单幅值循环动载下饱和砾砂动力特性试验研究

Experimental Study on Dynamic Characteristics of Saturated Gravel under Cyclic Dynamic Load with Single Amplitude

为探究动应力比和围压对饱和砾砂动力特性的影响,通过一系列饱和砾砂动三轴试验,分析了动应力比和围压对饱和砾砂轴向累积应变、回弹模量、动孔隙水压力以及滞回曲线的影响。结果表明:在同一围压下,动应力比增加时,砾砂的轴向累积应变、回弹模量增大,而动孔隙水压力减小;不同围压下,饱和砾砂的轴向累积应变、回弹模量以及动孔隙水压力均随围压的增加而增大;围压的增大有利于提高土体能量耗散的能力,而振次的增加会使土体的耗能作用减小;滞回曲线的倾斜程度随动应力比、围压以及振次的增加而增大,表明土体的回弹模量增加、刚度增大;滞回曲线的演化规律能够更加形象地反映出土体形变、刚度和耗能作用的变化,对土体动力特性进行分析时应结合滞回曲线的演化规律进行综合分析。

In order to explore the influence of dynamic stress ratio and confining pressure on the dynamic characteristics of saturated gravel sand,a series of dynamic triaxial tests of saturated gravel sand were carried out.The effects of dynamic stress ratio and confining pressure on the axial cumulative strain,rebound modulus,dynamic pore water pressure and hysteresis curve of saturated gravel sand were studied.The results show that under the same confining pressure,as the dynamic stress ratio increases,the axial cumulative strain and rebound modulus of the gravel increase,while the dynamic pore water pressure decreases.Under different confining pressures,the axial cumulative strain,rebound modulus and dynamic pore water pressure of saturated gravel sand increase with the confining pressure increase.The confining pressure increase is conducive to improving the energy dissipation ability of soil,while the vibration frequency increase will reduce the energy dissipation of soil.The inclination of the hysteresis curve increases with the increase of dynamic stress ratio,confining pressure and vibration frequency,indicating that the soil's rebound modulus and rigidity increase.The evolution law of hysteresis curve can vividly reflect the change of soil deformation,stiffness and energy dissipation.Comprehensive analysis combined with the evolution law of hysteresis curve should be conducted when analyzing the dynamic characteristics of soil.