Abstract: Based on the results of cyclic loading tests of two types of deep buried marbles and from Jinping II hydropower station, evolution of elastic parameters of marble under different confining pressures is studied. The results show that the elastic modulus changes significantly with the development of confining pressure and internal variable; while Poisson's ratio does not change significantly with confining pressure. Quantitative relationship between elastic modulus, confining pressure and internal variable is proposed based on the test results; and an elasto-plastic coupling model is set up considering the effect of confining pressure and implemented in FLAC3D by using C++ language. Then, the result of triaxial compression test is simulated. By comparing the simulating results with and without considering the effect of confining pressure, it is shown that there is significantly better agreement between the simulating results considering the effect of confining pressure and test data. Efforts of this paper can give an important reference to numerical accuracy for rockmass of deep engineering, especially for brittle rockmass with the characteristic of fracturing under small deformation.

Key words: deep buried marble, evolution of elastic parameters, effect of confining pressure, elasto-plastic coupling, numerical simulation