黄土边坡降雨冲刷模型试验研究

MODEL EXPERIMENT STUDY ON EROSION OF LOESS SLOPE DUE TO RAINFALL

针对边坡表层受降雨冲刷易引发水土流失并导致滑坡灾害的难题,以黄土边坡为例,提出了一种基于减排水理念的生态固坡综合防护方法。采用自主研制的边坡降雨模拟实验装置,考虑不同改良剂掺量、格构防护形式、雨强、历时、坡比等因素对防护效果的影响,研究不同因素组合影响下的边坡土体侵蚀规律与演化机理。试验结果表明,黄土边坡坡面侵蚀可归纳为溅蚀、片蚀、沟蚀、坍塌、滑坡的过程;随改良剂掺量增加,改良边坡抗侵蚀能力增强,综合考虑提出改良剂的最优掺量为3‰;与素土边坡相比,3‰改良剂改良边坡受雨强的影响较小;随降雨历时增加,改良剂改良效果越明显;改良剂、框格梁以及两者的综合利用,均能有效提高边坡抗雨水冲刷与侵蚀能力;边坡坡度增大至一定程度,坡体受降雨侵蚀易突然发生整体滑塌,需进行重点关注;改良剂主要通过絮凝作用使土颗粒之间镶嵌黏结更紧密,从而提高黄土的持水性和抗蚀性。

Slope surface erosion due to rainfall is liable to cause soil erosion and landslide hazard,which is a difficult problem. This paper takes a loess slope as an example and puts forward a comprehensive protection method of ecological slope based on the concept of water reducing and drainage. In order to study on soil erosion law andevolution mechanism of slope under different factors,the simulation experiments were carried out with the selfdeveloped slope rainfall simulator. It considers modifier content,lattice protective form,intensity,duration,aspect ratio on the effect of protection. Test results show that the loess slope surface erosion can be summarized as splash erosion,sheet erosion,gully erosion and landslides. With the increase of the modifier content,the corrosion resistance of the improved slope is enhanced,and the optimal dosage of the modifier is 3‰. Compared with the plain loess slope,rainfall intensity has little influence on improved slope with 3‰ modifier. With the increase of rainfall duration,the imp4rovement effect of the modifier is more obvious. Modifier and frame as well as their comprehensive utilization can effectively improve the slope resistance to rainfall erosion. When the slope gradient increases to a certain extent,the slope is prone to collapse suddenly due to the rainfall erosion,which needs to be emphasized. The modifier mainly makes the soil particles more compacted by flocculation,so as to improve the water holding capacity and corrosion resistance of loess.