Investigating the dynamic characteristics of crack formation of Jiangxi lateritic soil subjected to drying-wetting cycles

Abstract

Earthen dams made of Jiangxi lateritic soil are widely built in Jiangxi Province, China. Field observations showed uneven settlements and cracks in the earthen dams, which were attributed to the dynamic water-level fluctuation in the reservoir. Under this circumstance, the initiation and propagation of cracks of Jiangxi lateritic soil can be accelerated by the drying-wetting (D-W) cycles, threatening the safety and stability of earthen dams. For this reason, the dynamic characteristics of cracks in Jiangxi lateritic soil under D-W cycles and its microstructure mechanism were investigated in this study, for up to 5 cycles (N = 5). The microstructure of Jiangxi lateritic soil was measured using mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM), and its effect on the crack patterns was quantitatively analyzed through image processing technique. The results showed that: (1) The drying-induced desiccation cracks with increasing N was divided into three stages: the crack-generating stage (N ​= ​0–1), the crack-propagating stage (N ​= ​1–3) and the crack-stable stage (N ​= ​3–5). The initiation and propagation of cracks showed a strong correlation with microstructure damage (e.g., aggregate decomposition and pore expansion), which resulted from D-W cycles. With the penetration of large pores, the cracks were generated; (2) The wetting-induced healing behavior was categorized into two zones: the first zone corresponded to the healing of sub-cracks, while the second zone corresponded to that of primary cracks. With increasing N, the full-healing of primary cracks (N ​= ​2) was converted to the partial healing of primary cracks (N ​= ​3–4) and wetting-induced cracks (N ​= ​5); (3) The crack dynamic hysteresis (CDH) behavior consists of two stages, which were separated by a threshold water content (w_th). With increasing N, the w_th value decreased, indicating that more residual cracks, which were not healed in the wetting process, were accumulated. This study addressed the effect of D-W cycles on the cracks dynamic characteristics of Jiangxi lateritic soil, which can be helpful in the design of geotechnical engineering.