PDF(Pubmed)
Abstract：
Swell-shrink characteristic soils exhibit a high susceptibility to cracking during the drying process, which poses a significant risk of various geological disasters. Among these, the occurrence of drying shrinkage acts as a prerequisite for the cracking phenomenon. Therefore, it is of utmost importance to comprehend the specific characteristics associated with the drying shrinkage mechanism. To investigate the drying shrinkage behavior of swell-shrink characteristic soils, a series of drying shrinkage experiments were conducted on long strip samples of red clay and expansive soil. Utilizing three-dimensional digital image correlation (DIC) technology, the surface displacement, strain, and anisotropic shrinkage rates of the soil samples during the drying process were obtained, and the size effect on the drying shrinkage of swell-shrink characteristic soil were analyzed. The research findings are as follows: The displacement development of the soil samples in the X and Y directions can be divided into two stages: a linear growth stage and a stable displacement stage. In the Z direction, the soil surface deformation can be divided into three stages: soil surface arching, vertical shrinkage, and shrinkage stabilization. The drying shrinkage of swell-shrink characteristic soil exhibits anisotropy, with the vertical shrinkage rate being the largest, followed by the longitudinal and then the transverse directions. Additionally, the soil sample shrinkage exhibits a size effect, whereby the shrinkage rates in all directions increase with increasing sample width and thickness. During the drying shrinkage process, the stress state on the soil surface evolves from initial tensile strain to subsequent compressive strain. The strain at different positions and times within the soil sample is not uniform, resulting in the non-uniformity and anisotropy of the sample shrinkage. This study provides important insights into the cracking mechanism of swell-shrink characteristic soils and serves as a valuable reference for related laboratory experiments, which will contribute to better prediction and control the geological hazards caused by the drying shrinkage of swell-shrink characteristic soils.
摘要：
膨胀收缩特性土壤在干燥过程中表现出很高的开裂敏感性，这对各种地质灾害构成了重大风险。其中,干燥收缩的发生是开裂现象的先决条件。因此,了解与干燥收缩机理相关的具体特征至关重要。为了研究膨胀收缩特征土壤的干燥收缩行为，对红黏土和膨胀土的长条样进行了一系列干缩试验。利用三维数字图像相关(DIC)技术,表面位移，应变，并获得了土壤样品在干燥过程中的各向异性收缩率，分析了尺寸效应对胀缩特征土干燥收缩的影响。研究结果如下：土样在X和Y方向上的位移发展可分为两个阶段：线性生长阶段和稳定位移阶段。在Z方向,土面变形可分为三个阶段:土面拱,垂直收缩，和收缩稳定。胀缩特征土的干缩表现出各向异性,垂直收缩率最大，其次是纵向，然后是横向。此外,土壤样品收缩表现出尺寸效应，其中在所有方向上的收缩率随着样品宽度和厚度的增加而增加。在干燥收缩过程中，土壤表面的应力状态从初始拉伸应变演变为随后的压缩应变。土样内不同位置和时间的应变不均匀,导致样品收缩的不均匀性和各向异性。该研究为研究胀缩特性土的开裂机理提供了重要的见解，并为相关实验室实验提供了有价值的参考。这将有助于更好地预测和控制由胀缩特征土壤干燥收缩引起的地质灾害。
