| With the development of economy and society,China has made a lot of achievements in infrastructure and engineering construction.The infrastructures have brought convenience to people's life and production.At the same time,construction excavation has formed a large area of bare slope,which has caused a series of disasters such as soil erosion and landslide,so the ecological control is imminent.The eco-restoration technology of vegetation concrete is a kind of ecological protection technology developed for the protection and greening of rock slope,which can realize the double effects of slope wound reinforcement and vegetation restoration,and has been widely used in the field of slope eco-restoration.However,due to the characteristics of high and steep slopes,the natural rainfall intercepted by the slopes is very limited.At present,automatic sprinkling irrigation and artificial sprinkling irrigation are mostly used to supplement water.However,a large amount of water flows directly to the foot of slopes for gravity under sprinkling irrigation,resulting in a great waste of water resources,and the artificial irrigation is uneven,which is prone to omission.From the perspective of increasing irrigation efficiency and wetting uniformity,drip irrigation technology can be applied to vegetation concrete slope restoration project,which is of great significance to the development of slope eco-restoration technology and drip irrigation technology.Based on the above problems,this paper took vegetation concrete as the research object and conducted drip irrigation experiments with single point source and double point source indoors.The effect of emitter flow,irrigation volume,slope and emitter spacing on wetting peak transfer and water distribution of vegetation concrete were studied as well as the redistribution of wetted volume water after 24 hours of drip irrigation.The conclusions were as follows.Under the condition of drip irrigation with single dripper,the transfer distance of wetting peak increased with the increase of irrigation duration,but it always showed the maximum vertical downward and the smallest vertical upward.Through SPSS fitting,it was found that the relationship between wetting peak and irrigation duration was better fitted by power function,and the elliptic model was more accurate in fitting the contour eigenvalues of wetted zone.With the increase of irrigation duration,the transfer distance of wetting peak increased,and the minimum transverse-vertical infiltration ratio was 0.89 on90°slope.With the increase of flow rate,the water content around the emitter increased sharply,but the soil suction was limited and the water diffusion was less than the emitter outflow.Therefore,the emitter flow rate and the soil water conductivity should be fully considered to prevent soil erosion at the emitter.The water content of vegetation concrete was measured by drying method.It was found that the water content in the same position of wet soil increased with the increase of irrigation duration,up to 30%,and the water content under the dripper was always greater than that above the dripper and in the horizontal direction.In the same direction,the closer to the dripper,the higher and slower the moisture content changed.The water content of vegetation concrete above the dripper was affected by flow,irrigation volume and slope.The effect was the greatest,and the effect on the water content below the emitter was the smallest.Using CAD to calculate wetting volume,there was a significant linear relationship between wetting volume and infiltration time of vegetation concrete,and the average water content fluctuated greatly with larger dripper discharge.With the increase of flow rate,the effective wetting volume of vegetation concrete decreased at low effective water content boundary,while increased at high effective water content boundary,reaching a maximum of 19803 cm~3.24 hours after the end of drip irrigation,the transfer distance of wetting peak in vertical direction,vertical direction and horizontal direction increased correspondingly,and the transfer increment of wetting peak in the same direction was proportional to the flow rate.For effective wetted volumn,the volume of effective wet soil under 65%?80%water content boundary decreased,while the volume of effective wetted volume under 60%?65%water content boundary increased.Under the condition of drip irrigation with double dippers,before intersection infiltration,the infiltration rule of each point source of double point source still follows the previous single emitter infiltration rule.When the distance between emitters was 35 cm,the intersection time of adjacent wetting soil was the earliest,and the intersection chord length increased with the increase of intersection time in the same direction.The intersection chord length reached the maximum vertical direction when the distance between emitters was 35 cm,which was 36.6 cm.By measuring the water content in the wetted soil,it was found that the closer the intersection infiltration body was to the center of the intersection surface,the higher the water content of the sampling point was.At the same distance from the intersection surface center,the water content of the vertical downward sampling point was larger than that of the vertical upward and horizontal direction.The water content of vegetation concrete had a significant linear relationship with the distance from the center of the intersection surface,and the absolute slope value in the intersection chord length curve was slightly larger in horizontal direction than in vertical direction,that is,the water content of wetted body decreased greatly along the intersection chord migration direction in horizontal direction.With the increase of dripper spacing,the wetting uniformity and average water content of vegetation concrete in horizontal and vertical neighborhood of dripper decrease.The average moisture content in horizontal neighborhood was higher than that in vertical neighborhood of dripper at the same dripper distance,and the average moisture content was above the effective moisture content,that is,the average moisture content in different dripper spacing was greater than18%.The volume relationship of wettied zone after 24 hours of drip irrigation was consistent with that at the end of drip irrigation.Under the condition of drip irrigation with double drippers,the increase of intersection chord length was larger than that of wetting peak migration distance under single dripper irrigation with 24 hours after the end of drip irrigation,and the increase of intersection chord length in horizontal direction was obviously larger than that in vertical direction.According to the above results,considering the factors of wetting peak migration,effective wetted volume,intersection effect and redistribution process,it is considered that the flow of single dripper should be 0.8L/h to 1.2L/h,the irrigation volume of single dripper should be 2.4L.The reasonable range of transverse adjacent dripper spacing is35cm?40cm,and the reasonable range of longitudinal adjacent dripper spacing is40cm?45cm.In addition,the selection of specific irrigation parameters should be combined with slope gradient and effective water content boundary of slope. |
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