scholarly journals Laboratory pullout resistance of a new screw soil nail in residual soil

2018 ◽  
Vol 55 (5) ◽  
pp. 609-619 ◽  
Author(s):  
H. Tokhi ◽  
G. Ren ◽  
J. Li
Keyword(s):  
Shear Strength ◽  
Practical Importance ◽  
Shear Behaviour ◽  
Residual Soil ◽  
Ultimate Shear Strength ◽  
Interface Shear ◽  
Soil Nail ◽  
Testing Procedures ◽  
Pullout Load ◽  
And Performance

The ultimate shear strength at the interface between the soil nail and surrounding soil is of practical importance in the design and performance of a soil nail system. The most commonly adopted method of measuring this interface shear strength is by soil nail pullout testing. This study introduces a novel soil nail system in the form of a screw nail and compares its performance with a conventional grouted soil nail. Both types of soil nails are tested in a controlled laboratory setting using residual soil in a large purpose-made pullout box. The development of the screw nail and the laboratory testing procedures are briefly discussed first, followed by presentation and discussion of the results of the interface shear behaviour measured from pullout tests. It is shown that the screw nail offers many advantages in terms of pullout load–displacement behaviour and the interface shear mechanism than that of the conventional grouted soil nail.

Influence of degree of saturation on soil nail pull-out resistance in compacted completely decomposed granite fill

2007 ◽  
Vol 44 (11) ◽  
pp. 1314-1328 ◽  
Author(s):  
Li-Jun Su ◽  
Terence C.F. Chan ◽  
Y.K. Shiu ◽  
Tony Cheung ◽  
Jian-Hua Yin
Keyword(s):  
Shear Strength ◽  
Degree Of Saturation ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Soil Nails ◽  
Soil Nail ◽  
Pull Out ◽  
Decomposed Granite ◽  
Soil Interface ◽  
Completely Decomposed Granite

The nail–soil interface shear strength is a key parameter in the design and stability assessment of soil nailing systems. A number of factors will influence the nail–soil interface shear strength. Among these factors, the degree of saturation (Sr) of the soil is an important one especially for permanent soil nail structures. To study the influence of Sr on soil nail pull-out shear resistance, a series of laboratory pull-out tests have been conducted on soil nails in compacted completely decomposed granite (CDG) fill prepared to different Sr. The tests were conducted using two specially designed pull-out boxes (with same specifications). In the near-saturated tests, a high Sr (about 98%) was achieved using two special features of the apparatus: a waterproof front cap and back-water pressure pipes at the bottom of the pull-out box. Test results showed that the nail–soil shearing plane migrated outwards into the soil when the Sr of the soil increased. Also, peak pull-out strengths of soil nails were strongly influenced by the Sr of the soil. Among the tested Sr, the highest values of peak pull-out shear strength were obtained at Sr values between 50% and 75%.

scholarly journals Experimental Study on the Shearing Behaviour on the Interface between Coarse Sand and Concrete under High Stress

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Junkun Tan ◽  
Jiaqi Guo ◽  
Shifan Qiao ◽  
Changrui Dong ◽  
Ziyong Cai ◽  
...  
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Normal Stress ◽  
High Stress ◽  
Shear Stiffness ◽  
Coarse Sand ◽  
Shear Behaviour ◽  
Hyperbolic Model ◽  
Displacement Curve ◽  
Ultimate Shear Strength

The shear behaviour on the interface between soil and structure is a research hot point. Based on the RMT-150B rock mechanics test system, a series of high-stress direct tests were performed on the coarse sand under the condition of different moisture contents and concrete substrates with different rough and hardness. The results showed that the shear stress-displacement curve and volumetric strain-displacement curve of the interface under high stress could be fitted by a hyperbolic model; the ultimate shear strength and initial shear stiffness of the interface both increased with the normal stress while the shear stiffness decreased with the shear displacement. The crushing rate of the coarse sand particles on the interface increased with the normal stress. After the range analysis for the influencing factors of the interface’s shearing behaviour, it was shown that for the ultimate shear strength, their sequence of influencing degree was normal stress, the roughness of interface, moisture content, and hardness of concrete base; for the initial shear strength, the sequence was normal stress, moisture content, interface roughness, and basal hardness. As for dry sand, the possibility of relative particle crushing was higher than that of sand with a moisture content of 8%, and a peak of crushing occurred when the moisture content was 16%.

scholarly journals Effect of Particle-Size Gradation on Coarse Sand-Geotextile Interface Response in Cyclic and Postcyclic Direct Shear Test

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jun Wang ◽  
Meng-Jie Ying ◽  
Fei-Yu Liu ◽  
Hong-Tao Fu ◽  
Jun-Feng Ni ◽  
...  
Keyword(s):  
Particle Size ◽  
Shear Stress ◽  
Shear Strength ◽  
Shear Behaviour ◽  
Direct Shear ◽  
Interface Shear ◽  
Cycle Number ◽  
Cyclic Shear ◽  
Stress Degradation ◽  
Particle Size Gradation

In order to investigate the influence of sand particle-size gradation on cyclic and postcyclic shear strength behaviour on sand-geotextile interfaces, a series of monotonic direct shear (MDS), cyclic direct shear (CDS), and postcyclic direct shear (PCDS) tests were performed using a large-scale direct shear apparatus. The influence of cyclic shear history on the direct shear behaviour of the interface was studied. The results indicated that cyclic shear stress degradation occurred at the sand-geotextile interface. Shear volumetric contraction induced by the cyclic direct shear increased with the increase in cycle number. The lowest final contraction value was observed in discontinuously graded sand. In the MDS tests, there were great differences in interface shear strength due to the different particle-size gradations, whereas the differences between shear volumes were negligible. In the PCDS tests, the shear stress-displacement curves exhibited postpeak stress hardening behaviour for different particle-size gradations, and differences in shear volumes were detected. The well-graded sand-geotextile interface had a higher value of shear stiffness and a higher damping ratio relative to the other interfaces. Postcyclic shear stress degradation was observed for the discontinuously graded sand-geotextile interface.

scholarly journals Effect of temperature on the shear strength of soils and the soil–structure interface

2016 ◽  
Vol 53 (7) ◽  
pp. 1186-1194 ◽  
Author(s):  
Neda Yavari ◽  
Anh Minh Tang ◽  
Jean-Michel Pereira ◽  
Ghazi Hassen
Keyword(s):  
Shear Strength ◽  
Soil Structure ◽  
Shear Behaviour ◽  
Effect Of Temperature ◽  
Temperature Control System ◽  
Direct Shear ◽  
Ultimate Shear Strength ◽  
Direct Shear Tests ◽  
Direct Shear Apparatus ◽  
Concrete Interface

In the present work, the shear behaviour of soils and the soil–concrete interface is investigated through direct shear tests at various temperatures. A conventional direct shear apparatus, equipped with a temperature control system, was used to test sand, clay, and the clay–concrete interface at various temperatures (5, 20, and 40 °C). These values correspond to the range of temperatures observed near thermoactive geostructures. Tests were performed at normal stress values ranging from 5 to 80 kPa. Results show that the effect of temperature on the shear strength parameters of soils and the soil–concrete interface is negligible. A softening behaviour was observed during shearing of the clay–concrete interface, which was not the case with clay specimens. The peak strength of the clay–concrete interface is smaller than the ultimate shear strength of clay.

scholarly journals Asperities effect on polypropylene & polyester geotextile-geomembrane interface shear behaviour

2019 ◽  
Vol 92 ◽  
pp. 13017
Author(s):  
Daniel Adeleke ◽  
Denis Kalumba ◽  
Johnny Oriokot
Keyword(s):  
Shear Strength ◽  
Engineering Application ◽  
Friction Angle ◽  
Strength Properties ◽  
Shear Behaviour ◽  
Percentage Increase ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Direct Shear Tests ◽  
Shear Characteristics

The summary of this paper is focused on the result of a study that used quantitative measures of surface texture as the basis for examining the effects of asperities on the shear characteristics of geotextile-geomembrane interfaces. About 30 large direct shear tests were conducted to evaluate the geotextile-geomembrane interface shear strength properties. The results indicated a non-linear failure envelopes and strain softening behaviour at a normal stress range of 50 – 400 kPa. For most interface tested, the polyester-geotextiles resulted in higher shear strength as compared with polypropylene-geotextiles. Also, the polyester and polypropylene geotextile interface with the high asperity geomembrane produces a similar percentage increase in friction angle at the residual state. For textured geomembranes interfaced with both geotextile, polyester geotextile exhibited relatively less time before failure. Also, asperity height has a more pronounced effect than asperity density on the residual interface shear strength. The outcome of this study would provide a recommendation and guide that can lead to an improved basis for geosynthetics selection in various engineering application.

Measurement of unsaturated soil – geomembrane interface shear-strength parameters

2007 ◽  
Vol 44 (1) ◽  
pp. 78-88 ◽  
Author(s):  
J S Sharma ◽  
I R Fleming ◽  
M B Jogi
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Pore Pressure ◽  
Unsaturated Soil ◽  
Pressure Transducer ◽  
Shear Behaviour ◽  
Direct Shear ◽  
Shear Tests ◽  
Interface Shear Strength ◽  
Interface Shear

Laboratory tests of soil–geomembrane interface shear strength are typically carried out with no provision for the measurement of pore pressures at the soil–geomembrane interface. This paper describes a series of soil–geomembrane interface shear tests carried out with continuous measurement of suction close to the interface during the shearing process. The tests were conducted using a modified direct shear box with a miniature pore-pressure transducer installed adjacent to the surface of the geomembrane. Results of the interface shear tests conducted using this method show that it is quite effective in evaluating shear behaviour at the interface between a geomembrane and an unsaturated soil at low matric suction values. The results suggest that soil suction contributes to shearing resistance at low normal stress values. At higher normal stress values, the interface shear behaviour appears to be governed only by the magnitude of total normal stress.Key words: geomembrane, interface shear strength, suction, direct shear test, pore-pressure transducer.

Field Determined Live Load Distribution Factors for Modular Press-Brake-Formed Tub Girders

2021 ◽  
pp. 036119812098375
Author(s):  
Karl E. Barth ◽  
Gregory K. Michaelson ◽  
Adam D. Roh ◽  
Robert M. Tennant
Keyword(s):  
West Virginia ◽  
Experimental Testing ◽  
Field Performance ◽  
Live Load ◽  
Steel Bridge ◽  
Testing Procedures ◽  
Bending Capacity ◽  
Short Span ◽  
And Performance ◽  
Live Load Distribution

This paper is focused on the field performance of a modular press-brake-formed tub girder (PBFTG) system in short span bridge applications. The scope of this project to conduct a live load field test on West Virginia State Project no. S322-37-3.29 00, a bridge utilizing PBFTGs located near Ranger, West Virginia. The modular PBFTG is a shallow trapezoidal box girder cold-formed using press-brakes from standard mill plate widths and thicknesses. A technical working group within the Steel Market Development Institute’s Short Span Steel Bridge Alliance, led by the current authors, was charged with the development of this concept. Research of PBFTGs has included analyzing the flexural bending capacity using experimental testing and analytical methods. This paper presents the experimental testing procedures and performance of a composite PBFTG bridge.

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