093.
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This paper describes results from an experimental programme that investigated factors affecting the shaft capacity of open-ended (pipe) piles in sand. A number of jacked pile installations in a test chamber filled with loose sand were performed using both open- and closed-ended, 114 mm diameter piles. The test series was designed to investigate the effects of in situ stress level, pile end condition, and degree of plugging on the development of pile shaft resistance. The results indicate that the maximum local shaft resistance that can develop at a given location on a pipe pile may be expressed as a function of the incremental filling ratio of the soil plug during installation, the cone penetration test (CPT) qc value, and the relative position of the pile toe. The experimental results allowed a simple expression to be developed for the plug resistance during pile installation, and this is used in conjunction with a popular design method for closed-ended piles to provide a means of estimating the shaft capacity of open-ended piles. The new approach is shown to provide good estimates of overall shaft capacity and skin friction distribution.Key words: shaft capacity, pipe piles, sand.
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Zhang, Cong, Zhongju Feng, Yunhui Guan, Huiyun Chen, Fuchun Wang, and Boxi Xu. "Study on Liquefaction Resistance of Pile Group by Shaking Table Test." Advances in Civil Engineering 2022 (January 25, 2022): 1–12. http://dx.doi.org/10.1155/2022/5074513.
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This study investigated the antiliquefaction property of the pile group. It is shown in the pore pressure ratio, pile acceleration, and bending moment response of saturated silt fine sand. The response law of pile acceleration and bending moment during liquefaction development is proved. The results show that liquefaction occurs in single piles, four piles, and six piles under the action of 0.35 g seismic wave. But the time of liquefaction is different. There is an obvious difference in the response of pile acceleration and bending moment during liquefaction. Liquefaction in the saturated silt fine sand develops from shallow to deep. The complete liquefaction of six piles takes the longest time, while the single pile takes the shortest time, and the average delay was 8.82 s. With the increase of the number of piles, there are some differences in pile acceleration, magnification factor, and pile bending moment, which are mainly reflected in time. The peak acceleration appearance of six piles was 3.08 s later than that of the single pile on average. The maximum bending moment appearance of six piles was 1.96 s later than that of the single pile on average. The acceleration and bending moment of the pile begins to attenuate when the pore pressure ratio increases. It shows that the saturated silt fine sand has softening and damping effect before liquefaction. In summary, the antiliquefaction performance of the pile group is better than that of a single pile. In the seismic design of pile foundation in liquefied soil, the antiliquefaction performance of the pile group is better.
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Al-mosawe, Mosa Jawad, A’amal Abdul Ghani Al-Saidi, and Faris Waleed Jawad. "Experimental and Numerical Analysis of Piled Raft Foundation with Different Length of Piles Under Static Loads." Journal of Engineering 19, no. 5 (2023): 543–49. http://dx.doi.org/10.31026/j.eng.2013.05.02.
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In order to understand the effect of (length of pile / diameter of pile) ratio on the load carrying capacity and settlement reduction behavior of piled raft resting on loose sand, laboratory model tests were conducted on small-scale models. The parameters studied were the effect of pile length and the number of piles. The load settlement behavior obtained from the tests has been validated by using 3-D finite element in ABAQUS program, was adopted to understand the load carrying response of piled raft and settlement reduction. The results of experimental work show that the increase in (Lp/dp) ratio led to increase in load carrying capacity by piled raft from (19.75 to 29.35%), (14.18 to 28.87%) and (0 to 16.49%) , the maximum load carried by piles decrease from(9.1 to 22.72%), (15.79 to 47.37%) and (44 to 81.05%) and the response of settlement piled raftdecrease from (16.67 to 23.33%), (9.09 to 39.39%) and (30%) with increase the number of piles from 4 to (6 and 9) and (length of pile / diameter of pile) ratio increase to (14.14 and 21.2), respectively. The numerical and model test results are found to be in a good agreement.
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Chen, Yadong, Fan Lu, Abdoullah Namdar, and Jiangdong Cai. "Working Mechanism of Pile Group with Different Pile Spacing in Dense Sand." Advances in Civil Engineering 2019 (July 4, 2019): 1–16. http://dx.doi.org/10.1155/2019/5376594.
Full textAbstract:
Complex interaction mechanism exists between the pile group and soil. To realize the pile-soil load transmission mechanism in detail, the failure pattern of pile groups installed in dense sand considering different pile spacing was investigated by means of laboratory experimental model test and three-dimensional discrete element method. The results suggested that the narrow pile spacing was beneficial to the development of the pile tip resistance, and it enhanced the bearing performance of the pile group at the initial stage of settlement. The pile spacing changed the shaft resistance pattern with modification of the strain energy mechanism released within the subsoil. The pile group with 6b pile spacing had higher composite group efficiency. A joint fan-shaped displacement zone was formed beneath the pile tip for the pile group with 3b pile spacing; this pile foundation presented the block failure mechanism. The sand displacement beneath the cap for the pile group with 6b pile spacing mainly located on the upper part of the piles, the sand displacement around both sides of the piles presented asymmetric, and a relatively independent fan-shaped displacement zone was formed beneath the pile tip.
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Hanna, A. M., and A. Afram. "Pull-out capacity of single batter piles in sand." Canadian Geotechnical Journal 23, no. 3 (1986): 387–92. http://dx.doi.org/10.1139/t86-054.
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The pull-out capacity of single rigid vertical and batter piles in sand and subjected to axial loading has been investigated. Good agreement was found when test results on instrumented model piles were compared with theoretical estimates. The effect of pile inclination on the pull-out capacity has been explained by means of variable mobilized passive earth pressure on the pile's perimeter. A design method and charts are presented. Key words: pile foundation, pull-out capacity, vertical pile, batter pile, sand–soil mechanics.
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Ergun, Mehmet Ufuk, and Devrim Sönmez. "Negative skin friction from surface settlement measurements in model group tests." Canadian Geotechnical Journal 32, no. 6 (1995): 1075–79. http://dx.doi.org/10.1139/t95-105.
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Groups of model wood piles driven to end bearing through dense sand over soft clay were used to determine the relative settlement of the soil surface inside and outside the groups as the soil was compressed by air pressure. Square 30 mm piles at spacings of 2 to 6 times the pile width were used in groups of 3 × 3, 4 × 4, and 5 × 5. The results indicate that pile group effects were negligible at pile spacings at 5 to 6 pile widths. Key words : negative friction, model study, pile groups, sand.
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Bak, Jongho, Byung-hyun Choi, Junwon Lee, Jonghwan Bae, Kicheol Lee, and Dongwook Kim. "Behaviour of Single and Group Helical Piles in Sands from Model Experiments." MATEC Web of Conferences 278 (2019): 03007. http://dx.doi.org/10.1051/matecconf/201927803007.
Full textAbstract:
Mainly used foundations of oil sand plants are drilled shafts or driven piles. As environmental regulations become increasingly strict, complete removal of the foundation is becoming more important during the step of plant dismantling. However, it is difficult to remove completely drilled shafts or driven piles which are deeply installed to obtain more bearing capacity. Helical piles can be easily removed and recycled after use. This study analyses the behaviour of single and group helical piles in sands. For single helical piles, pile load tests of helical piles were conducted varying helix spacing, rotation speed and weight of axial loading during pile installation. The single pile tests determined the optimal helix spacing, rotation speed, weight of axial loading during pile installation. And then, pile load test of group helical piles was performed varying pile spacing from the centre place of upper connector based on the optimal installation conditions.
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Omer, Joshua, and Hasan Haroglu. "Tests on Model Piled Rafts in Sand: Measured Settlements Compared with Finite Element Predictions." Geotechnical and Geological Engineering 39, no. 4 (2021): 3271–83. http://dx.doi.org/10.1007/s10706-020-01664-0.
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AbstractLaboratory tests were carried out on non-piled rafts, single piles, surface contacting and non surface-contacting piled rafts which were made of aluminum and instrumented with strain gauges and deflection gauges. The foundations were installed in dry sand contained in a large metal tank to minimize boundary effects. Maintained loads were applied to each foundation until failure was closely approached. In parallel, analyses were performed using PLAXIS™ 3-D finite element program to compare the calculated and measured load-settlement trends hence assess the influence of soil stiffness on the foundation behaviour. The results confirmed that group efficiency of non-surface contacting piled increased with increasing pile–pile spacing and approached unity at a spacing equivalent to 8D (D = pile diameter). The data obtained from the strain gauges provided valuable insight into the load-transfer characteristics of different foundations and subsequently proved that the capacity of a surface contacting piled raft is significantly enhanced compared to that of either a non-piled raft or a non-surface contacting piled raft.
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Marshall, Alec M., and Robert J. Mair. "Tunneling beneath driven or jacked end-bearing piles in sand." Canadian Geotechnical Journal 48, no. 12 (2011): 1757–71. http://dx.doi.org/10.1139/t11-067.
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This paper presents centrifuge model test data that relate to the problem of tunneling beneath driven or jacked end-bearing piles in sand. The centrifuge model consisted of a tunnel and two piles and allowed for the acquisition of subsurface digital images throughout the tests. Soil and pile displacements were measured using particle image velocimetry and close-range photogrammetry techniques. The piles were jacked into the ground in-flight prior to tunnel volume loss to obtain ground stress profiles representative of conditions around driven or jacked piles. Patterns of displacements and calculated soil strains are presented to illustrate mechanisms of displacement and soil behavior. The measured soil and pile displacements are compared against greenfield test measurements. The results indicate that driving the piles significantly alters greenfield conditions and that greenfield displacements should not be used as an input for analytical tunnel–soil–pile interaction analyses for driven or jacked piles. Large pile displacements were observed to occur suddenly in the tests, illustrating the brittle nature of the soil in the areas affected by pile installation. A relationship between relative pile–tunnel location and the volume loss at which large pile displacements occurred is presented, which provides useful guidance to tunnel design engineers.
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Syed, Aaqib Javed, Salsabiyl Anika, Nasrin Jubaida Farhana, Zahidul Islam Md., and Islam Shafiqul. "Comparative Cost Analysis of Pile Foundation with Soil Improvemnet of a Reclaimed Area." Journal of Earthquake Science and Soil Dynamics Engineering 2, no. 3 (2020): 1–9. https://doi.org/10.5281/zenodo.3604609.
Full textAbstract:
Soil liquefaction is the most hazardous phenomenon for buildings, highways, railways and other structures in recent past years. Liquefaction of soil followed by earthquakes has always been a source of danger for the people living in the highly vulnerable seismic zones of the world. Dhaka city is expanding rapidly on reclaimed land due to rapid increase of population. The behavior of piles in reclaimed areas is significantly affected if the soil liquefies. Therefore, soil improvement is necessary. This paper discusses the variation of cost of piles of a reclaimed area with and without considering soil improvement technique like sand compaction pile and stone column. Cost analysis of sand compaction pile and stone column with different properties, i.e. diameter of the pile, Fineness modulus (FM) is also estimated in the context of Bangladesh. Sand Compaction pile is only 1.3% to 2.1% of pile cost. On the other hand, stone column is more than 50% of RCC pile. Sand compaction pile is more cheaper than stone columns. The cost of sand compaction pile, for 1000 m2 area with FM 1.8 and fill volume 0.15 cum/m are 3.2 lac, 3.1 lac and 2.8 lac for diameter 200 mm, 250mm and 300 mm respectively.
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Yuan, Bingxiang, Minjie Chen, Weijie Chen, Qingzi Luo, and Hongzhong Li. "Effect of Pile-Soil Relative Stiffness on Deformation Characteristics of the Laterally Loaded Pile." Advances in Materials Science and Engineering 2022 (May 12, 2022): 1–13. http://dx.doi.org/10.1155/2022/4913887.
Full textAbstract:
Laterally loaded piles are widely used in structural foundations under horizontal loads such as wave load, wind load, seismic load, and traffic load. Based on the complexity of pile-soil interaction, a test simulation of single pile through the indoor 1 g model test was conducted, in order to study the influence of different loading heights and relative stiffness of pile and soil on the bending moment, soil resistance, and horizontal displacement of pile. It is found that the shear modulus of soil from large to small is arranged as dry fine sand, dry coarse sand, saturated fine sand, and saturated coarse sand. The shear modulus of dry fine sand, dry coarse sand, and saturated fine sand are close under the same loading height and horizontal displacement of pile top, while the shear modulus of saturated coarse sand decreases sharply. Under the condition of water saturation, the particle size has a significant effect on the shear modulus of soil. The relative stiffness of pile soil is found to be the main influencing condition of pile horizontal displacement. Compared with the displacement and bending moment of the pile, the loading height has more influence on the soil resistance, and the main influence area is the soil resistance of the pile toe.
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Zhang, Limin, Michael C. McVay, and Peter W. Lai. "Centrifuge modelling of laterally loaded single battered piles in sands." Canadian Geotechnical Journal 36, no. 6 (1999): 1074–84. http://dx.doi.org/10.1139/t99-072.
Full textAbstract:
Centrifuge lateral load tests were performed on single battered piles at five pile inclinations founded in both medium-dense (relative density Dr = 55%) and loose (Dr = 36%) sands. The effects of pile batter and soil density on lateral resistance were studied. Pile batter had significant effects in dense sands but minor effects in loose sands. Based on the test results, nonlinear p-y curves, where p is the soil resistance in unit length and y is the lateral deflection of the pile, were developed for single piles at any angle (positive or negative) and sand density. The developed p-y curves were subsequently used with a Winkler model (COM624, LPILE, FLPIER, etc.) to predict all the test results with reasonable accuracy.
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Sakr, Mohammed. "Performance of helical piles in oil sand." Canadian Geotechnical Journal 46, no. 9 (2009): 1046–61. http://dx.doi.org/10.1139/t09-044.
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The results of a comprehensive pile load-test program and observations from field monitoring of helical piles with either a single helix or double helixes installed in oil sand are presented in this paper. Eleven full-scale pile load tests were carried out including axial compression, uplift, and lateral load tests. The results of the full-scale load tests are used to develop a theoretical design model for helical piles installed in oil sand. Test results confirm that the helical pile is a viable deep foundation option for support of heavily loaded structures. The test results also demonstrated that circular-shaft helical piles can resist considerable lateral loads.
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Huang, Zhen, Ben Liang, Ziming Xiong, Hao Lu, Minqian Sun, and Xiao Guo. "An Experimental Study on the Seismic Response of Vertical and Batter Pile Foundations at Coral Sand Sites." Journal of Marine Science and Engineering 13, no. 4 (2025): 640. https://doi.org/10.3390/jmse13040640.
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Liquefaction and earthquake damage to coral sand sites can cause engineering structure failure. Both testing and analyzing the seismic response characteristics of pile groups on coral sand sites are highly important for the seismic design of engineering structures. To address the lack of research on the seismic dynamic response of group pile foundations in coral sand sites, this study analyzes the characteristics of the seismic dynamic response of vertical and batter pile foundations for bridges in coral sand liquefaction foundations via the shaking table model test and investigates the variation patterns of acceleration, excess pore water pressure (EPWP), and the bending moment and displacement of foundations, soil, and superstructures under different vibration intensities. Results show that the excitation wave type significantly affects liquefaction: at 0.1 g of peak acceleration, only high-frequency sine wave tests liquefied, with small EPWP ratios, while at 0.2 g, all tests liquefied. Vertical pile foundations had lower soil acceleration than batter piles due to differences in bearing mechanisms. Before liquefaction, batter piles had smaller EPWP ratios but experienced greater bending moments under the same horizontal force. Overall, batter piles showed higher dynamic stability and anti-tilt capabilities but endured larger bending moments compared to vertical piles in coral sand foundations. In conclusion, batter pile foundations demonstrate superior seismic performance in coral sand sites, offering enhanced stability and resistance to liquefaction-induced failures.
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Li, Fu Rong, Hou Chao Sun, and Qian Zhou. "Design and Test of Self-Draining Pile." Applied Mechanics and Materials 353-356 (August 2013): 289–92. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.289.
Full textAbstract:
putting out a new pile type, that is, making the precast concrete pile with a vertical side channel and pouring the yellow sand, which lead to the pile had the self-draining function, reduce the soil squeezing effect of precast concrete pile construction in saturated soft clay, that is, the design principles and methods of self-draining pile. Indoor model test showed that the self-draining piles could reduce the pore water pressure, and its effect was obviously, its role is equivalent to sand wells, sand bags wells or plastic drain board, which meet the requirements of the construction technique.
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Ashour, Mohamed, and Hamed Ardalan. "p–y curve and lateral response of piles in fully liquefied sands." Canadian Geotechnical Journal 49, no. 6 (2012): 633–50. http://dx.doi.org/10.1139/t2012-019.
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This paper provides a technique to assess the response of laterally loaded piles and associated p–y curves in fully liquefied soils (where p is the soil–pile reaction and y is the pile deflection). The technique accounts for the variation of water pressure in the liquefied soils around the pile and its impact on the shape of the p–y curves and the pile lateral response. A constitutive undrained stress–strain model for fully liquefied saturated sands using the basic properties of sand is established to predict the post-liquefaction varying resistance of liquefied sands at different levels of loading assuming fully undrained conditions. The degradation in soil strength due to the free-field excess pore-water pressure (uxs,ff), caused by an earthquake and resulting in full liquefaction, is considered along with the near-field excess pore-water pressure (uxs,nf) induced by lateral loading from the superstructure. The presented procedure also accounts for the influence of the overburden pressure and sand density on the variation of excess water pressure in the near-field soil, the rebound of sand strength, and the shape of the p–y curve due to the dilative behavior of sands.
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Ismael, Nabil F., Hasan A. Al-Sanad, and Fahad Al-Otaibi. "Tension tests on bored piles in cemented desert sands." Canadian Geotechnical Journal 31, no. 4 (1994): 597–603. http://dx.doi.org/10.1139/t94-070.
Full textAbstract:
The load transfer of bored piles in medium dense cemented sands was examined by field tests at two sites. At the first site, two bored piles were tested in axial tension to failure. One pile was instrumented with strain guages to measure the axial load distribution at all load increments. The results indicate significant load transfer along the pile length. The average shaft resistance measured was 80 and 100 kN/m2 in medium-dense and very dense, weakly cemented calcareous sand, respectively. At the second site, a tension test was carried out on a bored pile in uncemented cohesionless sand. By comparing the results at the two sites the influence of cementation on the uplift capacity was assessed. The shaft resistance depends on many factors including the relative density, degree of cementation, soil fabric, and method of construction. It increases with the standard penetration test (SPT) N values; however, the SPT is not considered a reliable test for strength characterization of cemented sands. Analysis of the pile capacity can be made considering both components of soil strength, namely, cohesion intercept c and angle of shearing resistance [Formula: see text]. Key words : bored piles, cemented sands, uplift capacity, friction, shaft resistance.
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SALES, Mauricio Martines, Monica PREZZI, Rodrigo SALGADO, Yoon Seok CHOI, and Jintae LEE. "LOAD-SETTLEMENT BEHAVIOUR OF MODEL PILE GROUPS IN SAND UNDER VERTICAL LOAD." Journal of Civil Engineering and Management 23, no. 8 (2017): 1148–63. http://dx.doi.org/10.3846/13923730.2017.1396559.
Full textAbstract:
Model pile load testing is effective to study the load-settlement behaviour of pile foundations given the controlled environment in which the testing is done. This paper reports a testing program in a large calibration chamber involving individual piles and pile groups installed in sand samples of three different densities. Tests on both nondisplacement and driven piles are evaluated to assess the influence of the pile installation process on pile load-settlement response. A method is proposed to predict the load-settlement response of a pile group based on the response of a single pile. The method is shown to produce estimates that are in good agreement with measurements. The influence of pile group configuration, pile spacing, soil density and method of pile installation is discussed.
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Li, Pan, Yangyang Xia, Xinhui Xie, et al. "Study on Vertical Bearing Capacity of Pile Foundation with Distributed Geopolymer Post-Grouting on Pile Side." Materials 17, no. 2 (2024): 398. http://dx.doi.org/10.3390/ma17020398.
Full textAbstract:
To study the applicability of the new geopolymer grouting material for super-long and large-diameter post-grouting bored piles in silty fine sand geology, this paper compares the bearing capacity of two grouting materials, geopolymer and normal Portland cement, and different grouting volume pile side-distributed grouting piles in silty fine sand based on field model tests are analyzed through the diffusion forms of the two materials in silty fine sand through the morphology of the grouted body after excavation. The results show that the ultimate bearing capacities of P0 (ungrouted pile), P1 (8 kg cement grouted pile), P2 (6 kg geopolymer-grouted pile), P3 (8 kg geopolymer-grouted pile) and P4 (10 kg geopolymer-grouted pile) are 5400 N, 8820 N, 9450 N, 11,700 N and 12,600 N, respectively, and that the ultimate bearing capacity of the grouted pile is improved compared with that of the ungrouted pile since, under the same grouting amount, the maximum bearing capacity of the pile using geopolymer grouting is increased by 133% compared with that of the pile with cement grouting. This further verifies the applicability of the geopolymer grouting material for the post-grouting of the pile foundation in silty fine sand. Under the action of the ultimate load, the pile side friction resistance of P1, P2, P3 and P4 is increased by 200%, 218%, 284% and 319% compared with that of P0. In addition, the excavation results show that the geopolymer post-grouting pile forms the ellipsoidal consolidation body at the pile side grouting location, which mainly comprises extrusion diffusion with a small amount of infiltration diffusion, and the cement grouting pile forms a sheet-like consolidation body at the lower grouting location, which primarily comprises split diffusion. This study can provide a reference basis for the theoretical and engineering application of post-grouting piles using geopolymers.
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McVay, Michael C., Limin Zhang, Sangjoon Han, and Peter Lai. "Experimental and Numerical Study of Laterally Loaded Pile Groups with Pile Caps at Variable Elevations." Transportation Research Record: Journal of the Transportation Research Board 1736, no. 1 (2000): 12–18. http://dx.doi.org/10.3141/1736-02.
Full textAbstract:
A series of lateral load tests were performed on 3×3 and 4×4 pile groups in loose and medium-dense sands in the centrifuge with their caps located at variable heights to the ground surface. Four cases were considered: Case 1, pile caps located above the ground surface; Case 2, bottom of pile cap in contact with the ground surface; Case 3, top of pile cap at the ground surface elevation; and Case 4, top of pile cap buried one cap thickness below ground surface. All tests with the exception of Case 1 of the 4×4 group had their pile tips located at the same elevation. A special device, which was capable of both driving the piles and raining sand on the group in flight, had to be constructed to perform the tests without stopping the centrifuge (spinning at 45 g). The tests revealed that lowering the pile cap elevation increased the lateral resistance of the pile group anywhere from 50 to 250 percent. The experimental results were subsequently modeled with the bridge foundation-superstructure finite element program FLPIER, which did a good job of predicting all the cases for different load levels without the need for soil–pile cap interaction springs (i.e., p-y springs attached to the cap). The analyses suggest that the increase in lateral resistance with lower cap elevations may be due to the lower center of rotation of the pile group. However, it should be noted that this study was for pile caps embedded in loose sand and not dense sands or at significant depths. The experiments also revealed a slight effect for the case of the pile cap embedded in sand with a footprint wider than the pile row. In that case the size of the passive soil wedge in front of the pile group, and consequently the group’s lateral resistance, increased.
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Wang, Qingshan, Zhaoran Xiao, Xianqiang Zhao, and Dakuo Feng. "The Effects and Vertical Bearing Capacity of Two Jacked Model Piles in Sand." Sustainability 14, no. 21 (2022): 14493. http://dx.doi.org/10.3390/su142114493.
Full textAbstract:
The effects and vertical bearing capacity of two jacked piles in sand are still not well understood, and the mechanism of the adjacent pile’s uplift caused by the jacking pile in a double pile system is especially unclear, but these facets are important to the stability of the jacked pile. In this paper, a series of tests is performed on jacked model piles in sand, where in the influences of the pile length and the driving pile’s speed on the effects and vertical bearing capacity of two jacked piles were studied. The results revealed that the effects and vertical bearing capacity of the two jacked piles were mainly in relation to pile length and influenced by the driving speed. The horizontal displacement of the top of the first jacking pile during the installation of the post-jacking pile was caused by the difference in the stress state of the first jacking pile between the side of the pile’s face and its back side, in which the uplift displacement of the first jacking pile was also involved. The radial stress of the pile increased nonlinearly with the depth under different pile lengths and gradually converged to the passive earth pressure. The ultimate capacity of the double pile is approximately twice that of a single pile, and the ratio of the ultimate capacity of a single pile to the final jacking pressure was approximately 1.04.
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Gunawan, H., L. Flessati, and P. Marveggio. "Optimizing foundation performance: the impact of raft on piled raft foundation in sand." Géotechnique Letters 15, no. 2 (2025): 1–5. https://doi.org/10.1680/jgele.24.00136.
Full textAbstract:
Conventional piled foundation designs tend to be overly conservative since the beneficial role of the raft is often neglected by assuming the piles to be the only part of the structure interacting with the soil. The contribution of the raft to the global response of the foundation is particularly important in the case of “large” piled rafts, where the pile length is comparable to the raft width. This configuration, although not theoretically optimal, is common for existing foundations of bridges and high-rise buildings. Although the beneficial effect of raft–pile–soil interaction on both bearing capacity and stiffness is generally acknowledged, simple and reliable approaches recognized by design codes are not yet available. Aiming at providing simple tools for designing large piled rafts under static and dynamic/cyclic loads, in this paper a numerical study is presented, with preliminary finite element analyses performed to examine the mechanical behaviour of a “large” piled raft under vertical centred loads and positioned on a dry sand layer. This paper presents the findings of this study, comparing the performance of the piled raft to the corresponding pile group and unpiled raft, and highlights the importance of considering the presence of rafts in the design of piled foundations.
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Hsieh, Meng Hsiu, Wen Yi Hung, and Chung Jung Lee. "Centrifuge Seismic Test on Seismic Behavior of Pile Group in Liquefiable Soil." Applied Mechanics and Materials 764-765 (May 2015): 1041–45. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.1041.
Full textAbstract:
A series of grouped-model piles (2×2) centrifuge shaking table tests at an acceleration of 80 g was conducted to simulate seismic responses of a grouped-piles embedded in liquefiable sandy soil subjected to different magnitudes of earthquake loading. The tested grouped-piles connected with a pile cap are used to support 4 sets of model dry storage tank.Different test conditions including elevations of pile cap, elevations of ground water table, and dry and saturated sand beds all are reported in the study. Sensors (i.e., strain gauges along the depths of pile for measuring the bending moments, accelerometers for measuring the accelerations at different depths, LVDTs and pore water pressure transducers) densely instrumented in the piles and the surrounding soils provide valuable information for examining their evolution at various degrees of liquefaction. The magnitudes of bending moment along pile depths would increase with the increases of base shaking. The lowest bending moments were measured for the grouped–piles with the pile cap embedded in the dry sand bed while the largest lowest bending moments for the grouped–piles with the pile cap embedded in the saturated sand bed with the water table at the surface. The test results can be used to validate the results derived from the numerical simulation.
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Leung, C. F., F. H. Lee, and N. S. Yet. "The role of particle breakage in pile creep in sand." Canadian Geotechnical Journal 33, no. 6 (1996): 888–98. http://dx.doi.org/10.1139/t96-119.
Full textAbstract:
It has been reported in the literature that the settlement of pile foundations in sand under sustained service loads is time dependent. As this phenomenon is not well understood, an experimental study is conducted to investigate the mechanism of pile creep in sand. In the first part of the study involving centrifuge modelling of piles, the test results show that the pile settlement increases with the logarithm of time and the rate of settlement increase is dependent upon the magnitude of applied load and sand density. The changes in the soil and pile stresses observed from instruments installed in the soil and along the pile shaft reveal that under sustained loads, stress relaxation takes place at and around the pile tip area with consequent stress transfer to the shaft. Associated ground surface settlement shows that creep is related to volumetric compression rather than dilation of sand. The centrifuge test findings are then related to the creep behaviour of sand subjected to one-dimensional compression. Examination of sand particles before and after sustained compression loads reveals that sand grains have been broken with their angular protrusions gradually ground off with time. The phenomena of sand particle breakage and stress relaxation around the pile tip provide evidence for the hypothesis that the observed creep is due to the progressive breakdown of sand particules. Key words: centrifuge models, creep, mechanism, one-dimensional compression, pile, sand.
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Nguyen Quoc, Van, Sang Nguyen Thanh, Tien Trinh Trung, et al. "Study the working of piles on the slope ground subjected to horizontal loading by numerical simulation method." Transport and Communications Science Journal 72, no. 1 (2021): 58–65. http://dx.doi.org/10.47869/tcsj.72.1.7.
Full textAbstract:
Numerical modelling is an efficient method to investigate the effects of the distance from pile centreline to pile centreline on the working of laterally loaded piles considering the shear plastic deformations of the ground. The paper presents the research results the effects of piles spacing on the sloping ground including sand and clay layers subjected to horizontal loading according to the finite element method by ABAQUS software. Group of authors simulate the soil-pile interface, capable of incorporating the gapping and sliding in the soil-pile interfaces for both sand and clay layers. The research results are used to predict the lateral load-deformation of piles for different cases and comparison with published research results. On that basis predicting the suitable distance horizontal loading piles that a pile negligible influenced from adjacent pile on a slope. This is a matter of high scientific and practical significance in foundation engineering in general, as well as in calculating pile foundations on a slopes in particular.
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Nasr, Ahmed M. A. "Experimental and theoretical studies of laterally loaded finned piles in sand." Canadian Geotechnical Journal 51, no. 4 (2014): 381–93. http://dx.doi.org/10.1139/cgj-2013-0012.
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Large lateral loads may act on pile foundation supporting structures, such as bridge abutments, retaining walls, and structures subjected to wind–earthquake loads. A pile with fins is a newly developed type of pile foundation that is capable of supporting large lateral loads. In the present study an attempt is made to evaluate the improvement in lateral capacity of a pile with fins mounted close to the pile head. Small-scale model tests and a numerical study using finite element analysis were performed on regular piles without (fins) and piles with fins. These piles were installed in sand of different relative densities (Dr = 35% and 78%). The investigations were carried out by varying the length, width, and shape of the fins, and type of pile. Results reveal that there is a significant increase in lateral resistance of the piles after mounting the fins close to the pile head. The increase in lateral resistance gained by placing fins on a pile varies with geometries of the pile and fins. The lateral resistance increases with the increase in length of the fins until the fin’s length is equal to 0.4 of the pile length. Based on the results of the laboratory model and numerical analysis, critical values of fin parameters for maximum improvement are suggested. The agreement between observed and computed results is found to be reasonably good in terms of ultimate lateral load and fin efficiency. A comparison between the model results and the prototype-scale results is also studied.
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Trung, Le Thiet, Duong Diep Thuy, and Pham Viet Anh. "Experimental testing of a full-scale of group efficiency in multiple soil layers." Journal of Science and Technology in Civil Engineering (STCE) - NUCE 13, no. 3 (2019): 135–42. http://dx.doi.org/10.31814/stce.nuce2019-13(3)-13.
Full textAbstract:
Results of in-situ tests showed that the performance of single isolated piles and individual piles within a group is largely different. When piles are arranged in a group, the interaction between piles and the foundation depends on the pile arrangement and the pile group effect. To date, studies on the pile group effect in Vietnam have been limited to reduced-scale laboratory testing or static load testing where piles are installed into homogeneous sandy or clayey foundation. This paper presents in situ tests which were performed on both single piles and pile groups, loaded to failure, with the aim of studying the pile group effect of piles embedded in multi-layered foundation. Strain gauges were installed along the shaft of 10 m long steel pipe piles, with a diameter of 143 mm. The influence of loose sand layers on the group effect in case of friction piles was evaluated. The experimental results indicated that the influence of sand layers was evident, and the group factor was calculated to be 1.237.
 Keywords:
 group efficiency; pile groups; axial capacity; load transfer.