Abstract: The damage of many geotechnical buildings is closely related with the tensile strength of soil, which is a crucial mechanic indicator of soil. Nevertheless, compared with shear strength and compressive strength, tensile strength still lacks mature test instruments and theories. In this study, tensile strength tests were conducted on sandy clayey soil specimens with varied dry density, saturation degree, and sand content using self-made test equipment. The influences of these factors on the results of tensile strength were examined. The self-made instruments include a horizontal extensograph which reads data automatically, and a universal superimposed saturator which meets the requirements of specimens of special shapes. Results revealed that with the rising of dry density, tensile strength increased linearly; but with the rising of saturation degree, tensile strength increased and then declined, and reached peak at saturation degree of 60%; with the augment of sand content, tensile strength reduced slowly at first, and such reduction intensified when sand content reached 20%, and then tensile strength approached zero when sand content exceeded 40%. On this basis, the functional relations of tensile strength against the influential factors were established. The research findings offer reference for determining the tensile strength of sandy clayey soil in practical engineering.

Key words: sandy clayey soil, tensile strength, uniaxial tensile test, dry density, saturation degree, sand content