干湿循环作用下压实黄土裂隙演化特征

Evolution Characteristics of Cracks in Compacted Loess under Drying-Wetting Cycles

为了解干湿循环作用下压实黄土裂隙演化规律,通过自制装置开展考虑不同干密度和干湿循环路径的干湿循环裂隙试验,获取土样表面裂隙发育图像。采用PCAS软件对土样裂隙进行定量化分析,获得裂隙形态特征参数,并结合数字图像相关(DIC)法获得土样应变场。结果表明:①压实黄土裂隙发育随干湿循环次数的增长可划分为裂隙缓慢发展、快速增长和裂隙缓滞发展3个阶段;②裂隙发育程度受干密度、干湿循环路径共同影响,干密度越大,裂隙越难发育,干湿循环幅度越大、下限含水量越低,裂隙发育越充分;③裂隙中心线部位第一主应变随距起裂点距离的增大呈线性减小趋势,裂隙尖端、裂隙临近区块土体所受挤压作用随远离裂隙程度增大而减弱。研究成果可为压实黄土裂隙演化特征分析提供参考。

To investigate the evolution of fractures in compacted loess under drying-wetting cycles,we conducted crack tests by varying the dry density and drying-wetting path using a self-developed device,and captured the surface crack patterns of soil samples.Furthermore,we quantitatively analyzed the soil cracks using PCAS software for morphological parameters and obtained strain fields via DIC(Digital Image Correlation)method.Our findings revealed three distinct stages in the development of compacted loess cracks with increasing drying-wetting cycles:initial slow growth,subsequent rapid expansion,and stabilization.Crack development intensity was influenced by both dry density and drying-wetting cycle paths.Higher dry densities hindered crack propagation,while larger amplitude of drying-wetting and lower moisture thresholds cultivated crack development.Additionally,the first principal strain along the crack’s central line exhibited a linear decrease with distance from the crack initiation point,indicating diminishing soil compression effects near the crack tip and adjacent blocks.These results provide insights into understanding crack evolution in compacted loess.