Deformation model of sand around short piles under pullout test

Faizi, Koohyar; Armaghani, Danial Jahed; Sohaei, Houman; Rashid, Ahmad Safuan A.; Назир, Рамли

doi:10.1016/j.measurement.2014.11.028

Cited by 34 publications

(5 citation statements)

References 33 publications

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“…Selvadurai (1989) performed experiments on a pipe with diameter of 150 mm and suggested a method to enhance uplift resistance by placing geogrid on top of the pipe. Faizi et al (2015) studied the effect of increasing the geogrid compound on the uplift resistance of buried pipelines in loose sand. A pilot program consisting of 11 small-scale uplift experiments was carried out along with numerical modeling using PLAXIS 3D TUNNEL.…”

Section: Review Of Previous Workmentioning

confidence: 99%

Modeling of Uplift Resistance of Buried Pipeline by Geogrid and Grid-Anchor System

Maljaei

Katebi

Mahdi

2022

J. Pipeline Syst. Eng. Pract.

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This paper presents an experimental and numerical analysis of the uplift resistance of pipelines buried in reinforced soil. The behavior of the system is studied using a set of laboratory experiments. The pull-out forces of some reinforcing pipelines are the most important factors affecting the uplift resistance. Buried elements like pipelines that have high pressure fluids or are under the high temperature, need to be reinforced in order to increase their pull-out resistance. One of the efficient methods to reinforcement, is increasing the involvement between pipe and soil, by using of geogrids and anchors. Grid-anchor is a recent method for increasing the pull-out resistance of soil, and is the method used in this study. The Digital Image Correlation or Particle Image Velocimetry (DIC/PIV) method is used for measuring the displacement in the field of experimental mechanism. We also examined the influence of parameters affecting on the soil. An experimental study was performed to investigate the uplift resistance of the pipelines buried in sand reinforced with this system. The experimental results demonstrate that, for the pipes with a diameter of 50 mm, the grid-anchor system of reinforcement can increase the uplift capacity 2.4 times compared with the conventional geogrid and 4 times compared with non-reinforced sand. In the numerical modeling likewise, 23 experiments were back analyzed using the software FLAC-3D. It became known that experimental tests stand good comparison with the numerical results.

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Section: Review Of Previous Workmentioning

confidence: 99%

Modeling of Uplift Resistance of Buried Pipeline by Geogrid and Grid-Anchor System

Maljaei

Katebi

Mahdi

2022

J. Pipeline Syst. Eng. Pract.

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“…In geotechnics, the close-range photogrammetry is used among others to observe the deformation patterns due to uplift force during the investigation of the uplift resistance of short piles in loose sand [27]. Centrifuge tests performed to investigate the effects of tunnelling in sands on piled buildings are described in ref.…”

Section: Photogrammetrymentioning

confidence: 99%

Assessment of surface parameters of VDW foundation piles using geodetic measurement techniques

Muszyński

Wyjadłowski

2020

Open Geosciences

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This article presents in situ research on the side surface of Vor der Wand (VDW) foundation piles using 3D laser scanning and close-range photogrammetry to assess the morphology of pile concrete surface. Contemporary analytical methods for estimation of the bearing capacity of the foundation pile surface require determination of the parameters of the concrete roughness and the model of the surface being formed, which corresponds to the pile technology used. Acquiring these data is difficult due to the formation of piles in the ground and their subsequent work as a structure buried in the ground. The VDW pile technology is one of the widespread technologies of foundation pile used in practice. These piles exhibit a specific configuration of the lateral surface, which is related to the simultaneous use of auger drilling and casing that rotates in opposite directions. Two geodetic techniques most often used to measure the geometry of buildings are terrestrial laser scanning and close-range photogrammetry. To empirically verify the suitability of these two techniques for describing the VDW pile surface parameters, a two-stage field study was performed. In the first stage, the measurements of concrete test surfaces were conducted. This surface was formed in a smooth formwork and its roughness parameters (in accordance with ISO 25178-2: 2012) were calculated and compared with the reference surface. In the second stage, measurements of the secant VDW sheet pile wall protecting the deep excavation were carried out. The roughness parameters of the pile surface were calculated for the selected areas in diverse geotechnical conditions. The original procedure for processing data (obtained using the above techniques) for assessment of roughness parameters of unique concrete surfaces was presented. The conducted research demonstrates that a pulse scanner has very limited usefulness for determination of roughness parameters for very smooth concrete surface; however, the photogrammetry techniques give acceptable results. In regard to the VDW pile surface, the results obtained from both measurement techniques give satisfactory consistency of the roughness parameters. The relative errors of calculated roughness parameters do not exceed 29% (average 12%). The proposed procedure may improve the accuracy of the assumed friction factor between pile surface and soil for assessment of the pile shaft bearing capacity for various pile technologies and soil conditions.

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“…Brazilian tests were used to overcome the shortcomings of direct tensile strength tests, including sample processing difficulties and eccentricity existing during the loading process [37], [41], [42]. Because ITS tests can be conducted using conventional compressive test equipment, and 3 specimens per mixture were tested for each curing time.…”

Section: Its Testsmentioning

confidence: 99%

Influence of Polypropylene Fiber Reinforcement on Tensile Behavior and Failure Mode of Tailings Cemented Paste Backfill

et al. 2019

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Tailings were used to prepare cemented paste backfill (CPB) reinforced with polypropylene (PP) fiber, and fiber content and fiber length were 0-20 % and 3-12 mm, respectively. The Brazilian indirect tensile strength tests, macrostructural and microstructural (SEM) failure mode analyses and nuclear magnetic resonance (NMR) tests were performed. The results demonstrate that PP fiber with high tensile strength can substantially enhance the tensile strength and ductility of CPB specimens. The fiber-reinforced CPB exhibits superior performance during the pre-peak and post-peak stages and can retain its residual strength after being broken. The fiber-reinforced CPB provided a higher secant Young's modulus and strain at peak stress than that of the unreinforced CPB. From the failure mode analysis, fiber was used to bridge the CPB microelements and combine these effectively with calcium silicate hydrate gelling. The governing failure mode of fiber is pulled out or pull off, through which fiber absorbs the tensile stress and energy. However, fiber is also believed to have confusion distribution in CPB because fiber cannot reach their full strain capacity, especially at the later curing stage. And the weak structural layers in the CPB can also be formed, and the higher tensile strength is not achieved with the additional fiber content or longer fiber length. The optimal fiber content in this study is recommended to be 0.15 %, and it's better to choose 6 or 9 mm fiber. Moreover, fiber can reduce the original porosity by 10.72 %, but only has a slight influence on the pore size. The decrease in porosity helps increase the tensile strength of the fiber-reinforced CPB.INDEX TERMS Tailings, fiber-reinforced, cemented paste backfill, Brazilian indirect tensile strength.

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Deformation model of sand around short piles under pullout test

Cited by 34 publications

References 33 publications

Modeling of Uplift Resistance of Buried Pipeline by Geogrid and Grid-Anchor System

Modeling of Uplift Resistance of Buried Pipeline by Geogrid and Grid-Anchor System

Assessment of surface parameters of VDW foundation piles using geodetic measurement techniques

Influence of Polypropylene Fiber Reinforcement on Tensile Behavior and Failure Mode of Tailings Cemented Paste Backfill

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