Spudcan Penetration in Clay-Sand-Clay Soils

2011 ◽  
Author(s):  
Long Yu ◽  
Hui Zhou ◽  
Wen Gao ◽  
Jun Liu ◽  
Yuxia Hu
Keyword(s):  
Yield Criterion ◽  
Soft Clay ◽  
Friction Angle ◽  
Small Strain ◽  
Clay Soils ◽  
Soil Conditions ◽  
Sand Layer ◽  
Element Analysis ◽  
Dense Sand ◽  
Flow Mechanisms

Multi-layered soil conditions often exist in offshore practice. In some sites a thin layer of medium dense sand lays between firm to stiff clay layers. In these cases the ultimate bearing capacity of foundations can be increased due to the strong sand layer by comparing with foundations in uniform clay. However, there is also a potential of reduction in foundation capacity when the foundation punches through the sand layer. The punch-through failure can occur during either pre-loading or storm loading. In this study, the continuous penetration of spudcan foundations on clay-sand-clay soils was investigated by large deformation finite element analysis. The numerical simulation was carried out using Remeshing and Interpolation Technique with Small Strain (RITSS) model. The clays obey Tresca failure criterion for undrained analysis and the sands obey Mohr-Coulomb yield criterion for drained analysis. The friction angle of the sand was taken as φ = 32° and 40° with its dilation angle ψ = 2° and 10° respectively. The effects of the relative height of the top soft clay and the relative thickness of the middle sand layer on the load-displacement responses were investigated. The soil flow mechanisms at various penetration depths were also discussed.

Numerical study of ultimate bearing capacity of rectangular footing on layered sand

2020 ◽  
Vol 1 (101) ◽  
pp. 15-26
Author(s):  
V. Panwar ◽  
R.K. Dutta
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bearing Capacity ◽  
Numerical Study ◽  
Friction Angle ◽  
Ultimate Bearing Capacity ◽  
Loose Sand ◽  
Sand Layer ◽  
Element Analysis ◽  
Dense Sand

Purpose: The purpose of this study is to investigate the ultimate bearing capacity of the rectangular footing resting over layered sand using finite element method. Design/methodology/approach: Finite element analysis was used to investigate the dimensionless ultimate bearing capacity of the rectangular footing resting on a limited thickness of upper dense sand layer overlying limitless thickness of lower loose sand layer. The friction angle of the upper dense sand layer was varied from 41° to 46° whereas for the lower loose sand layer it was varied from 31° to 36°. Findings: The results reveal that the dimensionless ultimate bearing capacity was found to increase up to an H/W ratio of about 1.75 beyond which the increase was marginal. The results further reveal that the dimensionless ultimate bearing capacity was the maximum for the upper dense and lower loose sand friction angles of 46° and 36°, while it was the lowest for the upper dense and lower loose sands corresponding to the friction angle of 41° and 31°. For H/W = 0.5 and 2, the dimensionless bearing capacity decreases with the increase in the L/W ratio from 0.5 to 6 beyond which the dimensionless ultimate bearing capacity remains constant for all combinations of parameters. The results were presented in nondimensional manner and compared with the previous studies available in literature. Research limitations/implications: The analysis is performed using a ABAQUS 2017 software. The limitation of this study is that only finite element analysis is performed without conducting any experiments in the laboratory. Further the study is conducted only for the vertical loading. Practical implications: This proposed numerical study can be used to predict the ultimate bearing capacity of the rectangular footing resting on layered sand. Originality/value: The present study gives idea about the ultimate bearing capacity of rectangular footing when placed on layered sand (dense sand over loose sand) as well as the effect of thickness of top dense sand layer on the ultimate bearing capacity. The findings could be used to calculate the ultimate bearing capacity of the rectangular footing on layered sand.

Effect of Underlying Sand Layer on Undrained Capacity of Spudcan Foundations in Soft Clay Under Combined Loading

2018 ◽  
Author(s):  
Yifa Wang ◽  
Mark J. Cassidy ◽  
Britta Bienen
Keyword(s):  
Soft Clay ◽  
Three Dimensional ◽  
Small Strain ◽  
Combined Loading ◽  
Sand Layer ◽  
Element Analysis ◽  
Moment Capacity ◽  
Soil Failure ◽  
Failure Envelopes ◽  
Vertical Bearing

During the operational phase, the spudcan foundations of a mobile jack-up rig are subjected to combined vertical, horizontal and moment loading. Although previous research has indicated a substantial increase in vertical bearing capacity when a spudcan penetrates through a soft clay layer towards a sand layer, the response of spudcan foundations subjected to combined loadings in such stratification has yet to be understood. This study investigates the effect of the underlying stronger sand layer on the undrained VHM capacity of a spudcan foundation using three-dimensional small-strain finite element analysis. Results show the significant increase in vertical and moment capacity, whereas the horizontal capacity is minimally affected. The soil failure mechanisms are identified and changes in the size and shape of failure envelopes, accounting for the sand layer underneath, are quantified. An analytical expression is proposed to predict the combined capacity of a spudcan foundation in clay overlying sand.

scholarly journals Investigation of Diagonal Strut Actions in Masonry-Infilled Reinforced Concrete Frames

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Seung-Jae Lee ◽  
Tae-Sung Eom ◽  
Eunjong Yu
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Yield Criterion ◽  
Friction Angle ◽  
Concrete Frames ◽  
Element Analysis ◽  
Reinforced Concrete Frames ◽  
Infilled Frames ◽  
Masonry Infills ◽  
Push Down

AbstractThis study analytically investigated the behavior of reinforced concrete frames with masonry infills. For the analysis, VecTor2, a nonlinear finite element analysis program that implements the Modified Compression Field Theory and Disturbed Stress Field Model, was used. To account for the slip behavior at the mortar joints in the masonry element, the hyperbolic Mohr–Coulomb yield criterion, defined as a function of cohesion and friction angle, was used. The analysis results showed that the lateral resistance and failure mode of the infilled frames were significantly affected by the thickness of the masonry infill, cohesion on the mortar joint–brick interface, and poor mortar filling (or gap) on the masonry boundary under the beam. Diagonal strut actions developed along two or three load paths on the mortar infill, including the backstay actions near the tension column and push-down actions near the compression columns. Such backstay and push-down actions increased the axial and shear forces of columns, and ultimately affect the strength, ductility, and failure mode of the infilled frames.

Effect of Bridge-Soil Interaction on Behavior of Integral Bridge

2011 ◽  
Vol 137 ◽  
pp. 123-127
Author(s):  
Tian Lai Yu ◽  
Mohammed Awad
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Soil Condition ◽  
Soil Conditions ◽  
Integral Abutment ◽  
Soil Pressure ◽  
Element Analysis ◽  
Dense Sand ◽  
Integral Bridge ◽  
Axial Forces

In this paper analytical evaluation of influence of bridge-soil interaction on the structural behavior of integral bridge with adjacent concrete box beams deck subjected to temperature rise was performed. Three different soil conditions loose, medium, and dense sand for the uppermost layer soil adjacent to abutment and abutment column were studied. Long-term, field monitoring was performed on FuYu bridge located in Heilongjiang province, China. The recorded data was used to validate the accuracy of a finite element model of this bridge which explicitly incorporates the nonlinear soil spring response. The finite element analysis indicated that soil condition adjacent to the abutment and abutment column is important factor affecting the response of the integral abutment bridge to thermal loads in terms of soil pressure behind the abutment, and axial forces and moments in the composite deck. As the soil varied from loose to dense condition the soil pressure behind the abutment increases more than 4 times and axial forces in the bridge deck increases by about 50% and bending moments in the composite deck increases by about 40%.

Numerical Simulation of the Installation and Extraction Process of Spudcan Foundations in Clay

2009 ◽  
Author(s):  
Jun Liu ◽  
Yuxia Hu
Keyword(s):  
Plastic Material ◽  
Yield Criterion ◽  
Strain Analysis ◽  
Small Strain ◽  
Extraction Process ◽  
Interface Roughness ◽  
Large Displacement ◽  
Centrifuge Model Test ◽  
Element Analysis ◽  
Perfectly Plastic

This paper presents results from large displacement finite element analysis for spudcan foundation penetrating into and extracting from normally consolidated (NC) clay. The soil was idealized as an elastic-perfectly plastic material obeying a Mohr-Coulomb yield criterion and the large displacement analysis was carried out using Remeshing and Interpolating Technique with Small Strain (RITSS) model to simulate the full installation and extraction process. The numerical results were compared with centrifuge model test data and existing analytical solutions. A full parametric study was undertaken to quantify the influence on spudcan extraction process from soil strength profile, foundation interface roughness and penetration depth. The extraction results showed that the normalized uplift resistance after spudcan installation was much lower than that from small strain analysis, and it was also lower than that of pre-embedded case. Thus it is necessary to apply RITSS method in spudcan extraction simulation after installation.

scholarly journals Peak punch-through capacity of spudcan in sand with interbedded clay: numerical and analytical modelling

2017 ◽  
Vol 54 (8) ◽  
pp. 1071-1088 ◽  
Author(s):  
Shah Neyamat Ullah ◽  
Yuxia Hu
Keyword(s):  
Clay Soil ◽  
Soft Clay ◽  
Friction Angle ◽  
Analytical Models ◽  
Fe Model ◽  
Clay Layer ◽  
Dense Sand ◽  
Centrifuge Tests ◽  
Improved Performance ◽  
Sand Plug

The presence of a thin soft clay layer inside a bed of sand may significantly reduce the bearing capacity of the sand layer, imposing a risk of punch-through failure. In this paper, finite element (FE) simulations are reported using a hardening soil (HS) model for sand. The FE model has been verified against centrifuge tests involving loose and dense sand layers overlying clay soil. The effects of sand stiffness, foundation roughness, sand friction angle, undrained clay strength, clay strength nonhomogeneity, and sand and clay layer geometries on the foundation peak capacities have been studied. Punch-through failure is initiated with an inclined sand plug being sheared and pushed into the underlying soft clay. During punch-through, the clay layer fails due to significant radial squeezing. Existing analytical models do not capture the combined failure mechanism of sand shearing and clay radial squeezing. A new analytical model is developed to estimate the peak punch-through capacity of a spudcan in sand with an interbedded clay layer, showing improved performance over the current industry guidelines.

scholarly journals Technical performance of basalt fiber reinforced polymer BFRP confined RC driven piles new construction methodology

2018 ◽  
Vol 7 (3) ◽  
pp. 1685
Author(s):  
J Prakash Arul Jose ◽  
P Rajesh Prasanna ◽  
Fleming Prakash
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Basalt Fiber ◽  
Friction Angle ◽  
Load Test ◽  
Experimental Result ◽  
Soil Conditions ◽  
Load Carrying Capacity ◽  
Dense Sand ◽  
Load Carrying

Pile foundations are often necessary to support large structures when the surface soil conditions are not strong enough to support the structure with shallow foundations. Pile foundation can be founded in dense sand layers at deeper, and also provide additional frictional support along their length to resist vertical loads. Load carrying capacity of Basalt FRP confined and unconfined piles were found out using the dynamic formulae and pile load test. Safe load carrying capacity of piles determined from piles load test was slightly higher than the dynamic formulae. The experimental result also shows that surface roughness of specimen is significantly changes the interface friction angle. The shear strength at the interface increases with the increase in surface roughness of the specimens. 

Numerical Study of Spudcan Penetration in Clay-Sand-Clay Soil

2016 ◽  
Author(s):  
Qilin Yin ◽  
Sheng Dong ◽  
Jinjin Zhai
Keyword(s):  
Finite Element ◽  
Yellow River ◽  
Numerical Study ◽  
Soft Clay ◽  
River Estuary ◽  
Small Strain ◽  
Penetration Resistance ◽  
Sand Layer ◽  
Clay Layer ◽  
Set Up

Aiming at simulating the preloading process of jack-up rig at drilling locations with typical stratum combination near the Yellow River estuary, FE models of interaction between spudcan and sub-soil are set up based on a large deformation finite element method known as Remeshing and Interpolation Technique with Small Strain (RITSS). The ABAQUS finite element package is used to calculate small strain solutions following each step. The seabed can be simplified as a three-layer deposits with soft clay layer, sand layer and soft clay layer from surface to bottom according to geological data. The backfill phenomenon during preloading is described. The results show that the surface soft clay falls onto the upper surface of spudcan very soon after the preloading process begins, afterwards the backfill tendency occurs in the middle sand layer. SNAME recommends two sets of formulas for calculating penetration resistance respectively for backfill penetration and penetration with no backfill. In this study the model with no backfill is realized by condition control in program codes and the penetration resistance is compared with the results of practical backfill model. The variance proves the shortcomings of the method given by SNAME.

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.

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