Analysis of the Stability of Thawing Slopes by Random Finite Element Method

2019 ◽  
Vol 2673 (10) ◽  
pp. 465-476 ◽  
Author(s):  
Shaoyang Dong ◽  
Xiong (Bill) Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Element Model ◽  
Frozen Soil ◽  
Silty Clay ◽  
Local Factor ◽  
The Stability ◽  
Random Finite Element

A significant number of landslides occur in cold regions because of freezing and thawing cycles. The instability of thawing slopes can cause serious damage to transportation infrastructure and property, and even loss of human life. This type of landslide is difficult to analyze by the traditional limit-equilibrium methods, however, because of the complicated multi-physics processes involved. This paper describes a holistic microstructure-based random finite element model (RFEM) to simulate the stability of a thawing slope. The RFEM model is developed to simulate the bulk behaviors of frozen and unfrozen soils based on the behaviors of individual phases. The phase coded image of a frozen silty clay is first custom built and then converted into a finite element model. The mechanical behaviors of individual phases of the frozen soil are calibrated by uniaxial compressive test. The triaxial test is then simulated by RFEM to obtain the shear strength parameters of frozen and unfrozen soils. Coupled thermal-mechanical REFM models are developed to simulate the effects of temperature on the displacement field and stress field in the slope. From the results, the local factor of safety field can be determined. The development of local factor of safety and potential failure surface associated with the thawing process over a typical year are simulated by this new model. The variations in the stability of thawing slopes predicted by this model are consistent with field observations as well as the global-wise slope stability analysis.

Microstructure-Based Random Finite Element Method Simulation of Frost Heave: Theory and Implementation

2018 ◽  
Vol 2672 (52) ◽  
pp. 347-357 ◽  
Author(s):  
Shaoyang Dong ◽  
Xiong (Bill) Yu
Keyword(s):  
Finite Element ◽  
Ground Surface ◽  
Finite Element Method Simulation ◽  
Element Model ◽  
Frozen Soil ◽  
Traffic Load ◽  
Frost Heave ◽  
Holistic Model ◽  
Water Pipes ◽  
Random Finite Element

Frost heave can cause serious damage to civil infrastructure. For example, interactions of soil and water pipes under frozen conditions have been found to significantly accelerate pipe fracture. Frost heave may cause the retaining walls along highways to crack and even fail in cold climates. This paper describes a holistic model to simulate the temperature, stress, and deformation in frozen soil and implement a model to simulate frost heave and stress on water pipelines. The frozen soil behaviors are based on a microstructure-based random finite element model, which holistically describes the mechanical behaviors of soils subjected to freezing conditions. The new model is able to simulate bulk behaviors by considering the microstructure of soils. The soil is phase coded and therefore the simulation model only needs the corresponding parameters of individual phases. This significantly simplifies obtaining the necessary parameters for the model. The capability of the model in simulating the temperature distribution and volume change are first validated with laboratory scale experiments. Coupled thermal-mechanical processes are introduced to describe the soil responses subjected to sub-zero temperature on the ground surface. This subsequently changes the interaction modes between ground and water pipes and leads to increase of stresses on the water pipes. The effects of cracks along a water pipe further cause stress concentration, which jeopardizes the pipe’s performance and leads to failure. The combined effects of freezing ground and traffic load are further evaluated with the model.

Landslide Simulation Using Limit Equilibrium and Finite Element Method

2016 ◽  
Vol 857 ◽  
pp. 555-559 ◽  
Author(s):  
Zuhayr Md Ghazaly ◽  
Mustaqqim Abdul Rahim ◽  
Kok Alfred Chee Jee ◽  
Nur Fitriah Isa ◽  
Liyana Ahmad Sofri
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Main Concern ◽  
Analysis Method ◽  
Stability Of Slope ◽  
The Stability ◽  
Element Method

Slope stability analysis is one of the ancient tasks in the geotechnical engineering. There are two major methods; limit equilibrium method (LEM) and finite element method (FEM) that were used to analyze the factor of safety (FOS) to determine the stability of slope. The factor of safety will affect the remediation method to be underdesign or overdesign if the analysis method was not well chosen. This can lead to safety and costing problems which are the main concern. Furthermore, there were no statement that issued one of the analysis methods was more preferred than another. To achieve the objective of this research, the soil sample collected from landslide at Wang Kelian were tested to obtain the parameters of the soils. Then, those results were inserted into Plaxis and Slope/W software for modeling to obtain the factor of safety based on different cases such as geometry and homogenous of slope. The FOS obtained by FEM was generally lower compared to LEM but LEM can provide an obvious critical slip surface. This can be explained by their principles. Overall, the analysis method chosen must be based on the purpose of the analysis.

scholarly journals Modeling inflatable fabric with undevelopable surfaces by motion folding method

2019 ◽  
Vol 14 ◽  
pp. 155892501988640
Author(s):  
Xiao-Shun Zhao ◽  
He Jia ◽  
Zhihong Sun ◽  
Li Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Numerical Study ◽  
Technical Problem ◽  
Three Dimensional ◽  
Element Model ◽  
Model Errors ◽  
Folding Model ◽  
Study Results ◽  
The Stability

At present, most space inflatable structures are composed of flexible inflatable fabrics with complex undevelopable surfaces. It is difficult to establish a multi-dimensional folding model for this type of structure. To solve this key technical problem, the motion folding method is proposed in this study. First, a finite element model with an original three-dimensional surface was flattened with a fluid structure interaction algorithm. Second, the flattened surface was folded based on the prescribed motion of the node groups, and the final folding model was obtained. The fold modeling process of this methodology was consistent with the actual folding processes. Because the mapping relationship between the original finite element model and the final folding model was unchanged, the initial stress was used to modify the model errors during folding process of motion folding method. The folding model of an inflatable aerodynamic decelerator, which could not be established using existing folding methods, was established by using motion folding method. The folding model of the inflatable aerodynamic decelerator showed that the motion folding method could achieve multi-dimensional folding and a high spatial compression rate. The stability and regularity of the inflatable aerodynamic decelerator numerical inflation process and the consistency of the inflated and design shapes indicated the reliability, applicability, and feasibility of the motion folding method. The study results could provide a reference for modeling complex inflatable fabrics and promote the numerical study of inflatable fabrics.

scholarly journals Vibration Control of an Unbalanced Single-Side Cantilevered Rotor System with a Novel Integral Squeeze Film Bearing Damper

2019 ◽  
Vol 9 (20) ◽  
pp. 4371 ◽  
Author(s):  
Yipeng Zhang ◽  
Lidong He ◽  
Jianjiang Yang ◽  
Fangteng Wan ◽  
Jinji Gao
Keyword(s):  
Finite Element ◽  
Energy Distribution ◽  
Finite Element Model ◽  
Vibration Control ◽  
Element Model ◽  
Rotor System ◽  
Squeeze Film ◽  
Single Side ◽  
The Stability ◽  
Stability Energy

In this paper, vibration control of an unbalanced single-side cantilevered rotor system using a novel integral squeeze film bearing damper in terms of stability, energy distribution, and vibration control is analyzed. A finite element model of such a system with an integral squeeze film bearing damper (ISFBD) is developed. The stability, energy distribution, and vibration control of the unbalanced single-side cantilevered rotor system are calculated and analyzed based on the finite element model. The stiffness of the integral squeeze film bearing damper is designed using theoretical calculation and finite element model (FEM) simulation. The influence of installation position and quantity of integral squeeze film bearing dampers on the vibration control of the unbalanced cantilevered rotor system is discussed. An experimental platform is developed to validate the vibration control effect. The results show that the installation position and quantity of the integral squeeze film bearing dampers have different effects on the stability, energy distribution, and vibration control of the unbalanced cantilevered rotor system. When ISFBDs are installed at both bearing housings, the vibration control is best, and the vibration components of the time and frequency domains have good vibration control effects in four working conditions.

Study on the Stability of the Bearing Capacity of Wedge Connected Scaffold

2015 ◽  
Vol 17 ◽  
pp. 24-29
Author(s):  
Shi Hui Zhou ◽  
Guo Dong ◽  
Zheng Ji Li
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Finite Element Model ◽  
Bearing Capacity ◽  
Theoretical Basis ◽  
Element Model ◽  
Theoretical Support ◽  
The Stability ◽  
Technical Regulations ◽  
Step Distance

Experimental data obtained from full-scale experiments determines the stiffness of wedge connected of scaffold.A finite element model is developed using semi-rigid scaffold node mode.And a reasonable combination of longitudinal span,transverse span and step distance is obtained.The results accords with the relevant standard of vertical load.It provides a theoretical support for the application of wedge connected scaffold.Additionally,the study explores the safety height of the wedge connected scaffold with or without bridging.It provides a theoretical basis for technical regulations.

The Analysis of Finite Element about the Interaction between Seasonal Frozen Soil and Tower Pile Foundation

2014 ◽  
Vol 680 ◽  
pp. 220-223
Author(s):  
Feng Lin Gan ◽  
Di Zhao
Keyword(s):  
Finite Element ◽  
Pile Foundation ◽  
Element Model ◽  
Frozen Soil ◽  
Finite Element Software ◽  
Key Factor ◽  
Seasonal Frozen Soil ◽  
The Stability ◽  
Expansion Effect ◽  
Line Engineering

In the northern frozen-soil region,the heaving soil’s low temperature is the key factor that impacts the stability of foundation. This paper makes the heat-stress coupled numerical analysis on the cold expansion effect of the pile foundation to the Ulanhot-Baicheng 500kV transmission line engineering by finite element software ABAQUS. Firstly, the seasonal frozen soil’s temperature field should be calculated. Then, the temperature value acting as the temperature model’s initial condition is put into the structure model for computation, which can help to get the pile foundation’s stress field and strain field. The results show that, the stress state of pile-frozen soil under external load can be reflected accurately through the finite element model and the related parameters proposed, along with the finite element software.

scholarly journals Analysis on the design of steel wire wound extrusion containers for hot extrusion process

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771241
Author(s):  
Changyong Liu ◽  
Renji Zhang ◽  
Yongnian Yan ◽  
Changshi Lao
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Steel Wire ◽  
Hot Extrusion ◽  
Element Model ◽  
Extrusion Process ◽  
Stability Factor ◽  
Improved Design ◽  
The Stability ◽  
The Finite Element Model

Extrusion container is the most important tooling for steel hot extrusion process. Conventional design using large castings and forgings is very difficult to execute due to high cost and risk. Steel wire wound containers have many advantages over conventional designs. However, conventional wire wound containers are developed for use at room temperature which are not applicable to steel hot extrusion process. In this article, the impacts of preheating on the design of steel wire wound containers are discussed in detail. A finite element model was established to examine the preheating temperature distribution, and a 1:10 scaled extrusion container was manufactured to verify the effectiveness of the finite element model. Based on the finite element model–computed temperature field, thermal stress analysis was performed. The thermal impacts on the stress of extrusion container and steel wire were obtained. Results showed that insufficient stability of internal cylinder and greatly enhanced steel wire stress may lead to the failure of extrusion container. To solve the problems, an improved design was put forward by increasing the stability factor of internal cylinder, reducing the prestress factor and lowering the allowable stress of steel wire. Results showed that the improved design can meet the requirements and counteract the thermal impacts.

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