一种测试动三轴试样泊松比的方法

Measuring method for Poisson ratio of cyclic triaxial specimens

利用非接触式位移传感器研制了一套测量动三轴试样径向变形的装置。针对试样两端透水石对试样径向变形的约束,推导了对实测径向变形的修正关系。利用径向与轴向变形测量装置,就可以依据实测动三轴试样的轴向与径向变形确定其泊松比。通过橡胶、饱和细砂、饱和软粘土试样固结不排水动三轴试验与结果分析,说明利用这里提出的方法可以比较客观地确定动三轴试样的泊松比。这里的研究结果还表明,固结后的饱和三轴土样在不排水条件下受振动应力作用时,当其轴向动应变从10-5增大至10-3时,泊松比的变化基本为一常数,且与固结压力的大小无关,将其取为接近0.5是合理的。

A new device measuring the radial displacement of cyclic triaxial specimens is developed using non-contact displacement transducer.Formulas correcting measuring radial displacements are derived to consider the effects of porous stones at the ends of specimens on radial displacements.Poisson ratio of cyclic triaxial specimens can be determined based on measuring axial and radial displacements using radial and axial displacement measurement devices.It is shown that the method determining Poisson ratios is reasonable by analyzing consolidation undrained cyclic triaxial test results of rubber,saturated fine sand and soft clay specimens.Research results also show that Poisson ratio is almost constant and independent of the consolidation pressure when axial strains increase from 10-5 to 10-3 for consolidated saturated specimens with cyclic stresses in undrained condition.It is reasonable that the Poisson ratio of a saturated specimen be considered as 0.5.