CIVL 326 GEOTECHNICAL DESIGN
REVIEW ASSIGNMENT 2
Question 1
The rectangular footing below will carry 2 column loads as shown below. The footing is 3 m by 5 m and is installed 3.0 m below ground surface founded on a hard clay. The clay’s unit weight is 18.0 kN/m3 , its cohesion is 10 kPa and its angle of internal friction is 22° . Groundwater was not detected during the drilling program. Determine the ultimate bearing capacity for the footing, the minimum and maximum stresses below the footing based on the column loads and the factor of safety against bearing capacity failure for this problem. Is the footing safe? (qu = 823.9 kPa, qmin = 193.3 kPa, qmax = 273.3 kPa, FS = 3.01)
Scale: NTS
Question 2
A proposed strip footing carrying a line load of 150 kN/m is to be constructed on a uniform. compact silty sand. The sand’s dry unit weight is 19.6 kN/m3, its cohesion is 5 kPa and its angle of internal friction is 28° . The depth of the footing will be 1.5 m below ground surface. Groundwater was not detected during the drilling program. Determine the minimum width of this proposed footing, using a factor of safety of 3, an assumed footing thickness of 0.5 m and a unit weight of concrete of 24 kN/m3 . (B = 0.8 m)
Question 3
A 500 mm diameter smooth steel pipe pile is driven through stiff clay to a depth of 16.0 m. A site investigation showed that the upper 5 m of clay had an unconfined compressive strength of 25 kPa while the lower clay had an unconfined compressive strength of 85 kPa. The groundwater table was located at 5.0 m below ground surface. Determine the total allowable vertical load on the pile using a factor of safety of 2. (QAllow ~ 400 kN depending on your selection of alpha)
Question 4
A straight shaft augered pile is constructed in a clayey soil as shown in the figure. The diameter of the shaft is 0.75 m. The drilled pile extends to a total depth of 15 m. Soil conditions are as shown in the following figure. Groundwater was encountered at a depth of 8 m below ground surface. Compute the maximum allowable design load on the pile using a factor of safety of 2.5. (QAllow = 1181.2 kN)