Cone penetration testing in unsaturated soils

Abstract Results of Cone Penetration Tests (CPTs) on compacted clayey silt under different moisture contents and matric suctions conducted in a calibration chamber are presented along with results of CPTs conducted in unsaturated clayey soil at two test sites over a period of approximately two years. CPT data obtained from published literature are presented for comparison. The accumulated data demonstrate the dependence of penetration resistance on moisture content and suction and reveal empirical relationships that can be exploited for preliminary assessment of tip resistance under changing moisture conditions. A preliminary treatment of tip resistance in unsaturated soil using bearing capacity theory is presented and shows promise as a semi-empirical method for assessing changes in tip resistance as a function of matric suction.