考虑时间效应的人工制备结构性土应变软化特性影响研究

The Study on the Effect of Curing Time on the Properties of Artificial Structural Soil Strain Softening Considering the Time Effect

通过人工制备结构性土的室内试验获取相关参数是构建土体结构性数学模型的基础和关键。选取结构性黄土作为代表性试验研究对象,在土样加入一定含量的硅酸盐水泥,将装有标准试样的饱和器放入饱和罐进行抽气饱和并养护,将每组试样分别在100、150、200 kPa的围压中进行多次不固结不排水三轴压缩试验,获得了不同养护时间的试样在不同围压条件下的偏应力-轴向应变曲线,并探讨了应变软化系数与养护时间的规律以及不同养护时间对试样应变软化特性的影响。分析结果表明:养护时间对人工制备结构性土强度和结构性影响较大,养护时间越长,强度和结构性越高;应变软化系数能较好地反应土体的结构性特征,通过线性拟合得到了不同围压下养护时间和应变软化系数关系;为了更好地模拟天然结构性土,需要合理选取养护时间,3～7 d较为合理。

It is the foundation and key to build the mathematical model of the soil structure through the indoor test of artificially prepared structural soil to obtain relevant parameters. The structural loess was selected as the representative experimental study object. A certain amount of Portland cement was added to the soil sample. The saturator equipped with the standard sample was put into a saturated tank to conduct gas saturation and conservation. The unconsolidated and undrained triaxial compression tests were performed in confining pressures of 100 kPa, 150 kPa, and 200 kPa for each group of samples, and the deviatoric stress-axial strains of samples with different curing times were obtained under different confining pressures. The law of strain softening coefficient and curing time and the influence of different curing times on the strain softening characteristics of the samples were also studied. The analysis results show that： The curing time has a great influence on the strength and structural properties of artificially prepared structural soils, and the longer the curing time, the higher the strength and structure; The strain softening coefficient can reflect the structural characteristics of soil better, and the relationship between curing time and strain softening coefficient under different confining pressures is obtained by linear fitting; In order to better simulate the natural structural soil, it is necessary to reasonably select the conservation time, which is reasonable for 3～7 days.