- 16 Storey Office Building Is To Be Designed On A Mat Foundation On A 20 M Deep Soft Clay Deposit The Ground Water Level 1 (36.76 KiB) Viewed 76 times
(n=?) Assume that the building load will be shared by
stone columns and the soft clay together. (Hint: make a
reasonable assumption for stress concentration factor) Allowable
carrying capacity of a single stone column is estimated to be 450
kN.
Properties of the soft and stiff clay layers:
......Soft
Clay...... ...........Stiff
Clay..........
Cc /(1+e0) =
0.06
mv =
0.008x10-2 m2/kN
cu = 45
kPa
cu = 180 kPa
gammasat = 18
kN/m3
gammasat = 20 kN/m3
Stress influence factors (Is) for the mat (20m x 30m)
at 5m, 10m, 15m and 20m depths are 0.94, 0.78, 0.58 and 0.40
respectively
Assume that the stiff clay is almost
incompressible compared to the soft clay. Remember
that;
16-storey office building is to be designed on a mat foundation on a 20 m deep soft clay deposit. The ground water level is at the ground surface and the mat will rest at the ground surface (no basements). The mat foundation has been designed on stone columns. 80 cm diameter stone columns will have square pattern, 1.6m x 1.6m and rest on the stiff clay layer at 20 m depth. The total loading of the building including the mat foundation (20m x 30m dimensions) is 200 kPa (average contact pressure). Calculate the settlement improvement ratio. (n=?) Assume that the building load will be shared by stone columns and the soft clay together. (Hint: make a reasonable assumption for stress concentration factor) Allowable carrying capacity of a single stone column is estimated to be 450 kN. Properties of the soft and stiff clay layers: Soft Clay..... stiff Clay........ -2 2 my = 0.008x10m/N {{1+e,) = 0.06 = 45 kPa = 180 kPa 3 3 gamma = 18 kN/m sat gamma = 20 kN/m sat Stress influence factors (1) for the mat (20m x 30m) at 5m, 10m, 15m and 20m depths are 0.94, 0.78, 0.58 and 0.40 respectively A0, = ls. Assume that the stiff clay is almost incompressible compared to the soft clay. Remember that: Cg (s = H Log 1+eo (0,0'+AC), Oro'