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King Fahd University of Petroleum and Minerals. (Saudi Arabia) (1999)

Interface frictional characteristics of non-woven geotextile - Sabkha and - sand using pull-out tests

Ali, Syed Muhammad

Titre : Interface frictional characteristics of non-woven geotextile - Sabkha and - sand using pull-out tests

Auteur : Ali, Syed Muhammad

Université de soutenance : King Fahd University of Petroleum and Minerals. (Saudi Arabia)

Grade : MSc thesis 1999

Résumé
Sabkha soil is widely spread along the Arabian Gulf and Red Sea coasts and is found to be a problematic soil due to its acute water sensitivity and chemical aggressiveness. In many situations, there is a need to improve the load carrying capacity of sabkha and the use of geotextile for such purpose was found appropriate. The lack of information regarding pull-out resistance of locally available geotextiles embedded within local soils including sand and sabkha led to this experimental research program. The objectives of this research were to study frictional characteristics of sand-geotextile-sand and sabkha-geotextile-sand interfaces and to compare the pull-out resistance of locally available non-woven geotextiles taking into account different test parameters. A detail literature review was carried out to determine the parameters that strongly affect the pull-out characteristics. An experimental setup was then developed in soil laboratory at KFUPM to conduct the pull-out tests. Normal applied pressure, geotextile type, geotextile length, water content and soil type were the five parameters that were considered in this investigation. Strength test results indicated that the strength of sabkha decreases with the increase in moisture content where the angle of internal friction decreases by up to 8° upon soaking. Pull-out test results have indicated the existence of three stages of deformation in the geotextile under pull-out testing, which ultimately leads to the slippage of the entire length of the geotextile. This condition was labeled the residual state. The Interface characteristics were determined for this state, which is considered a limit for the pull-out resistance at failure. The use of the pull-out plate reduces the effects of the lateral earth pressure developed on the front wall of the pull-out box. Furthermore, the plate insures that the free geotextile is kept within the box and thus under the applied confinement, throughout the test. The pull-out tests results also indicated that the geotextile having high tensile strength takes large pull-out force in the case of sand-geotextile-sand interface whereas, the least extensible geotextile takes the maximum pull-out force in the case of sabkha-geotextile-sand interface. It was also found that the surface texture and extensibility of the geotextile are the two main factors, in addition to the mass per unit area of the geotextile, in the case of sabkha-geotextile-sand interface. The results indicated that the interface interaction factor is not constant but depends on the normal pressure, the geotextile type and the moisture content of the sabkha soil. Furthermore, the results indicated that soaking of the bottom sabkha layer improved the shear stresses mobilized on the sabkha-geotextile interface.

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Page publiée le 26 septembre 2010, mise à jour le 4 décembre 2017