Predicting the overall horizontal bearing capacity of jack-up rigs using deck–foundation–soil-coupled model

2020 ◽  
pp. 147509022092590
Author(s):  
Qilin Yin ◽  
Jinjin Zhai ◽  
Sheng Dong
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Double Layer ◽  
Soft Clay ◽  
Coupled Model ◽  
Single Layer ◽  
Horizontal Load ◽  
Foundation Soil ◽  
Failure Envelopes ◽  
Jack Up

The overall bearing capacity of a jack-up rig under horizontal load is conducted using finite element models that consider the deck–foundation–soil interaction. In these models, the simplified horizontal load acts on the deck and increases until the platform loses its stability. The effects of the self-weight of the platform W and load direction α on the ultimate horizontal bearing capacity Hult are investigated, and W- Hult failure envelopes under different α conditions are obtained. Two typical seabed types, including the double-layer seabed of sand overlying soft clay and the single-layer seabed of sand, are considered. The results show that a critical self-weight Wcritical exists in the double-layer seabed. Based on Wcritical, the failure of the platform presents two different modes. When W <  Wcritical, the windward leg is pulled up, and Hult increases with the increase in W. When W >  Wcritical, the failure mode is the leeward leg or legs puncturing the bearing sand layer, and Hult decreases with the increase in W. In the single-layer seabed, the failure mode is the windward leg being pulled up, and Hult increases with the increase in W throughout the whole range. The W- Hult envelopes in these two types of seabeds are basically the same when W <  Wcritical.

scholarly journals Numerical Analysis of Bearing Capacity of a Ring Footing on Geogrid Reinforced Sand

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 68
Author(s):  
Haidar Hosamo ◽  
Iyad Sliteen ◽  
Songxiong Ding
Keyword(s):  
Numerical Analysis ◽  
Bearing Capacity ◽  
Double Layer ◽  
Practical Importance ◽  
Single Layer ◽  
Outer Diameter ◽  
Storage Container ◽  
Reinforced Sand ◽  
Oil Storage ◽  
Ring Footing

A ring footing is found to be of practical importance in supporting symmetrical constructions for example silos, oil storage container etc. In the present paper, numerical analysis was carried out with explicit code FLAC3D 7.0 to investigate bearing capacity of a ring footing on geogrid reinforced sand. Effects of the ratio n of its inner/outer diameter (Di/D) of a ring footing, an optimum depth to lay the geogrid layer were examined. It was found that an intersection zone was developed in soil under inner-side (aisle) of ring footing, contributing to its bearing capacity. Substantial increase of bearing capacities could be realized if ratio n of a ring footing was around 0.6. Numerical results also showed that, bearing capacity of a ring footing could increase significantly if a single-layer geogrid was laid at a proper depth under the footing. Similar contribution was found if a double-layer geogrid was implemented. However, such increases appeared to be rather limited if a triple-layer geogrid or a four-layer geogrid was used. A double-layer geogrid was recommended to increase the bearing capacity of a ring footing; the depth to lay this double-layer geogrid was also discussed.

scholarly journals The influence of single-layer and double-layer bases vertical soil pressing on the bearing capacity of piles

2019 ◽  
Vol 10 (1) ◽  
pp. 5-16
Author(s):  
Maxim Stepanov ◽  
◽  
Karina Dzhabrailova ◽  
Gennadiy Rybak ◽  
Mikhail Stepanov
Keyword(s):  
Bearing Capacity ◽  
Double Layer ◽  
Single Layer

Effect of a Strong Middle Layer on Spudcan Penetration

2014 ◽  
Author(s):  
Wen Gao ◽  
Tom Harrup ◽  
Yuxia Hu ◽  
David White
Keyword(s):  
Bearing Capacity ◽  
Layer Thickness ◽  
Soft Clay ◽  
Soil Layer ◽  
Strength Ratio ◽  
Top Soil ◽  
Flow Mechanisms ◽  
Soil Flow ◽  
Jack Up ◽  
Peak Resistance

The rapid penetration of one or more of the foundations of a mobile jack-up rig into the seabed is an ongoing major problem in the offshore industry, with the potential to cause major damage to the structure and endangering any personnel on board. A recent example is the jack-up drilling rig Perro Negro 6 incident happened near the mouth of the Congo river in July 2013 with one of the rig’s crew of 103 reported missing and six others injured. This uncontrollable displacement is due to a form of failure known as punch through failure and commonly occurs on stratified seabed profiles. It has been reported that unexpected punch-through accidents have resulted in both rig damage and lost drilling time at a rate of 1 incident per annum with consequential costs estimated at between US$1 and US$10 million [1]. This paper presents the bearing capacity profiles and associated soil flow mechanisms of a common spudcan foundation penetrating into a three layer soft-stiff-soft clay soil through the use of large deformation finite element (LDFE) analysis. The Remeshing and Interpolation with Small Strain (RITSS) [2, 3] technique was implemented in the software package AFENA [4] to conduct the LDFE analysis. Both soil layer thickness and soil layer strength ratios were varied to study their effect on the spudcan penetration responses. The LDFE results of spudcan penetration into the soft-stiff-soft clay soils were calibrated by existing centrifuge test data. A parametric study was then conducted to study the bearing capacity responses and soil flow mechanisms during spudcan large penetrations by varying the soil layer strength ratio and relative layer thickness to the diameter of spudcan. It was found that there were three types of bearing responses during continuous penetration of spudcan: (a) when the top soft layer is relatively thin, the spudcan bearing response was similar to that of two layer soils with stiff over soft clays; (b) when the top soil layer thickness is medium, a peak resistance is observed when spudcan penetrates into the middle stiff layer followed by reduction; (c) when the soil layer is thick, the peak resistance occurs when spudcan gets into the bottom soft soil layer. The critical thickness of top soil layer is a function of soil strength ratio and middle stiff soil layer thickness. The bearing response types were also corresponding to the soil cavity formations during spudcan initial penetration.

Field Plate Load Tests on Dredged Sediment Dump Pond with Cement Solidified Crust Above

2011 ◽  
Vol 255-260 ◽  
pp. 2751-2755
Author(s):  
Chun Lei Zhang ◽  
Qing Song Liu ◽  
Jin Bao Liu
Keyword(s):  
Compressive Strength ◽  
Bearing Capacity ◽  
Failure Mode ◽  
Double Layer ◽  
Unconfined Compressive Strength ◽  
Test Results ◽  
Dredged Sediment ◽  
Field Plate ◽  
Failure Angle ◽  
Load Tests

In order to improve the bearing capacity of dredged sediment dump pond for succeeding foundation reinforcement construction, upper layer was placed with a layer of cement solidified crust (CSC). For the special double layer foundation, field plate load tests were conducted to study the behaviors of failure mode, deformation and ultimate bearing capacity. Test results show the failure mode of the double layer foundation takes punch failure mode, the settlement around 10-15cm, the failure angle around 33-36 degree, the ultimate bearing capacities have a lineal relationship with the unconfined compressive strength and thickness of CSC, respectively.

The Experimental Research on the Vertical and Horizontal Bearing Capacity of Hollow Latticed Steel Columns

2012 ◽  
Vol 461 ◽  
pp. 425-428 ◽  
Author(s):  
Lu Yan Shi ◽  
Zhen Bao Li ◽  
Zhi Yu Zhang
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Experimental Research ◽  
Second Order ◽  
Order Effects ◽  
Horizontal Load ◽  
Deformation Capacity ◽  
Vertical Load ◽  
Experimental Conditions ◽  
Steel Columns

The paper researched on the strain, the deformation and the failure mode of hollow latticed steel columns through two experimental conditions. They were respectively about the vertical load and the horizontal load. The results showed that for the hollow latticed steel columns with upper columns, because of the stiffness of upper columns was obviously higher than the lower ones’, the upper columns were destroyed earliest under the vertical load. In addition, the columns had good horizontal bearing and deformation capacity, and the gravity second-order effects were not obvious for the columns.

Bearing Capacity Characteristics of Lacustrine Soft Clay Hard Shell Layer Foundation

2013 ◽  
Vol 347-350 ◽  
pp. 1203-1206
Author(s):  
Jia Jia Zheng ◽  
Li Jian Wu ◽  
Run Hua Guo
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Shear Failure ◽  
Soft Soil ◽  
Soft Clay ◽  
Soil Layer ◽  
Shell Layer ◽  
Soft Foundation ◽  
Hard Shell ◽  
Punching Failure

In order to provide a theoretical basis for the use of lacustrine soft clay hard shell layer, the first thing to do is understanding its bearing capacity characteristics. Based on the project of Nan-Mao section in Hunan provincial highway S204, combining with bearing capacity test, the bearing capacity characteristics and failure mode of hard shell foundation was comprehensively analyzed. From the field bearing capacity test, it is found that the PS curve of hard shell layer has obvious changes from elastic to plastic, while the PS curve of soft soil layer under hard shell layer just has elastoplastic stage from the beginning, and the failure mode of foundation mainly are punching failure and general shear failure. So for the quality control of lacustrine hard shell soft foundation mainly includes two aspects: the deformation and overall stability.

Bearing Capacity of Suction Caisson for Offshore Floating Wind Turbine

2011 ◽  
Vol 243-249 ◽  
pp. 4718-4722
Author(s):  
Xiu Bin Gong ◽  
Qing Lai Fan ◽  
Ke Wu
Keyword(s):  
Bearing Capacity ◽  
Wind Turbine ◽  
Soft Clay ◽  
Combined Loading ◽  
Failure Envelope ◽  
Suction Caisson ◽  
Floating Wind Turbine ◽  
Failure Envelopes ◽  
Offshore Floating Wind Turbine ◽  
Suction Caisson Foundation

Presented in this paper are the three-dimensional nonlinear finite element analyses of the failure envelopes of suction caisson under torsion, vertical and lateral pullout combined load in soft clay. The soft clay under undrained condition is simulated by perfectly elasto-plastic Tresca model. Through the numerical analyses, the failure envelopes for combined loading (V-T、H-T、V-H-T) of suction caisson is reviewed. And the mathematical expression of failure envelope is deduced. It is shown that (1) the circular plastic failure area is outward-extending. (2) The bearing capacity of suction caisson foundation in V-T、H-T load spaces is increasing with the aspect ratio L/D. (3) The equation of failure envelope can be used to evaluate the stability of suction caisson foundation for offshore floating wind turbine.

scholarly journals Armor Damage of Overtopped Mound Breakwaters in Depth-Limited Breaking Wave Conditions

2021 ◽  
Vol 9 (9) ◽  
pp. 952
Author(s):  
Patricia Mares-Nasarre ◽  
Gloria Argente ◽  
M. Esther Gómez-Martín ◽  
Josep R. Medina
Keyword(s):  
Failure Mode ◽  
Double Layer ◽  
Wave Energy ◽  
Single Layer ◽  
Rear Side ◽  
Breaking Wave ◽  
Wave Zone ◽  
Physical Tests ◽  
Wave Conditions ◽  
Hydraulic Stability

Armor damage due to wave attack is the principal failure mode to be considered when designing conventional mound breakwaters. Armor layers of mound breakwaters are typically designed using formulas in the literature for non-overtopped mound breakwaters in non-breaking wave conditions, although overtopped mound breakwaters in the depth-induced breaking wave zone are common design conditions. In this study, 2D physical tests with an armor slope H/V = 3/2 are analyzed in order to better describe the hydraulic stability of overtopped mound breakwaters with double-layer rock, double-layer randomly-place cube and single-layer Cubipod® armors in depth-limited breaking wave conditions. Hydraulic stability formulas are derived for each armor section (front slope, crest and rear slope) and each armor layer. The front slope of overtopped double-layer rock structures is more stable than the front slope of non-overtopped mound breakwaters in breaking wave conditions. When wave attack increases, armor damage appears first on the front slope, later on the crest and, finally, on the rear side. However, once the damage begins on the crest and rear side, the progression is much faster than on the front slope, because more wave energy is dissipated through the armored crest and rear side.

Bearing capacity of rigid piles under eccentric and inclined loads

1985 ◽  
Vol 22 (3) ◽  
pp. 267-276 ◽  
Author(s):  
G. G. Meyerhof ◽  
V. V. R. N. Sastry
Keyword(s):  
Bearing Capacity ◽  
Soft Clay ◽  
Horizontal Load ◽  
Soil Pressure ◽  
Pile Capacity ◽  
Inclined Loads ◽  
Pure Moment ◽  
Load Tests ◽  
Rigid Model ◽  
Test Pile

The ultimate bearing capacity of instrumented vertical single rigid model piles in homogeneous loose sand and soft clay under vertical eccentric and central inclined loads has been investigated. The results of these load tests provide a more realistic lateral soil pressure distribution on the pile shaft and better theoretical estimates of pile capacity under pure moment and under horizontal load. For intermediate eccentricities and inclinations of the load, the bearing capacity can be obtained from simple interaction relationships between the axial load and moment capacities and between the axial and horizontal load capacities, respectively. The influence of lateral soil pressures due to installation of displacement piles in clay is examined in relation to the ultimate load of the pile. The analyses are compared with the results of model tests and some field case records. Key words: bearing capacity, clay, eccentric loading, horizontal load, instrumentation, model test, pile, sand.

Behaviour of rigid piles in layered soils under eccentric and inclined loads

1986 ◽  
Vol 23 (4) ◽  
pp. 451-457 ◽  
Author(s):  
V. V. R. N. Sastry ◽  
G. G. Meyerhof ◽  
T. Koumoto
Keyword(s):  
Bearing Capacity ◽  
Soft Clay ◽  
Layered System ◽  
Horizontal Load ◽  
Eccentric Load ◽  
Pile Capacity ◽  
Total Load ◽  
Tip Resistance ◽  
Inclined Loads ◽  
Predicted Values

The lateral soil pressures, ultimate bearing capacity, and displacements of instrumented vertical single rigid model piles in a layered system consisting of soft clay overlying loose sand and subjected to vertical eccentric and central inclined loads have been investigated. The variation of lateral soil pressures and the tip resistance of the pile are analysed with respect to the total load or moment on the pile. Theoretical estimates of pile capacity in homogeneous soils under pure moment and under horizontal load have been extended to piles in a layered system. For intermediate eccentricities and inclinations of the load, the pile capacity can be estimated from simple interaction relations or semiempirical eccentricity and inclination factors. The pile displacements are analysed in the light of linear elastic theory and nondimensional p − y curves. Reasonable agreement has been found between the measured and predicted values. Key words: bearing capacity, clay, displacements, eccentric load, horizontal load, lateral pressure, layered system, model test, pile, sand.

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