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

Abstract

During the long-term reservoir operation, the seismic capability and dynamic response characteristics of the bank slope are of great importanceto itssafety evaluationcontent. Aimedattypical bank slopes,consideringreservoirwater levelfluctuationand 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 dynamicelasticmodulusdecreased.Itisobviousthatthedynamicelasticmodulusofsandstonedecreasesdramaticallyduringthe immersion-airdrycirculationprocess,especiallyinthefirstsixperiods.Also,itsvariationcurvefitswiththelogarithmiccurve.(2) When the cyclic load stress amplitude increases from 10MPa to 35MPa, 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 whenthestressamplitudeislowerthan25MPa.(3)Duringthewater-rockinteractionprocess,thecloselyknitmicrostructureof rockgraduallybecomeslooseandporous,whichresultedinthedegradationofmacroscopicphysicalandmechanicalpropertiesof sandstone.(4)Intheanalysisoftheseismicresponseofthebankslope,theactualwater-rockinteractionprocessandtheseismic levelofthebankslopeshouldbemoreconsidered.Tofindoutfurtheraccuratereflectionintheearthquakeresistanceanddynamic response of the bank slope, it is necessary to select the reasonable dynamic parameter to carry out seismic research.