Bearing capacity of model piles driven into dense overconsolidated sands

1998 ◽  
Vol 35 (2) ◽  
pp. 374-385 ◽  
Author(s):  
P Foray ◽  
L Balachowski ◽  
J -L Colliat
Keyword(s):  
Bearing Capacity ◽  
Skin Friction ◽  
Petroleum Industry ◽  
Design Parameters ◽  
Soil Conditions ◽  
Compression Tests ◽  
Dense Sand ◽  
Axial Capacity ◽  
Cone Penetration Tests ◽  
Tension And Compression

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.

A Study of Anchorages for Transmission Tower Foundations

1972 ◽  
Vol 9 (1) ◽  
pp. 89-104 ◽  
Author(s):  
J. I. Adams ◽  
T. W. Klym
Keyword(s):  
Soft Clay ◽  
Adhesive Bond ◽  
Silty Sand ◽  
Design Parameters ◽  
Soil Conditions ◽  
Transmission Tower ◽  
Dense Sand ◽  
Thunder Bay ◽  
Bond Theory ◽  
Sand And Gravel

A number of uplift tests have been conducted on anchors proposed for use to support high voltage transmission line towers both for the conventional four legged structure and for the guyed-type structure with a single central footing. Tests were carried out at seven sites, six in the Toronto-Barrie Area and one at Thunder Bay, Ontario. The soil conditions included very dense till, soft clay up to 130 ft (39.62 m) in depth, dense sand and gravel and loose to compact silty sand. The test installations included both power installed multi-helix anchors and grouted anchors with a single reinforcing rod. These were installed at various depths. In the very deep clay only multi-helix anchors were tested. Most of the tests were in uplift on anchors installed vertically. A few group tests were conducted both in uplift and compression. The results of all of the tests are presented along with fairly detailed information on the properties of the soil at each site. An attempt to analyze the results of the helix anchor tests using simplified bearing theory was made. The grouted anchor tests were analyzed using either frictional or adhesive bond theory depending on the soil type. The results indicate that the theories using conventional soil properties provide reasonable design parameters for initial planning. Further confirmation by fullscale testing, however, is essential.

Influence of Different Pile Installation Methods on Dense Sand

2019 ◽  
Author(s):  
Severin Spill ◽  
Tulio Quiroz ◽  
Aligi Foglia
Keyword(s):  
Soil Conditions ◽  
Published Data ◽  
Initial State ◽  
Dense Sand ◽  
Pile Installation ◽  
Cone Penetration Tests ◽  
Before And After ◽  
Realistic Representation ◽  
Area Of Influence ◽  
Surrounding Soil

Abstract A current investigation subject of geotechnical modelling is the realistic representation of the installation process of offshore piles and its influences on the surrounding soil. Depending on the soil conditions piles can be installed with different installation technologies like impact driving, vibratory driving or jacking. The soil disturbances produced as a consequence of the pile installation affect the pile capacity. The dimension of the affected region depends on the installation process itself and its parameters as well as the soil initial state and the pile geometry. Currently, there are no general approaches which can predict the effects of pile installation on the soil conditions. In this contribution a brief summary of published data describing installation effects for impact driven, vibratory driven and jacked piles is given. Secondly, the influences of different pile installation methods on the surrounding soil are presented based on experimental results for non-cohesive soils from various projects. These will be analyzed by means of a comparison of dynamic probe light (DPL) and cone penetration tests (CPT) executed before and after the pile installations. Additionally the area of influence will be quantified with respect to their relative distance to the pile axis. Finally, based on these results recommendations for future works will be given.

Modelling the asymmetric tension–compression properties of additively manufactured alloys using continuum damage mechanics

2021 ◽  
pp. 146442072110134
Author(s):  
A Nayebi ◽  
H Rokhgireh ◽  
M Araghi ◽  
M Mohammadi
Keyword(s):  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Element Model ◽  
Continuum Damage ◽  
Compression Tests ◽  
Compression Properties ◽  
Mechanics Model ◽  
Stress Components ◽  
Tension And Compression ◽  
Closure Effect

Additively manufactured parts often comprise internal porosities due to the manufacturing process, which needs to be considered in modelling their mechanical behaviour. It was experimentally shown that additively manufactured parts’ tensile and compressive mechanical properties are different for various metallic alloys. In this study, isotropic continuum damage mechanics is used to model additively manufactured alloys’ tension and compression behaviours. Compressive stress components can shrink discontinuities present in additively manufactured alloys. Therefore, the crack closure effect was employed to describe different behaviours during uniaxial tension and compression tests. A finite element model embedded in an ABAQUS’s UMAT format was developed to account for the isotropic continuum damage mechanics model. The numerical results of tension and compression tests were compared with experimental observations for additively manufactured maraging steel, AlSi10Mg and Ti-6Al-4V. Stress–strain curves in tension and compression of these alloys were obtained using the continuum damage mechanics model and compared well with the experimental results.

Bearing Capacity of Foundations with Inclusion of Dense Sand Layer over Loose Sand Strata

2017 ◽  
Vol 17 (10) ◽  
pp. 06017018 ◽  
Author(s):  
Vishwas N. Khatri ◽  
Jyant Kumar ◽  
Shamim Akhtar
Keyword(s):  
Bearing Capacity ◽  
Loose Sand ◽  
Sand Layer ◽  
Dense Sand

Experimental and Numerical Investigation on Radial Stiffness of Origami-inspired Tubular Structures

2021 ◽  
pp. 1-30
Author(s):  
Weijun Shen ◽  
Yang Cao ◽  
Xuepeng Jiang ◽  
Zhan Zhang ◽  
Gül E. Okudan Kremer ◽  
...  
Keyword(s):  
Circular Tube ◽  
Weight Ratio ◽  
Design Parameters ◽  
Thin Wall ◽  
Tubular Structures ◽  
Compression Tests ◽  
Element Analysis ◽  
Radial Stiffness ◽  
Paper Folding ◽  
Engineering Problems

Abstract Origami structures, which were inspired by traditional paper folding arts, have been applied for engineering problems for the last two decades. Origami-based thin-wall tubes have been extensively investigated under axial loadings. However, less has been done with radial stiffness as one of the critical mechanical properties of a tubular structure working under lateral loadings. In this study, the radial stiffness of novel thin-wall tubular structures based on origami patterns have been studied with compression tests and finite element analysis (FEA) simulations. The results show that the radial stiffness of an origami-inspired tube can achieve about 27.1 times that of a circular tube with the same circumcircle diameter (100 mm), height (60 mm), and wall-thickness (2 mm). Yoshimura, Kresling, and modified Yoshimura patterns are selected as the basic frames, upon which the influences of different design parameters are tested and discussed. Given that the weight can vary due to different designs, the stiffness-to-weight ratio is also calculated. The origami-inspired tubular structures with superior stiffness performances are obtained and can be extended to crashworthy structures, functional structures, and stiffness enhancement with low structural weight.

Development and Mechanical Characterization of a Collagen/Hydroxyapatite Bilayered Scaffold for Ostechondral Defect Replacement

2011 ◽  
Vol 493-494 ◽  
pp. 890-895 ◽  
Author(s):  
Francesca Gervaso ◽  
Francesca Scalera ◽  
Sanosh Kunjalukkal Padmanabhan ◽  
Antonio Licciulli ◽  
Daniela Deponti ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Sol Gel ◽  
Three Dimensional ◽  
Collagen Scaffold ◽  
Mechanical Analysis ◽  
Design Parameters ◽  
Compression Tests ◽  
Templating Method ◽  
Organic Part ◽  
Hydroxyapatite Scaffold

In this work a novel three-dimensional ostechondral substitute is proposed that is made of an inorganic/organic hybrid material, namely collagen/hydroxyapatite. The two components of the substitute have been characterized separately. The inorganic part, a hydroxyapatite scaffold, was fabricated by a polymer sponge templating method using a reactive sub-micron powder synthesized in our laboratory by hydroxide precipitation sol-gel route. The organic part, a collagen scaffold, was fabricated by a freeze-dying technique varying design parameters. Both the parts were analysed by scanning electron microscopy and their mechanical properties assessed by compression tests. The hydroxyapatite scaffold showed a high and highly interconnected porosity and a mechanical strength equal to 0.55 MPa, higher than those reported in literature. The collagen scaffolds were seeded by chondrocytes, processed for histology analysis and tested in compression. The biological tests proved the ability of the scaffolds to be positively populated by chondrocytes and the mechanical analysis showed that the mechanical strength of the scaffolds significantly increased after 3 weeks of culture.

scholarly journals A reduced order computational model of a semi-active variable-stiffness foot prosthesis

2020 ◽  
Author(s):  
Michael McGeehan ◽  
Peter Adamczyk ◽  
Kieran Nichols ◽  
Michael Hahn
Keyword(s):  
Body Weight ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Variable Stiffness ◽  
Performance Standard ◽  
Design Parameters ◽  
Compression Tests ◽  
Static Compression ◽  
Lumped Parameter ◽  
Contact Models

INTRODUCTION: Passive energy storage and return (ESR) feet are the current performance standard in lower limb prostheses. A recently developed semi-active variable-stiffness foot (VSF) prosthesis balances the simplicity of a passive ESR device with the adaptability of a powered design. The purpose of this study was to model and simulate the ESR properties of the VSF prosthesis. METHODS: The ESR properties of the VSF were modeled as a lumped parameter overhung beam. The overhung length is variable, allowing the model to exhibit variable ESR stiffness. Foot-ground contact was modeled using sphere-to-plane contact models. Contact parameters were optimized to represent the geometry and dynamics of the VSF and its foam base. Static compression tests and gait were simulated. Simulation outcomes were compared to corresponding experimental data. RESULTS: Stiffness of the model matched that of the physical VSF (R2: 0.98, RMSE: 1.37 N/mm). Model-predicted resultant ground reaction force (GRFR) matched well under optimized parameter conditions (R2: 0.98, RMSE: 5.3% body weight,) and unoptimized parameter conditions (R2: 0.90, mean RMSE: 13% body weight). Anterior-posterior center of pressure matched well with R2 > 0.94 and RMSE < 9.5% foot length in all conditions. CONCLUSIONS: The ESR properties of the VSF were accurately simulated under benchtop testing and dynamic gait conditions. These methods may be useful for predicting GRFR arising from gait with novel prostheses. Such data are useful to optimize prosthesis design parameters on a user-specific basis.

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