Question

An embankment is to be constructed rapidly over a soft clay deposit.

i. Prescribe the kind of triaxial test to be conducted on the soil sample to determine shear strength parameters.

ii. Which stage of the construction is assumed to be the most critical design condition and explain the reason?

Answer 1

Due to the rapid construction, pore water is not dissipated and hence undrained condition prevails and positive pore water pressure develops.Therefore UU triaxial test is done and the total stress parameters are determined.Since it is difficult to find excess pore water pressure in field.

The excess pore water pressure dissipates with time and hence effective stress increases as a result shear strength increases.Therefore for the most critical case , stability should be checked immediately after construction as shear strength is least then.