1. A triaxial test is performed on a normally consolidated clay. The sample is further consolidated by the test of all-around confining pressure prior to the application of the axial load. The axial force is applied very slowly. The equipment pore pressure lines remain open so that drainage of the soil pore water can occur during the test. The sample fails when minor principal stress is 29 kPa and the major principal stress is 110 kPa. Determine the angle of internal friction with no decimal places.

 

2. A dry sand sample was tested in direct shear and yielded a shear strength of 130 kPa under a normal stress of 211 kPa. Lab results indicate the soil's wet unit weight is 16.9 kN/m³ and the saturated unit weight is 20.4 kN/m³. Determine the shear strength, in kPa, within the native sand deposit at a depth of 4 m below the water table. The water table is 3 m below ground surface. Provide your answer with 2 decimal places, do not include the units and assume a unit weight for water of 9.81 kN/m³.

 

3. A dry sand is known to have an angle of internal friction of 36. A triaxial test is planned, where the confining pressure will be 34 kPa. What is the maximum axial stress, in kPa, (major principal stress) that can be applied? Calculate the value to 1 decimal place. Do not provide units in your answer.

 

4. A clay soil is subjected to a triaxial test under unconsolidated-undrained conditions. At failure, the major and minor principal stresses are 7901 psf and 3055 psf, respectively. What is the shear strength of this soil if the confining pressure is doubled? Provide your answer in psf with no decimals.