Experimental Research On Tensile Behaviors Of Cohesive Soil

The tensile failure of soil is one of the most common potential safety hazards in geotechnical engineering. It is of theoretical and practical significance to study the tensile characteristics of soils. A new tension apparatus was developed, with which different tension tests, including uniaxial tension test, Brazilian test, and axial splitting test, can be conducted on cohesive soils. The three kinds of tests were used to study the tensile behaviors of cohesive soil in this thesis. The main conclusions are as follows:(1) A new tension apparatus was developed to investigate the tensile characteristics of soils. The apparatus, with a better integrity, a higher continuity and a higher stability of test results, can record the tensile process of soil specimen.(2) The effects of the dry density and moisture content of soil and the loading conditions on the uniaxial tensile behaviors were studied. Dry density and moisture content have a crucial influence on tensile behaviors of soil:there are two failure modes and three types of stress-strain curve with different water content and dry density. Generally speaking, the tensile strength and peak strain decrease with the increasing moisture content, and increase with the increasing dry density. Loading rate has an important influence on tensile behaviors of soil. The type of stress-strain curve, the tensile strength and the peak strain change with different loading rate.(3) The differences between indirect methods and uniaxial tension test were evaluated. For the three tests, the variations of tensile strength with dry density and water content are consistent. The results of the Brazilian test are similar to those of the axial splitting test, and are smaller than that of the uniaxial tension test. There is a conversion relationship between the tensile strength obtained from uniaxial tensile test and that from the two indirect tests. (4) The effects of the diameter of the gasket and the height of specimen on the tensile strength were studied for axial splitting test. The tensile strength increases with the diameter of the gasket. With the height of specimen increasing, the tensile strength decreases, but it nearly remains a constant when the height of the specimen is great enough.