室内外陡坡降雨侵蚀产沙过程相似性模拟分析

Similarity Between Erosion and Sediment Yield Processes on Steep Slopes with Simulated Rainfalls Under Indoor and Outdoor Conditions

为了探讨降雨条件下室内外不同土地侵蚀产沙的特性,在25°陡坡、人工降雨条件下,对邙山黄土和原状土侵蚀产沙过程的相似特性进行了室内外模拟试验,利用模糊贴近度计算方法对室内外侵蚀产沙过程进行分析研究。结果表明,在一定的雨强条件下,降雨初期小区径流量、含沙量、剪切力和产沙量相对都较小,随着降雨时间的延长均逐渐增大;当降雨进行到一定时间段时,各指标均会出现激增点,此后急剧增加,最终达到相对稳定状态;在25°情况下,室内2种容重土样的径流剪切力、径流量、含沙量以及产沙量的变化过程与野外原状土的贴近程度都比较高,且同种雨强情况下容重较大的土样贴近度基本上都大于容重较小的土样,这说明要想达到与野外更好的相似,容重1.2g/cm3的邙山黄土比1.0g/cm3的模拟情况更好。

In order to study the chatacteristics of different soil erosion and sediment yield indoor and outdoor under rainfall condition,the erosion processes of Mangshan mountain loess were tested under laboratory and undisturbed conditions on 25° steep slopes under artificial simulated rainfalls.The similarity characteristics of the indoor and outdoor process of erosion and sediment yield were analyzed by the fuzzy closeness degree calculation method.The results show that with the rains of same intensity,runoff amount,sediment concentration,shear stress,and sediment yield of different soil bulk densities were fairly low at the initial stage and increased gradually over time;when the rain intensity reached the hyperplastic spot,these indicators increased sharply to the steady state within a few minutes.On 25° steep slopes,the nearness degree of the shear strength,runoff rate,sediment concentration and sediment yield of both indoor and outdoor simulation were very similar for the two kinds of soil bulk densities.The nearness degree of the high bulk density（1.2 g/cm3） soil was greater than the low bulk density（1.0 g/cm3） soil.This implies that in order to achieve a laboratory condition similar to the field condition,the soil with higher bulk density should be applied in the simulations.