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Unformatted text preview: CIVE 310 Soil Mechanics Direct Shear Test on Sand Section Assigned Due Before lab : Read this handout. 101 102 DIRECT SHEAR TEST ON SAND The shear strength, s, of a granular soil may be expressed by the equation; s= σ ' tan φ where σ ' = effective normal stress φ = angle of friction of soil The angle of friction, φ , is a function of the relative density of compaction of sand, grain size, shape and distribution in a given soil mass. For given sand, an increase in the void ratio (i.e., a decrease in the relative density of compaction) will result in a decrease of the magnitude of φ . However, for a given void ratio, an increase in the angularity of the soil particles will give a higher value of the soil friction angle. Equipment 1. Direct shear test machine (strain controlled) 2. Balance sensitive to 0.1 g 3. Large porcelain evaporating dish 4. Tamper (for compacting sand in the direct shear box) 5. Spoon A direct shear test machine consists primarily of a direct shear box, which is split into two halves (top and bottom) and which holds the soil specimen; a proving ring to measure the horizontal load applied to the specimen; two dial gauges (one horizontal and one vertical) to measure the deformation of the soil during the test; and a yoke by which a vertical load can be applied to the soil specimen. A horizontal load to the top half of the shear box is applied by a motor and gear arrangement. In a strain-controlled unit, the rate of movement of the top half of the shear box can be controlled....
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This note was uploaded on 04/03/2008 for the course CIVE 310 taught by Professor Iforget during the Spring '08 term at Drexel.
- Spring '08