初始剪应力与振动频率对饱和粘土动强度特性影响研究

Effects of Initial Shear Stress and Vibration Frequency on Dynamic Strength of Saturated Clay

在初始剪应力作用下,土体会表现出不同的动力特性。通过对汶川重塑粘土的循环三轴试验,对地震荷载作用下饱和粘土动强度特性进行了研究,分析了破坏标准、初始剪应力和振动频率对饱和粘土动强度特性的影响。研究结果表明:选用应变破坏标准为应变值2.5%或转折应变能比较真实的反应土体破坏情况。通过引入地震荷载下土体等效破坏振次,计算得出了不同地震震级下饱和粘土动强度参数,从而为地震荷载作用下粘土地基稳定性分析提供数据支撑。初始剪应力和振动频率对饱和粘土的动强度有显著影响。相同振动次数下,初始剪应力越大,土体达到破坏所需的动应力越小,动强度参数也越小,初始剪应力的存在降低了土体动强度。相同振动次数下,振动频率越高,土体达到破坏所需的动应力越大,动强度参数也越大,土体动强度越大。

The soils would exhibit different dynamic characteristics under the initial shear stress.Through the dynamic triaxial test of remolded clay in Wenchuan area,the dynamic strength characteristics of saturated clay under seismic loading were studied,and the effects of failure criterion,initial shear stress and vibration frequency on the dynamic strength characteristics of saturated clay were analyzed.The results show that the strain failure criterion with strain value of 2.5%or the transitional strainεtp can reflect the soil damage situation more realistically.By introducing the equivalent failure vibration times of soil under seismic loading,the dynamic strength parameters of saturated clay under different earthquake magnitudes were calculated,which provides data support for the stability analysis of clay foundation under seismic loading.The initial shear stress and vibration frequency have a significant effect on the dynamic strength of saturated clay.Under the same vibration frequency,the larger the initial shear stress,the smaller the dynamic stress required for the soil to break,and the smaller the dynamic strength parameter.The existence of the initial shear stress reduces the dynamic strength of the soil.Under the same vibration times,the higher the vibration frequency,the greater the dynamic stress required for the soil to break,the larger the dynamic strength parameter,and the greater the dynamic strength of the soil.