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

Earth dams using Jiangxi lateritic soil have been widely constructed in Jiangxi Province, China. Field observations showed uneven settlements and cracks on the earth dams, which was 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 cycles, threatening the safety and stability of Earth dams. For this reason, the dynamic characteristics of cracks of Jiangxi lateritic soil under drying-wetting (D-W) cycles and its microstructure mechanism were investigated in this study, with a maximum number N = 5 cycles considered. The microstructure of Jiangxi lateritic soil was measured using mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) tests, and its effect on the cracks patterns was quantitatively investigated through image processing technique. The results showed that: (i)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 cracks initiation and propagation was strongly related to the microstructure damage (e.g. aggregate decomposition and pore expansion), which was resulted from the applied D-W cycles. With the penetration of large pores, the cracks were generated; (ii) 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 and 4) and wetting-induced cracks ( N = 5). (iii) The crack dynamic hysteresis (CDH) behavior consists of two stages, which was 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 drying-wetting cycles on the cracks dynamic characteristics of Jiangxi lateritic soil, which can be helpful in the design of geotechnical engineering.