You should use excel functions and capabilities to solve the
problem. Inputs and outputs should be clear using different
colours. There is no mark for copying and pasting the
solution.
Q3
A rigid strip footing with a width of B is constructed above
the ground on a clay deposit, overlying bedrock. The depth of clay
layer is H and the water level is at the natural ground surface.
Before construction of the footing, laboratory tests on a saturated
clay sample, taken at a depth of H/2 below the ground surface,
provided the following properties:
Compression Index = Cc , Recompression Index = Cr ,
Consolidation Coefficient = cv
Over Consolidation Ratio = OCR, Water Content = w% and
Specific Gravity = Gs
Assume the vertical uniform surcharge stress on the footing
including the weight of footing and column = q
(a) Calculate the initial saturated unit weight of clay
deposit.
(b) Based on the elastic theory (Boussinesq’s equation),
calculate the excess pore water pressures at the depth of H/2
immediately after applying the surcharge load. Assume the vertical
stress (q) is applied instantaneously.
(c) Using theory of 1-D consolidation, calculate the total
average settlement of this rigid footing due to consolidation of
the clay layer, long time after applying the total load.
(d) Determine the average settlement of this rigid footing
after n days of applying the total load due to consolidation of
clay deposit. Assume the bedrock is permeable (i.e. Drainage path =
H/2)
(e) Plot the graph of settlement versus time (in log scale)
for this footing.