In Situ Tests by Flat Dilatometer

A flat blade shaped tip, with a thin flat circular steel membrane fitted flush with one side, is jacked into the ground. At 20-cm depth intervals the penetration is stopped, the membrane is inflated and the following readings are taken: A = pressure at which the membrane starts to expand against the soil; B = pressure needed to deflect the membrane center 1.00 mm against the soil. Simple expressions derived in the paper are used to determine the parameters ID (material index), KD (horizontal stress index), ED (dilatometer modulus) from the field readings. The profiles of ID, KD, ED are used with the empirical correlations presented in the paper to obtain estimates of a number of soil parameters used in geotechnical engineering design.