Staged Pullout Testing of Extensible and Inextensible Reinforcements

Mittal, Ankur Kumar and B, Umashankar (2018) Staged Pullout Testing of Extensible and Inextensible Reinforcements. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Disposal of waste material like pond ash is a major concern to environment. One of the possible applications of this type of waste material is to utilize them as backfill material in reinforced earth structures. To proper design of any reinforced earth structure, soil reinforcement interactions are important where shear and pullout are the most common internal failure modes. Pullout parameters have an important role in design of reinforced earth structure and to determine these parameters pullout test has been carried out at different samples. In this study it is proposed to use pond ash and sand as a backfill material so, this study is carried out to determine the axial pullout resistance of smooth metal strip reinforcement and geogrids. Pond ash from Narla Tarato thermal plant, Vijaywada, Andhra Pradesh has been used. Here, a new test method has been developed named as staged pullout test (SPOT) where a model ground can be tested for two or more than two normal stress conditions. SPOT has advantage over conventional pullout test (CPOT) because CPOT requires three or more model ground to get the pullout properties and it is very difficult to maintain same properties for each model ground while for SPOT only one ground has been used to get the pullout properties. In the SPOT, normal loads are in staged condition or changing the normal load after stopping the test when pullout displacement reaches to 20 mm. In order to investigate the SPOT method, both CPOT and SPOT have been performed on the same model ground and results have been compared. From the comparison, SPOT results of smooth metal strip reinforcement were found to be closer with CPOT results for 17 kPa and 52 kPa while for 87 kPa SPOT results can be used with a factor of safety of 1.2. It has been also observed that SPOT results produce comparable results with CPOT for first 20 mm displacement irrespective of the reinforcement. For geogrids, logarithmic fitted test results are differ by less than 10% for first 20 mm displacement and 15-20% for remaining displacement up to 60 mm. The percentage change for logarithmic fitted results is going to higher when moving to higher normal stress conditions. So, SPOT method could be used instead of CPOT with a factor of safety of 1.2 to 1.3. From the results, SPOT has a probability to be used as a new pullout test method instead of CPOT.

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IITH Creators:
IITH CreatorsORCiD
B, UmashankarUNSPECIFIED
Item Type: Thesis (Masters)
Subjects: Civil Engineering
Divisions: Department of Civil Engineering
Depositing User: Team Library
Date Deposited: 17 Jul 2018 11:33
Last Modified: 17 Jul 2018 11:33
URI: http://raiith.iith.ac.in/id/eprint/4273
Publisher URL:
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