Soil Strength (CH13)

Strength Greatest stress a material can sustain Concrete strength?

Soil Strength Soil fails in shear SHEAR Earth slopes Foundations Retaining Walls Tunnels Pavements

Shear Strength Failure definition Loose (or NC) vs. Dense (or OC)…  –  curves depend on the soil and the testing conditions. We must simulate field loading in the lab.

Shear Strength Mohr – Coulomb Failure Criterion Concrete strength?

Hydrostatic Pore Pressure, u h z Ground surface Soil,  “hydrostatic pore water pressure at A” hphp

Excess Pore Pressure, u e Pore pressure generated in excess of hydrostatic due to an applied load. u e is temporary

Loading Conditions shear LOOSE DENSE Soil densifies due to the change in structure (e ) (water squeezes out of the voids)

shear LR: Loading rate? DR: Drainage rate? = fn (k) Water drains out, volume change, e Water carries load, no volume change, e = ct. DRAINED UNDRAINED Loading Conditions