scholarly journals Evaluation of Undrained Bearing Capacities of Wide-Shallow Bucket Foundation with Honeycomb Bulkheads in Clay

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Qingshan Wang ◽  
Xun Han ◽  
Yunfei Guan ◽  
Yongyong Cao ◽  
Wenxuan Li
Keyword(s):  
Shear Strength ◽  
Three Dimensional ◽  
Offshore Wind ◽  
Combined Loading ◽  
Vertical Load ◽  
Bucket Foundation ◽  
Failure Envelopes ◽  
Soil Shear Strength ◽  
New Type ◽  
The Moment

As a new type of offshore wind foundation, the wide-shallow bucket foundation with honeycomb bulkheads mainly bears vertical, horizontal, and moment loads. As yet, no systematic study has been conducted regarding the effects of honeycomb bulkheads on the undrained bearing capacities of the wide-shallow bucket foundation. In this study, a large number of three-dimensional (3D) finite element (FE) analyses were performed to investigate the undrained bearing capacities of the wide-shallow bucket foundations with and without honeycomb bulkheads, thereby evaluating the influence of honeycomb bulkheads on the bearing capacities under different conditions. The results show that under uniaxial loading, the uniaxial bearing capacities of the wide-shallow bucket foundation are basically unaffected by the honeycomb bulkheads in homogeneous clay. For nonhomogeneous clay, the moment bearing capacity will be considerably enhanced with the increase in soil shear strength heterogeneity. Under combined loading, the honeycomb bulkheads will enhance the combined bearing capacities only in nonhomogeneous clay. The enhancement effects will increase with the increase in soil shear strength heterogeneity but decrease with the increase in vertical load. Besides, the simplified equations for calculating the uniaxial bearing capacities of the wide-shallow bucket foundation with honeycomb bulkheads are also proposed considering the influence of embedment ratio and soil shear strength heterogeneity. At last, the parameters of an approximating expression are fitted to predict the failure envelopes of this foundation under combined loading.

Two- and three-dimensional analyses of translational slides in soils with nonlinear failure envelopes

2010 ◽  
Vol 47 (4) ◽  
pp. 388-399 ◽  
Author(s):  
Hisham T. Eid
Keyword(s):  
Shear Strength ◽  
Dimensional Stability ◽  
Three Dimensional ◽  
Shear Resistance ◽  
Fast Method ◽  
Stability Number ◽  
Stability Function ◽  
Case Histories ◽  
Failure Envelopes ◽  
Soil Shear Strength

This paper aims to assess the effect of nonlinearity of the soil shear strength envelope on the sliding mass configurations and the minimum two- and three-dimensional factors of safety for slopes susceptible to translational failure in both static and seismic conditions. An extensive parametric study was conducted using slope models and nonlinear soil strength envelopes that simulate translational failure case histories. Analysis of the results led to the development of stability charts that do not require an iterative procedure when determining the factors of safety. The introduction of a two-dimensional stability number and three-dimensional stability function, the values of which depend on the degrees of nonlinearity of the involved soils’ strength envelopes, has made it possible to develop such charts. These charts give the practicing geotechnical engineer a reliable and fast method to analyze translational failures. Using available software in such an analysis can be complicated if shear resistance along the sliding mass vertical sides and nonlinearity of soil shear strength envelopes are considered. Numerical examples and a case history are given to verify the reliability and illustrate the different applications of these charts.

scholarly journals Failure Envelopes of Composite Bucket Foundation for Offshore Wind Turbines under Combined Loading with considering Different Scour Depths

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yuanxu Jing ◽  
Yuan Wang ◽  
Jingqi Huang ◽  
Wei Wang ◽  
Lunbo Luo
Keyword(s):  
Wind Turbines ◽  
Bending Moment ◽  
Offshore Wind ◽  
Combined Loading ◽  
Failure Envelope ◽  
Bucket Foundation ◽  
Offshore Wind Turbines ◽  
Failure Envelopes ◽  
The Stability ◽  
The Right

The composite bucket foundation of offshore wind turbines is subjected to a variety of loads in the marine environment, such as horizontal load H, vertical load V , bending moment M, and torque T. In addition, due to the characteristics of its connection section, the water flow around the foundation will produce scour pits of various degrees, reducing the depth of the bucket foundation, which has a nonnegligible impact on the overall stability of the bucket foundation. In this paper, the failure envelope characteristics of different combinations of loads on bucket foundations, including V -H-T, V -M-T, conventional V -H-M, and noncoplanar V -H-M, are numerically investigated with considering different scour depths. The numerical results indicate that the V -H-T, V -M-T, conventional V -H-M, and noncongruent V -H-M failure envelopes gradually shrink inwards with increasing scour depth, and the stability of the composite bucket foundation decreases; the conventional V -H-M failure envelope shows an asymmetry of convexity to the right, and the noncongruent V -H-M failure envelope shows an asymmetry of outward convexity to the left and right. The corresponding mathematical expressions for the failure envelope are obtained through the normalized fitting process, which can be used to evaluate the stability of the bucket foundation based on the relative relationship between the failure envelope and the actual load conditions, which can provide practical guidance for engineering design.

scholarly journals Comparative Analysis of Static Loading Performance of Rigid and Flexible Road Wheel based on Finite Element Method

2020 ◽  
Vol 70 (1) ◽  
pp. 41-46
Author(s):  
Yaoji Deng ◽  
Youqun Zhao ◽  
Mingmin Zhu ◽  
Zhen Xiao ◽  
Qiuwei Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Static Loading ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Vertical Load ◽  
New Type ◽  
Stress And Deformation ◽  
Nonlinear Finite Element Model

To overcome the shortcomings of traditional rigid road wheel, such as poor damping effect and low load-bearing efficiency, a new type of flexible road wheel, having a unique suspension-bearing mode, was introduced. The three-dimensional nonlinear finite element model of rigid and flexible road wheel, considering the triple nonlinear characteristics of geometry, material and contact, is established for numerical investigation of static loading performance. The accuracy of the finite element model of the rigid and flexible road wheel is verified by static loading experiment. The static loading performance of the rigid and flexible road wheels is numerically analyzed. The influence of vertical load on maximum stress and deformation of the rigid and flexible wheels is also studied. The results show that the contact pressure uniformity of the flexible road wheel is better than that of the rigid road wheel under the static vertical load, but the maximum stress and deformation of the flexible road wheel are greater than that of the rigid road wheel. However, this problem can be solved by increasing the number of hinge sets and optimising the joints. The research results provide theoretical basis for replacing rigid road wheel with flexible road wheel, and also provide reference for structural optimisation of flexible road wheel.

Pressure-Plus-Moment Limit-Load Analysis for a Cylindrical Shell Nozzle

1987 ◽  
Vol 109 (3) ◽  
pp. 297-301 ◽  
Author(s):  
C. J. Tabone ◽  
R. H. Mallett
Keyword(s):  
Cylindrical Shell ◽  
Three Dimensional ◽  
Limit Load ◽  
Element Model ◽  
Combined Loading ◽  
Inelastic Behavior ◽  
Limit Loads ◽  
Out Of Plane ◽  
Load Analysis ◽  
The Moment

A finite element model of a nozzle in a cylindrical shell is analyzed for three cases; pressure, out-of-plane moment and combined pressure plus out-of-plane moment. The model uses three-dimensional finite elements and the analysis considers inelastic behavior at small displacements. Load versus displacement behavior is given for the three cases. Estimates of limit loads are obtained based upon extrapolation of load versus inverse displacement data curves. An interaction expression is used to show the effect of the combined loading for a case in which an internal pressure reduces the moment capability of the nozzle by 35 percent.

scholarly journals Bearing Capacity Characteristics of Composite Bucket Foundation Under Torque Loading

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2487 ◽  
Author(s):  
Puyang Zhang ◽  
Yan’e Li ◽  
Yajun Lv ◽  
Hongyan Ding ◽  
Conghuan Le
Keyword(s):  
Bearing Capacity ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Horizontal Force ◽  
Vertical Load ◽  
Failure Envelope ◽  
Bucket Foundation ◽  
Loading Method ◽  
Torque Load ◽  
Soil Foundation

The composite bucket foundation for offshore wind turbine bears the vertical load from not only the superstructure and the horizontal load, caused by wind and wave, but also from the torque load caused by rotating structures, such as blades. Based on layered soil foundation, the influence of the skirt height, the friction coefficient between soil and bucket foundation and the diameter of the bucket foundation on the stress of the bucket skirt under the torque load are studied in this paper. Moreover, the envelope curves of the bearing capacity of H–T and V–H–T are obtained by the fixed displacement ratio loading method. The bearing capacity characteristics of composite bucket foundation under different loading combinations are analyzed. The results show that: (1) The effect of inside soil on the bucket skirt is greater than that of the outside soil; (2) when composite loads are applied, the torque-bearing capacity decreases slowly with the increase of horizontal force, and when the horizontal force increases to a certain value, the value of the torque decreases significantly; and (3) the shape of the H–T failure envelope of the bucket foundation has no obvious change, vertical load have less effect on horizontal and torque load.

Study on the Bearing Mechanism of Bucket Foundation for Offshore-Wind Turbine in Soft Clay

2011 ◽  
Vol 71-78 ◽  
pp. 1795-1804
Author(s):  
Jian Feng Wang ◽  
Hai Tao Dai ◽  
Ming Qin
Keyword(s):  
Large Scale ◽  
Soft Clay ◽  
Bending Moment ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Horizontal Load ◽  
Vertical Load ◽  
Bucket Foundation ◽  
Finite Element Software ◽  
Moment Load

Based on numerical platform of large-scale finite element software, this paper investigates the function mechanisms of vertical load, horizontal load, and bending moment load of soft-clay-base bucket foundation. Then the corresponding load bearing characteristics of each load type of soft-clay-base bucket foundation are determined.

scholarly journals Dynamic Analysis of Helical Planetary Gear Sets under Combined Force and Moment Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Yanfang Liu ◽  
Junbin Lai ◽  
Peng Dong ◽  
Xiangyang Xu
Keyword(s):  
Dynamic Model ◽  
Dynamic Behavior ◽  
Three Dimensional ◽  
Axial Loading ◽  
Planetary Gear ◽  
Combined Loading ◽  
External Loading ◽  
Parameter Method ◽  
Vibration Responses ◽  
The Moment

The dynamic behavior of a single-stage planetary gear set with helical gears of multishaft automotive automatic transmissions has been studied, in which one component of the planetary gear set is imposed by additional external vertical and axial loading from countershaft gear pair in addition to the moment. Under these combined loading conditions, the contributions of the deflections of the ring gear and the carrier cannot be neglected. A three-dimensional nonlinear time-variant dynamic model considering not only the transverse, torsional, axial, and rotational motions of the gears but also the elasticity of the mounted shafts has been developed by combining the lumped parameter method with finite element method. The natural modes and the forced vibration responses due to static transmission errors have been obtained. The proposed dynamic model is employed to describe the effects of the combined external loading condition and positioning on the dynamic behavior of a four-planet system.

Bearing Capacities of Shallow Skirted Foundations After the Action of Multi-Directional Cyclic Displacements Considering Soil Degradation

2019 ◽  
Author(s):  
Zhong Xiao ◽  
Donghai Zhang ◽  
Haixiao Liu ◽  
Ying Liu
Keyword(s):  
Shear Strength ◽  
Soil Degradation ◽  
Soft Soil ◽  
Ocean Engineering ◽  
Loading Paths ◽  
Plastic Shear Strain ◽  
Failure Envelopes ◽  
Soil Shear Strength ◽  
Service State ◽  
Continuous Accumulation

Abstract Shallow skirted foundations have been applied widely in ocean engineering. Under the action of external excitation, the shallow skirted foundations on soft soil undergo cyclic displacements during service state. Under the action of cyclic displacements, the foundations drive the surrounding soft soil to produce a continuous accumulation of absolute plastic shear strain, which weakens the shear strength of the soft soil around the foundations. Therefore, the bearing capacities of shallow skirted foundations reduce after the action of cyclic displacements considering soil degradation. In order to study the evolutions of bearing capacities of shallow skirted foundations after the action of multi-directional cyclic displacements considering soil degradation, the elastoplastic finite element models of shallow skirted foundations with different embedment ratio are established. Cyclic displacements are applied along different displacement loading paths, and the evolutions of soil shear strength and bearing capacities of shallow skirted foundations after the action of cyclic displacements are analyzed. The results show that the soil softening zone gradually expands from the stress concentration zone of the soft soil to the surrounds with increasing number of loading cycles. Due to the enlargement and weakening of the soil softening zone, the failure envelopes of shallow skirted foundations gradually shrink, but the shrinkage trend gradually converges with increasing number of loading cycles. The shapes of the failure envelopes are relatively less affected by the cyclic number of displacements. The size of the failure envelopes is greatly affected by the loading paths while the shape of the failure envelopes is relatively less affected.

Sign in / Sign up

Export Citation Format

Share Document