scholarly journals Topographic Effects on Three-Dimensional Slope Stability for Fluctuating Water Conditions Using Numerical Analysis

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 615
Author(s):  
Yue Zhou ◽  
Shun-Chao Qi ◽  
Gang Fan ◽  
Ming-Liang Chen ◽  
Jia-Wen Zhou
Keyword(s):  
Slope Stability ◽  
Unsaturated Soils ◽  
Three Dimensional ◽  
Matric Suction ◽  
Surface Shape ◽  
Engineering Practice ◽  
Topographic Effects ◽  
Water Conditions ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

With recent advances in calculation methods, the external factors that affect slope stability, such as water content fluctuations and self-configuration, can be more easily assessed. In this study, a three-dimensional finite element strength reduction method was used to analyze the stability of three-dimensional slopes under fluctuating water conditions. Based on soil parameter variations in engineering practice, the calculation models were established using heterogeneous layers, including a cover layer with inferior properties. An analysis of seepage, deformation and slope stability was carried out with 27 different models, including three different slope gradients and nine different corner angles under five different hydraulic conditions. The failure mechanism has been shown to be closely related to the change in matric suction of unsaturated soils and the geometric slope configuration. Finally, the effect of geometry (surface shape, turning corner and slope gradient) and water (fluctuations) on slope stability are discussed in detail. Emphasis is given to comparing safety factors obtained considering or ignoring matric suction.

Three-Dimensional Finite Element Analysis of Qingyi River Aqueduct during Operation Period

2014 ◽  
Vol 556-562 ◽  
pp. 679-682
Author(s):  
Yan Yan Zhang ◽  
Cai Ying Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Engineering Practice ◽  
Good Precision ◽  
Operation Condition ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper, finite element model of the Qingyi River rectangular section reinforced concrete aqueduct is set up by using three-dimensional finite element analysis software ANSYS. Considering the conventional static load, the seismic loads which use quasi-static method, and considering five combinations of operation condition of aqueduct in operation process, the structure stress and displacement rules of aqueduct are obtained in the different conditions. The results show that the rectangular cross-section aqueduct in the water level under the action of the full tank, the vertical displacement of the aqueduct body structure is nearly doubled than the empty slot, indicating the water load have a significant impact on the aqueduct. The calculated results has a good precision, can meet the needs of practical engineering, can provide a reference basis for the design of thin-walled rectangular aqueduct and the theoretical basis for engineering practice and guidance recommendations.

Modeling the unsaturated soil zone in slope stability analysis

2014 ◽  
Vol 51 (12) ◽  
pp. 1384-1398 ◽  
Author(s):  
L. L. Zhang ◽  
Delwyn G. Fredlund ◽  
Murray D. Fredlund ◽  
G. Ward Wilson
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Slope Stability ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Matric Suction ◽  
Slope Stability Analysis ◽  
Engineering Practice ◽  
Rate Of Increase ◽  
Nonlinear Shear

The linear form of the extended Mohr–Coulomb shear strength equation uses a [Formula: see text] parameter to quantify the rate of increase in shear strength relative to matric suction. When the [Formula: see text] value is unknown, a [Formula: see text] equal to 15° is sometimes used in the slope stability study to assess the influence of matric suction on the stability of a slope. In many cases, however, a [Formula: see text] value of zero is used, signifying that the effect of matric suction is ignored. Experiment results have shown that the relationship between the shear strength of an unsaturated soil and matric suction is nonlinear. Several semi-empirical estimation equations have been proposed relating the unsaturated shear strength to the soil-water characteristic curve. In this paper, the results of a study using two-dimensional slope stability analysis along with an estimated nonlinear shear strength equations is presented. The effects of using an estimated nonlinear shear strength equation for the unsaturated soils are illustrated using three example problems. Several recommendations are made for engineering practice based on the results of the example problems. If the air-entry value (AEV) of a soil is smaller than 1 kPa, the effect of matric suction on the calculated factor of safety is trivial and the [Formula: see text] value can be assumed to be zero. If the AEV of a soil is between 1 and 20 kPa, the nonlinear equations of unsaturated shear strength should be adopted. For soils with an AEV value between 20 and 200 kPa, an assumed [Formula: see text] value of 15° provides a reasonable estimation of the effects of unsaturated shear strength in most cases. For soils with an AEV greater than 200 kPa, [Formula: see text] can generally be assumed to be equal to the effective angle of internal friction, [Formula: see text], in applications where geotechnical structures have matric suctions around 100 kPa.

scholarly journals Effect of embedment on consolidated undrained capacity of skirted circular foundations in soft clay under planar loading

2017 ◽  
Vol 54 (2) ◽  
pp. 158-172 ◽  
Author(s):  
Cristina Vulpe ◽  
Susan M. Gourvenec ◽  
Alexander F. Cornelius
Keyword(s):  
Soft Clay ◽  
Three Dimensional ◽  
Soil Mass ◽  
Relative Magnitude ◽  
Interface Roughness ◽  
Engineering Practice ◽  
Straightforward Method ◽  
Failure Envelopes ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The effect of foundation embedment ratio and soil–skirt interface roughness on the consolidated undrained capacity of skirted circular foundations under planar loading in normally consolidated clay has been investigated through coupled three-dimensional finite element analyses. Results are presented as failure envelopes, and changes in shape and size of the normalized vertical–horizontal–moment (VHM) failure envelopes are described as a function of relative magnitude and duration of applied preload. Results show that embedment ratio and interface roughness affect the load distribution within the soil mass, but that consolidated undrained capacity under planar loading scales proportionately with the (unconsolidated) undrained capacity of the foundation. This latter feature enables the results to be neatly synthesized into a relatively straightforward method for use in engineering practice for prediction of gain in undrained VHM capacity due to preload and consolidation.

Closed Analytical Expressions for Stress Distributions in Two-Layer Cylinders and Their Application to Offshore Lined and Clad Pipes

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Knut Vedeld ◽  
Håvar A. Sollund ◽  
Jostein Hellesland
Keyword(s):  
Plane Strain ◽  
Thermal Loading ◽  
Three Dimensional ◽  
Engineering Practice ◽  
Start Up ◽  
Clad Layer ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Hoop Stresses ◽  
Analytical Expressions

Closed-form analytical expressions are derived for the displacement field and corresponding stress state in two-layer cylinders subjected to pressure and thermal loading. Solutions are developed both for cylinders that are fully restrained axially (plane strain) and for cylinders that are axially loaded and spring-mounted. In the latter case, it is assumed that the combined two-layer cross section remains plane after deformation (generalized plane strain). The analytical solutions are verified by means of detailed three-dimensional finite element (FE) analyses, and they are easily implemented in, and suitable for, engineering applications. The chosen axial boundary conditions are demonstrated to be particularly relevant for pipeline and piping applications. By applying the exact solutions derived in the present study to typical offshore lined or clad pipelines, it is demonstrated that thermal expansion of the liner or clad layer may cause higher tensile hoop stresses in the pipe steel wall than accounted for in current engineering practice. It is shown that repeated cycles of start-up and shut-down phases for lined or clad pipelines cause significant plastic stress cycles in liners or claddings, which may pose a risk to the integrity of such pipelines.

scholarly journals Three-Dimensional Numerical Investigation on the Efficiency of Subsurface Drainage for Large-Scale Landslides

2020 ◽  
Vol 10 (10) ◽  
pp. 3346
Author(s):  
Der-Guey Lin ◽  
Kuo-Ching Chang ◽  
Cheng-Yu Ku ◽  
Jui-Ching Chou
Keyword(s):  
Slope Stability ◽  
Large Scale ◽  
Three Dimensional ◽  
Drainage System ◽  
Subsurface Drainage ◽  
Dimensional Finite Element ◽  
Unstable Slope ◽  
Horizontal Drains ◽  
Typhoon Season ◽  
Three Dimensional Finite Element

This paper presents a field monitoring study with emphasis on the design and construction of a subsurface drainage system and evaluation of its stabilization efficiency on the slope of You-Ye-Lin landslide using a three-dimensional finite element method program (Plaxis 3D) for the groundwater flow and slope stability analyses. The subsurface drainage system consists of two 4-m diameter drainage wells with multi-level horizontal drains and was installed to draw down the groundwater level and stabilize the unstable slope of the landslide. Results demonstrate that the subsurface drainage system is functional and capable of accelerating the drainage of the infiltrated rainwater during torrential rainfalls during the typhoon season. The large groundwater drawdown by the subsurface drainage system protects the slopes from further deterioration and maintains the slope stability at an acceptable and satisfactory level.

Three-Dimensional Finite Element Analysis Shelves

2011 ◽  
Vol 117-119 ◽  
pp. 639-642
Author(s):  
Xiu Ting Zhao ◽  
Jin Meng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Value Engineering ◽  
Integrated Analysis ◽  
Production Cycle ◽  
Engineering Practice ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The use of Pro/E features a powerful solid modeling and ANSYS finite element analysis a powerful, integrated analysis of the two methods on the shelf for static analysis and modal analysis, obtained the stress, strain and natural frequency and the cloud vibration mode, the correct design of the shelf provides a reasonable theoretical basis. Checking the strength of the shelf structure can shorten the shelf of the production cycle, reduce costs and improve shelf quality, has a certain value engineering practice.

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