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.

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.

Statics and Dynamics of Elastic Shells with Cutouts —A Review

1974 ◽  
Vol 18 (02) ◽  
pp. 113-126
Author(s):  
J. Pattabiraman ◽  
V. Ramamurti ◽  
D. V. Reddy
Keyword(s):  
Dynamic Loading ◽  
Nuclear Reactors ◽  
High Reliability ◽  
Pressure Vessels ◽  
Experimental Investigations ◽  
Concentrated Loads ◽  
Stress Concentrations ◽  
Elastic Shells ◽  
Statics And Dynamics ◽  
Static And Dynamic Loading

The purpose of this survey is to give a review of the methods and results of analytical and experimental investigations for stress concentrations in thin elastic shells subjected to static and dynamic loading. The increasing use of higher-strength materials in the design of pressure vessels, aircraft, ships, and nuclear reactors with high reliability necessitates more precise analyses in the regions of cutouts and concentrated loads.

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.

Experimental Study on Mechanism of Crack Coalescence between Two Pre-Existing Flaws under Dynamic Loading

2006 ◽  
Vol 324-325 ◽  
pp. 117-120 ◽  
Author(s):  
Ping Zhang ◽  
Ning Li ◽  
Ruo Lan He
Keyword(s):  
Crack Propagation ◽  
Dynamic Loading ◽  
Static Loading ◽  
Crack Coalescence ◽  
Engineering Practice ◽  
Strength Increase ◽  
Strain Rates ◽  
Inertia Effect ◽  
Coalescence Pattern ◽  
Static And Dynamic Loading

More and more engineering practice indicates rock mass is prone to lose its stability through crack coalescence under dynamic loading, such as blasting and earthquake. However, the crack coalescence pattern of rock specimens containing two or more flaws has not been studied comprehensively under dynamic loading. In this paper, the mechanism of the crack coalescence and peak strength of sandstone-like materials containing two parallel flaws are studied under uniaxial static and dynamic loading with strain rates 1.7×10-5 s-1 and 1.7×10-1 s-1. Through the comparisons of the propagation length, coalescence pattern of the cracks and strength increase of the pre-cracked specimens under static and dynamic loading, the dynamic response of the crack coalescence is found different from static loading under different geometric setting of the flaws. The inertia effect of the crack propagation is revealed under dynamic loading, that is to say, the growth of the secondary cracks tends to the original propagation direction, and the direct and immediate coalescence is taken place easily between two pre-existing flaws, which is different from the kinking coalescence under static loading. So, the inertia effect of the crack propagation is regarded as the main cause of the strength increase of the brittle material under dynamic loading for medium strain rates. In virtue of the explanation, another cause of the mode II shear fracture occurred under earthquake is opened out.

Response of Silica-Nylon6 Nanocomposites to Static and Dynamic Loading

2012 ◽  
Vol 706-709 ◽  
pp. 786-792
Author(s):  
V.P.W. Shim ◽  
Y.B. Guo ◽  
H. W. Gu ◽  
Xu Li
Keyword(s):  
Dynamic Loading ◽  
Static Loading ◽  
Silica Nanoparticle ◽  
Particle Dispersion ◽  
Type B ◽  
Dynamic Tension ◽  
Range Interaction ◽  
Covalent Bonds ◽  
Long Range Interaction ◽  
Static And Dynamic Loading

Silica-nylon6 composites were fabricated using two types of silica nanoparticle fillers with different surface modifications. Type A particles (treated with hexamethyldisilazane) were uniformly dispersed but only displayed weak long-range interaction with the nylon6 matrix; in contrast, type B particles (modified with 3-aminopropyltriethoxysilane) formed covalent bonds with the nylon6 chains but their dispersion is not good. The silica-nylon6 composites synthesized were subjected to quasi-static and dynamic tension to study the effects of strain rate and nanoparticle fraction. Results show that compared to quasi-static loading, both pure nylon6 and the composites exhibit a higher strength but lower ductility under dynamic loading. With respect to the influence of the nanoparticles, both particle types cause an increase in the elastic modulus and tensile strength. The effect of the two particles on ductility differs – particle A reduces ductility, while particle B decreases ductility under quasi-static loading but enhances it noticeably for dynamic loading. Particle B enhances the mechanical properties more significantly, especially in terms of ductility. These results suggest that ensuring strong particle-matrix bonding is more crucial than good particle dispersion.

scholarly journals COMPARISON OF NECK MUSCLE ELECTROMYOGRAPHY ACTIVITY IN RESPONSE TO EXTERNAL FORCE BETWEEN STATIC AND DYNAMIC LOADING

2019 ◽  
Vol 19 (04) ◽  
pp. 1850034
Author(s):  
D. W. KAK ◽  
A. R. ANITA ◽  
N. M. NIZLAN ◽  
I. NORMALA ◽  
N. A. ABDUL JALIL ◽  
...  
Keyword(s):  
Dynamic Loading ◽  
Static Loading ◽  
Muscle Activation ◽  
Motor Vehicle ◽  
Neck Muscles ◽  
Motor Vehicle Crash ◽  
Neck Muscle ◽  
Activation Level ◽  
Static And Dynamic Loading ◽  
Head Neck

Understanding the behavior of neck muscles is essential to accurately simulate the human head-neck segment movement especially for low-speed motor vehicle crash situation. Some head-neck mathematical models were designed using neck muscle activation behavior in isometric contraction (static loading) as the properties of neck muscle activation. However, neck muscle activation pattern and strength capability may vary between static and dynamic loading. This study aimed to determine the differences between neck muscle activation level under static and dynamic loading. A neck strength test involving 22 human volunteers was conducted with two different tasks in extension and flexion direction with three different loads. The neck muscle activation level is determined through measuring the electromyography (EMG) responses of selected flexor and extensor muscles using surface bilateral electrode and recorded. The findings showed that neck muscle activation level was significantly greater in dynamic loading than static loading ([Formula: see text]). These implied that more efforts from neck muscles were required to resist against dynamic loading than static loading. Nonetheless, the differences in EMG activities between these two loading conditions progressively decreased when more loads were applied. This study has established an empirical model to describe the relationship between neck muscle activation level and force output for both loading condition in flexion and extension.

STUDY OF CHARACTERISTICS OF MECHANICAL PROPERTIES OF GAS-DISTRIBUTING STATION PIPES METAL AFTER LONG-TERM OPERATION

2015 ◽  
pp. 86-91
Author(s):  
I. Yu. Bykov ◽  
I. N. Birillo ◽  
P. A. Kuzbozhev
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Internal Pressure ◽  
Dynamic Loading ◽  
Static Loading ◽  
High Speed ◽  
Term Operation ◽  
Loading Effects ◽  
Static And Dynamic Loading

During operation the technological pipelines of gas-distributing station are affected by mechanical static loading resulted from internal pressure of gas in the high pressure pipelines and a dynamic loading from a high-speed stream of gas in low pressure pipelines. A comparison is made of characteristics of mechanical properties of gas-distributing station pipes metal after a long-term operation for the conditions of static and dynamic loading effects.

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 Mechanical Behavior of Triaxial Geogrid Used for Reinforced Soil Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jun Zhang ◽  
Wen-Zhao Cao ◽  
Yan-Jun Zhou
Keyword(s):  
Tensile Strength ◽  
Mechanical Behavior ◽  
Laboratory Tests ◽  
Reinforced Soil ◽  
Geological Hazards ◽  
Grid Structure ◽  
Interface Friction ◽  
Pullout Tests ◽  
Soil Structures ◽  
Improved Performance

Geosynthetics-reinforced soil (GRS) structures have been widely used for the prevention of geological hazards. As a recently introduced product, the triaxial geogrid has been confirmed to provide improved performance due to the more stable grid structure. This paper presents an evaluation of the mechanical behavior based on a series of laboratory tests. The unconfined tensile strength of biaxial geogrid and triaxial geogrid in different loading directions relative to the orientation of ribs was investigated. Then, more than 8 pullout tests were conducted on the triaxial geogrid specimens embedded in the compacted sand. The internal displacements along the geogrid length were monitored. The results show that the triaxial geogrid has been shown to provide nearly uniform tensile strength in all loading directions as compared with the biaxial geogrid. The triaxial geogrid deformation is mainly characterized by rib bending and nodal distortion along with an inward squeeze perpendicular to the pullout direction. The interface friction between the soil and the geogrid develops in a progressive mode, and an elasto-plastic-softening characteristic is detected experimentally due to the extensibility of geogrid.

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