Question 1. The maximum dry density of a given soil is 1.5 g/cm3 and its specific gravity was determined to be 2.65. Determine the moisture content corresponding to this density on the zero air void curve. Also, determine the optimum moisture content of this soil if we know that the saturation at OMC was 95%.
Question 2. What is the basic principle for soil liquefaction? List five possible ground improvement methods that can be used to mitigate soil liquefaction and explain why and how.
Question 3. A fill material has 10% oversized particles. The compaction tests on the fill without oveisized particles result in a maximum dry unit weight of 18.71cN/m3 and its corresponding optimum moisture content of 12%. The oversized particles have specific gravity of 2.67 and saturated surface dry (SSD) moisture content of 3%. Calculate the corrected maximum dry unit weight and optimum moisture content including the oversized particles.
Question 4. Explain the four main mechanisms involved in dynamic consolidation.
Question 5. A four stou hospital building is to constructed on a landfill that contained construction debris. The design indicates that shallow foundations can be used for this project provided a homogeneous soil layer with no voids could be ensured within a depth of 10 m below ground surface. Assume ground water table is deep enough that it is not a concern. Dynamic compaction was proposed to improve the ground. The local contractor doing dynamic compaction has a 15-ton tamper with a diameter or 1.5 m and thickness of 1.0 m. You are requested to conduct a preliminary design for this dynamic compaction project that includes drop height, spacing, number of passes and number of drops. Also, estimate the total settelment using the area ratio of improvement.
Question 6. A circular concrete footing of 1.5m in diameter has an embedment depth of 0.6m in a uniform loose sand. The column load on the footing is 300 kN. The loose sand has a unit weight of 16 kN/m3 and a friction angle of 26°. The groundwater table is 10m below the ground surface. The required factor of safety is 3.0.
Calculate the ultimate bearing capacity and factor of safety against bearing failure. If a replaced zone of 2.5 m in diameter and 1.0 m thick granular fill with unit weight of 20 kN/m3, cohesion of 0, and friction angle of 40° is constructed under the footing, what are the ultimate bearing capacity and factor of safety for all four modes of failure?
Question 7. Explain the main reasons why granular columns likely bulge near the ground surface. What are the main functions of columns in ground installed by deep replacement methods?