DESIGN AND FABRICATION OF A CONE-PENETROMETER FOR MEASUREMENT OF UNDRAINED STRENGTH OF INDIAN COHESIVE SOILS

Abstract

Whenever soft saturated clays are involved during the investigation for foundations, and rapid means of obtaining the shear strength of soils is required for preliminary studies; cone penetration test is considered most suitable. In this study an attempt has been made to design and fabricate a simple cone penetrometer, based on the 0 = 0 analysis and taking into consideration., Drzaahit s theory of failure of soil below the strip footing. It utilises the relationship 4 = k ~fh2 given by Hun so (1957) for the computation of the undrained shear strength of soils by cone penetrometer. Two cones of 600 and 90o apex angle have been studied and compared for their suitability for measurement of un--drained shear strength of soils, Tkn remoulded soils were studied with the above cones and it was found that 900 cone seems to give more consistent values of 'k' a constant which depends mainly on the apex angle. M.e results obtained from the cone test were compared with those of the other tests viz laboratory vane shear test and unconfined compression test and found that they seemed to agree favourably. ' kvill) It i s appearent, that this apparatus cannot be used in cohesive soils where both C and 0 are important design factors. The instrument designed and fabricated in this study is vary simple, strong and sturdy and can be used both in laboratory any field for the measurement of unr drained, strength of soils. The results can be used, in 0 = analysis for the Engineering problems.