为了研究红土边坡在干湿交替条件下的破坏特征及其破坏机理,根据相似理论,建立了与工程边坡相似的模型边坡,采用测试元件,对试验边坡开展了长达一年半的监测,分析其在降雨、非降雨等干湿交替条件下边坡破坏特征及其破坏机理。研究结果表明:在非降雨条件下,试验边坡表面红土层裂缝的产生与其含水率有关,当其含水率低于27.5%时,其表面红土层开始产生裂缝,且裂缝数量和裂缝宽度随含水率的减小经历了缓慢增加、急剧增加和稳定发展的3个阶段;在干湿循环条件下,试验边坡表面红土层的裂缝经历了开裂、愈合、再开裂的循环过程,随降雨次数的增多,裂缝将沿边坡表面向其深部发展,且其宽度和深度也逐渐增加,地表水将沿裂缝深度方向渗流到边坡底部的红土层中,造成红土颗粒泥质化;在干湿交替作用一年半后,地表水将沿试验边坡2条垂直裂缝渗流到边坡底部的土体中,导致其由下往上逐层被软化崩解,最终形成导水通道,诱发边坡大规模滑坡。

To obtain the failure characteristics and failure mechanism of red soil slope in cyclic wetting-drying condition, physical model test was conducted in line with the similarity theory by monitoring the slope model for one year and a half. Results revealed that under drying condition, the generation of cracks on the surface of the red soil slope is related to water content; in particular, when water content is below 27.5%, cracks were generated on the surface of red soil; and with the decline of water content, the number and width of cracks experienced gentle increase, sharp increase and steady development in sequence. Under cyclic wetting and drying, cracks on red soil surface were generated, coalesced, and then regenerated; and with the increase of rainfall cycles, cracks developed towards the deep, correspondingly with a gradual increase in crack width and depth; surface water permeated along the cracks into the red soil layer at the bottom of slope, resulting in the argillation of red soil particles. Furthermore after one and a half years of cyclic wetting and drying, surface water permeated to the bottom of slope along two vertical cracks, and softened and disintegrated the slope from bottom to the top, finally gave rise to water conducting channels which induce large-scale landslides.