Shear strength properties of sand with fines for various moisture contents

Ball, Ryan (2021) Shear strength properties of sand with fines for various moisture contents. [USQ Project]

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BALL Ryan dissertation_redacted.pdf

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This honours research project will experimentally investigate the shear strength properties of sandy soil with varying moisture content and fines content. The shear strength of a soil is perhaps its most essential property, as this shear strength is the major force resisting loading. The shear strength properties of soil are therefore paramount to the design and construction of engineered infrastructure inclusive of dams, roads, bridges, rail, retaining structures, and residential and commercial buildings. Whilst sand has been researched extensively, Mifta et al (2020) states that the shear strength of clayey and silty sands is not well investigated in relation to cyclic loading. These sands with plastic fines exist in many geological formations.

Development of experimental equations to model the shear strength of sandy soils for various conditions is to be carried out for various conditions. Sandy soil samples are prepared for three phases of testing for various water contents and clay mixtures. Samples are sheared in the direct shear testing machine at the rate of 1 mm/min to determine the shear strength properties for various normal stress values. Preliminary testing to determine the characteristics othe sand and clay materials includes the determination of Atterberg limits, particle size distributions, USCS classification and particle density testing.

A total of 56 direct shear tests have been carried out. The internal angle of friction of the dry sand sample is 28.9°, whilst the sand with various moisture contents varies between 24.6° and 26.2°. The friction angle of the dry clay sample is 33.2°, whilst the sand with various clay contents varies between 27.3° and 33.5°. An increase in moisture content resulted in a decrease in shear strength for sand samples which is attributed to the effective stress principles of the MohrCoulomb failure criterion. The increase in fines content resulted in an increase in shear strength which is attributed to the increased particle-to-particle contacts whilst maintaining connected chains of granular materials.

Two experimental equations have been developed based on the Mohr-Coulomb failure criterion and the direct shear test results to model the shear strength properties of sand with various moisture and fines conditions. Further research is required to develop additional equations for other conditions and rigorously test assumptions.

This progress report is submitted in conjunction with a Laboratory Z1 induction (Appendix D and a USQ risk management plan (Appendix E). Appendix B contains extensive graphical data for the consolidation tests and direct shear tests conducted.

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Item Type: USQ Project
Item Status: Live Archive
Additional Information: File reproduced in accordance with the copyright policy of the publisher/author.
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Mirzaghorbanali, Ali
Qualification: Bachelor of Engineering
Date Deposited: 12 Jul 2023 01:10
Last Modified: 12 Jul 2023 01:10
Uncontrolled Keywords: soil cohesion, stress, shear, soil, moisture, cyclic loading, fines, sand

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