降雨-蒸发条件下土体开裂临界含水率演变规律研究

Evolution law of critical moisture content of soil cracking under rainfall-evaporation conditions

为研究降雨-蒸发过程中土体裂隙发展演化规律,依托裂土边坡足尺模型试验,测量土体表层含水率,采用图像矢量化技术提取裂隙率,对土体裂隙域及基质域开裂含水率演变规律进行了研究,基于非饱和土水平应变增量本构模型推导并计算了土体基质域临界开裂基质吸力及含水率。研究结果表明,降雨-蒸发过程中土体开裂具有可重复特征,且裂隙率随降雨-蒸发次数增加总体呈增加趋势;土体裂隙域开裂含水率随降雨-蒸发次数增加而增加,基质域与之相反;基质吸力对裂隙的开裂扩展既可有抑制作用,也可产生促进作用;基于均质各向同性非饱和土应变增量本构模型计算得到的土体基质域开裂含水率范围与实测值较为接近,且该模型能较好地解释裂隙域与土体基质域开裂含水率的变化规律。

This paper aims to investigate the evolution law of soil cracks in the rainfall-evaporation process.Based on a full-scale slope model test,the surface moisture content of soil was measured,and the crack ratio was extracted by image vectorization technology.The critical water content during the repeated cracking process was studied by dividing the cracked soil into soil matrix and crack domains,respectively.The critical cracking matric suction and water content of the soil matrix domain were deduced and calculated according to the horizontal strain increment constitutive model of unsaturated soil.The results show that the soil cracking during the rainfall-evaporation process has repeatable characteristics,and the crack rate generally increases with the increase of rainfall-evaporation times;the cracking water content in the crack domains increases with the increase of rainfall-evaporation cycles,while the matrix domain has the opposite result.The matrix suction can both inhibit or promote the generation and propagation of the cracks.In the soil matrix domain,the cracking water content range calculated based on the constitutive model of the homogeneous isotropic unsaturated soil strain increment is close to the measured value,and the model can explain the variation law of cracking water content in soil matrix and crack domains.