A 2.8 m wide reinforced concrete strip footing is situated at2.5 m below ground level in a thick deposit of a saturated clay.The footing is loaded centrally, and the total vertical line loadincluding the weight of the concrete and backfill is 308 kN/m. Theclay has a bulk density (Ï) of 2250 kg/m3 and an undrained shearstrength (cu) of 42 kPa.
a) Calculate the factor of safety against bearing capacityfailure considering the short term response of the soil.
b) If the strip footing in part a) has to carry an additionalhorizontal line load of 50 kN/m, calculate the new factor of safetyagainst bearing
capacity failure.
c) Briefly define the terms compression, compaction andconsolidation and explain what are the resulting changes in voidratio and moisture content in each of the above cases, assuming aconstant total stress is applied onto the soil.
d) A normally consolidated and an over-consolidated clay aresubjectedto the same increment of effective stress. Which wouldresult in a higher settlement? Assume the initial void ratio andthe height of the soil layer to be the same for both cases. Justifyyour answers using appropriate plots and/or equations.
