Laboratory Experimental Study on Pullout Behavior of Mortar Grouted GFRP Soil Nails

2010 ◽  
Vol 168-170 ◽  
pp. 1069-1072
Author(s):  
Zhong Yu Liu ◽  
Chong Wu Ma ◽  
Zhuo Zhao
Keyword(s):  
Large Scale ◽  
Axial Strain ◽  
Hyperbolic Function ◽  
Overburden Pressure ◽  
Soil Nails ◽  
Pullout Resistance ◽  
Pull Out ◽  
Glass Fiber Reinforced ◽  
Dilatancy Effect ◽  
Pullout Load

A large-scale laboratory apparatus has been built to study the pullout behavior of mortar grouted glass fiber reinforced polymer (GFRP) soil nails. The axial strain along the nail length and the displacement of the nail head under different pullout loads are measured, and the ultimate pullout load under the overburden pressure is obtained. Then, the influence of the overburden pressure on the ultimate value of the interface friction force is investigated. The experimental results illustrate that the pullout behavior of mortar grouted GFRP soil nails is similar to that of mortar grouted steel soil nails, and the relation between the displacement and the pullout load can be described with the hyperbolic function. In addition, the dilatancy effect of the soil near the nail during pull out should be taken into account in estimating the pullout resistance of soil nails in dense fills.

Experimental investigation on the creep behavior of an unsaturated clay

2014 ◽  
Vol 51 (6) ◽  
pp. 621-628 ◽  
Author(s):  
X.L. Lai ◽  
S.M. Wang ◽  
W.M. Ye ◽  
Y.J. Cui
Keyword(s):  
Strain Rate ◽  
Large Scale ◽  
Axial Strain ◽  
Creep Model ◽  
Three Gorges Reservoir Area ◽  
Hyperbolic Function ◽  
Creep Tests ◽  
Suction Control ◽  
Strain And Strain Rate ◽  
Influence Of Water

To better understand the long-term deformation of landslides with consideration of the influence of water content variation, a series of triaxial creep tests with suction control was conducted on clay specimens taken from one large-scale landslide in the Three Gorges Reservoir area in China. Results indicate that, in the double-logarithmic coordinates, the axial strain increases linearly and the axial strain-rate decreases linearly with the elapsed time; the axial strain and strain rate increase with increasing deviator stress levels and decreasing matric suction. For theoretical analysis, based on the simulation of the test results by an empirical creep model developed for saturated soils, a linear relationship was established between suction and one of the parameters of the model. Then, a revised model with consideration of suction effects was developed. In the revised model, a power function was adopted for the description of the strain–time relationship and a hyperbolic function was employed for the stress–strain relationship. Verification indicated that the calculated results were in good agreement with the experimental ones.

Experimental investigation of compaction-grouted soil nails

2017 ◽  
Vol 54 (12) ◽  
pp. 1728-1738 ◽  
Author(s):  
Qiong Wang ◽  
Xinyu Ye ◽  
Shanyong Wang ◽  
Scott William Sloan ◽  
Daichao Sheng
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Interface Shear ◽  
Soil Nails ◽  
Soil Nail ◽  
Pull Out ◽  
Grouting Pressure ◽  
Large Scale Model ◽  
Ultimate Failure ◽  
Surrounding Soil

An innovative compaction-grouted soil nail was designed by injecting grout into a special latex balloon (grouting bag) to avoid bleeding and penetration of grout into the surrounding soil. A series of large-scale model tests was performed to study the surrounding soil responses due to grouting and the subsequent pull-out resistance of the soil nail. The experimental results show that grouting pressure plays an important role in the enhancement of the density and (or) strength of the surrounding soil. In addition, during the pull-out process, the compaction-grouted soil nail exhibits a strain-hardening behaviour without a yield point. This is a significant advantage of this new soil nail, indicating that it can enable soil masses to remain stable against a relatively large deformation before ultimate failure. The main factors behind the improvement of the pull-out resistance of the new soil nail are, first, the compaction–densification of the soil near the grouting bag due to grouting, resulting in the enhancement of the shear strength of the soil, and, second, the enlargement of the grouting bag, causing the increase of the interface shear and end resistance to the pull-out of the soil nail.

Pullout Resistance Factors for Inextensible Mechanically Stabilized Earth Reinforcements in Sandy Backfill

2013 ◽  
Vol 2363 (1) ◽  
pp. 21-29 ◽  
Author(s):  
William D. Lawson ◽  
Priyantha W. Jayawickrama ◽  
Timothy A. Wood ◽  
James G. Surles
Keyword(s):  
Large Scale ◽  
Steel Strip ◽  
Mechanically Stabilized Earth ◽  
Overburden Pressure ◽  
Welded Steel ◽  
Pullout Resistance ◽  
Resistance Factors ◽  
Granular Fill ◽  
Mechanically Stabilized ◽  
Grid Reinforcement

This paper presents results from a laboratory program of 402 pullout tests of inextensible reinforcements used for walls of mechanically stabilized earth (MSE). Results focus on the evaluation of pullout resistance factors for ribbed-steel strip and welded-steel grid reinforcements embedded in sandy backfill that marginally met AASHTO requirements for select granular fill. This project used Texas Tech University's large-scale MSE test box with dimensions of 12 3 12 3 4 ft and an applied overburden capacity of 40 ft of backfill. This test box facilitated pullout testing at a scale not unlike typical field construction. The research design evaluated pullout resistance factors for both ribbed-strip and welded-grid reinforcements for a variety of independent variables, including overburden pressure, reinforcement length, level of compaction, grid wire size, and grid geometry, such as transverse and longitudinal wire spacing. Appropriate statistical analyses were used to interpret the data within the context of published AASHTO design guidance for inextensible MSE reinforcements. The results show that pullout behaviors of both ribbed strips and welded grids in properly compacted sandy backfill are conservative compared with the default pullout resistance factors provided by AASHTO. The data also suggest that the current AASHTO equations for pullout resistance factors for grid reinforcement do not accurately capture the influence of transverse and longitudinal bar spacings.

Pullout resistance of single and double nails in a model sandbox

2003 ◽  
Vol 40 (5) ◽  
pp. 1039-1047 ◽  
Author(s):  
Yung-Shan Hong ◽  
Cho-Sen Wu ◽  
Shang-Heng Yang
Keyword(s):  
Surface Roughness ◽  
Unit Length ◽  
Test Surface ◽  
Roughness Factor ◽  
Test Results ◽  
Overburden Pressure ◽  
Soil Nails ◽  
Pullout Resistance ◽  
Soil Nail ◽  
Group Efficiency

Pullout tests on single and double soil nails were conducted in a model sandbox. The test parameters included variations in the surface roughness, the ratio of nail length to nail diameter, the overburden pressure, and the distance between two nails. The characteristic of a single asperity, the asperity number per unit length, and the ratio of the thread depth to the soil particle size were used to define the surface roughness factor. The test results showed that the apparent friction coefficients at the soil–nail interface were dependent upon the surface roughness of the nail. Group efficiency was used to evaluate the effectiveness of a nail when installed within a group. The test results showed that the group efficiency of a double-nail system was dependent upon the surface roughness factor and has a linear relationship with the nail distance until 100% efficiency is reached. The minimum required distance for 100% efficiency also varied with the surface roughness factor.Key words: apparent friction coefficient, group efficiency, pullout test, surface roughness factor.

Pull-Out Performance of T-Stub End Plate Connected To Concrete Filled Thin-Walled Steel Tube (CFTST) using Lindapter Hollo-Bolts

2018 ◽  
Vol 15 (1) ◽  
pp. 59
Author(s):  
NAZRUL AZMI AHMAD ZAMRI ◽  
CLOTILDA PETRUS ◽  
AZMI IBRAHIM ◽  
HANIZAH AB HAMID
Keyword(s):  
Limit Load ◽  
Steel Tube ◽  
Limit States ◽  
End Plate ◽  
Pull Out ◽  
Pullout Load ◽  
Thin Walled ◽  
Stub End ◽  
Concrete Filled Steel Tubes ◽  
Ultimate Limit

The application of concrete filled steel tubes (CFSTs) as composite members has widely been used around the world and is becoming popular day by day for structural application especially in earthquake regions. This paper indicates that an experimental study was conducted to comprehend the behaviour of T-stub end plates connected to concrete filled thin-walled steel tube (CFTST) with different types of bolts and are subjected to pullout load. The bolts used are normal type bolt M20 grade 8.8 and Lindapter Hollo-bolt HB16 and HB20. A series of 10 mm thick T-stub end plates were fastened to 2 mm CFTST of 200 mm x 200 mm in cross-section. All of the specimens were subjected to monotonic pull-out load until failure. Based on test results, the Lidapter Hollo-bolts showed better performance compare to normal bolts. The highest ultimate limit load for T-stub end plate fasten with Lindapter Hollo-bolt is four times higher than with normal bolt although all end plates show similar behaviour and failure mode patterns. It can be concluded that T-stub end plate with Lindapter Hollo-bolt shows a better performance in the service limit and ultimate limit states according to the regulations in the design codes.

scholarly journals Optimizing Manufacturing and Osseointegration of Ti6Al4V Implants through Precision Casting and Calcium and Phosphorus Ion Implantation? In Vivo Results of a Large-Scale Animal Trial

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1670 ◽  
Author(s):  
Wölfle-Roos JV ◽  
Katmer Amet B ◽  
Fiedler J ◽  
Michels H ◽  
Kappelt G ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Large Scale ◽  
In Vivo Studies ◽  
Control Group ◽  
Implant Surface ◽  
Precision Casting ◽  
Pull Out ◽  
Significant Difference ◽  
Calcium And Phosphorus

Background: Uncemented implants are still associated with several major challenges, especially with regard to their manufacturing and their osseointegration. In this study, a novel manufacturing technique—an optimized form of precision casting—and a novel surface modification to promote osseointegration—calcium and phosphorus ion implantation into the implant surface—were tested in vivo. Methods: Cylindrical Ti6Al4V implants were inserted bilaterally into the tibia of 110 rats. We compared two generations of cast Ti6Al4V implants (CAST 1st GEN, n = 22, and CAST 2nd GEN, n = 22) as well as cast 2nd GEN Ti6Al4V implants with calcium (CAST + CA, n = 22) and phosphorus (CAST + P, n = 22) ion implantation to standard machined Ti6Al4V implants (control, n = 22). After 4 and 12 weeks, maximal pull-out force and bone-to-implant contact rate (BIC) were measured and compared between all five groups. Results: There was no significant difference between all five groups after 4 weeks or 12 weeks with regard to pull-out force (p > 0.05, Kruskal Wallis test). Histomorphometric analysis showed no significant difference of BIC after 4 weeks (p > 0.05, Kruskal–Wallis test), whereas there was a trend towards a higher BIC in the CAST + P group (54.8% ± 15.2%), especially compared to the control group (38.6% ± 12.8%) after 12 weeks (p = 0.053, Kruskal–Wallis test). Conclusion: In this study, we found no indication of inferiority of Ti6Al4V implants cast with the optimized centrifugal precision casting technique of the second generation compared to standard Ti6Al4V implants. As the employed manufacturing process holds considerable economic potential, mainly due to a significantly decreased material demand per implant by casting near net-shape instead of milling away most of the starting ingot, its application in manufacturing uncemented implants seems promising. However, no significant advantages of calcium or phosphorus ion implantation could be observed in this study. Due to the promising results of ion implantation in previous in vitro and in vivo studies, further in vivo studies with different ion implantation conditions should be considered.

Experimental Study on Bond Behavior of GFRP-to-Cement Mortar

2011 ◽  
Vol 94-96 ◽  
pp. 543-546
Author(s):  
Ning Zhang ◽  
Ai Zhong Lu ◽  
Yun Qian Xu ◽  
Pan Cui
Keyword(s):  
Aluminium Alloy ◽  
Cement Mortar ◽  
Bond Stress ◽  
Reinforcing Bars ◽  
Bond Performance ◽  
Gfrp Bars ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Average Bond

Direct pull-out tests were performed to evaluate the bond performance of glass fiber-reinforced polymer (GFRP) reinforcing bars in cement mortar. Specimens with different bar diameters and different grouted lengths (i.e., 5d, 10d and 15d, d is the diameter of bars) are prepared for the pull-out tests. For comparison, specimens with plain aluminium alloy bars (AAB) were tested as well. The result shows that the average bond stress between plain aluminium alloy bars and cement is much smaller than that between the deformed GFRP bars and cement; thin GFRP bars tended to have larger average bond stress; the shorter the grouted length, the smaller the maximum average bond stress. Only part of grouted length undertakes the bond stress and the length depends on the shear modulus of GFRP and the surrounding material.

Molecular Dynamics Simulation of a Pullout Test on a Carbon Nanotube in a Polymer Matrix

2014 ◽  
Vol 1700 ◽  
pp. 61-66
Author(s):  
Guttormur Arnar Ingvason ◽  
Virginie Rollin
Keyword(s):  
Molecular Dynamics ◽  
Polymer Matrix ◽  
Large Scale ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Atomistic Simulations ◽  
Polymer Molecules ◽  
Molecular Potential ◽  
Pull Out ◽  
Walled Carbon Nanotubes

ABSTRACTAdding single walled carbon nanotubes (SWCNT) to a polymer matrix can improve the delamination properties of the composite. Due to the complexity of polymer molecules and the curing process, few 3-D Molecular Dynamics (MD) simulations of a polymer-SWCNT composite have been run. Our model runs on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), with a COMPASS (Condensed phase Optimized Molecular Potential for Atomistic Simulations Studies) potential. This potential includes non-bonded interactions, as well as bonds, angles and dihedrals to create a MD model for a SWCNT and EPON 862/DETDA (Diethyltoluenediamine) polymer matrix. Two simulations were performed in order to test the implementation of the COMPASS parameters. The first one was a tensile test on a SWCNT, leading to a Young’s modulus of 1.4 TPa at 300K. The second one was a pull-out test of a SWCNT from an originally uncured EPON 862/DETDA matrix.

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