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 I_D (material index), K_D (horizontal stress index), E_D (dilatometer modulus) from the field readings. The profiles of I_D, K_D, E_D are used with the empirical correlations presented in the paper to obtain estimates of a number of soil parameters used in geotechnical engineering design.