Homework%2018-2009 - ) is 50 psi? (a) Calculate the angle...

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The University of Missouri-Columbia Department of Civil Engineering Assigned: Mon Nov 16, 2009 Due: Wednesday Dec. 2, 2009 CE 3400 - Homework No. 18 Shear Strength of Sand 1. The angle of internal friction of a dry sand is 32°; the cohesion is zero. The sample was tested in a direct shear apparatus with a 2 inch by 2 inch square specimen, 0.5 inches in height. A normal load of 1000 pounds was applied to the specimen. What shear stress will be required to fail the specimen? Express your answer in units of pounds per square foot. 2. A sample of dense sand has an angle of internal friction of 39° and no cohesion. (a) What shear stress would be required to fail a specimen of the sand in a direct shear test if the normal stress is 50 psi? (b) What principal stress difference σ 1 - σ 3 would be required to a fail a specimen of the sand in a triaxial compression test if the confining pressure ( σ 3 3. A specimen of sand fails in a direct shear test when the normal stress is 10000 psf and the shear stress is 5500 psf.
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Unformatted text preview: ) is 50 psi? (a) Calculate the angle of internal friction for the sand. (b) Based on the strength, would you expect the sand to be dense or loose? 4. A specimen of sand, 2 inches in diameter, is to be tested in a triaxial cell using a confining (cell) pressure of 100 psi. What axial force would need to be applied through the load piston of the triaxial cell to fail the sand if the angle of internal friction is 36°? The cohesion is zero. Express your answer in pounds 5. Three triaxial compression tests were performed on specimens of sand using consolidated-drained (S) test procedures. At failure, the following information is known from the three tests: . Test Effective Confining Pressure, σ ’ 3 Principal Stress Difference, σ ’ (psf) 1 - σ ’ 3 (psf) 1 1000 2400 2 2000 4300 3 4000 9500 Plot the Mohr’s circles of stress at failure. Assume that the sand has no cohesion and determine as best you can the angle of internal friction of the sand....
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This note was uploaded on 06/21/2010 for the course CE 3400 taught by Professor Brentrosenblad during the Fall '09 term at Missouri (Mizzou).

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