The Rock Directly Tensile And Compression Cyclic Loading Test And Deformation Characteristics

The rock deformation behavior and deformation characteristics is the most basic research direction of rock mechanics and the research core of the rock constitutive relation. The early rock deformation characteristics has most been obtained from the compression test, which cannot meet the need of the actual geotechnical engineering.The rock deformation characteristics in tension differs from that in compression. More rock deformation modulus in tension is smaller than that in compression, which has been accepted by researchers. However, the deformation research in tension is seldom, the constitutive relation in compression and tension and failure criteria is not perfect too. To solve these problems, it is necessary to do some deformation researches in compression and tension.This article has conducted the three tests, uniaxial compression test, Brazilian test, compression-tension cyclic loading test. The compression-tension cyclic loading test with different loading routes and stress levels were porformed. It was developed by Kunming University of Science and Technology that the testing apparatus can conduct both compression and direct tension tests with the same rock sample.According to the test researches, the following conclusions are obtained:(1) Cyclic loading in compression has little impact on the rock deformation and the deformation modulus increases as compressive stress is applied. (2) In compression-tension cyclic loading tests, deformation modulus in compression is greater than that in tension and the Poisson's ratio in compression is greater than that in tension; Deformation modulus and the Poisson's ratio in compression increase as compressive stress is applied; Deformation modulus in tension decreases as compressive stress is applied, while the Poisson's ratio changes unstably. (3) In compression-tension cyclic loading tests, loading-unloading in tension could descend the following deformation modulus in compression and loading-unloading in compression could descend the following deformation modulus in tension too. (4) In every loading cycle of the test, the bigger the compressive stress, the smaller the deformation modulus on tension. The smaller the compressive stress, the bigger the deformation modulus on tension.