干密度初始含水率坡度对紫色土崩解特性的影响

Effects of dry density,initial water content,and slope gradient on the disintegration characteristics of purple soil

为研究干密度、初始含水率和坡度对紫色土崩解特征的影响,通过采用自制仪器对27种不同干密度、不同初始含水率和不同坡度的紫色土进行崩解试验,为三峡库区消落带静水侵蚀导致的水土流失现象提供理论依据,分别得到试样的崩解速率与干密度、初始含水率和坡度的曲线关系。结果表明:在相同初始含水率和坡度下,随着干密度的增加,崩解速率随着浸泡时间增加呈现先增加后减小;在相同干密度和坡度下,随着初始含水率的增加,崩解速率是随着浸泡时间的增加呈现先增加后减小;相同含水率且干密度一定下,随着坡度的增加,崩解速率随着浸泡时间的增加呈现先增加而后减小。研究发现试样崩解均是从底部开始崩解,且崩解区域随浸泡时间的增长由底部逐渐延伸到顶部。

[Background] Reservoir water fluctuation and the change of hydrogeological conditions lead to the destruction of coastal vegetation and the exposure of ground. The soil has been eroded severely under the influence of precipitation,periodic fluctuation of reservoir water level and surge,which brought significant influence on the local economy and environment. There will be the annual of 30 m in water level due to the completion of the Three Gorges Reservoir,thus there will be a water-level-fluctuation zone. In order to provide a reliable theoretical basis for the soil erosion control in the water-levelfluctuation zone of the Three Gorges Reservoir,this paper focuses on the effects of dry density,initial water content and slope gradient on the disintegration characteristics of purple soil. [Methods]Through the study of the relative fields to disintegration test,the self-made disintegration tank was used. The 10 degrees,20 degrees and 30 degrees of wedge were placed in the bottom of tank respectively. The sample case with the inner dimensions of 10 cm × 10 cm × 10 cm was placed on the wedge. In order to prevent the specimen from sliding during the experiment,naps were arranged at the tip of the wedge. There were27 kinds of purple soil in different initial water contents,dry densities and slope gradients by self-made instrument,which respectively provided the curve relationships among disintegration rate and dry density,initial water content,and slope gradient. [Results]The results showed that under the same initial watercontent and slope gradient,with the increase of dry density,the disintegration rates increased in the first and then decreased with the increase of immersion time. Under the same dry density and slope gradient,with the increase of initial water content,the disintegration rates increased first and then decreased with the increase of immersion time. Under the same initial water content and dry density,with the increase of slope gradient,the disintegration rates increased first and then decreased with the increase of immersion time. [Conclusions]By researching the experiment process,the disintegration region is always from the bottom of the sample,and then slowly extends to the top with the increase of immersion time. The research offers a foundation for the exploration of the disintegration mechanism in the water-levelfluctuation zone of the Three Gorges Reservoir. It provides theoretical basis for the protection and control of the water-level-fluctuation zone in the Three Gorges Reservoir. The research is also instructive,and provides technological support for the sustainable development of the environment,economy and society and the sustainable utilization in the Three Gorges Reservoir.