The horizontal-moment capacity of embedded foundations in undrained soil

2007 ◽  
Vol 44 (4) ◽  
pp. 409-424 ◽  
Author(s):  
Gijae Yun ◽  
M Fraser Bransby
Keyword(s):  
Bearing Capacity ◽  
Horizontal Load ◽  
Failure Envelope ◽  
Numerical Work ◽  
Moment Capacity ◽  
Failure Envelopes ◽  
Embedded Foundations ◽  
Pure Moment ◽  
Foundation Base ◽  
Undrained Soil

The bearing capacity of embedded foundations subject to combined horizontal and moment loading in undrained soils is of interest particularly to the offshore geotechnical engineer. These loadings can be experienced by monopod foundations and offshore manifolds and often take the form of a horizontal load applied at a lever arm height above the foundation base. Previous design methods using the failure envelope approach have suggested that peak moment capacity of a foundation is mobilized with positive horizontal loads, but that peak horizontal load is mobilized with no additional moment loading. This paper reports numerical work specifically investigating the effects of the embedment ratio on the horizontal-moment foundation capacity under no vertical load in both uniform strength and "normally consolidated" undrained soil. It is shown that the embedment ratio significantly affects the eccentricity of the M–H failure envelope so that the shape varies when normalized by the pure moment (M0) and pure horizontal load (H0) capacity. The reasons for the eccentricity of the failure envelopes are understood by investigating soil deformation mechanisms calculated during FE analysis and by accompanying upper bound plasticity analysis. This mechanistic understanding is used to suggest load reference point translations that ease curve-fitting of the complex failure envelopes for use in design.Key words: bearing capacity, foundations, numerical modelling and analysis, plasticity.

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.

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.

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.

scholarly journals Triaxial Strength Criteria in Mohr Stress Space for Intact Rocks

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Baohua Guo ◽  
Long Wang ◽  
Yizhe Li ◽  
Yan Chen
Keyword(s):  
Tensile Strength ◽  
Compression Strength ◽  
Triaxial Compression ◽  
Stress Space ◽  
Failure Envelope ◽  
Limit Values ◽  
Strength Criteria ◽  
Triaxial Strength ◽  
Failure Envelopes ◽  
Exponential Equations

Conventional triaxial strength criteria are important for the judgment of rock failure. Linear, parabolic, power, logarithmic, hyperbolic, and exponential equations were, respectively, established to fit the conventional triaxial compression test data for 19 types of rock specimens in the Mohr stress space. Then, a method for fitting the failure envelope to all common tangent points of each two adjacent Mohr’s circles (abbreviated as CTPAC) was proposed in the Mohr stress space. The regression accuracy of the linear equation is not as good as those of the nonlinear equations on the whole, and the regression uniaxial compression strength (σc)r, tensile strength (σt)r, cohesion cr, and internal frictional angle φr predicted by the regression linear failure envelopes with the method for fitting the CTPAC in the Mohr stress space are close to those predicted in the principal stress space. Therefore, the method for fitting CTPAC is feasible to determine the failure envelopes in the Mohr stress space. The logarithmic, hyperbolic, and exponential equations are recommended to obtain the failure envelope in the Mohr stress space when the data of tensile strength (σt)t are or are not included in regression owing to their higher R2, less positive x-intercepts, and more accurate regression cohesion cr. Furthermore, based on the shape and development trend of the nonlinear strength envelope, it is considered that when the normal stress is infinite, the total bearing capacity of rock tends to be a constant after gradual increase with decreasing rates. Thus, the hyperbolic equation and the exponential equation are more suitable to fit triaxial compression strength in a higher maximum confining pressure range because they have limit values. The conclusions can provide references for the selection of the triaxial strength criterion in practical geotechnical engineering.

Effect of soil rigidity and tensile strength on bearing capacity of embedded foundations

2020 ◽  
Vol 10 (2) ◽  
pp. 162-167
Author(s):  
M. Jafari ◽  
H. Gharsallaoui ◽  
A. Holeyman
Keyword(s):  
Tensile Strength ◽  
Bearing Capacity ◽  
Embedded Foundations

scholarly journals Influence of Karst Caves at Pile Side on the Bearing Capacity of Super-Long Pile Foundation

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Peisen Wang ◽  
Hongyan Ding ◽  
Puyang Zhang
Keyword(s):  
Bearing Capacity ◽  
Pile Foundation ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Horizontal Load ◽  
Karst Cave ◽  
Karst Caves ◽  
Karst Areas ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity

The differences in development and situation of karst caves lead to two kinds of karst caves, and the karst cave may be on the pile side or at the pile bottom, which has a different influence on the bearing capacity of pile foundation. The paper presents a numerical analysis of the influence of karst caves at pile side on the bearing capacity of super-long pile foundation in karst areas. According to the size of pile foundation of a real bridge project, this paper modelized karst caves and investigated the karst cave from the effect of length, height, and thickness of roof on horizontal and vertical bearing capacity of pile foundation. The main conclusions can be drawn as: when the horizontal displacement at the top of pile foundation is greater than 0.05 m, the horizontal load is correlated positively with the length of karst cave; when the vertical displacement is greater than 0.07 m, the vertical load is correlated negatively with the thickness of the roof of karst cave. However, the height of karst cave has little effect on the bearing capacity; also the existence of karst cave has little influence on the dynamic response of pile foundation. The results of this study can be important with reference to the design and construction of pile foundations in karst areas.

Ultimate Tensile Properties of Elastomers. II. Comparison of Failure Envelopes for Unfilled Vulcanizates

1964 ◽  
Vol 37 (4) ◽  
pp. 792-807 ◽  
Author(s):  
Thor L. Smith
Keyword(s):  
Natural Rubber ◽  
Elevated Temperatures ◽  
Cross Sectional Area ◽  
Chemical Degradation ◽  
Sectional Area ◽  
Failure Envelope ◽  
Cross Sectional ◽  
Failure Envelopes ◽  
The Moment ◽  
Styrene Butadiene

Abstract The tensile stress-at-break σb (based on the initial cross-sectional area) and the corresponding ultimate extension ratio λb of unfilled vulcanizates of silicone, hydrofluorocarbon (Viton B), butyl (both sulfur-cured and resin-cured), and natural rubber were determined at many strain rates and temperatures; the latter ranged from slightly above the glass transition temperature Tg, up to a temperature somewhat below that at which chemical degradation affected the results. For each vulcanizate except natural rubber, data obtained over an extended temperature range superposed to give a time- and temperature-independent failure envelope on a plot of log (σb273/T) vs log (λb−1), where T is the test temperature in °K; for natural rubber, data obtained between 90° and 120° C superposed, but those at lower temperatures did not because of strain-induced crystallization. For each vulcanizate, data at elevated temperatures gave, or tended toward, a line of unit slope on a plot of log (λbσb273/T) vs log (λb−1), where λbσb is the breaking stress based on the cross-sectional area at the moment of rupture. The position of each line corresponded to the equilibrium modulus Ee derived from stress-strain curves. Failure envelopes previously obtained for two styrene—butadiene vulcanizates, which had different crosslink densities, superposed to give a master failure envelope on a plot of log (λbσb273/T) vs logEe(λb−1). On this type of plot, failure envelopes for all the vulcanizates except silicone and natural rubber were found to be essentially identical. At a given value of λbσb, silicone had a smaller λbλb and natural rubber a somewhat larger λbλb than the vulcanizates of the three other rubbery polymers.

Numerical Analysis of the Influence of Vertical Load on the Horizontal Bearing Capacity of Single Pile

2011 ◽  
Vol 374-377 ◽  
pp. 1947-1952 ◽  
Author(s):  
Zhao Yun Xiao ◽  
Guo Xun Zhang ◽  
Wei Xu ◽  
Zhong Ming Xue
Keyword(s):  
Numerical Simulation ◽  
Bearing Capacity ◽  
Pile Foundation ◽  
Sandy Soils ◽  
Single Pile ◽  
Horizontal Load ◽  
Clayey Soils ◽  
Vertical Load ◽  
Concrete Pile ◽  
Finite Element Numerical Simulation

It is a complicated progress of interaction between pile and soil when pile is under both vertical load and horizontal load. This paper analyzes the variation of stress, strain, deformation and deflection of the pile body by finite element numerical simulation of single bored concrete pile under vertical load together with horizontal load. Based on the existing research results, conclusions could be that the vertical load can increase horizontal bearing capacity of the pile in sandy soils, but horizontal bearing capacity of the pile in clayey soils is more complicated. Hope that the simulation can provide some references for the design of pile foundation.

scholarly journals Interaction peculiarities of a single unit bored pile with the surrounding rock mass under the horizontal load effect

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Ivan Khokhlov ◽  
Mikhail Zertsalov
Keyword(s):  
Numerical Modeling ◽  
Rock Mass ◽  
Bearing Capacity ◽  
Single Unit ◽  
Surrounding Rock ◽  
Design Stage ◽  
Horizontal Load ◽  
Rock Foundation ◽  
Load Effect ◽  
Bored Pile

Interaction peculiarities of a single unit bored pile with the surrounding rock mass under the horizontal load effect, as well as loss mechanism of piles bearing capacity, are considered. The article presents the numerical modeling results and a method developed on their basis for calculating piles in rocky soils under the horizontal load effect under the spatial elastic-plastic problem conditions, with the account of the contact behavior between the pile and the rock mass. The study of the single unit bored pile interaction and the surrounding rock mass under the horizontal and moment loads effect was carried out based on the numerical models’ analysis of the piles and the surrounding rock mass in a spatial setting using the finite element method. The use of regression analysis methods made it possible, to obtain parametric equations, based on the numerical modeling obtained results, that connected the studied response functions (bearing capacity and horizontal displacement of the pile) from preselected independent factors reflecting the geomechanical properties of the body and the design piles peculiarities. The developed calculation method allows at the preliminary design stage to estimate the horizontal pile displacement value, as well as its bearing capacity. Also, using the proposed technique, it is possible to make a piles load test schedule, which can be used in the field observation preparation at the design stage. The relevance of the topic is due to the fact that in modern construction practice, bored piles are used to transfer to the foundation significant loads, on the rock foundation from structures for various purposes, including transport (bridges and overpasses piers’ foundations, etc.).

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