堆石料的三轴松弛试验

Triaxial Relaxation Tests of Rockfill

针对以一个试样进行分级加载松弛试验的可行性问题,并研究堆石料的应力松弛规律,使用大型三轴仪对堆石料进行了常应变速率排水压缩试验和不同围压、不同应变水平的分级加载排水松弛试验,并建立了双曲线应力松弛方程。结果表明应力松弛阶段对后续常应变速率加载的应力应变关系趋势基本无影响,以一个试样分级加载方式进行松弛试验是可行的。在应力松弛阶段,体应变将增大0.13%～0.71%;偏应力将降低16%～28%,并最终趋于一非零稳定值。双曲线应力松弛方程能较好地模拟堆石的应力松弛规律,参数分析表明偏应力松弛的初始速率与围压和应变水平无关。

In order to analyze the feasibility of a single specimen used for step-loaded relaxation tests and study the time dependent stress relaxation properties of rockfill,two types of the drained triaxial compression tests were carried out with large-scale triaxial apparatus for rockfill.One was the constant-strain-rate triaxial compression tests,and the other was the step-loaded drained triaxial relaxation tests under different confined pressures and strain levels.A hyperbolic function was presented to simulate the laws of stress relaxation.The results showed that the relaxation phases have little effect on stress-strain behavior at subsequent constant-strain-rate triaxial compression tests.This means that a single specimen can be used reliably for step-loaded relaxation tests.The volumetric strain increase is 0.13%~0.71% and the magnitude of stress decrease is 16%~28% during relaxation phases.The rockfill can sustain a constant,nonzero value of deviator stress in the end.The laws of stress relaxation of rockfill can be simulated by the hyperbolic functions reasonably.Parameter analyses showed that the decay of the deviator stress rate at the initial time is a constant value,independent of the confined pressure and strain level.