In offshore foundation designs,such as displacement piles,spudcan,mud mats and torpedo anchors,site invesigations of the seabed characteristics,such as shear strenght profiles and seabed stratification,are crucially important.Cone,T-bar and Ball penetrometers are the commonly used devices for offshore in situ investigations.The latter two are referred as full-flow penetrometers as their geometries allow soil to flow-around the advancing probs to obviate the need for correction on over burden stress as for cone penetrometer.As the offshore oil and gas industry is striving new locations in frontier regions,highly layered soils are prevalent.Due to the high cost and difficulty in obtaining high-quality soil samples for laboratory tests,in situ site investigations become more attractive.Cone,T-bar and Ball penetrometers have been studied extensively.However,most of their studies have been focusing on their performance in single uniform soil layers,with few studies in layered soil profiles.