On the pullout resistance of geosynthetics

1993 ◽  
Vol 30 (3) ◽  
pp. 409-417 ◽  
Author(s):  
R.J. Fannin ◽  
D.M. Raju
Keyword(s):  
Relative Displacement ◽  
Coarse Sand ◽  
Reinforced Soil ◽  
Small Displacement ◽  
Sand Sample ◽  
Similar Response ◽  
Pullout Resistance ◽  
Interaction Factor ◽  
Values In Design ◽  
Stress Dependent

Pullout tests are reported on geosynthetic test specimens embedded in a relatively dense, coarse sand sample. The tests are displacement controlled and are performed at different vertical effective stresses. Tests are reported for a smooth and textured geomembrane and for geogrids of a high and low junction strength. Behaviour is compared with an inextensible, rough sheet. Pullout resistance is governed by progressive tensile strain in the geosynthetic which is a result of relative displacement between it and the soil. Values of interface bond that are described by an interaction factor vary significantly and are stress dependent. Both types of geogrid and the textured geomembrane exhibit a similar response to loading at small displacement, and mobilize a much larger interaction factor than the smooth geomembrane. A rationale is suggested for selection of appropriate values in design. Key words : pullout testing, geogrid, geomembrane, interface friction, reinforced soil.

scholarly journals Effect of Boundary Conditions on the Mechanical Behavior of the Geogrid–Soil Interface

2021 ◽  
Vol 11 (21) ◽  
pp. 9942
Author(s):  
Zheng Zuo ◽  
Guangqing Yang ◽  
Zhijie Wang ◽  
He Wang ◽  
Jing Jin
Keyword(s):  
Boundary Conditions ◽  
Coarse Sand ◽  
Reinforced Soil ◽  
Normal Loading ◽  
Pullout Resistance ◽  
Vertical Loading ◽  
Economical Design ◽  
Reduction Coefficient ◽  
The Relationship ◽  
Soil Interface

Geogrid-reinforced structures are extensively adopted in various engineering fields. At present, the influence of boundary conditions was not considered in design methods, bringing hidden dangers to the safety of the structure. In the current study, a series of pullout tests were carried out on high-density polyethylene (HDPE) geogrid-reinforced coarse sand. The magnitude and growth pattern of pullout resistance and the variation laws of interfacial shear strength indexes under four types of boundary conditions were analyzed. Additionally, the boundary reduction coefficient (BRC) was introduced to establish the relationship between rigid and flexible boundary for the design of the structure. The tests results showed that the boundary conditions cannot be ignored in the design of structures, especially in the front. When the normal loading was up to 120 kPa, the BRC-top and BRC-positive could be taken as 0.9 and 0.5, respectively, and verified by fitting results. The boundary conditions affected the pullout resistance, while the vertical loading corresponding to the maximum pullout resistance was not related to boundary conditions. Investigating the interaction of the geogrid–soil under different boundary conditions can help to improve the understanding of the behavior of reinforced soil structure, and to achieve a more efficient and economical design.

scholarly journals Experimental Investigations on Pullout Behavior of HDPE Geogrid under Static and Dynamic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zheng Zuo ◽  
Guangqing Yang ◽  
He Wang ◽  
Zhijie Wang
Keyword(s):  
Dynamic Loading ◽  
Static Loading ◽  
Coarse Sand ◽  
Reinforced Soil ◽  
Growth Patterns ◽  
Experimental Investigations ◽  
Pullout Resistance ◽  
Pullout Tests ◽  
Soil Structures ◽  
Static And Dynamic Loading

This paper describes a series of laboratory pullout tests that were performed to investigate the pullout behavior of high-density polyethylene (HDPE) uniaxial geogrid subjected to static and dynamic loading. Pullout tests were conducted on HDPE geogrid reinforced coarse sand under normal static loading (60–300 kPa), dynamic loading with different amplitudes (20, 40, and 60 kPa), and different frequencies (2, 4, and 6 Hz) by using the newly developed pullout apparatus. The results indicated that the pullout resistance of geogrid presented different growth patterns with the increase of normal loads under static loading. The amplitude and frequency both had significant effects on the interaction between reinforcement and soil, and the increment of the pullout resistance was 0.6 kN and 0.3 kN, respectively. The effect of dynamic loading on the soil-geogrid interface can be gradually equivalent to that of static loading corresponding to the balance position of dynamic loading with the increase of frequency compared with the static loading. The results of this study are helpful for the selection of the strength of the reinforcement in different locations and to simplify the study on the stress of reinforcement in reinforced soil structures under traffic loads.

Analytical model of interaction between hexagonal wire mesh and silty sand backfill

2001 ◽  
Vol 38 (4) ◽  
pp. 782-795 ◽  
Author(s):  
D T Bergado ◽  
P Voottipruex ◽  
A Srikongsri ◽  
C Teerawattanasuk
Keyword(s):  
Analytical Model ◽  
Relative Displacement ◽  
Wire Mesh ◽  
Silty Sand ◽  
Hyperbolic Function ◽  
Friction Resistance ◽  
Pullout Resistance ◽  
Mesh Reinforcement ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The interaction behavior between hexagonal wire mesh and silty sand backfill can be evaluated from pullout tests. The pullout resistance of the hexagonal wire mesh reinforcement consists of two components, namely friction resistance and passive bearing resistance. The friction resistance – relative displacement relationship of a hexagonal wire mesh can be simulated by a linear elastic – perfectly plastic model. The passive bearing resistance of an individual bearing member can be modelled by a hyperbolic function. The friction resistances for galvanized and PVC-coated hexagonal wire mesh were 25 and 21%, respectively, of the total pullout resistance. A new analytical model for predicting the pullout resistance of hexagonal wire mesh reinforcement has been proposed. The proposed solution can estimate the maximum pullout force at different reinforcement levels from observed horizontal movement of a hexagonal wire mesh reinforcement.Key words: hexagonal wire mesh, necking phenomena, bearing resistance, analytical model, pullout box, bearing resistance.

Load-strain-displacement response of geosynthetics in monotonic and cyclic pullout

1998 ◽  
Vol 35 (2) ◽  
pp. 183-193 ◽  
Author(s):  
D M Raju ◽  
R J Fannin
Keyword(s):  
Relative Displacement ◽  
Cyclic Loads ◽  
Normal Stresses ◽  
Constant Ratio ◽  
Pullout Resistance ◽  
Maximum Resistance ◽  
Constant Rate ◽  
Pullout Testing ◽  
Pullout Behaviour ◽  
Cyclic Dynamic

Mobilization of the pullout resistance of geosynthetics in monotonic and cyclic modes is described from both displacement- and load-controlled tests performed at normal stresses in the range 4-17 kPa. The tests were performed on three geogrids and two geomembranes embedded nearly 1.0 m in a uniformly graded sand. Results for load-controlled tests at a constant rate of 0.25 kN/(m ·min-1), followed by several series of load cycles of increasing amplitude, are compared with displacement-controlled tests at a constant rate of 0.5 mm/min. In general the geogrids behave as an equivalent textured sheet. Pullout behaviour, and especially the incremental displacement mobilized at cyclic loads close to the maximum resistance, is found to vary with type of geogrid. In only one case was cyclic pullout resistance of a grid found to exceed the monotonic resistance. A comparison of the cyclic and monotonic response yields a constant ratio of pullout resistance at large displacement, but one which is not unique to a particular specimen. Cyclic strains of decreasing amplitude are mobilized along a test specimen, with most of the necessary relative displacement occurring close to the loaded end and the embedded end showing little response.Key words: pullout testing, monotonic, cyclic, dynamic, geosynthetics, reinforced walls.

Some techniques for finite element analysis of embankments on soft ground

1993 ◽  
Vol 30 (4) ◽  
pp. 710-719 ◽  
Author(s):  
J.C. Chai ◽  
D.T. Bergado
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
Relative Displacement ◽  
Technical Note ◽  
Reinforced Soil ◽  
Soil Reinforcement ◽  
Soft Ground ◽  
Element Analysis ◽  
Consolidation Process ◽  
Interface Elements

The accuracy of finite element results depends on the numerical models and the parameters used as well as the numerical techniques adopted. Three aspects of modelling the behavior of embankment on soft ground are discussed in this technical note: (i) simulating the actual construction process, (ii) modelling the soft ground permeability variation during the loading and consolidation process, and (iii) selecting proper soil–reinforcement interface properties according to the relative displacement pattern of the upper and lower interface elements placed between the soil and reinforcement in the case of a reinforced embankment. The significance of these factors on the performance of the embankment on soft ground is demonstrated by case studies. Key words : finite element method, loading, permeability, reinforced soil.

Comparison of Pullout Behaviour on Sand between Planer Grid Forms and Grid with Rib of Reinforcement

2010 ◽  
Vol 143-144 ◽  
pp. 1012-1016
Author(s):  
Yong Liang Lin ◽  
Meng Xi Zhang ◽  
Chun Cai
Keyword(s):  
Reinforced Soil ◽  
Grid Size ◽  
Soil Reinforcement ◽  
Testing Program ◽  
Pullout Force ◽  
Pullout Resistance ◽  
Pullout Tests ◽  
Soil Structures ◽  
Pullout Behaviour ◽  
Grid Reinforcement

In conventional reinforced soil structures, the reinforcements are often laid horizontally in the soil. In this paper, a new concept of grid reinforcement with ribbed inclusions is proposed. In the proposed of soil reinforcement, besides conventional grid reinforcements, some vertical and 3D reinforcing rib are also placed in the soil. Pullout tests are necessary in order to study the interaction behavior between soil and geosynthetics in the anchorage zone. Then, a series of pullout tests are conducted and the various parameters studied in this testing program include rib height and grid size of reinforcement. The result shows that the ultimate pullout force of plexiglass with rib is significantly larger than ordinary ones in the same normal stress. Ultimate pullout resistance increased as the increase of the height of tooth, and also is significantly impacted by grid size.

scholarly journals Pullout Behavior of Nail Reinforcement in Nailed Soil Slope

2021 ◽  
Vol 11 (14) ◽  
pp. 6419
Author(s):  
Mahmoud H. Mohamed ◽  
Mohd Ahmed ◽  
Javed Mallick
Keyword(s):  
Reinforced Soil ◽  
Control Technique ◽  
Laboratory Model ◽  
Soil Slope ◽  
Soil System ◽  
Pullout Resistance ◽  
Soil Nail ◽  
Pull Out ◽  
Devices And Instruments ◽  
Laboratory Models

The pullout resistance and displacement performance of reinforcement have significant effects on the safe and economic design of a reinforced-soil system. In this study, the nail pullout tests are conducted to assess the pullout behavior of soil nail reinforcement at different levels in the soil slope of granular materials. The similitude laboratory models of a reinforced soil system with a scale of 1:10 are prepared. The construction sequence used in a full scale slope was precisely followed in the laboratory model. The models consist of a Perspex wall box filled with sand and steel bars as a reinforcement. The models of sand beds are formed using an automatic sand raining system. Devices and instruments are installed to record the nails pullout resistance and displacement. The tests are carried out at variable footing pressures to get the pullout force of the nails based on a strain control technique. The finite element models of nailed soil slope are also analyzed to validate the laboratory model results. It infers from the numerical model results that the laboratory models underestimate the pullout behavior of nail reinforcement in nailed soil slope. The pull-out force in nail reinforcement increases as the displacement increases and then decreases slightly and becomes constant with an increase in displacement in the case of deeper placed nails, but it becomes constant immediately for upper nails.

Numerical simulation of pullout response for planar soil reinforcements

1999 ◽  
Vol 36 (3) ◽  
pp. 455-466 ◽  
Author(s):  
N Gurung ◽  
Y Iwao
Keyword(s):  
Numerical Simulation ◽  
Parametric Study ◽  
Interface Design ◽  
Interaction Mechanism ◽  
Relative Displacement ◽  
Reinforced Soil ◽  
Test Results ◽  
Relative Stiffness ◽  
Pullout Tests ◽  
Pullout Testing

This paper presents a series of numerical simulations for laboratory and field pullout tests. A nonlinear differential expression for interface pullout from simple equilibrium of forces and hyperbolic interface model for shear displacement variation along the length of the planar reinforcement is utilised. Finite difference numerical method and nondimensional expressions are adopted for wider application. The relative stiffness and relative displacement parameters are defined and related to the interface pullout interaction mechanism. A parametric study to develop computer-simulated interface design charts for a practical range of relative stiffness and relative bond resistance is theoretically illustrated. The pullout model is capable of simulating the responses of inextensible as well as highly extensible planar reinforcements. The model responses compared satisfactorily with the available theoretical and experimental pullout test results for steel straps, polymer strips, geotextiles, geomembranes, nylon geosynthetics, and geogrid reinforcements.Key words: geosynthetics, extensible reinforcement, numerical simulation, parametric study, pullout testing, reinforced soil.

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