Mechanical Stability Analysis of Subsea Wellhead for Deepwater Production to Earthquake Load

2010 ◽  
Vol 44-47 ◽  
pp. 1061-1065
Author(s):  
Wen Sheng Xiao ◽  
Xiu Juan Lin ◽  
Hong Yan Wang
Keyword(s):  
Mechanical Stability ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Lateral Force ◽  
Angular Distortion ◽  
Soil Reaction ◽  
Seismic Load ◽  
Earthquake Load ◽  
The Stability

Subsea wellhead for deepwater production subjects to axial force, lateral force and bending moment under the seismic loading, the effect of subsea christmas tree and casing string’s gravity. Joint action of these forces makes it is possible that horizontal displacement exceeds the limitation and thus loses the stability. A mechanical analytical model of subsea wellhead for deepwater production is established on the basis of the pile foundation theories and material mechanics, the seismic load and behavior between casing string and formation are considered. The analyses on lateral displacement, angular distortion, bending moment and shear force show that the affection of lateral load is focus on the upper section of casing string, and the lateral displacement of subsea wellhead for deepwater production increases along with earthquake load and thus decreases stability. The stability improves notably with the increase of coefficient of soil reaction. Therefore it is necessary to obtain the on-the-spot geological data in shallow formation. The wellhead stability may be improved to different degrees by taking measures such as minimizing axial load, enhancing the conductor bending strenth, increasing the depth of the casing string in soil, reducing the outcropping length of the casing string.

Character Analysis of Balance and Imbalance of Varying Rigidity of Rigid Pile Composite Foundation under Seismic Load

2014 ◽  
Vol 1065-1069 ◽  
pp. 19-22
Author(s):  
Zhen Feng Wang ◽  
Ke Sheng Ma
Keyword(s):  
Finite Element ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Element Model ◽  
Composite Foundation ◽  
Seismic Load ◽  
Seismic Loads ◽  
Element Analysis ◽  
Rigid Pile ◽  
Rigid Pile Composite Foundation

Based on ABAQUS finite element analysis software simulation, the finite element model for dynamic analysis of rigid pile composite foundation and superstructure interaction system is established, which selects the two kinds of models, by simulating the soil dynamic constitutive model, selecting appropriate artificial boundary.The influence of rigid pile composite foundation on balance and imbalance of varying rigidity is analyzed under seismic loads. The result shows that the maximum bending moment and the horizontal displacement of the long pile is much greater than that of the short pile under seismic loads, the long pile of bending moment is larger in the position of stiffness change. By constrast, under the same economic condition, the aseismic performance of of rigid pile composite foundation on balance of varying rigidity is better than that of rigid pile composite foundation on imbalance of varying rigidity.

Comparative Study on The Stability of Hydropower Station Slope under Different Earthquake Conditions

2021 ◽  
Author(s):  
wang zhongchang ◽  
Bo Li
Keyword(s):  
Ground Motion ◽  
Working Conditions ◽  
The Other ◽  
Hydropower Station ◽  
Seismic Load ◽  
Seismic Action ◽  
Reference Period ◽  
Amplification Effect ◽  
Earthquake Load ◽  
The Stability

Abstract In order to explore the stability characteristics of hydropower station slope under different working conditions under seismic action, The three-dimensional dynamic finite element method is used to analyze the working conditions of the hydropower station slope under the seismic load with a probability of exceeding 5% in 50 years, 2% in 100 years, and 1% in 100 years, through comparing the dynamic response characteristics and the stability of the slope under different seismic load were obtained. The results showed that under the influence of different earthquake loads, the ground motion response of the slope would increase with the increase of the peak value of the excited ground motion, and all would be forced to vibrate according to the vibration form of the excited ground motion; compared with the amplification effect of the slope on the displacement, the amplification effect of the slope on the acceleration was more obvious, this phenomenon was more obvious when the slope was under the action of an earthquake load with a probability of exceeding 1% within 100 years of the reference period; with the increase of seismic load, the possibility of bedding sliding and failure of the slope surface would be greater; when the three types of seismic loads act on the slope respectively, the other surfaces of the slope would generate instantaneous tensile stress, but they are less than the tensile strength of the slope rock mass. when the slope was under rare ground motion with a 100-year exceeding probability of 1% and 2%, the maximum relative dynamic displacement was about 5cm, and the slope was sufficient to withstand the test of strong ground motion; for the other two seismic conditions, when the slope was under the action of an earthquake load with a probability of exceeding 1% within 100 years of the reference period, the damage effect of the slope near the empty surface under the action of the earthquake was more obvious than that of the center of the slope.

ANALYSIS AND DESIGN OF MULTI-STOREY STEEL STRUCTURES ACCORDING TO DIFFERENT METHODS IN 2018 EARTHQUAKE REGULATIONS

2021 ◽  
Vol 0 (15) ◽  
pp. 0-0
Author(s):  
Fahım Ahmad NOWBAHARI ◽  
Elif AĞCAKOCA
Keyword(s):  
Steel Structure ◽  
Steel Structures ◽  
Horizontal Displacement ◽  
Combination Method ◽  
Seismic Load ◽  
Earthquake Loads ◽  
Analysis And Design ◽  
Earthquake Load ◽  
Earthquake Faults ◽  
Earthquake Zone

Earthquake loads are the biggest obstacle to the design of multi-storey and irregular structures in countries located in the earthquake zone and with active earthquake faults. It is a dangerous natural disaster that can result in loss of life and property depending on the intensity of the earthquake. It is important to use comprehensive and up-to-date standards and regulations for the calculation of earthquake loads. In this study, considering TBDY-2018, dynamic behavior of multi-storey steel structure with irregularity called A1 Torsional Irregularity has been investigated. For seismic load calculations, mode combination method and equivalent earthquake load method, which are linear analysis methods, were used. In a 10-storey steel structure, central inverted V braces were used and the positions of these braces were changed and a total of 4 models were produced. Structural analyzes were made using the "Etabs" program. Then, the results obtained in the two methods used were compared, and in the structural analysis of the models used, it was seen that the internal forces and displacements gave greater results when the calculations were made with the Equivalent Earthquake Load Method. In addition, it has been stated that the torsional irregularity coefficient of the structure is effective in the horizontal displacement of the structure.

Study of Safety Influence Factor of Bridge Substructure in Loess Gulch

2012 ◽  
Vol 546-547 ◽  
pp. 89-96
Author(s):  
Jin Wei ◽  
Zhong Ju Feng ◽  
Feng Ma
Keyword(s):  
Soil Erosion ◽  
Debris Flow ◽  
Pile Foundation ◽  
Influence Factor ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Zero Point ◽  
Internal Force ◽  
Prevention Measures ◽  
The Stability

In this paper, the geology characteristics of loess gulch area were summarized. The mechanical models of the influence of landslide, debris flow and soil erosion on the safety of the pile foundation were created. The influence of the geology casualty on the safety of the pile foundation were analyzed. The analyses showed, when the pile foundation located the varied position of the loess gulch, the influence of soil erosion on the pile foundation character (acting force of pile side, free length of the pile, the first zero point position of the flexure curve, drawdown of the maximum bending moment, the increment of the lateral displacement, the drawdown of the lateral bearing capacity, the drawdown of the stability, etc.) were strikingly different. The calculation method of the pile and pier internal force was put forward under the function of landslide thrust and pressing force of debris flow. The corresponding prevention measures to different influencing factors were presented in the end.

Analysis of Earth Berm on the Impact of Cantilever Retaining Structure Based on ABAQUS

2014 ◽  
Vol 1065-1069 ◽  
pp. 3-6 ◽  
Author(s):  
Zhen Yu Wu ◽  
Zhong Yuan Duan
Keyword(s):  
Bending Moment ◽  
Horizontal Displacement ◽  
Retaining Structure ◽  
Supporting Structure ◽  
The Stability ◽  
The Cost ◽  
The Impact

Software ABAQUS was carried out to analyze the effect of earth berms on behavior of cantilever retaining structure, and the soil was in modified Cambridge model. The results showed that: in the premise of ensuring the stability of earth berm itself, height and width of earth berm increased reasonably can reduce the horizontal displacement and bending moment of supporting structure, so as to improve the safety of the supporting structure, and save the cost of project.

scholarly journals Modeling Riverbank Slope Reinforcement Using Anti-Slide Piles with Geocells

2021 ◽  
Vol 9 (4) ◽  
pp. 394
Author(s):  
Zhen Liu ◽  
Pengzhen Liu ◽  
Cuiying Zhou ◽  
Yasheng Li ◽  
Lihai Zhang
Keyword(s):  
Lateral Displacement ◽  
Measurement Data ◽  
Bending Moment ◽  
Theoretical Models ◽  
Friction Mechanism ◽  
Support Mechanism ◽  
Vertical Support ◽  
Parametric Studies ◽  
The Stability ◽  
Vertical Action

Geocells are increasingly used in engineering applications, but the design of riverbank slope reinforcements that use only geocells limits reinforcement performance. Moreover, the design and use of anti-slide piles with geocells are mainly based on experiences that are unsupported by theoretical models. In this paper, by combining the confinement effect and vertical action mechanism of geocells, the horizontal friction mechanism of the geocell layer and the vertical support mechanism of piles, a theoretical model of riverbank slope reinforced by anti-slide piles with geocells was constructed. In addition, to describe the mechanical behavior of a riverbank slope reinforced by anti-slide piles with geocells, the slip-resisting mechanism of the anti-slide pile with interaction between geocells and their internal filler is considered in the model. Furthermore, to investigate the influence of changes in water level on riverbank slope stability, the developed model takes into account settlement, lateral displacement, pile bending moment and pile axial force. The model predications were validated by the field measurement data. The results from a series of parametric studies show that the use of anti-slide pile and geocells can effectively reduce the settlement and the lateral displacement of a riverbank slope. The developed model could contribute to an optimal design of anti-slide pile with geocells for enhancing the stability of a riverbank slope.

Comparative Study on Force Characteristics of Vertical and Inclined Cantilever Retaining Pile

2013 ◽  
Vol 353-356 ◽  
pp. 558-561
Author(s):  
De Sen Kong ◽  
Qiu Hua Zhang
Keyword(s):  
Comparative Study ◽  
Lateral Displacement ◽  
Three Dimensional ◽  
Bending Moment ◽  
Simulation Models ◽  
Horizontal Displacement ◽  
Foundation Pit ◽  
Geological Conditions ◽  
Inclined Pile ◽  
Force Characteristics

In order to comparative study the force characteristics of vertical and inclined cantilever retaining pile in foundation pit engineering, a practical excavation engineering was considered. Based on the engineering geological conditions of this foundation pit, two three-dimensional simulation models for computing the force characteristics of vertical and inclined cantilever retaining pile were built. Then the horizontal displacement of pile top, the lateral displacement and the bending moment of pile body were illustrated and contrasted in detail. It was shown that the horizontal displacement of inclined pile top is significantly less than that of vertical retaining pile. Moreover, the deformation and bending moment of inclined pile body are more reasonable than that of vertical retaining pile. Therefore, the stability of foundation pit was guaranteed through inclined pile support.

INVESTIGATING THE INTERACTION BETWEEN STABILIZED EXCAVATION BY NAILING AND ADJACENT URBAN TUNNELS: CASE STUDY

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Somaye Hosseini ◽  
Mahmood Parsaei
Keyword(s):  
Large Scale ◽  
Lateral Displacement ◽  
Retaining Wall ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Analysis Tool ◽  
Horizontal Distance ◽  
Subway Tunnel

Urban development could be evaluated by considering the transportation and construction industries. The transportation industry development causes an increase in the urban subway lines as well as underground tunnels. Concerning the construction industry, the large-scale buildings development such as commercial malls, high-rise buildings, and underground parking structures may require deep excavations at metropolitan projects. In this paper, a parametric study is carried out by considering the distance of a tunnel from a retaining wall with the staged construction. PLAXIS 2.0D ver.8.5 software is used as an analysis tool. The results show that existing tunnels are affected more than retaining walls during an excavation when the structural response is considered. By increasing the horizontal distance of tunnel center from the wall, lateral displacement and the bending moment of the tunnel would decrease 14% and the vertical displacement and bending moment of tunnel’s Crown would reduce by 15% and 12%, respectively. These interaction effects become negligible after a distance of 5 times the tunnel diameter. Besides, the existence of the tunnel in the vicinity of excavations would increase the top horizontal displacement of the retaining wall by about 13%. It is worthwhile to point out that the current paper is based on a case study on Sharif University multistory underground parking located near the subway tunnel in Tehran city stabilized by deploying a nailing and anchorage system.

scholarly journals Influence of skirt reinforcement in passive zone on deformation of excavation

2020 ◽  
Vol 198 ◽  
pp. 02012
Author(s):  
Peng-fei CHEN ◽  
Xiao-nan GONG
Keyword(s):  
Lateral Displacement ◽  
Soft Soil ◽  
Bending Moment ◽  
Protection Scheme ◽  
Soil Mixing ◽  
Set Up ◽  
The Stability ◽  
Cement Soil ◽  
Plaxis 3D ◽  
Passive Area

In the design of the excavation protection scheme in the soft soil area, it is often necessary to set up cement-soil mixing piles in the passive area. In this way, the stability requirements of the excavation can be met, and the lateral displacement of the retaining pile can be greatly restricted. This paper uses PLAXIS 3D to establish a excavation model in a soft area, and discusses the influence of various parameters of the passive zone mixing pile on the deformation and force of the excavation. Within a certain range, as the cohesive force or secant modulus or reinforcement width or depth of the reinforcement area increases, the lateral displacement and settlement outside the pit will decrease. But when it exceeds a certain range, the decreasing trend becomes very slow. With the increase of the four parameters of the reinforcement zone, bending moments in opposite directions appear below the bottom of the excavation. Moreover, the value of the bending moment is getting larger and larger. Therefore, considering the force, it is not that the wider and deeper the reinforced zone is, the more advantageous is.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

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