The Influence of Asperities and Surface Roughness on Geomembrane/Geotextile Interface Friction Angle

Author(s):  
Daniel Adeleke ◽  
Denis Kalumba ◽  
Lita Nolutshungu ◽  
Johnny Oriokot ◽  
Alejandro Martinez
2014 ◽  
Vol 984-985 ◽  
pp. 707-710 ◽  
Author(s):  
V. Jeyanthi Vineetha ◽  
K. Ganesan

In soil-structure interaction problems, the frictional resistance between soil and structure is very important to have an appropriate system analysis. It includes retaining walls, deep foundations, soil samplers, soil and geo-membrane interface strength, and the stability of mechanically stabilized structures. Fibre Reinforced Polymer (FRP) is a synthetic material and can be effectively used for strengthening of soils and substructures, and hence it is important to study the interface friction between these FRP sheets with soil. This study will provide some insight knowledge regarding the interfacial friction between gravel soil with glass fibre reinforced polymer. It will be beneficial to the researchers and practicing engineers working in soil-structure interaction problems. The parameters varied in this investigation are surface roughness, orientation of fibre and normal stress (0.05 N/mm2 to 0.20 N/mm2). Experimental results show that surface roughness of specimens and fibre orientation was significantly changes the interface friction angle. Shear strength at the interface increases with increase in normal stress and surface roughness. Key words: Direct shear test, gravel soil, internal friction angle, interface friction angle, GFRP.


2020 ◽  
Vol 857 ◽  
pp. 203-211
Author(s):  
Majid Hamed ◽  
Waleed S. Sidik ◽  
Hanifi Canakci ◽  
Fatih Celik ◽  
Romel N. Georgees

This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.


2010 ◽  
Vol 47 (6) ◽  
pp. 635-647 ◽  
Author(s):  
Cristina de Hollanda Cavalcanti Tsuha ◽  
Nelson Aoki

The empirical torque correlation factor (KT), which relates the uplift capacity to the installation torque of helical piles, is routinely used as an on-site instrument for quality control with this type of foundation. This paper presents a theoretical relationship between uplift capacity and installation torque of deep helical piles in sand. An experimental program, including centrifuge and direct shear interface tests, was carried out to validate this expression. The experimental results were compared with the values predicted by the suggested approach and showed good agreement. As the developed model depends on the residual interface friction angle (δr) between the helix surface and the surrounding sand, results of δr, extracted from different sand samples, are presented for use in this suggested relationship on site. Also, the values of KT found in this work were compared with those of field and laboratory tests on helical piles in sand reported in the literature. From this analysis, it was found that the measured values of KT decrease with an increase in pile dimensions and, in most of cases, with an increase in sand friction angle. These results were explained by the presented model.


2018 ◽  
Vol 55 (5) ◽  
pp. 666-679 ◽  
Author(s):  
Z. Hu ◽  
Z.X. Yang ◽  
S.P. Wilkinson

Using an assumed vertical retaining wall with a drainage system along the soil–structure interface, this paper analyses the effect of anisotropic seepage flow on the development of passive earth pressure. Extremely unfavourable seepage flow inside the backfill, perhaps due to heavy rainfall, will dramatically increase active earth pressure while reducing passive earth pressure, thus increasing the probability of instability of the retaining structure. A trial and error analysis based on limit equilibrium is applied to identify the optimum failure surface. The flow field is computed using Fourier series expansion, and the effective reaction force along the curved failure surface is obtained by solving a modified Kötter equation considering the effect of seepage flow. This approach correlates well with other existing results. For small values of both the internal friction angle and interface friction angle, the failure surface can be appropriately simplified with a planar approximation. A parametric study indicates that the degree of anisotropic seepage flow affects the resulting passive earth pressure. In addition, incremental increases in the effective friction angle and interface friction angle both lead to an increase in passive earth pressure.


Author(s):  
Zdzisław Kaliniewicz ◽  
Zbigniew Żuk ◽  
Zbigniew Krzysiak

The aim of this study was to determine the correlation between the external friction angle of cereal kernels and the roughness of a steel friction plate. The experiment was performed on the kernels of five principal cereals: wheat, rye, barley, oats and triticale. Flat seed units composed of three spaced kernels joined by adhesive tape were analyzed in each experimental variant. The external friction angle of flat seed units was determined on 9 steel friction plates with different roughness. Measurements were performed in 3 replications with a photosensor device which registered the external friction angle of cereal kernels. On friction plates with surface roughness Ra=0.36 to Ra=6.72, the average values of the angle of external friction ranged from 17.56° in rye kernels to 34.01° in oat kernels. The greatest similarities in the angle of external friction were observed between wheat and triticale kernels, whereas the greatest differences were noted between barley and oat kernels and between barley and triticale kernels. Friction plates made of ST3S steel should be characterized by the lowest surface roughness to minimize energy consumption during grain processing. The optimal surface roughness of steel friction plates was determined at Ra=0.9.


Author(s):  
Zdzisław Kaliniewicz ◽  
Zbigniew Żuk ◽  
Zbigniew Krzysiak

The aim of this study was to determine the correlation between the external friction angle of cereal kernels and the roughness of a steel friction plate. The experiment was performed on the kernels of five principal cereals: wheat, rye, barley, oats and triticale. Flat seed units composed of three spaced kernels joined by adhesive tape were analyzed in each experimental variant. The external friction angle of flat seed units was determined on 9 steel friction plates with different roughness. Measurements were performed in 3 replications with a photosensor device which registered the external friction angle of cereal kernels. On friction plates with surface roughness Ra=0.36 to Ra=6.72, the average values of the angle of external friction ranged from 17.56° in rye kernels to 34.01° in oat kernels. The greatest similarities in the angle of external friction were observed between wheat and triticale kernels, whereas the greatest differences were noted between barley and oat kernels and between barley and triticale kernels. Friction plates made of ST3S steel should be characterized by the lowest surface roughness to minimize energy consumption during grain processing. The optimal surface roughness of steel friction plates was determined at Ra=0.9.


2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Liu Fei ◽  
Zhongxi Jiang

The antiseepage membrane applied to the slope of solid waste landfill often shows tensile failure in projects, which results in ineffective antiseepage system and serious environmental pollution. In order to ensure the practical performance of the antiseepage membrane, the tensile force of it was studied, and the settlement mechanical model of the interaction between landfill body, antiseepage membrane, and cushion was established after comprehensively considering the effects of dead weight, lateral pressure, settlement, and foundation boundary. The analytical solutions of the tensile force and displacement of the antiseepage membrane was calculated through differential equation of equilibrium. With general slag and ardealite slag as the research objects, the major parameters affecting the internal tensile force of the antiseepage membrane were analyzed and studied by the combination of numerical and theoretical methods. The results show that the internal tensile force of the antiseepage membrane is greatly affected by the parameters such as the membrane-slag interface friction angle, the membrane-cushion interface friction angle, the buried depth, and the single step height. The theoretical slope normal stress and membrane pull-up force are basically consistent with the numerical calculation results, which indicates that the theory is universally applicable to tackle the tensile failure of the antiseepage membrane in the solid waste landfill system.


Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5866
Author(s):  
Wang-chun Zhang ◽  
Hao Jing ◽  
Hai-lei Kou

The interface behavior between a caisson and the surrounding soil plays an important role in the installation of suction caissons as foundations for offshore wind turbines. A series of shear tests were carried out using a modified direct shear apparatus to study the interface shear behavior between sand and concrete. Sand samples with three particle size ranges (0.63–1.25 mm, 1.25–2.5 mm, 2.5–5.0 mm) and concrete plates with different relative roughness were used to explore the influence of the relative roughness parameter (Rn) and mean particle size (D50) on shear behavior. The responses from the pure sand shear test are also discussed for comparison. Test results show that the higher the relative roughness (Rn), the greater the maximum shear stress (τmax) appeared. The interface shear stress was weaker than that of the pure sand test. Furthermore, the interface friction angle (φ) of sand–concrete was closely related to the relative roughness of the concrete surface. Under the same conditions, the interface friction angle (φ) increased with relative roughness due to the effect of sand particles breakage and redistribution. By contrast, the effect of the mean particle size (D50) on the interface friction angle (φ) was less significant. However, for the pure sand shear test, the friction angle (φ′) obtained from the traditional shear test apparently increased with D50, indicating that the friction angle was more affected by D50 in the pure sand test than in the interface shear test.


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