LEARNING OUTCOMES
1. Apply soil and rock mechanics principles in building design and construction.
2. Interpret the influences of geological processes and natural environments on geotechnical design.
3. Explain the use and limitations of geotechnical design in built environment projects.
4. Perform basic geotechnical calculations including soil phase relationships, strength, stability, stress, compressibility, permeability and bearing capacity.
Question 1
An exploratory drill hole was made in a stiff saturated clay having a moisture content of 30% and Gs = 2.58 as shown below. The sand layer underlying the clay was observed to be under artesian pressure. Water in the drill hole rose to a height of 6 m above the top of sand layer.
a) If an open excavation is to be made in the clay, determine the safe depth of excavation before the bottom heaves.
b) Discuss, in your own words, factors affecting the determination of the safe depth above.
Question 2
Consider the upward flow of water through a layer of sand in a tank as shown in the figure below. For the sand, the followings are given: void ratio (e) = 0.50 and specific gravity of solids (Gs) = 2.60.
a) Calculate the total stress, pore water pressure, effective stress at points A and B, and upward seepage force per unit volume of soil.
b) What are the benefits of determining the above effective stress and seepage force (both upward and downward) in the fields of building design and construction management
Question 3
A pole carries a vertical load of 200 kN. Determine the vertical total stress increase at a depth 5m:
a) Directly below the pole
b) At a radial distance of 1 m
c) Furthermore, how would you apply your soil stress knowledge especially related to calculation of the vertical total stress above in the fields of building design and construction management? Your answer should also include examples.
Question 4
For a dry sand specimen in a direct shear test box, the following details are given:
Size of specimen : 63.5 mm * 63.5 mm * 31.75 mm (height)
Angle of friction : 33°
Normal stress : 200 kN/m2
a) Estimate the shear force required to cause failure. Please state your assumptions clearly.
b) Discuss benefits and drawbacks of direct shear test.
Question 5
You are a construction manager for a company contracted to construct a runway that is to be located on saturated clay/silt material near the coast. In a preconstruction meeting you are asked how to accelerate the consolidation settlement of the in-situ material to ensure that your company is not liable for liquidated damages due to over-running the construction program. Discuss your choice of soil testing and your proposal to accelerate the consolidation settlement.