Sandstone Dynamical Characteristics Influenced by Water-Rock Interaction of Bank Slope

During the long-term reservoir operation, the seismic capability and dynamic response characteristics of the bank slope are of great importance to its safety evaluation content. Aimed at typical bank slopes, considering reservoir water level fluctuation and soaking-air drying cyclic interaction, an experiment has been designed and conducted. In addition, the cyclic loading test with different stress amplitudes was carried out in different water-rock cycles. The laboratory results indicate that (1) during the immersion-air dry circulation process, the damping ratio and damping coefficient of sandstone gradually increased while the dynamic elastic modulus decreased. It is obvious that the dynamic elastic modulus of sandstone decreases dramatically during the immersion-air dry circulation process, especially in the first six periods. Also, its variation curve fits with the logarithmic curve. (2) When the cyclic load stress amplitude increases from 10 MPa to 35 MPa, the damping ratio and coefficient of the rock sample gradually decreased while dynamic elastic modulus increased. each dynamic parameter shows a more obvious variation trend when the stress amplitude is lower than 25 MPa. (3) During the water-rock interaction process, the closely knit microstructure of rock gradually becomes loose and porous, which resulted in the degradation of macroscopic physical and mechanical properties of sandstone. (4) In the analysis of the seismic response of the bank slope, the actual water-rock interaction process and the seismic level of the bank slope should be more considered. To find out further accurate reflection in the earthquake resistance and dynamic response of the bank slope, it is necessary to select the reasonable dynamic parameter to carry out seismic research.

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