Question

INSTRUCTIONS Determine what is required in each situation using Mohr circle analysis. Use a compass to create a perfect circle, and a protractor to measure angles.
Problem 2. A consolidation test has been performed on a sample obtained from a saturated clay at a point 6.50m below the ground surface. The groundwater table is at the ground surface
and the unit weight of the clay is 18.5 kN/m3. The measured preconsolidation stress was 260
kPa. (a) Determine if the soil is normally consolidated (use ±10% offset) or overconsolidated, (b) Compute the overconsolidation margin and the overconsolidation ratio, and (c) compute the preconsolidation stress at depth of 12m in the same soil. Draw the figure.

Answer 1

Criven data Wit a) preconsolidation stress ope 260kpa for finding effective. 6.5m = 18.5KN/m² stress - Total stress - effect repore water preveure = YXZ – 8w x 2 = 18.5X6.5-9.81X615 = 56.485 kN/m² we seen that after calculation effective stress is not greater than pre candidation stress, so the deposite will said to be normally consolidated. Difference in both the values that is pre consolidation stress values gines over consolidation stress & effective margin ie = 205.515 kPa over consolidation ratio (OCR): It is defined as the highest stress experienced devided by the current stress. OCR - 260 56.485 TOCR = 4.603 OCR will be one. for normally careolidated soil

9 Preconsolidation stress at 12m depth G-WT Totalstress = 12x1815 - 222 kN/m2 7 = 18.5 kN/m3 bore water pressure = 80 x 12 - 9.81x12 = 117.72 kN/m² precarsolidation stress a effective stress 822 - 117.72 = 104.28 kN/m2 1104.28K N/m2 n Effedive 222 kN/m2 Total stress 117.7214/m2 pore water рокие Istress.