饱和重塑黏性土一维固结状态下应变率效应的经验模型研究

Empirical model study on strain-rate effect of saturated remolded cohesive soil under one-dimensional consolidation

为考察饱和重塑黏性土应力应变率的相关响应,本文基于主次固结耦合思想设计了单轴恒定应变率固结试验,以取自西安北郊重塑饱和后的土样为研究对象,在0.9~55.4%/h的加载速率范围内开展试验研究,依据试验曲线的特征定义了表观固结阻力,并分析其应变率效应。试验结果表明:当轴向应力小于表观固结阻力时,无明显的应变率效应,反之,应变率效应表现明显;试验土样在竖向应变率增大62倍时,其表观固结阻力平均增大60.2%。根据表观固结阻力体现的应变率效应,借助其为中间变量建立时间隐式率相关的经验本构模型,该模型参数简单,代表的物理意义明确,对研究饱和重塑黏性土的应变率效应具有较好的理论参考价值。

In order to investigate the stress-strain rate-dependent response of saturated remolded cohesive soil,a uniaxial constant strain rate consolidation test was designed based on the idea of primary-secondary consolidation coupling.Taking the saturated remolded cohesive soil from the northern suburb of Xi’an as the research object,the experimental research was carried out in the loading range of 0.9%/h~55.4%/h,and according to the curve characteristics of the experimental data,the apparent consolidation resistance was defined,and the strain rate effect was analyzed.The results showed that when the axial stress was less than the apparent consolidation resistance,there was no obvious strain-rate effect;otherwise,the strain-rate effect was obvious;When the vertical strain rate of the soil sample increased by 62 times,its apparent consolidation resistance increased by an average of 60.2%.According to the strain-rate effect of apparent consolidation resistance,a rate-dependence empirical constitutive model with time implicit was established for intermediate variables by using the apparent consolidation resistance.The model parameters are simple,and the physical meaning is clear.It has certain theoretical value for the study of strain-rate effect of saturated remolded cohesive soil.