Reference no: EM132855319

Problem 1:

A retaining wall with a height of 16 feet and a surcharge q = 550 lb/ft² as short n in the figure below is proposed for a roadway. During the subsurface exploration the soil test borings drilled at the site encountered a layer of sand from 0 to 5 feet a layer of normally consolidated clay from 5 to 11 feet, and another layer of sand from 11 to 16 feet. SPT tests were performed within the sand layers and an undisturbed sample mas obtains d within the clay layer. A consolidated-untrained triaxial test was performed on the undisturbed sample. Using the data given, determine the Rankine active force per foot of wall and the location of the line of action of the resultant.

Use Schmertmann's (1975) correlation between SPT and Φ' , and round to nearest degree.

Atmospheric pressure Pa = 2000 lb/ft²
water table is located at 5.0 feet below the top of the wall.
The SPT hammer was calibrated and found to have an efficiency of 80 percent.
Neglect correction factor for borehole diameter, sampler correction and correction for rod length.

Figure for Problem 1

Problem 2: A rectangular footing with a length of 8 feet and a width of 6 feet is subjected to a vertical load and a moment M. The following data are available for design of the footing:
• e_L = 2.0 feet and e_B = 1.4 feet
• Depth of foundation, D_f = 6 feet
• Unit Weight of Soil, γ = 125 lb/ft³
• Friction angle, Φ' = 33°
• c' = 0
Determine the allowable load that the footing can carry using a factor of safety of 3.

Problem 3:

A water storage tank is to be constructed on a site located in the coastal plain area. The subsurface exploration used CPT to determine the soil profile which consisted mostly of sand and silty sand. The average cone resistance for a 22-meter layer is shown in the figure below. At the time of the exploration, groundwater was measured at 3.0 m below the ground surface. The footing for the water tank will be a circular footing with a diameter of 9 meters and the tank itself will be 8.5 meters in diameter and 12 meters high. The maximum height of the water in the tank is anticipated to be 11.5 meters. Calculate the factor of safety on the ultimate bearing capacity of the circular foundation for the tank. Assume the weight of the tank and its footing to be about 200% of the weight of water in the tank at its maximum level. Use Kulhawy and Mayne's (1990) correlation between qc and drained friction angle.

Figure for Problem 3

Problem 4:

Using the figure shown on the next page, determine the amount of settlement under a (12-ft by 12-ft) rectangular footing that is subjected to a maximum column load of 320 kips. Use the Schmertmann Approximation (Strain Influence Factor) to estimate the settlement, 25 years after construction. A soil test boring was performed at the location of the footing and Standard Penetration Test was performed at several intervals. The results of the SPTs are shown in the figure below. Please use the following correlation between N60 and Dutch Cone Tip Resisitance qc.

Please note that the units for qc are in tons per square foot (tsf) and N60 is in blows per foot (bpf)

Soil properties:

Problem 5:

An 8ft by 8ft square footing will be designed to bear on the profile shown below. A soil test boring was performed at the location of the footing and Standard Penetration Tests were performed at several intervals. Based on local building codes, the footing should be designed to bear below the frost depth of 3 feet. Furthermore, based on the blow counts and soil types, the soil profile shown below was generated. Calculate the allowable load for the foundation based on a factor of safety of 3. Use Hatanaka and Uchida's (1996) correlation between (N1)60 and φ'.