scholarly journals Penetration and Pullout Capacity of Low-Skirted Suction Caissons

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Mingyuan Wang ◽  
Xiaoke Liu ◽  
Xinglei Cheng ◽  
Qun Lu ◽  
Jiaqing Lu ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Limit Equilibrium ◽  
Offshore Structures ◽  
Pullout Capacity ◽  
Soil Plug ◽  
Suction Caisson ◽  
Element Simulation ◽  
New Type ◽  
New Formula ◽  
Suction Caissons

The bearing capacity of suction caissons is the key to the design of offshore structures. A new type of cross-shaped low-skirted suction caisson is invented to effectively improve the bearing capacity, considering inevitable “soil plug” phenomenon. The behaviors of penetration and pullout for new low-skirted suction caisson are investigated by performing model tests. A new formula for calculating the penetration resistance is suggested based on the limit equilibrium theory and the test data, which can consider the change of the lateral area of the suction caisson during penetration. The behaviors of low-skirted suction caisson under inclined loading are analyzed by carrying out finite element simulation. The effects of loading angles and loading positions on the ultimate bearing capacity and failure mechanism of low-skirted suction caissons are discussed. The research results can provide a reference for the design of suction bucket foundation for offshore structures.

A Study on the Failure Mechanism of Suction Caisson under Vertical Load

2012 ◽  
Vol 256-259 ◽  
pp. 1985-1989
Author(s):  
Shu Cheng Jin ◽  
Yong Tao Zhang ◽  
Qi He Wu
Keyword(s):  
Bearing Capacity ◽  
Failure Mechanism ◽  
Offshore Structures ◽  
Engineering Practice ◽  
Vertical Load ◽  
Suction Caisson ◽  
Methods Of Evaluation ◽  
New Type ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity

As a new type of deep water offshore foundation, suction caisson is widely used to offshore structures. However, the current methods of evaluation and design cannot meet the increasing requirement of engineering practice. In this dissertation, the studies are emphasized on finite element method for analyzing the suction caisson bearing capacity behavior and the failure mechanism under the vertical load. Based on studying the vertical bearing behavior of caissons with different ratio of length to diameter L / D, it shown that as L / D increases, the vertical bearing capacity growth slowed.

Limit Equilibrium Solutions to Anti-overturning Bearing Capacity of Suction Caissons in Uniform and Linearly Increasing Strength Clays

2021 ◽  
Author(s):  
Yuqi Wu ◽  
Qing Yang ◽  
Dayong Li ◽  
Yu Zhang
Keyword(s):  
Bearing Capacity ◽  
Failure Mechanism ◽  
Wind Turbines ◽  
Limit Equilibrium ◽  
Soil Surface ◽  
Equilibrium Analysis ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Aspect Ratios ◽  
Suction Caissons

Suction caissons supporting offshore wind turbines are exposed to great horizontal loading above the soil surface, which may lead to overturning failure of the caisson. This paper presents a modified three-dimensional failure mechanism to analyze the anti-overturning bearing capacity of suction caissons. The modified failure mechanism is composed of meniscus-conical wedge having meniscus shape at the soil surface and scooped shape. The analytical solution to the anti-overturning bearing capacity of suction caisson is deduced in terms of the limit equilibrium method, following by a parametric study of wedge depth ratio (c) to optimize the critical failure mechanism that satisfies both the force and moment equilibriums. Thus, the methodologies are relatively easy to implement in traditional spreadsheets and the analyses tend to perform very fast. Meanwhile, the effects of gap formation at the rear side of the caisson, loading eccentricity and adhesion factor at caisson-soil interface on anti-overturning bearing capacity are investigated. Comparing with finite element limit analysis results, experimental data and existing theoretical solutions, it is proved that the presented limit equilibrium analysis can satisfactorily predict the anti-overturning bearing capacity of suction caissons with low aspect ratios for offshore wind turbines in uniform and linearly increasing strength clays.

scholarly journals The Seepage and Soil Plug Formation in Suction Caissons in Sand Using Visual Tests

2020 ◽  
Vol 10 (2) ◽  
pp. 566
Author(s):  
Liquan Xie ◽  
Shili Ma ◽  
Tiantian Lin
Keyword(s):  
Rapid Development ◽  
Offshore Wind ◽  
Quadratic Regression ◽  
Soil Plug ◽  
Suction Caisson ◽  
Offshore Wind Turbines ◽  
Green Development ◽  
Hydraulic Gradients ◽  
The Relationship ◽  
Suction Caissons

The rapid development of offshore wind energy in China is becoming increasingly relevant for movement toward green development. This paper presents the results of visual tests of a suction caisson used as foundation for offshore wind turbines. The distribution of hydraulic gradients of sand at the mudline in the caisson was obtained to find out the relationship with the heights of soil plugs. The relationship equation was proposed and obtained by using quadratic regression, guiding project designs, and construction. It was found that there was no soil plug in the caisson when small suction was applied during the suction penetration. The relationship between the heights of the soil plugs and the hydraulic gradient of the soil was proposed and obtained by using quadratic regression to predict (roughly) the height of soil plugs in suction caissons in sand during suction penetration. The influence of settlement outside caissons on the soil plug was found to decrease as the buried depth rose.

Experimental Study on the Strain Softening Behavior of Plate Anchors in Clay Under Cyclic Loading

2014 ◽  
Author(s):  
Long Yu ◽  
Qi Zhou ◽  
Jun Liu
Keyword(s):  
Cyclic Loading ◽  
Bearing Capacity ◽  
Stress Level ◽  
Strain Softening ◽  
High Stress ◽  
Offshore Structures ◽  
Pullout Capacity ◽  
Softening Behavior ◽  
Plate Anchors ◽  
High Stress Level

Many geotechnical designs require knowledge of soil uplift resistance where the foundation must withstand tensile forces, such as wind loading on transmission towers, wave action on offshore structures, and buoyancy forces on buried pipelines. Most existing researches on the bearing capacity of plate anchors are limited to static analyses. The effects of offshore cyclic loading on the bearing capacity of plate anchors are not very clear. The ultimate pullout capacity of plate anchors in clay may decrease as the accumulated plastic shear strain grows due to the strain-softening of clay under cyclic loading. In this study, 1 g model tests were carried out to estimate the softening behavior of plate anchors including one low stress level case and two high stress level cases. PIV (Particle Image Velocimetry) technique was used to investigate the soil flow mechanism of the anchor at low stress level. Numerical analyses are carried out to simulate the large deformation behavior of the anchor at high stress level under cyclic loading.

Reliability Analyses of Suction Caissons for FPSO Systems

2008 ◽  
Author(s):  
Celestino Valle-Molina ◽  
Ernesto Heredia-Zavoni ◽  
Francisco L. Silva-Gonza´lez
Keyword(s):  
Limit Equilibrium ◽  
Limit State ◽  
Ultimate Limit State ◽  
Suction Caisson ◽  
Capacity Model ◽  
Probabilistic Characterization ◽  
Partial Safety Factors ◽  
Ultimate Limit ◽  
Suction Caissons

The reliability formulation for the analyses of suction caissons subjected to environmental loadings from FPSO systems is presented in this paper. The capacity model for the suction caisson assumes normally consolidated clays with a linear variation on the undrained shear strength. The limit equilibrium method was used to assess the inclined capacity of suction caissons. The probabilistic characterization of the environmental loading is associated to deep water sites in the Bay of Campeche in the Gulf of Mexico. The reliability of the suction caissons was performed by means of Monte Carlo simulations and calibration of partial safety factors was carried out for the ultimate limit state using the design equation proposed by DNV [1].

Numerical Investigation on the Pull-Out Behaviour of Suction Caissons in Clay

2006 ◽  
Author(s):  
Mostafa Zeinoddini ◽  
Mahmood Nabipour
Keyword(s):  
Aspect Ratio ◽  
Numerical Investigation ◽  
Production Systems ◽  
Friction Angle ◽  
Critical Issue ◽  
Order Effect ◽  
Offshore Structures ◽  
Pull Out ◽  
Soil Cohesion ◽  
Suction Caissons

Since their inception suction caisson foundations have presented themselves as proven means of anchoring floating production systems and fixed offshore structures. The pull-out capacity of suction caissons remains a critical issue in their applications, and in order to produce effective designs, reliable methods of predicting the capacity are required. In this paper results from a numerical investigation on the behaviour of the suction caissons in clays against pull-out loading have been presented. Soil nonlinearities, soil/caisson interactions and the effects from the suction on the behaviour have been taken into account. A linear relationship has been observed between the soil cohesion values and the pull-out capacity. Under drained conditions, beyond specific limits of soil cohesion values, the increase in the cohesion value have found to demonstrate no further influence on the pull-out capacity. The soil internal friction angle has been noticed to have an exponential increasing effect on the pull-out capacity. With constant values of the caisson diameter, an increase in the aspect ratio noticed to have a second order effect of the friction originated part and a linear influence on the cohesion originated part of the resistance. With constant values of the caisson length, an increase in the aspect ratio values has found to result in an exponential decrease of the pull-out capacity. Based on the obtained numerical results simple formulations and approximations have been proposed in order to estimate the effects of the studied parameters on the pull-out capacities.

Parameter Analysis on Bearing Capacity of Concrete-Filled Square Steel Tubular Column to Steel-Encased Concrete Composite Beam Joint with through Diaphragm

2014 ◽  
Vol 1065-1069 ◽  
pp. 1203-1207
Author(s):  
Yan Lin ◽  
Xue Jun Zhou ◽  
Yu Chen Liu ◽  
Wen Qing Kong
Keyword(s):  
Bearing Capacity ◽  
Composite Beam ◽  
Plastic Hinge ◽  
Nonlinear Finite Element ◽  
Parameter Analysis ◽  
Longitudinal Reinforcement ◽  
Element Analysis ◽  
Obvious Effect ◽  
Axial Compression Ratio ◽  
New Type

A new type of concrete-filled square steel tubular column to steel-encased concrete composite beam joint is proposed. In order to study the influences of parameters on bearing capacity for the joint formed plastic hinge in the beam end, nonlinear finite element analysis under monotonic loading is conducted by software ANSYS. The results show that axial compression ratio has little influence on joint bearing capacity, and with the increasing of it, the bearing capacity is enhanced slightly. The height of U-shape steel has a significant impact on joint bearing capacity, and with the rise of it, the bearing capacity is enhanced obviously. The thickness of U-shape steel has a comparatively obvious effect on joint bearing capacity with certain limits, and with the growth of it, the bearing capacity of the joint is also grown observably. The diameter of longitudinal reinforcement in the flange slab of beam has some effects on joint bearing capacity, and with the improvement of diameter, the bearing capacity is achieved.

Failure Modes of Tapered Suction Caissons Under Vertical Pull-Out Loads

2007 ◽  
Author(s):  
Mahmood Nabipour ◽  
Mostafa Zeinoddini ◽  
Mahmood R. Abdi
Keyword(s):  
Failure Modes ◽  
Numerical Approach ◽  
Local Failure ◽  
Superior Performance ◽  
Soil Plug ◽  
Pull Out ◽  
Modes Of Failure ◽  
Numerical Studies ◽  
Second Mode ◽  
Suction Caissons

The pull-out performance of conventional upright suction caissons has been investigated by different researchers. However, no attention has been formerly paid to tapered suction caissons. Some numerical studies already conducted by the authors demonstrated that tapered caissons exhibit pull-out capacities well above than that from their corresponding upright caissons. This paper deals with different failure mechanisms of tapered suction caissons and discusses some reason for their superior performance. A numerical approach has been used and different combinations of caisson types/ soil categories have been examined. With tapered suction caissons two different modes of failure have been discerned. The first mode has been noticed to develop in weak clays and sands under drained conditions. This mode corresponds to a shear sliding failure in the soil plug along the caisson’s interior wall. Concurrently a soil wedge is formed in the soil body adjacent to the caisson. The second mode of failure has been observed in higher strength drained clays and undrained clays and sands. With this failure mode a local failure at the bottom of the soil plug has been noticed to happen. At the same time the failure is extended to the lower surfaces of a soil wedge outside of the caisson. The detached soil plug accompanies the caisson in its movement upward following the local failure.

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