Net pressure to Soil
Net pressure to Soil
(OP)
Dear Expert,
Can we allow deduction of overburden pressure from raft pressure (superstructure) for estimating settlement?? if depth of excavation is high. Type of soil is pure clay.
ie, Pressure on soil = Footing pressure (from building) - overburden pressure.
Regards
Bala
Can we allow deduction of overburden pressure from raft pressure (superstructure) for estimating settlement?? if depth of excavation is high. Type of soil is pure clay.
ie, Pressure on soil = Footing pressure (from building) - overburden pressure.
Regards
Bala





RE: Net pressure to Soil
RE: Net pressure to Soil
If the water table is at surface, should I take submerged density or saturated density.
Regards
Bala
RE: Net pressure to Soil
RE: Net pressure to Soil
here is a worked example to help you...
unit weight of soil = say 18kN/m3 for "pure clay:
buoyant unit weight = 8 kN/m3 (18-10)
depth to underside of proposed raft = say 3m
water at surface as per your thread
so take current overburden pressure = 3m x 8 kN/m3 = 24 kPa
if you're assessing settlement, then recommend taking the dead load only + the live load but don't; factor them up (for calculating the "gross structural bearing pressure")
lets say the gross structural bearing pressure comes out at 50 kPa
The net bearing pressure will be 50 - 24 = 26kPa.you can use this for the calc of settlement.
Doug Hole
Junior Geotechnical Engineer