Estimation of Bearing Capacity Dropping Due to Cavities from Gypseous Soils Melting

2020 ◽  
Vol 857 ◽  
pp. 409-416
Author(s):  
Ahmed Al-Obaidi ◽  
Reem S. Najim
Keyword(s):  
Bearing Capacity ◽  
Three Dimensional ◽  
Horizontal Distance ◽  
Finite Element Program ◽  
Significant Movement ◽  
Gypsum Content ◽  
Dimensional Finite Element ◽  
Element Program ◽  
Permeable Soil ◽  
Three Dimensional Finite Element

The presence of gypsum in the soil will cause problems if the source of freshwater is available and permeable soil permitting significant movement of water is to take place. The solubility of gypsum by excess water from irrigation or localized leak into the gypseous soil may cause cavity formation. In this research, a model was developed for governing the mass-transport to assess the variation of gypsum content of the soil during dissolution. A general three-dimensional finite element program (PLAXIS tunnel) was selected for the numerical analysis method to generate the solution. Parameters that affect the bearing capacity of a square footing represented by the gypsum content, the cavity volume, and the location of the cavity which represent by three offset distances from the footing center to the cavity center (x, y, and z), where (X) represents the horizontal distance, (Y) represents the vertical (depth) distance, and (Z) represents the diagonal distance. The main results show that the cavity location found to be the most parameter that affects the bearing capacity ratio (BCR). The minimum values are found when the cavity locates at the center of the footing base, and the lowest one (0.211) when the gypsum dissolved equal to 40%, also there is no effect of the cavity location when the ratio of (X/B) and (Z/B) exceed (3.0) for any depth and when the gypsum dissolved less than 10%. For high gypsum dissolution (more than 30%), the dimensionless ratios (X/B), (Z/B), and (Y/B) of the cavity must be more than 5.0.

Effect of Cavities from Gypsum Dissolution on Bearing Capacity of Soil under Square Footing

2020 ◽  
Vol 857 ◽  
pp. 221-227
Author(s):  
Israa Saleh Hussein ◽  
Lamyaa Najah Snodi
Keyword(s):  
Bearing Capacity ◽  
Water Flow ◽  
Three Dimensional ◽  
Cavity Volume ◽  
Finite Element Program ◽  
Square Footing ◽  
Gypsum Content ◽  
Element Program ◽  
Three Dimensional Finite Element ◽  
Gypseous Soil

This study deals with cavities under square footing which resulted from gypsum dissolving due to water flow in gypseous soil. This process leads to collapse of soil structure and progressive compression. A model was developed for governing the mass-transport to assess the variation of gypsum content of the soil during dissolution by ground water flow then cavity formation was adopted. A general three-dimensional finite element program (PLAXIS 3D) was selected for numerical analysis method to generate the solution. The study included a number of variables and their effect on bearing capacity of gypseous soil such as (gypsum content, cavity volume and location). The cavity was represented as axis and plane cavity which has square section. The results show that the most dangerous case is found when the cavity locates at the center of footing base (Z/B = 0), where the bearing capacity decreased by (14, 37, and 69%) for (20, 30, and 40%) gypsum dissolving ratio respectively. Also, the bearing capacity decreased when the cavity volume increases due to increasing dissolution ratio. The effect of cavity became disappear after (Z/B = 4). While, when using plane cavity, there was no cavity at center of footing base (Z/B = 0) because it considered as a hole not cavity. When using plane cavity, the bearing capacity decreased by (28, 43, and 53%) for (20, 30, and 40%) dissolving ratio respectively when (Z/B=1). The effect of cavity on the bearing capacity would be disappear as the distance from footing center increase until it became disappear at (Z/B = 6 m). The plane cavity is more dangerous than axis cavity.

Comparative Analysis of Several Construction Scheme of a Large-Sized Tie-Arch Aqueduct

2011 ◽  
Vol 94-96 ◽  
pp. 2350-2354
Author(s):  
Shu Zhong Lei ◽  
Zhong Xin Wang ◽  
Jian Ting Xu ◽  
Chi Peng Liu
Keyword(s):  
Comparative Analysis ◽  
Prestressed Concrete ◽  
Three Dimensional ◽  
Stability Control ◽  
River Diversion ◽  
Finite Element Program ◽  
Dimensional Finite Element ◽  
Element Program ◽  
Stress And Deformation ◽  
Three Dimensional Finite Element

An aqueduct of larger-span prestressed concrete arch structure for river diversion project is located in coastal areas, and raises difficult questions on deformation and stability control of the construction process due to greater wind load and poor soil. Due to the limited width of bracket erection, this paper put forward five possible construction schemes, and does the comparative analysis using three-dimensional finite element program, and gets the economic and reasonable one. Finally conduct a pressure test after the bracket erection, and verify the analysis results using measured stress and deformation data.

Analysis on Avoid Incision in Underground Engineering Reinforcement Technique against Cutting Resistance

2013 ◽  
Vol 853 ◽  
pp. 596-599
Author(s):  
Bo Wang ◽  
Yong Zhang ◽  
Hong Wei Liu
Keyword(s):  
Three Dimensional ◽  
Penetration Resistance ◽  
Surrounding Rock ◽  
Underground Engineering ◽  
Finite Element Program ◽  
Cutting Resistance ◽  
Dimensional Finite Element ◽  
Element Program ◽  
Three Dimensional Finite Element ◽  
Poor Stability

In view of serious degree of mouth formation rock weathering, poor stability, the construction excavation characteristics such as easy to collapse of underground engineering, incision reinforcement technology is used in underground engineering in the mouth period of construction, which changes the mechanical properties of surrounding rock and improves the penetration resistance of surrounding rock. Using three dimensional finite element program (ls-dyna) numerical simulations show that the stratified structure of the grouting tube in the surrounding rock is similar with covering layer thickness steel ball, which makes the projectile yaw in the process of penetration movement. As is shown through comprehensive calculation and analysis, the zero incision reinforcement technology can make the penetration resistance of the underground engineering mouth period increased by 30% ~ 40%.

Hydroelasticity Vibration of a Rectangular Tank Wall

2005 ◽  
Author(s):  
K. S. Kim ◽  
D. W. Kim ◽  
Y. B. Lee ◽  
S. H. Choi ◽  
Y. S. Kim
Keyword(s):  
Fluid Velocity ◽  
Three Dimensional ◽  
Tank Wall ◽  
Finite Element Program ◽  
Assumed Mode Method ◽  
Rectangular Tank ◽  
Mode Method ◽  
Dimensional Finite Element ◽  
Element Program ◽  
Three Dimensional Finite Element

A theoretical study is carried out on the hydroelasticity vibration of a rectangular tank wall. It is assumed that the tank wall is clamped along the plate edges. The fluid velocity potential is used for the simulation of fluid domain and to obtain the added mass due to wall vibration. In addition, the vibration characteristics of stiffened wall of the rectangular tank are investigated. Assumed mode method is utilized to the stiffened plate model and hydrodynamic force is obtained by the proposed approach. The coupled natural frequencies are obtained from the relationship between kinetic energies of a wall including fluid and the potential energy of the wall. The proposed analytical approach was found to be in good agreement with the results of a well-known commercial three-dimensional finite element program.

Dynamic Impact Simulation Study of Tubeless Pneumatic Tires

2016 ◽  
Author(s):  
Floyd Linayao ◽  
Raymond K. Yee
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Design Parameters ◽  
Inflation Pressure ◽  
Element Analysis ◽  
Finite Element Program ◽  
First Case ◽  
Dimensional Finite Element ◽  
Element Program ◽  
Three Dimensional Finite Element

Traditionally speaking, prototype tires are designed, and then tested on an experimental basis to evaluate performance. Using finite element analysis instead allows tire design parameters to be modified at will and underperforming architectures to be ruled out. This paper characterizes the dynamic response of a tubeless pneumatic vehicle tire as it is exposed to sudden impact and determines conditions under which failure would occur. Three cases were studied using a 175SR14 passenger tire, since passenger tires are most commonly used and impacts are more substantial on smaller tires. ABAQUS finite element program was used to perform nonlinear transient dynamic three-dimensional finite element analyses for three commonly tire encountered conditions. The first case, direct curb impact, determined that a safe inflation pressure range for tire velocities exists between 10 and 60 km per hour (kph). The second case, angled curb impact, found a smaller range of 10 to 40kph. The third case, impact with a pothole, found that at low inflation pressures, less stress is produced at higher velocities; increasing inflation pressure results in a transition point, causing larger stresses to be produced at higher velocities. From these analyses, several conclusions are drawn: inflation pressures below 100KPa do not produce a useful relationship between tire velocity and stress; thicker sidewalls help shield the tire from impact failure; and it is better for the tire to accelerate past a pothole in the 30 to 70kph range.

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