循环球应力对饱和软黏土动应变发展规律的影响及其作用机制

EFFECTS OF CYCLIC SPHERICAL STRESS ON DYNAMIC STRAIN LAW OF SATURATED SOFT CLAY AND ITS ACTION MECHANISM

循环球应力在土体动应力场中是普遍存在的,但是在以往的研究中往往被忽视。基于循环围压动三轴试验,通过循环围压和循环偏应力的耦合,初步研究循环球应力对饱和软黏土动应变发展规律的影响,并分析其作用机制。试验结果表明:循环球应力的存在不但改变动应变的发展速度,而且改变最大压应变与最大拉应变的比值,这种影响不但与循环球应力与循环偏应力的相位差有关,而且与循环偏应力的幅值有关。当相位差为180°时,压应变发展速度更快,而当相位差为0°时,拉应变发展速度更快。基于试验结果,分别从总应力和有效应力的角度解释循环球应力影响动应变发展规律的作用机制。

The cyclic spherical stress is very common in the dynamic stress field of soils;however,in previous researches,it was usually neglected.Based on the dynamic triaxial tests with cyclic confining pressure,the influences of cyclic spherical stress on the strain behavior of saturated clays are studied through coupling cyclic confining pressure and cyclic deviatoric stress.Moreover,the action mechanisms are also discussed.Test results show that the existence of cyclic spherical stress not only changes the development speeds of cyclic strain,but also changes the ratios of maximum compression strain to maximum extension strain.The influences are not only related to the phase differences between cyclic spherical stress and cyclic deviatoric stress,but also related to the amplitude of cyclic deviatoric stress.When the phase angle is 180°,the compressive strain develops more quickly;and when the phase angle is 0°,the tension strain develops more quickly.Based on the test results,the action mechanisms of cyclic spherical stress on the changes of dynamic strain behavior are explained from the perspective of the total stress and the effective stress,respectively.