Experimental study on dynamic characteristics of deep-sea energy gas-bearing soil under cyclic loading
Previous studies on deep-sea energy gas-bearing soil mainly focus on static load effects and uncontrollable discrete small bubbles of gas-bearing soil in size.In this study,a sample preparation method for controllable gas content and bubble size was proposed and consolidated undrained cyclic loading dynamic triaxial tests were conducted on deep-sea energy gas-bearing soil containing discrete large bubbles to analyze the cumulative plastic strain,hysteresis curve,dynamic pore pressure,and dynamic strength development of deep-sea energy gas-bearing soil under different cyclic stress ratios(CSR),effective confining pressures,saturation levels,and clay contents.The results show that the cumulative plastic strain can be divided into"stable growth type"and"unstable failure type".The rate of cumulative plastic strain growth increases with the the decrease of saturation and the increase of CSR,confining pressure,and clay content.The hysteresis loop of gas-bearing soil increases with the decrease of saturation and the increase of vibration frequencies,confining pressure and clay content,showing a decrease in elastic modulus and an increase in damping ratio.The development mode of dynamic pore pressure in gas-bearing soil can be divided into"slow growth type"and"sudden increase type".The rate of pore pressure growth accelerates with the decrease of saturation and the increase of CSR and clay content.Moreover,under cyclic loading,the dynamic pore pressure does not reach the same level as the effective stress,that is,no liquefaction failure phenomena occur to the sample before the axial strain reaches 5%.The dynamic intensity decreases with the decrease of saturation and the decrease magnitude shows an increasing trend with the decrease of saturation.
deep-sea energy soilgas-bearing soildynamic characteristicsdynamic triaxial testdisplacement dis-crimination criteria
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