Question

Using the data in Textbook Problem 8.8:

a. Plot the vertical effective consolidation stress versus void ratio on both arithmetic and semi-log graphs. For the arithmetic graph, constrain the vertical axes to 0.55 and 0.95; and the horizontal to 0 to 1,500 kPa; for the semi-log graph, use the same vertical axis constraints, but use 10 kPa and 10,000 kPa to ease interpretation. Plot the data points only, and draw in a smooth curve by hand. Plot each graph on a full sheet of paper with void ratio oriented on the long axis.

b. Determine the Coefficient of Compressibility, av, and Compression Index, Cc, over the stress ranges of (320 to 640 kPa) and (640 to 1280 kPa). Compare these two sets of values. Which approach (av, or Cc) would you feel more comfortable using in a design setting and why?

c. Determine the Recompression Index starting at 1280 kPa (i.e., use the first and last data points of the unload cycle, not the load cycle. The unload cycle is not affected by sample disturbance, whereas the load cycle almost always is…).

d. Determine the preconsolidation stress using the Casagrande method.

An existing 5 m tall, wide embankment of structural fill (fill = 22 kN/m3) sits atop a 30 m thick saturated clay layer (e0 = 0.88, sat = 16 kN/m3), and is to be altered to accommodate regional growth. The embankment will be widened considerably, and the grade raised 5 m. Using the 1D stress-strain behavior for the soil examined in Problem 3, determine the settlement experienced by the raised embankment due to compression within the clay layer (neglect embankment compression). Use Cc over the stress range of 320 to 1280 kPa (i.e., re-compute it from Problem 3).

you will find the answer of the previous question. use it to answer the 2nd question. thanks

Answer 1