Numerical analysis of large penetration of a cone and a large diameter footing into dense sand overlying clay

2014 ◽  
pp. 883-888
Author(s):  
B Bienen ◽  
G Qiu
Keyword(s):  
Numerical Analysis ◽  
Large Diameter ◽  
Dense Sand

scholarly journals Evaluation of p-y Curves and p-multiplier of Pile Groups Corresponding to Sand Properties Change Based on 3D Numerical Analysis

2020 ◽  
Vol 20 (4) ◽  
pp. 207-217
Author(s):  
Yongjin Choi ◽  
Jaehun Ahn
Keyword(s):  
Numerical Analysis ◽  
Soil Properties ◽  
Pile Group ◽  
Friction Angle ◽  
Dominant Factor ◽  
Group Effect ◽  
Pile Groups ◽  
Dense Sand ◽  
Laterally Loaded Pile ◽  
Laterally Loaded

The <i>p-y</i> curve method and </i>p</i>-multiplier (<i>P<sub>m</sub></i>), which implies a group effect, are widely used to analyze the nonlinear behaviors of laterally loaded pile groups. Factors affecting <i>P<sub>m</sub></i> includes soil properties as well as group pile geometry and configuration. However, research on the change in <i>P<sub>m</sub></i> corresponding to soil properties has not been conducted well. In this study, in order to evaluate the effect of soil properties on the group effect in a laterally-loaded pile group installed in sandy soil, numerical analysis for a single pile and 3×3 pile group installed in loose, medium, and dense sand, was performed using the 3D numerical analysis program, Plaxis 3D. Among the factors considered in this study, the column location of the pile was the most dominant factor for <i>P<sub>m</sub></i>. The effect of the sand property change on <i>P<sub>m</sub></i> was not as significant as that of the column location of the pile. However, as the sand became denser and the friction angle increased, the group effect increased, leading to a decrease in <i>P<sub>m</sub></i> of approximately 0.1. This trend was similar to the result reported in a previous laboratory-scale experimental study.

Axial performance of micropile groups in cohesionless soil from full-scale tests

2020 ◽  
Vol 57 (7) ◽  
pp. 1006-1024
Author(s):  
Maged A. Abdlrahem ◽  
M. Hesham El Naggar
Keyword(s):  
Group Performance ◽  
Large Diameter ◽  
Small Diameter ◽  
Element Model ◽  
Cohesionless Soil ◽  
Drill Bit ◽  
Load Testing ◽  
Dense Sand ◽  
Full Scale Tests ◽  
Square Configuration

Hollow bar micropile (HBMP) groups are used for supporting large loads as an alternative foundation option to large diameter drilled shafts. In such cases, it may be necessary to increase the micropile’s diameter by increasing the drill bit diameter (Db). This paper investigates experimentally and numerically the effect of increasing Db and micropile spacing on the group performance. A field load testing program was conducted on four groups of HBMPs installed in sand; each group comprised four micropiles arranged in a square configuration. All micropiles were constructed with the same size hollow bar, Dh = 51 mm; two groups comprised micropiles constructed with drill bit, Db = 115 mm, and two groups comprised micropiles constructed with drill bit, Db = 152 mm. One group of each set was installed with spacing to micropile diameter ratio, S/Db = 3 and the other group with S/Db = 5. In addition, full 3D finite element model (FEM) was developed and calibrated to simulate the behaviour of micropile groups and to evaluate the failure load for groups that were not loaded to failure. The results demonstrated that micropile groups constructed with the large diameter drill bits displayed higher stiffness and load carrying capacity than the groups constructed with small diameter bits, which confirms the effectiveness of using a larger drill bit. In addition, the group efficiency ratio values at both working load and ultimate capacity were found to be close to unity for all groups. The ultimate skin friction values of grouted micropiles obtained from this study were higher than the values suggested by the US Federal Highway Administration for medium to very dense sand. It was also found that the settlement of the 4-HBMP group increased by 25% to 33% over that of a single HBMP due to group effect.

Numerical Analysis of Flow-Induced Vibration of Large Diameter Pipe With Short Elbow

2017 ◽  
Author(s):  
Shigeru Takaya ◽  
Tatsuya Fujisaki ◽  
Masaaki Tanaka
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Fast Reactor ◽  
Pressure Fluctuation ◽  
Cooling System ◽  
Large Diameter ◽  
Recirculation Region ◽  
Flow Induced Vibration ◽  
Scaled Model ◽  
Energy Agency

Japan Atomic Energy Agency is now conducting design study and R&D of an advanced loop-type sodium cooled fast reactor. The cooling system is planned to be simplified by employing a two-loop configuration and shortened piping with less elbows than a prototype fast reactor in Japan, Monju, in order to reduce construction costs and enhance economic performance. The design, however, increases flow velocity in the hot-leg piping and induces large flow turbulence around elbows. Therefore, flow-induced vibration (FIV) of a hot-leg piping is one of main concerns in the design. Numerical simulation is a useful method to deal with such a complex phenomenon. We have been developing numerical analysis models of the hot-leg piping using Unsteady Reynolds Averaged Navier-Stokes simulation with Reynolds stress model. In this study, numerical simulation of a 1/3 scaled-model of the hot-leg piping was conducted. The results such as velocity profiles and power spectral densities (PSD) of pressure fluctuations were compared with experiment ones. The simulated PSD of pressure fluctuation at the recirculation region agreed well with the experiment, but it was found some underestimation at other parts, especially in relatively high frequency range. Eigenvalue vibration analysis was also conducted using a finite element method. Then, stress induced by FIV was evaluated using pressure fluctuation data calculated by URANS simulation. The calculated stress generally agrees well the measurement values, which indicates the importance of precise evaluation of the PSD of pressure fluctuation at the recirculation region for evaluation of FIV of the hot-leg piping with a short elbow.

Surface foundation subjected to strike-slip faulting on dense sand: centrifuge testing versus numerical analysis

Géotechnique ◽  
2021 ◽  
pp. 1-58
Author(s):  
Athanasios Agalianos ◽  
Evangelia Korre ◽  
Tarek Abdoun ◽  
Ioannis Anastasopoulos
Keyword(s):  
Numerical Analysis ◽  
Strike Slip ◽  
Dense Sand ◽  
Centrifuge Testing ◽  
Surface Foundation
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