在三轴固结排水试验中,偏应力大小的求解过程是基于试样始终是等体积圆柱体的假定来进行推导的,该假定认为在整个试验过程中,试样任意横截面的面积相等。但是在试验过程中,由于端部效应的存在,使得试样在轴向加载的过程中逐渐变成了鼓形,这与偏应力的计算假定不符。为了计算三轴试验中鼓形试样受偏应力的大小,进行了一系列固结排水三轴试验,并根据试样的实际变形情况对试样所受的偏应力进行了重新推导。结果表明按照实际变形情况推导出的偏应力计算公式与规范采用公式不同,根据推导公式计算的偏应力值在一个范围内变化,其最小值较规范值小,最大值较规范值大;通过计算坝体沉降量从坝体安全的角度给出了粗粒土三轴固结排水试验强度计算时偏应力的推荐值。

The deviatoric stress calculating process of triaxial consolidation test is based on the assumption that the sample always keeps a cylinder shape with equivalent volume and the cross sectional area of the sample is equal at any location during the test. But in actual test the sample is drum shape in the test process due to end effect, which is inconsistent with the assumption. We deduce the deviatoric stress calculation formula according to the actual situation of sample deformation in consolidated drained triaxial test. Results show that different with that in specification, the value calculated from deduced deviatoric stress formula according to the actual deformation changes in a scope, with the minimum value lower and maximum value higher than standard value. By calculating dam subsidence, we also give the recommended value of deviatoric stress in coarse-grained soil’s triaxial consolidated drained test.