Evaluation of the contact pressure and response of a buried structure with a flat roof

2016 ◽  
Vol 43 (9) ◽  
pp. 830-843
Author(s):  
Yuri S. Karinski ◽  
Avraham N. Dancygier ◽  
Aaron Chacha
Keyword(s):  
Contact Pressure ◽  
Free Field ◽  
Relative Displacement ◽  
Soil Parameters ◽  
Soil Arching ◽  
Surface Loading ◽  
Column System ◽  
Continuous Concept ◽  
Flat Roof ◽  
Two Degree Of Freedom

The paper presents a model to analyze the response of a buried structure to surface loading, which is based on a discrete-continuous concept, taking into consideration a possible variation of the soil arching coefficient with depth. The structure and the soil are represented by equivalent two degree of freedom and one-dimensional column system. The shear soil resistance is represented by a vertical friction traction that depends on the relative displacement between the column and the free field. At the bottom, the system is supported by a semi-infinite medium. An analytical solution for the mid-roof deflection and average contact pressure has been derived and verified against published experimental results. Examination of the effects of the soil parameters on the mid-roof deflection demonstrates their different weights in the analysis. The present model may be used for future solutions of corresponding dynamic problems, for which the variation of the arching coefficient with depth is especially important.

Numerical analysis of kinematic response of single piles

2000 ◽  
Vol 37 (6) ◽  
pp. 1368-1382 ◽  
Author(s):  
Kevin J Bentley ◽  
M Hesham El Naggar
Keyword(s):  
Finite Element ◽  
Human Life ◽  
Free Field ◽  
Time History ◽  
Benchmark Problems ◽  
Soil Parameters ◽  
Nonlinear Behaviour ◽  
Pile Head ◽  
Element Mesh ◽  
Single Piles

Recent destructive earthquakes have highlighted the need for increased research into the revamping of design codes and building regulations to prevent further catastrophic losses in terms of human life and economic assets. The present study investigated the response of single piles to kinematic seismic loading using the three-dimensional finite element program ANSYS. The objectives of this study were (i) to develop a finite element model that can accurately model the kinematic soil–structure interaction of piles, accounting for the nonlinear behaviour of the soil, discontinuity conditions at the pile–soil interface, energy dissipation, and wave propagation; and (ii) to use the developed model to evaluate the kinematic interaction effects on the pile response with respect to the input ground motion. The static performance of the model was verified against exact available solutions for benchmark problems including piles in elastic and elastoplastic soils. The geostatic stresses were accounted for and radiating boundaries were provided to replicate actual field conditions. Earthquake excitation with a low predominant frequency was applied as an acceleration–time history at the base bedrock of the finite element mesh. To evaluate the effects of the kinematic loading, the responses of both the free-field soil (with no piles) and the pile head were compared. It was found that the effect of the response of piles in elastic soil was slightly amplified in terms of accelerations and Fourier amplitudes. However, for elastoplastic soil with separation allowed, the pile head response closely resembled the free-field response to the low-frequency seismic excitation and the range of pile and soil parameters considered in this study.Key words: numerical modelling, dynamic, lateral, piles, kinematic, seismic.

scholarly journals Response Analysis of the Free Field under Fault Movements

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
H. L. Qu ◽  
Y. Wu ◽  
B. K. Zhang ◽  
Q. D. Hu ◽  
Z. L. Xiao
Keyword(s):  
Free Field ◽  
Development Program ◽  
Normal Fault ◽  
Nonlinear Problems ◽  
Secondary Development ◽  
Response Analysis ◽  
Soil Parameters ◽  
Reverse Fault ◽  
Critical Displacement ◽  
Highly Nonlinear

A quasistatic simulation of highly nonlinear problems under fault movements was carried out using the EXPLICIT module of ABAQUS. Combined with the secondary development program of the software, the application of the strain softening Mohr–Coulomb model in the simulation was realized. Free field-fault systems were simulated with two types of fault types (normal and reverse faults), four fault dip angles (45°, 60°, 75°, and 90°), and two kinds of soil (sand and clay). Moreover, the rupture laws and sensitivities of the sand and clay were studied with different soil thicknesses and different fault dip angles in the free field. The results show that the width of the ground zone with obvious deformation, which represents the point of the fault outcrop, the critical displacement of the fault, and the rupture characteristics of the overlying soil are closely related to the fault type and soil parameters. The critical displacement of the reverse fault is larger than that of the normal fault. The width of the ground zone with obvious deformation varies from 0.65 to 1.3 and does not exhibit a regular relationship with the type of soil. Compared with a normal fault, the rupture of a reverse fault is not prone to exposure at the surface.

Experimental Investigation of Soil Arching Mobilization and Degradation under Localized Surface Loading

2019 ◽  
Vol 145 (12) ◽  
pp. 04019114 ◽  
Author(s):  
Mahdi Al-Naddaf ◽  
Jie Han ◽  
Chao Xu ◽  
Saif Jawad ◽  
Ghaith Abdulrasool
Keyword(s):  
Experimental Investigation ◽  
Soil Arching ◽  
Surface Loading

Study of a Major Mechanism for Self-Loosening of Bolted Joints

2006 ◽  
Author(s):  
Ziqin Wang ◽  
Yanyao Jiang
Keyword(s):  
Contact Pressure ◽  
Three Dimensional ◽  
Bending Moment ◽  
Tangential Direction ◽  
Relative Displacement ◽  
Bolted Joints ◽  
Major Mechanism ◽  
Fe Simulations ◽  
Local Slip ◽  
D Model

A recent three-dimensional (3-D) finite element (FE) investigation on self-loosening of bolted joints revealed that two major mechanisms were responsible for the second-stage (nut rotation) self-loosening of bolted joints. One of the mechanisms is the slip-stick contact of the thread surfaces under the combined contact pressure and reversed bending moment exerted from the reversed transverse loading. The current investigation is a detailed study of the slip-stick contact of the thread surfaces with models that mimic the bolt loading condition. The contact pressure and the reversed bending moment are obtained from an earlier simulation for an M12 bolt. The FE simulations indicate that, with the contact pressure on the thread surface of the bolt and nut, the alternating bending moment results in the gradual motion between the contact thread surfaces. A detailed look at the contact surfaces reveals that localized slip along the tangential direction occurs in part of the contact area and the accumulation of this local slip is responsible for the gradual relative motion between bolt and nut. The FE simulations also indicate that the amplitude of the bending moment greatly influences the relative displacement between the bolt and the nut. There exists a threshold below which local slip will not occur. Results from a two-dimensional (2-D) model are discussed and compared with those obtained from a 3-D model.

Modeling of Turbine Blade Tip Contact

1976 ◽  
Vol 98 (4) ◽  
pp. 435-440
Author(s):  
R. A. Burton ◽  
S. R. Kilaparti ◽  
S. R. Heckmann
Keyword(s):  
Mathematical Model ◽  
Thermal Expansion ◽  
Contact Pressure ◽  
Turbine Blade ◽  
Relative Displacement ◽  
Operating Conditions ◽  
Dynamic Displacement ◽  
Contact Patch ◽  
Full Contact ◽  
Blade Tip

A mathematical model is developed for the condition where turbine blade/shroud contact occurs at discrete patches on the shroud. The contact patch is treated as having uniform time-mean contact pressure; and several components of relative displacement are identified, these having to sum to zero in the contact patch to assure an unbroken interface in the patch. Operating conditions which meet this requirement permit the postulated patchlike contact to exist. Operating conditions which do not meet it will not be associated with such patches. The components of relative displacement are almost independent of one another and are treated as linearly additive. These are: (1) thermal expansion of the shroud material in the patch, (2) elastic indentation of the shroud by the blade tip, (3) wear of the shroud material, (4) wear of the blade tip, (5) dynamic displacement of the blade tip, (6) dynamic displacement of the shroud, (7) elastic compression of the thinned blade tip portion. Using these components and applying the foregoing condition for full contact, the speed at which the contact patch traverses along the shroud surface is solved for, and the factors which determine the width of the contact patch are determined.

A Numerical Analysis of Soil Arching in Piled Embankments

2012 ◽  
Vol 468-471 ◽  
pp. 638-642
Author(s):  
Min Zhao ◽  
Wei Ping Cao
Keyword(s):  
Numerical Analysis ◽  
Stress Concentration ◽  
Concentration Ratio ◽  
Friction Angle ◽  
Relative Displacement ◽  
Soil Arching ◽  
Pile Cap ◽  
Stress Concentration Ratio ◽  
Embankment Height ◽  
Piled Embankments

Soil arching has important influence on the behavior of piled embankments. How to calculate stress concentration ratio is of great concern when designing embankment over soft soils reinforced by rigid concrete piles. A numerical analysis by using a commercial FEM program was conducted to reveal the mechanism of soil arching in piled embankments. And also, the influence of embankment height, pile-soil relative displacement, cohesion and internal friction angle on the equal settlement plane was evaluated. The results indicate that the stress concentration ratio varies with the pile-subsoil relative displacement and has upper and lower bound value. The effect of pile-soil displacement and the strength parameters of embankment material on the equal settlement plane can be neglected. It was also found that the equal settlement plane height is equal to 1.6 times the pile-cap clear spacing. When the ratio of embankment height to the pile-cap clear spacing is greater than 1.6, no apparent differential settlement will occur on the embankment surface.

An Improved Shearing Displacement Law for Analyzing Pile-Soil Interaction

2013 ◽  
Vol 639-640 ◽  
pp. 581-586
Author(s):  
Xue Liang Jiang ◽  
Hui Yang ◽  
Jun Fu
Keyword(s):  
Growth Rate ◽  
Axial Force ◽  
Deformation Characteristic ◽  
Back Analysis ◽  
Frictional Resistance ◽  
Fine Sand ◽  
Relative Displacement ◽  
Soil Parameters ◽  
Vertical Loading ◽  
Soil Slip

The Soil Improved shearing displacement law is used to analyze Pile-soil interaction and this method can consider stratified foundation, but can’t consider pile-soil slip. An improved shearing displacement law analyzing pile-soil interaction was proposed in this article which could think over pile-soil slip on interfaces and interaction of pile-soil on stratified foundation. Rock and soil’s parameter is very crucial in geological engineering, the soil parameters were determined by parameter back analysis theory and the stress and deformation characteristic for vertical loading piles were analyzed by the improved shearing displaces law. These process was simulated by my own program. The calculation results show that the axial force of pile decreases with pile depth and the pile tip axial force is zero. The pile bottom resistance increases with load and the soil’s resistance increases with the relative displacement between pile and soil. But,the frictional resistance growth rate with displacement is different in different soil. The silt’s growth rate is minimum and the medium-fine sand mixed mucky soil is maximum. The pile frictional resistance increases with load and depth. It has greater directive significance for the pile design.

Measuring Soil Contact Pressure on a Solid Boundary and Quantifying Soil Arching

2005 ◽  
Vol 28 (2) ◽  
pp. 12484 ◽  
Author(s):  
L David Suits ◽  
TC Sheahan ◽  
M Talesnick
Keyword(s):  
Contact Pressure ◽  
Solid Boundary ◽  
Soil Arching

Numerical Simulation of the Forming and Failure Process of Soil Arching Between Anti-slide Piles

2011 ◽  
Vol 261-263 ◽  
pp. 1614-1618
Author(s):  
Jin Shan Sun ◽  
Ming Chen ◽  
Qing Hui Jiang
Keyword(s):  
Cross Section ◽  
Numerical Models ◽  
Rectangular Cross Section ◽  
Failure Process ◽  
Failure Surface ◽  
Soil Parameters ◽  
Soil Arching ◽  
Forming Mechanism ◽  
Arching Effect ◽  
Crown Shape

The mechanism of soil arching effect is important for anti-slide pile design. With the 2D particle flow method (PFC2D), the forming and failure process of the soil arching between anti-slide piles are simulated. The results show that the forming mechanism of soil arching mainly depended on stress transit process of micro soil granule. In the anti-slide pile numerical models (PFC2D), the contact stress transit trace lines present the tree crown shape, which centered about the anti-slide pile. The load from far field is transited to the front and side part of piles through the compress soil. When the soil between anti-slide piles collapses, the failure surface presented the arching shape. The cross-section and spacing of anti-slide piles affect the soil arching shape strongly. With the same pile spacing and soil parameters, the ultimate bearing capacity of rectangular cross-section pile is larger than the circle cross-section pile.

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