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为了探明排水条件对高温冻土应力松弛特性的影响,开展了室内松弛试验,研究了排水和不排水情况下高温冻土的应力松弛过程.结果表明:围压对高温冻土的松弛过程影响明显;不排水情况下,围压增大,松弛稳定历时延长,瞬时松弛量增大;松弛过程初期松弛速率受围压影响较大,而后逐渐减弱;排水情况下,松弛过程发展初期的松弛速率略高于不排水情况,但随松弛历时延长这种差别逐渐减小.随着预应变量增大,体积-时间曲线从应变软化状态过渡到应变硬化状态.不排水情况下,松弛过程中的体积变化过程呈先体积收缩后体积膨胀;排水情况下,高温冻土体积在较短历时内迅速收缩,而后基本保持不变.排水情况下,高温冻土的体积变形大于不排水条件下,围压愈大,这种趋势愈明显.
In order to find out the effect of drainage conditions on the stress relaxation characteristics of permafrost, an indoor relaxation test was conducted to study the stress relaxation process of permafrost with drainage and undrained conditions.The results show that the effect of confining pressure on the relaxation process of permafrost Obviously; under the condition of no drainage, the confining pressure increases, the laxity and stability extend for a long time, the instantaneous laxity increases; the initial relaxation rate is greatly affected by confining pressure and then gradually decreases; in the case of drainage, the relaxation rate at the initial stage of relaxation process Slightly higher than that of undrained condition, but the difference gradually decreases with the extension of relaxation time.With the increase of prestrain, the volume-time curve transition from strain softening to strain hardening.Under undrained conditions, The volume of the first volume shrinks after the volume expansion; under the condition of drainage, the volume of the permafrost shrinks rapidly within a short period of time, and then remains basically unchanged.Drainage case, the volume deformation of the permafrost is greater than the undrained condition, The bigger the pressure, the more obvious this trend.