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1
Foray, P., L. Balachowski, and J. L. Colliat. "Bearing capacity of model piles driven into dense overconsolidated sands." Canadian Geotechnical Journal 35, no. 2 (April 1, 1998): 374–85. http://dx.doi.org/10.1139/t97-082.
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Model piles were driven into dense siliceous sand samples and tested in a large calibration chamber. Axial tension and compression tests were performed on open-ended pipe piles. The objective of this research was to study the effect of overconsolidation on the bearing capacity of piles driven into dense sands representative of North Sea soil conditions. Emphasis was put on points of interest for the offshore petroleum industry in particular: dense to very dense normally consolidated (NC) and overconsolidated (OC) sands, unit end bearing and unit skin friction capacities, and comparison with tip resistances from cone penetration tests. Design parameters are proposed for computing the axial bearing capacity of piles driven into dense to very dense siliceous sands. They are compared with those given in the current American Petroleum Industry's Recommended Practice 2A document. A relationship between CPT cone resistance and ultimate unit end bearing and skin friction capacities of piles is also proposed.Key words: model test, dense sand, offshore pile driving, axial capacity, end bearing, skin friction, design parameters, cone penetrometer.
2
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 (November 4, 2022): 14493. http://dx.doi.org/10.3390/su142114493.
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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.
3
Gavin, Kenneth, and Barry Lehane. "Base load – displacement response of piles in sand." Canadian Geotechnical Journal 44, no. 9 (September 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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Bisi, C., G. Chiaselotti, and P. A. Oliverio. "Sand Piles Models of Signed Partitions with Piles." ISRN Combinatorics 2013 (January 13, 2013): 1–7. http://dx.doi.org/10.1155/2013/615703.
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Let be nonnegative integers. In this paper we study the basic properties of a discrete dynamical model of signed integer partitions that we denote by . A generic element of this model is a signed integer partition with exactly all distinct nonzero parts, whose maximum positive summand is not exceeding and whose minimum negative summand is not less than . In particular, we determine the covering relations, the rank function, and the parallel convergence time from the bottom to the top of by using an abstract Sand Piles Model with three evolution rules. The lattice was introduced by the first two authors in order to study some combinatorial extremal sum problems.
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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 (August 1, 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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Latapy, Matthieu, Roberto Mantaci, Michel Morvan, and Ha Duong Phan. "Structure of some sand piles model." Theoretical Computer Science 262, no. 1-2 (July 2001): 525–56. http://dx.doi.org/10.1016/s0304-3975(00)00363-7.
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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 (October 1, 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.
8
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 (November 22, 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.
9
Cai, Q., B. Xiang, C. W. W. Ng, K. S. Wong, X. Chen, and Y. Zhuang. "Loading transfer mechanism of a piled raft subjected to normal faulting in sand." Géotechnique Letters 12, no. 1 (March 2022): 14–19. http://dx.doi.org/10.1680/jgele.21.00098.
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Although different kinds of foundations have been investigated against an earthquake faulting, the interaction between pile group and dip–slip fault has not yet been fully understood. This paper investigates the interaction between piled raft and normal faulting by means of centrifuge and numerical modelling. In centrifuge test, a piled raft was simulated with a half model for a better observation of fault rupture path under the raft. The loading transfer mechanism was further examined using a three-dimensional finite difference software. The measured and computed results showed that the piled raft displaced and tilted linearly with the magnitude of faulting. The fault rupture bifurcated into two and diverted towards both edges of the raft. Two types of loading transfer mechanism were identified during faulting. Working load transferred from the raft to the underneath piles, and also from the piles on the side of the hanging wall to the piles on the footwall side, resulting in compression failure of the piles on the footwall side.
10
Hanna, A. M., and A. Afram. "Pull-out capacity of single batter piles in sand." Canadian Geotechnical Journal 23, no. 3 (August 1, 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.
11
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 (April 1, 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.
12
Duong, Phan Thi Ha, and Tran Thi Thu Huong. "On the stability of Sand Piles Model." Theoretical Computer Science 411, no. 3 (January 2010): 594–601. http://dx.doi.org/10.1016/j.tcs.2009.09.022.
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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.
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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.
14
Lee, Junhwan, and Rodrigo Salgado. "Analysis of calibration chamber plate load tests." Canadian Geotechnical Journal 37, no. 1 (February 1, 2000): 14–25. http://dx.doi.org/10.1139/t99-061.
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The estimation of base resistance is a key step in the design of piles embedded in moderately dense to dense sand. Calibration chamber plate load tests are sometimes used to investigate the base load - settlement relationship of nondisplacement piles in sand. In such tests, the sand specimens are carefully prepared to simulate the installation of nondisplacement piles. In this paper, calibration chamber tests are analyzed using the finite element method; experimental and numerical results are compared. The finite element models are axisymmetric and use a nonlinear, elastic-plastic constitutive model. Plate resistance values predicted using the finite element analysis are shown to be in good agreement with measured values, which validates the proposed numerical model. Questions regarding the existence of calibration chamber size effects have not, to this date, been adequately addressed. Finite element analyses of both pile base resistance and plate resistance for sands with various relative densities and stress states show that size effects are usually small for settlement levels of interest in practice. This suggests that the use of calibration chambers in pile base capacity studies is justified.Key words: calibration chambers, plate load tests, constitutive modeling, size effects, piles, sands.
15
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.
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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.
16
Dickin, E. A., and C. F. Leung. "Performance of piles with enlarged bases subject to uplift forces." Canadian Geotechnical Journal 27, no. 5 (October 1, 1990): 546–56. http://dx.doi.org/10.1139/t90-070.
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The influence of embedment, base diameter, and backfill density on the uplift behaviour of piles with enlarged bases embedded in sand was investigated in a centrifuge. Comparitive tests on straight-shafted piles are also reported. For piles in dense sand, sensible agreement was found with earlier research on anchor plates and published field data. However, uplift capacities in loose sand were considerably lower than previously observed for anchor plates. A number of theories for anchors considerably overpredict the observed capacity for belled piers in both dense and loose sand, although in the case of dense sand, reasonable values are obtained using an empirical equation derived from centrifuge tests on anchor plates and a finite element based design approach. The normally conservative vertical slip-surface model is alone in providing reasonable agreement with the surprisingly low observations for piles in loose sand. Key words: piles, uplift capacity, centrifuge tests, sand.
17
Doubrovsky, M. P., and V. O. Dubravina. "MODEL TESTING OF THE "PILE-SOIL" INTERACTION UNDER AXIAL FORCE." Bulletin of Odessa State Academy of Civil Engineering and Architecture, no. 83 (June 4, 2021): 102–11. http://dx.doi.org/10.31650/2415-377x-2021-83-102-111.
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Modern marine structures (berths, breakwaters, offshore platforms, etc.) often include steel tubular piles of essential length (80-100 m and more) that should provide high bearing capacity in case of external axial loads application. Interaction between elements of the system “piled structure – soil media” is not studied sufficiently yet. It relates also to the bearing capacity of the long steel tubular piles of large diameter. One of the interesting peculiarities of long tubular piles behavior is the formation of soil plug at the piles tip. There are a lot of suggestion and methods aimed to increase piles bearing capacity under static pressing load. One of them relates to use of the additional structural element, i.e., the internal diaphragm welded to the internal surface of the pile shaft. Such approach has been applied in some practical cases of marine construction and demonstrated its effectiveness. At the moment there are no researches focused on study of the peculiarities of internal diaphragm application. So proposed research aimed to study two connected processes during steel tubular pile driving: soil plug formation at the tip of the open-end pile and soil behavior under the internal diaphragm fixed inside the tubular pile shaft. To study mentioned processes we provided several series of laboratory experiments fulfilled at the Geotechnical laboratory of the Department “Sea, River Ports and Waterways” in Odessa National Maritime University. In these experiments the model of steel tubular pile has been driven (pressed) into fine sand by mechanical jack. The first series was devoted to determination of the conditions related to the soil plug formation at the pile tip. The next series were aimed to study the influence of the flat rigid diaphragm inside the pile shaft. Obtained experimental results allow to conclude that (a) in the fine sand the plug is formatted at the comparatively early stage of pile installation (in case of our modeling – at the penetration depth of some 4-5 pile diameter); (b) our empirical assessment of the conditions of soil plug formation corresponds to the approaches based on PLR and IFR characteristics; (c) formation of soil plug at the pile tip is followed by decreasing of soil level in the pile shaft relatively its initial value (on completing the plug formation the soil level in the shaft become stable); (d) regarding above mentioned, we may note that in case of use of internal diaphragm on the recommended depth (5-7 pile diameters) there may be no contact between diaphragm and the soil inside the pile (e) application of the diaphragm may lead to increasing of the pile’s bearing capacity. It was proposed (and checked by our tests) the technological improvement based on sand filling into space under the internal diaphragm to provide constant diaphragm-soil contact and related soil resistance.
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Phan, Thi Ha Duong. "Two sided Sand Piles Model and unimodal sequences." RAIRO - Theoretical Informatics and Applications 42, no. 3 (June 3, 2008): 631–46. http://dx.doi.org/10.1051/ita:2008019.
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Chaney, DR, K. Demars, JT Chin, and HG Poulos. "Tests on Model Jacked Piles in Calcareous Sand." Geotechnical Testing Journal 19, no. 2 (1996): 164. http://dx.doi.org/10.1520/gtj10339j.
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Goles, Eric, Gregorio González, Hans Herrmann, and Servet Mart´inez. "Simple lattice model with inertia for sand piles." Granular Matter 1, no. 3 (December 1, 1998): 137–40. http://dx.doi.org/10.1007/s100350050019.
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Hartono, Edi. "Analisis Lendutan Model Pelat Fleksibel dengan Tiang Perbesaran Ujung dan Pelat Tidak Rapat Tanah Pada Tanah Pasir." Semesta Teknika 17, no. 1 (November 25, 2015): 10–16. http://dx.doi.org/10.18196/st.v17i1.410.
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Problems in sandy soil may occur when sand has low density, uniform gradation and thick deposit. Flexible plate foundation may used in this condition but plate deflection still high. To reduce deflection and to improve soil density, piles were used to support the plate. Installing piles made foundation system stiffer. The objectives of this study are to studies about behavior of plates and plate with pile on sandy soil. Plate deflection was observed with variation of plate thickness, bottom pile enlargement, and soil-plate-pile interaction (free standing pile and piled foundation). 1,2 x 1,2 x 1,2 m box container filled with sandy soil was used as soil media. Square and rectangular plexiglass plate were used to modelled plate. Steel pipe with 2,5 cm in diameter were used as pile model. The behavior of the plates were observed under loading (point load). The results shows that plate deflections were affected on plate thickness, bottom pile enlargement and soil-plate-pile interaction. For a ticker plate, contact surface between plate and soil was wider. For the 40 cm x 10 cm plates with base pile enlargement, deflections were found to reduced up to 21,26%. The ‘piled foundation’ on 40 cm x 10 cm plates, (installing with 20 cm pile length, and 10 cm spacing between pile), deflections were reduced 83,63% compared with free standing foundation.
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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 (June 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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Georgiadis, M., C. Anagnostopoulos, and S. Saflekou. "Centrifugal testing of laterally loaded piles in sand." Canadian Geotechnical Journal 29, no. 2 (April 1, 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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Craig, William H., and Suhail K. Sabagh. "Stress-level effects in model tests on piles." Canadian Geotechnical Journal 31, no. 1 (February 1, 1994): 28–41. http://dx.doi.org/10.1139/t94-004.
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Results are presented from several series of centrifuge model tests of piles installed in beds of uniform dry sand. Using identical model geometries, but varying acceleration factors, the tests demonstrate quite clearly the nature and extent of stress-level variations on the performance of piles. The results are interpreted initially in terms of bearing capacity coefficients Nt and lateral earth pressure coefficients Ks, and subsequently in terms of angle of friction [Formula: see text], determined using available relationships. Controlled laboratory experiments with varying levels of overburden pressure around the piles indicated consistent reductions in Nt, and to a lesser extent in Ks. Quantitative interpretations in terms of angle of friction variations depend on selection from a range of empirical correlations available and have been made for two of those commonly used. Comparison of shaft loads in compression and extension confirms the widespread belief that there is a difference, which is found to vary quantitatively depending on the relative density. Key words : model tests, piles, sand, centrifuge, stress level.
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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 (March 7, 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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Leong, Wong Kok, Nor Azizi Yusoff, Ameer Nazrin Abd Aziz, and Zaihasra Abu Talib. "Theoretical and Actual Bearing Capacity of Driven Piles Using Model Piles in Sand." Applied Mechanics and Materials 773-774 (July 2015): 1453–59. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.1453.
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In general, increasing of penetration rate may result in an increased of pile capacity. Occasionally, there were differences between theoretical and actual bearing capacity of the piles. Rate of penetration of pile influenced the pile bearing capacity. The bearing capacity of model pile increased as the rate of loading increased based on pile driving formula. Therefore, the study was conducted to determine the bearing capacity of model piles with different penetration forces based on theoretical method and experimented analysis. Five circular hollow section model piles using pipe pile were used to penetrate into cohesionless soil with different penetration force respectively. The loading for ultimate bearing capacity using theoretical calculation was approximately about 0.163kN.However, referring to the limitation of a laboratory setup, the maximum loading was 0.12kN. Several trials had been initiated but when it reached 0.14kN, the setup was unstable and dangerous to be continued. Therefore, the ultimate bearing capacity derived by the pile load test results were based on a pile moved up to 10% of its tip diameter criteria. In the future, both theoretical and actual calculation must be made to avoid any confusion and detect mistakes in near future.
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Meyerhof, G. G., V. V. R. N. Sastry, and A. S. Yalcin. "Lateral resistance and deflection of flexible piles." Canadian Geotechnical Journal 25, no. 3 (August 1, 1988): 511–22. http://dx.doi.org/10.1139/t88-056.
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The ultimate lateral resistance and the groundline lateral deflections under working loads of freestanding single model piles and small pile groups, of various materials and different embedded lengths, subjected to horizontal load have been investigated. The test results of piles of various stiffnesses in sand and clay are compared with theoretical analyses based on the concept of an effective embedment depth in terms of the behaviour of equivalent rigid piles. Key words: clay, piles, displacements, lateral load, lateral resistance, pile stiffness, sand, ultimate load.
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Nasr, A. M., W. R. Azzam, and K. E. Ebeed. "Bearing Capacity of Defective Reinforced Concrete Pile in Sand-model Study." Advances in Geological and Geotechnical Engineering Research 4, no. 3 (August 16, 2022): 1. http://dx.doi.org/10.30564/agger.v4i3.4808.
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Concrete piles that were poorly constructed or analyzed in their soil analyses may have structural or geotechnical defects. To examine such defects, an experimental study was conducted to investigate how a defective reinforced concrete pile behaved. These piles were installed and subjected to a compression axial load in the sand that had relative densities of 30%,60%, and 80%. The tests were performed using four concrete model piles: one intact pile and the other three piles had a structural defect (necking) at three different positions of the pile at (0.25 L from the top, center, and 0.25 L bottom). Geotechnical defect (soft layer or debris) was studied using Styrofoam layer at various vertical distances under the pile toe with Y/D = (0, 0.5, 1 and 1.5) D. The test results showed that the bearing capacity of the structural defect was the most in the case of a neck at 0.25 L from the bottom, followed by a neck at the center, and finally a neck at 0.25 L from the top. In the case of a geotechnical defect, the bearing capacity of the pile decreased with the decrease of the vertical distance between the soft layer and the pile toe.
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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 (August 1, 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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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 (May 18, 2023): 543–49. http://dx.doi.org/10.31026/j.eng.2013.05.02.
Full textAbstract:
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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Sakr, Mohammed. "Performance of helical piles in oil sand." Canadian Geotechnical Journal 46, no. 9 (September 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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Ergun, Mehmet Ufuk, and Devrim Sönmez. "Negative skin friction from surface settlement measurements in model group tests." Canadian Geotechnical Journal 32, no. 6 (December 1, 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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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 (December 1, 1991): 909–17. http://dx.doi.org/10.1139/t91-108.
Full textAbstract:
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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Baek, Sung-Ha, and Joonyoung Kim. "Investigation of p-y Behaviors of a Cyclic Laterally Loaded Pile in Saturated Silty Sand." Advances in Civil Engineering 2022 (December 5, 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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T, Aruna, K. V. S. B. Raju, and Swathi Gowda. "Experimental Investigation of piled raft foundation on Cohesionless Soil." International Journal of Research and Scientific Innovation 09, no. 02 (2022): 113–18. http://dx.doi.org/10.51244/ijrsi.2022.9207.
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The combination of piles and raft foundation is known as piled raft foundation. Piled raft foundations have proven to be more cost-effective and capable of meeting safe bearing capacity and serviceability norms in the case of high-rise buildings on cohesionless soil. The behavior of a stacked raft foundation is influenced by the piles, raft, and soil. The stacked raft system’s bearing capacity is improved and settlement is minimized when the ground beneath the raft foundation bears the burden of supporting the applied loads. The piled raft foundation minimizes total settlement and improves bearing capacity more than the raft foundation. When isolated footings cover more than 70% of the building area under a superstructure, raft foundations are used, and the present study focuses on the vertical load bearing capability of piled raft foundation systems on cohesionless soil for concentric loading. The use of strategically positioned piles increases the load capacity of the raft while reducing differential settlement. The present study sheds some light on the use of piles as raft foundation settlement reducers, as well as the behavior of a piled raft in sand. A series of small-scale model experiments were carried out. The present investigation studies by varying pile length and alignment on the ultimate load of piled raft foundation. The results indicate that for a 10mm raft thickness, installing 4 piles, 6 piles, and 9 piles by varying L/D ratios of 5,10,15,20 carries significant load. In this present work for a 50mm length of pile, and the value of load improvement ratio increases by 36 percent, 60 percent, and 68 percent, respectively, when compared to plain raft.
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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 (February 2, 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 (December 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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Zhu, Xiao-jun, Kang Fei, and Sheng-wei Wang. "Horizontal Loading Tests on Disconnected Piled Rafts and a Simplified Method to Evaluate the Horizontal Bearing Capacity." Advances in Civil Engineering 2018 (September 16, 2018): 1–12. http://dx.doi.org/10.1155/2018/3956509.
Full textAbstract:
Disconnected piled raft (DPR) foundations have been widely adopted as an effective foundation system where the piles are separated from the raft by a granular layer, which can limit the shear forces and moments transmitted between the raft and the piles. Thus, DPR foundations may avoid the problem of horizontal forces, such as those from an earthquake or dynamic loads, which damage the structural connection between the pile head and raft. A series of static horizontal loading tests were carried out on three types of foundation models, i.e., piled raft, disconnected piled raft, and raft alone models, on fine sand using a geotechnical model in a 1 g field. In this paper, the influences of vertical loading and interposed layer thickness were presented and discussed. The results showed that most of the horizontal force was carried by raft/interposed layer friction in the DPR foundation type, and the shear force and moment of the piles were greatly reduced due to the gap between the raft and the heads of the piles. The tested foundations were simulated using a simplified method with theoretical equations derived by making several approximations and assumptions. The simulated results agreed well with the test results.
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Lu, Shi Jie, Hua Dong Chen, Wei Chen, Tong Xiang, and Xie Feng Hong. "Model Tests of Foundation Bearing Capacity of Sandy Soil and Pile Foundation Bearing Capacity." Applied Mechanics and Materials 580-583 (July 2014): 113–17. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.113.
Full textAbstract:
Using self―made model device, researchers studied the characteristics of foundation settlement of sandy soil and pile foundation load―bearing in sandy soil. Through weight loading, researchers analyzed the phenomenon of foundation settlement. Then, researchers embedded friction piles in sand, so as to analyzed pile foundation bearing capacity. The methods and results of the research can provide guidance for teaching of Soil mechanics and foundation engineering.
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Sastry, V. V. R. N., and G. G. Meyerhof. "Behaviour of flexible piles under inclined loads." Canadian Geotechnical Journal 27, no. 1 (February 1, 1990): 19–28. http://dx.doi.org/10.1139/t90-003.
Full textAbstract:
The lateral soil pressures, bending moments, pile displacements at ground surface, and bearing capacity of instrumented vertical single flexible model piles in homogeneous loose sand and soft clay under 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: bending moments, clay, displacements, inclined loads, instrumentation, lateral soil pressure, model test, pile, sand.
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Zhu, Bin, Tao Li, Gen Xiong, and Jin Chao Liu. "Centrifuge model tests on laterally loaded piles in sand." International Journal of Physical Modelling in Geotechnics 16, no. 4 (December 2016): 160–72. http://dx.doi.org/10.1680/jphmg.15.00023.
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Chaney, RC, KR Demars, AI Al-Mhaidib, and TB Edil. "Model Tests for Uplift Resistance of Piles in Sand." Geotechnical Testing Journal 21, no. 3 (1998): 213. http://dx.doi.org/10.1520/gtj10895j.
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Joshi, R. C., H. D. Sharma, and D. G. Sparrow. "Comparison of pile load test methods." Canadian Geotechnical Journal 26, no. 4 (November 1, 1989): 742–44. http://dx.doi.org/10.1139/t89-086.
Full textAbstract:
Instrumented model piles were loaded to failure using slow-maintained-load, quick-maintained-load, and constant-rate-of-penetration methods of loading. The piles were driven in a prepared dry-sand bed. The applied load, point load, and shaft resistance were measured using load cells and strain gauges, and axial force distribution was determined. Test data indicate that all the three methods give similar ultimate load at failure. Nonetheless, out of the three methods, the slow-maintained-load method of testing piles, which seems to simulate field conditions, gives the largest settlement for the same applied load. The axial force distribution and shaft resistance along the pile were observed to be identical for all the three pile test methods. Key words: model piles, laboratory study, axial loading, test methods, sands, point load, shaft resistance, ultimate load.
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Meyerhof, G. G., and D. P. Ghosh. "Ultimate capacity of flexible piles under eccentric and inclined loads." Canadian Geotechnical Journal 26, no. 1 (February 1, 1989): 34–42. http://dx.doi.org/10.1139/t89-004.
Full textAbstract:
The ultimate bearing capacity of flexible single model piles and small pile groups of timber and nylon in loose sand and soft clay has been determined under various combinations of eccentricity and inclination of the load varying in direction from vertical to horizontal. The results of the load tests are presented in the form of polar bearing capacity diagrams and they are compared with the theoretical estimates based on the concept of an effective embedment depth in terms of the behaviour of equivalent rigid piles. Reasonable agreement has been found between the observed and predicted ultimate bearing capacity of flexible piles under any combination of eccentricity and inclination of loads. Key words: flexible piles, pile groups, ultimate bearing capacity, ultimate moment, model test, eccentric load, inclined load, sand, clay.
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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.
Full textAbstract:
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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Kong, Desen, Yifei Bai, Yongpo Chen, and Meixu Deng. "A Study on the Seismic Response Characteristics of an Oblique Pile Group-Soil-Structure with Different Pile Caps." Shock and Vibration 2019 (October 30, 2019): 1–12. http://dx.doi.org/10.1155/2019/8141045.
Full textAbstract:
For the study of interaction between piles-soil-structure with different caps, the FLAC3D finite difference software was used as the research tool, and dynamic load was El Centro seismic wave. The numerical model of obliquely pile groups of the pile-soil-structure with low cap and high cap was established, respectively. The variation of pore pressure, the moment, the displacement of piles, and the displacement of pier was analyzed. The results indicate that under the action of earthquake, the distribution of pore water pressure in the soil layer increases gradually from top to bottom. The instantaneous negative value of partial soil due to shear dilation occurs at the peak of vibration acceleration. The middle area of the pile foundation in sandy soil is prone to liquefaction. In the same model, the maximum bending moment of inclined piles is greater than that of vertical piles. The vertical displacement of the vertical piles is a constant value along the depth, while the vertical displacement of the inclined piles is changed along the depth of the buried piles. In the high cap model, the horizontal displacement of the inclined piles is no longer monotonous along the burying depth, and the maximum value occurs in the sand soil layer. The vertical and horizontal displacements of the inclined piles and vertical piles in the high cap model are obviously greater than those of the low cap model. The maximum horizontal displacement of the pier of the two models occurs at the same time.
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Koumoto, T., G. G. Meyerhof, and V. V. R. N. Sastry. "Analysis of bearing capacity of rigid piles under eccentric and inclined loads." Canadian Geotechnical Journal 23, no. 2 (May 1, 1986): 127–31. http://dx.doi.org/10.1139/t86-022.
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An investigation is made of the eccentricity and inclination factors for estimating the ultimate bearing capacity of rigid single piles in homogeneous soils under eccentric and inclined loads. For combined eccentric inclined loads the corresponding theoretical factors are obtained by combining inclination factors and eccentricity factors, which are derived from extending the theory of inclination factors for shallow strip footings. The theoretical values of inclination factors, eccentricity factors, and eccentric inclination factors are compared with some experimental results of model piles in sand and clay. Key words: bearing capacity, clay, eccentricity factors, eccentric inclination factors, inclination factors, rigid piles, sand, ultimate load.
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Al-Saidi, A’amal Abdul Ghani. "Correction Factor for Methods of Installation of Piles Group in Sandy Iraqi Soils." Journal of Engineering 22, no. 9 (September 1, 2016): 172–81. http://dx.doi.org/10.31026/j.eng.2016.09.11.
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Many problems are facing the installation of piles group in laboratory testing and the errors in results of load and settlement are measured experimentally may be happened due to select inadequate method of installation of piles group. There are three main methods of installation in-flight, pre-jacking and hammering methods. In order to find the correction factor between these methods the laboratory model tests were conducted on small-scale models. The parameters studied were the methods of installation (in-flight, pre-jacking and hammering method), the number of piles and in sandy soil in loose state. The results of experimental work show that the increase in the number of piles value led to increase in load carrying capacity of piled raft and decrease in settlement value for three methods of installation. The response of increases load capacity for hammering method is the same value of pre-jacking method at the number of piles less than (N=2), while when the number of piles are beyond (N=3 to 9). The load capacity of hammering method is more than pre-jacking method and the correction factor of method of installation depend on the type of method of installation and the piles number. The increase in carrying capacity by hammering method is due to mobilize the dynamic soil structure interaction (soil-pile and pile-pile interaction) and the change in properties for surrounding soil for loose state of sand is more effective than static soil structure interaction mobilize by pre-jacking method. The correction factor of increase in load capacity and the correction factor of the percentage of settlement reduction for pre-jacking and hammering methods are compared with in-flight method of installation are changed with the number of piles and these values are increased with increasing the number of piles.
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Altaee, Ameir, Bengt H. Fellenius, and Erman Evgin. "Load transfer for piles in sand and the critical depth." Canadian Geotechnical Journal 30, no. 3 (June 1, 1993): 455–63. http://dx.doi.org/10.1139/t93-039.
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The authors analyzed the results from a static loading test on a 11.0-m, intrumented, precast concrete pile and presented the findings in two earlier papers. The findings are here extrapolated to verify the dependability of applying the results and analysis methods to predict the detailed behavior of a similar test pile driven 5 m away from the first pile and to a 4.0 m deeper embedment. This paper offers conclusions drawn from the analyses of both piles with regard to residual load and resistance distribution. A primary result of the analyses is the indication that the critical-depth concept is not valid. For full-length piles, the critical-depth concept originates because of neglects in analysis of test data, such as omission of the residual load and testing-sequence history. For tests on short piles and laboratory studies of model piles, a critical depth appears as a result of neglect of the influence of shallow-depth variation of the earth pressure coefficient. Key words : instrumented piles, sand, loading test, residual load, load transfer, finite element, constitutive modelling, critical-depth concept.
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Tsuha, Cristina de Hollanda Cavalcanti, and Nelson Aoki. "Relationship between installation torque and uplift capacity of deep helical piles in sand." Canadian Geotechnical Journal 47, no. 6 (June 2010): 635–47. http://dx.doi.org/10.1139/t09-128.
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The empirical torque correlation factor (KT), which relates the uplift capacity to the installation torque of helical piles, is routinely used as an on-site instrument for quality control with this type of foundation. This paper presents a theoretical relationship between uplift capacity and installation torque of deep helical piles in sand. An experimental program, including centrifuge and direct shear interface tests, was carried out to validate this expression. The experimental results were compared with the values predicted by the suggested approach and showed good agreement. As the developed model depends on the residual interface friction angle (δr) between the helix surface and the surrounding sand, results of δr, extracted from different sand samples, are presented for use in this suggested relationship on site. Also, the values of KT found in this work were compared with those of field and laboratory tests on helical piles in sand reported in the literature. From this analysis, it was found that the measured values of KT decrease with an increase in pile dimensions and, in most of cases, with an increase in sand friction angle. These results were explained by the presented model.