unsat9 - Shear Strength of Unsaturated Soil Shear Strength...

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Shear Strength of Unsaturated Soil Shear Strength Characterization Requirements for Shear Strength Cannot use saturated soil parameters c' and φ ' and effective stresses because effective stresses are unknown. To characterize the shear strength of unsaturated soil, it is necessary to measure the three stresses σ , u a , and u w at failure to determine the stress state variables ( σ - u a ) a n d ( u a - u w ) at failure. Test Procedures 1) Specimen preparation: - undisturbed specimens should be taken from representative samples where the soil properties (composition, moisture condition, and density) are the same; - disturbed samples are prepared by reconstitution of soil from dry or saturated (slurry) state, or by recompaction of soil samples; - disturbed samples must be prepared at the same moisture condition and density to be "identical". Unsat9 - 1
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2) Sample "consolidation": - stresses are applied and the soil is allowed to come to equilibrium so that the initial stress state variables will be known; - the matric suction pressures can be achieved by: a) directly measuring the pore water and air pressures of a specimen; b) applying both air and water pressures keeping u a > u w (axis-translation technique).
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This note was uploaded on 12/12/2011 for the course CIVIL ENGI 7004 taught by Professor Hasan during the Spring '11 term at Auckland.

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unsat9 - Shear Strength of Unsaturated Soil Shear Strength...

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