Figure P9.31 shows a soil profile at a certain site, including an 8.5 m thick stratum of saturated, normally consolidated clay overlying an impermeable rock formation. The groundwater location is not known; however, a pore pressure measurement device (piezometer) has been installed in the middle of the clay and reads 52 kPa. A settlement plate has also been installed at the top of the clay to measure the deformation of the clay layer only (doesn't include any deformation of overlying materials).

(a) A 2.6 m deep layer of fill (unit weight 19.2 kN/m3) is placed on the ground surface. At 220 days after the fill is placed, the piezometer reads 77 kPa of pore pressure, and the settlement plate has moved downward by 0.54 m. What is the cv for the clay?

(b) Based on these readings at 220 days, what total settlement can be expected at the end of consolidation?

(c) Compute the modified compression index, Cce for this loading increment.

Settlement plate Ground surface Dense sand Y = 19.2 kN/m 2.6 m Saturated, nomally consolidated clay, Y = 18.3 kN/m 8.5 m Piezometer Impermeable rock