Оценка прочности стальной винтовой однолопастной сваи при действии осевых нагрузок

2021 ◽  
pp. 546-553
Author(s):  
Maxim А. Liplenko ◽  
Eduard F. Klimkin ◽  
Georgy V. Mosolov
Keyword(s):  
Numerical Modeling ◽  
Analytical Method ◽  
Engineering Calculation ◽  
Necessary Condition ◽  
Soil Conditions ◽  
Pressure Curve ◽  
Stiffness Modulus ◽  
Soil Stiffness ◽  
Screw Pile ◽  
Comparison Results

The purpose of this work is resolving the problem of evaluating the structural strength of the steel screw single-bladed pile under the pressure of axial loads in various soil conditions. Calculations in this area constitute the necessary condition for assessing the possibility and feasibility of using pile-screw technology in specific construction conditions, inter alia, at main pipeline facilities. The dependence of the pressure curve on the blade on the soil stiffness modulus was revealed in the course of numerical simulation performed by the finite element method in the ANSYS software. The maximum pressures are observed at the junction of the blade and the pile shaft with a large soil stiffness modulus, if the soil stiffness modulus is small, then the maximum pressures are observed at the edge of the blade. An analytical method for assessing the strength of a single-blade screw pile is proposed based on the theory of bending of circular and annular plates, as well as the results of numerical modeling. Comparison of the analytical method for calculating the strength of a screw pile with the results of numerical modeling to assess the accuracy. The comparison results showed an accuracy sufficient for engineering calculation methods. Цель настоящей работы – решение задачи оценки прочности конструкции стальной винтовой однолопастной сваи при воздействии осевых нагрузок в различных грунтовых условиях. Расчеты в этой области – необходимое условие для оценки возможности и целесообразности применения свайно-винтовой технологии в конкретных условиях строительства, в том числе на объектах магистральных трубопроводов. По результатам численного моделирования, выполненного методом конечных элементов в ПК ANSYS, выявлена зависимость изменения эпюры давления на лопасть винтовой сваи от модуля деформации грунта: с увеличением значения модуля деформации грунта максимальные давления наблюдаются в узле сопряжения лопасти и ствола сваи, при малых значениях модуля деформации максимальные давления отмечаются у края лопасти. На основании теории изгиба круглых и кольцевых пластин, а также результатов численного моделирования предложен расчетный метод оценки несущей способности однолопастной винтовой сваи по материалу. Для оценки точности разработанного подхода к расчету прочности винтовой сваи проведено сравнение предложенного аналитического метода с результатами численного моделирования, которое показало достаточную для инженерных методов расчета точность. Общий принцип, заложенный в рассмотренном методе расчета, может быть использован для создания различных эпюр давления на лопасть в зависимости от модуля деформации грунта и характеристик винтовой сваи.

The Analytical Modeling and Finite Element Analysis of a Bridge-Type Displacement Amplifier

2013 ◽  
Vol 397-400 ◽  
pp. 652-655
Author(s):  
Chuan Liang Shen ◽  
Jing Shi Dong ◽  
Feng Jun Tian
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Analytical Method ◽  
Analytical Relationship ◽  
Link Length ◽  
Element Analysis ◽  
Amplification Ratio ◽  
Comparison Results ◽  
Bridge Type ◽  
Element Method

The bridge-type displacement amplifier is modeled by the analytical method and finite element method. The analytical relationship between the input displacement and output displacement is established. The analytical model is validated by finite element method. The geometric parameters influence of amplification ratio is studied. The comparison results show that the link length and the link angle influence the amplification ratio dramatically. A small link angle and a large link length is beneficial to the amplification ratio. The finite element method has a more precise simulation results than the analytical method under the circumstance of small link angle and short link length.

scholarly journals Analysis on Laterally Loaded Group Piles by Plaxis 3D Foundation

2011 ◽  
Vol 2 (2) ◽  
pp. 1023 ◽  
Author(s):  
Sri Dewi ◽  
Gouw Tjie Liong
Keyword(s):  
Pile Group ◽  
Reduction Factor ◽  
Efficiency Factor ◽  
Stiffness Modulus ◽  
Soil Stiffness ◽  
Lateral Capacity ◽  
Finite Element Software ◽  
Group A ◽  
Group Piles ◽  
Plaxis 3D

It has been known that a group pile lateral capacity is smaller than the sum of each pile capacity composing the group. A reduction factor, also known as efficiency factor, is required to determine the effective lateral capacity of group piles. To the authors’ knowledge, in most geotechnical text books, only the spacing of piles is considered in evaluating the pile group lateral capacity. No consideration on the effects of soil stiffness modulus and the total number of piles forming the group is taken into account. This research tried to investigate the influence of those factors by using geotechnical 3D finite element software, namely Plaxis 3D foundation. It is found that the bigger the number of piles in a group, the lower the efficiency factor is; the higher the soil stiffness modulus, the greater the efficiency is. 

scholarly journals Numerical simulation of the stress strain state of base of the multi-helix screw pile under static loading in clay soil

2020 ◽  
pp. 28-36
Author(s):  
Volodymyr Sedin ◽  
Vladyslav Kovba ◽  
Yurii Volnianskyi ◽  
Kateryna Bikus
Keyword(s):  
Numerical Modeling ◽  
Bearing Capacity ◽  
Static Loading ◽  
Strain State ◽  
Clay Soil ◽  
Full Scale ◽  
Stress Strain ◽  
Foundation Construction ◽  
Stress Strain State ◽  
Screw Pile

A full-scale experiment was conducted to study the operation of a multi-helix screw pile under static pressing and pulling load in dusty clay soil. Based on the full-scale test of a multi-helix screw pile under static loading in dusty clay soil, numerical modeling of the stress-strain state of the base of the multi-helix screw pile was performed. Multi-helix screw piles are actively used all over the world, and have also become widespread in Ukraine. Foundations made of multi-helix screw piles are often used for industrial construction as well as the foundations of low-rise buildings and structures. Despite the growing demand for the use of multi-helix screw piles in modern construction, there is no official document calculating the features of their design and bearing capacity of a multi-helix screw pile. This poses a number of new tasks for engineers and geotechnical: a) development of new modern calculation methods; b) development and use of modern normative documents and recommendations for the calculation of foundations from multi-helix screw piles in various soil conditions; с) use of computer-aided design systems for calculation of complex geotechnical tasks; d) development of calculation models that will take into account nonlinear models of deformation of materials and soil base. Foundations made of multi-helix screw piles are a promising direction in the field of foundation construction due to the reduction of the duration of the foundation and its economic. This requires the development of regulations with recommendations for the calculation and use of multi-helix screw piles in the field of foundation construction, development of modern calculation models for the calculation of bearing capacity and settling of multi-helix screw piles in different geological conditions. Based on the results of the field study of the work of multi-helix screw piles in clay soils, numerical modeling of the stress-strain state of the base of the multi-turn pile was performed, and their results were compared.

Analysis of dry conditions compared with wildfires: an application in Calabria (Southern Italy)

2021 ◽  
Author(s):  
Roberto Coscarelli ◽  
Enric Aguilar ◽  
Sergio Vicente-Serrano ◽  
Fabio Zimbo
Keyword(s):  
Risk Reduction ◽  
Forest Fires ◽  
Management Practices ◽  
Southern Italy ◽  
Soil Conditions ◽  
The European Union ◽  
Climate Services ◽  
Comparison Results ◽  
The World ◽  
Burnt Areas

<p>All over the world wildfires destroy property and vegetation and can have an adverse effect on slope stability and soil erosion. Even though the number and the size of wildfires are often related to changes in land cover, population, and fire management practices, climatic and soil conditions remain the main factors influencing the extension of burnt areas. The goal of the EC Project INDECS, in which this study has been carried out, is to develop an integrated approach to produce a series of climate indicators aimed at the high priority sectors of the Global Framework for Climate Services of the World Meteorological Organization (agriculture, risk reduction, energy, health, water), with the addition of tourism. The study area is Calabria, a region of Southern Italy frequently affected by wildfires. In this research, data about the burnt areas (monthly data of extension - in hectares - and the number of fires in the period 2008-2018), provided by means of the module “Rapid Damage Assessment” (R.D.A.) of E.F.F.I.S. (European Forest Fire Information System) have been compared with the Keetch-Byram Drought Index (KBDI). This index, ranging between 0 and 203.2 (extreme dry condition of the soil), is used all over the world for monitoring and forecasting forest fires. The index was calculated with the daily rainfall and temperature data of 79 stations presenting complete and homogeneous databases. The monthly mean values were evaluated and the KBDI values were averaged for each province, given that the data of the wild fires are available for each of the five provinces of the region. The comparison results show that the peaks of the burnt areas almost always correspond with the highest of the KDBI values. Analogous results were obtained considering the number of fires. It is important to highlight that the results can be influenced by the following factors: a) the KBDI monthly mean value is evaluated by means of a database with a variable number of monthly values owing to missing data; b) the extension of the burnt areas is determined by the efficiency of the fire monitoring system and by the rapidity of first response operations; c) the RDA module database of EFFIS is referred to burnt areas with an extension greater than 30 hectares (in Europe, these fires are about 75-80% of the total fires) and does not contain differences between natural fires and human-induced fires. However, the obtained results can help to predict the impacts that tendencies of the KBDI patterns can have on the territory as an extension of burnt areas. In this way, the present study gives a useful service for agriculture and risk reduction sectors.</p><p>Acknowledgments:</p><p>The Project INDECIS is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462).</p>

A Unified Analytical Method of Stress Analysis for Tubesheet—Part II: Case Study

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Hongsong Zhu
Keyword(s):  
Stress Analysis ◽  
Analytical Method ◽  
Heat Exchangers ◽  
Numerical Comparison ◽  
Element Analysis ◽  
Comparison Results ◽  
Different Types ◽  
The Unified Method ◽  
Unified Method

Based on the unified analytical method of stress analysis for fixed tubesheet (TS) heat exchangers (HEX), floating head and U-tube HEX presented in Part I, numerical comparisons with ASME method are performed in this paper as Part II. Numerical comparison results indicate that predictions given by the unified method agree well with finite element analysis (FEA), while ASME results are not accurate or not correct. Therefore, it is concluded that the unified method deals with thin TS of different types of HEX in equal detail with confidence to predict design stresses.

Discussion of an instrumented screw pile load test and connected pile group load settlement behavior

2013 ◽  
Vol 1 (1) ◽  
pp. 13-36 ◽  
Author(s):  
P.O. Van Impe ◽  
W.F. Van Impe ◽  
L. Seminck
Keyword(s):  
Pile Group ◽  
Load Test ◽  
Soil Conditions ◽  
Pile Capacity ◽  
Screw Pile ◽  
Settlement Behavior ◽  
Heterogeneous Soil ◽  
Pile Load Test ◽  
The One ◽  
Oil Tanks

The aim of the paper is to discuss a fully instrumented screw pile load test up to failure, in difficult heterogeneous soil conditions along the shaft. The pre-stressing of the pile during its installation process has been brought to attention as an important item to assisting in explaining the differences in pile capacity and load settlement curve on the one hand, and the data as registered from the pile shaft instrumentation. In the second part of the paper, starting info on the registered load settlement data of the foundation slabs of each of the three, closely positioned, oil tanks of 48 m diameter and 19 m of height are shared and briefly analyzed.

Dynamically Loaded Finite Length Journal Bearings: Analytical Method of Solution

1999 ◽  
Vol 121 (4) ◽  
pp. 844-852 ◽  
Author(s):  
H. Hirani ◽  
K. Athre ◽  
S. Biswas
Keyword(s):  
Pressure Distribution ◽  
Closed Form ◽  
Analytical Method ◽  
Journal Bearings ◽  
Positive Pressure ◽  
Maximum Pressure ◽  
Pressure Curve ◽  
Connecting Rod ◽  
Dynamically Loaded ◽  
Form Pressure

A closed-form pressure distribution, using a combination of short- and long-bearing approximations, is proposed for dynamically loaded journal bearings. The angles for start and finish of positive pressure curve are determined employing simple analytical equations. The mobility method, based on the suggested pressure distribution is easy to use, predicts results of acceptable accuracy and the execution time is comparable to that required for the short bearing approximation. This paper also provides a conceptually simple analytical method for evaluating angular location of the instantaneous maximum pressure using proposed closed form pressure distribution. Simple algebraic equations are derived to obtain the instantaneous maximum pressure in dynamically loaded bearings directly, without involving any iteration. To illustrate the validity of present study, a connecting rod big end bearing and two crankshaft main bearings are analyzed. The mobility components, minimum film thickness and maximum pressure are plotted over a load cycle and compared with established analytical and curve fit methods. The results are also compared with those obtained using finite element method.

Predicting Corrosion Under Disbonded Coating Using Modeling and Cathodic Protection Monitoring Coupon

2002 ◽  
Author(s):  
N. Sridhar ◽  
D. S. Dunn ◽  
O. Moghissi ◽  
F. King ◽  
J. Been
Keyword(s):  
Numerical Modeling ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Cathodic Protection ◽  
Corrosion Cracking ◽  
Soil Conditions ◽  
Modeling Approach ◽  
Bare Steel ◽  
Disbonded Coating

Coating defects generally take the form of either exposed bare steel or a disbondment, where a gap is formed between a relatively intact coating and bare steel. Cathodic protection can be difficult to achieve and monitor in the disbonded regions depending on the type of coating and soil conditions. Furthermore, stress corrosion cracking occurs predominantly under disbonded coatings. This paper describes a numerical modeling approach to predict the potential and chemistry under disbonded coating. In addition, the use of a monitoring coupon to simulate pipeline disbondments is demonstrated.

On the Dead-Center Positions of Stephenson Six-Bar Linkage

2011 ◽  
Vol 52-54 ◽  
pp. 915-919
Author(s):  
Yan Huo Zou ◽  
Xiao Ning Guo ◽  
Jin Kui Chu
Keyword(s):  
Analytical Method ◽  
Input Parameter ◽  
Polynomial Equation ◽  
New Method ◽  
Necessary Condition ◽  
Input Output ◽  
Simple Analytical Method ◽  
Condition Equation ◽  
The Dead

A new method for identifying the dead-center positions of the Stephenson six-bar linkage is presented by this article. This method uses the input-output polynomial equation of the linkage and the corresponding Sylvester's resultant to formulate the necessary condition of the dead-center configurations as a polynomial equation in terms of the input parameter; then through a simple analytical method to obtain all the truly dead-center positions among the double roots to the condition equation. An example is given to demonstrate the validity of this method.

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