The Research Of The Basic Performance Of Asphalt Concrete Cores--The Research Of The Static Triaxial Test And The Stress Relaxation Test

Because of its excellent inpenetrative performance, asphalt concrete has been widely used increasingly in watertight of dams. Till now there are nearly 400 asphalt concrete embankment dams (including headers) built in the world. The embankments with asphalt concrete cores are more than 80 including 20 in China and none of them has been repaired since 1955.At present plenty of experimental study has been made on the materials and structural performance of asphalt concrete cores in the world, and the design methods and construction technique as well as equipments have been more mature. However, there is still lack of the research of its basic performance. In this thesis, in combination with the actual project, the experimental study has been employed with the field core specimen and the specimen made in laboratory, mainly include the static triaxial test, confinement pressure stabilization test and stress relaxation test. Through the tests, conclusions are summarized as below:1. The static triaxial test of two engineerings shows that the breaking strength of asphalt concrete declines significantly as the temperature rises and the strain increases noticeably when breaking. Increase in the asphalt content leads to decrease in tangentmodulus and cohesion, but the internal friction angle tends to increase. Increasing confining stress results in the augment of the maximum stress and the ultimate value of volumetric strain.2. If asphalt concrete specimen is in stabilization by exert confining stress before the static triaxial test, it is then found that under the condition that time is long enough, the volume of the specimen will shorten gradually and stable around a fixed value, and the amount of compression is essentially the half of the volume of void itself. It is also found that in stabilization by exert confining stress the linear phrase will be shorten in the figure of the static triaxial test of specimen, while the initial tangent modulus will be augment.3. Through the stress relaxation test we can get relaxation modulus under various strain, and it indicate that the relaxation modulus of asphalt concrete specimen will turn minish along with the augment of the strain. Which is to say the relaxation will be better if the strain is small.