本文選題：生物埂　切入點：粘聚力　出處：《草業(yè)學報》2017年06期 　論文類型：期刊論文

【摘要】：在次降雨過程中,生物埂土壤內(nèi)部經(jīng)歷了干燥-濕潤-再干燥的干濕循環(huán)過程,對生物埂坎土壤抗剪強度和穩(wěn)定性造成潛在影響;本文主要研究次降雨后干濕作用對桑樹生物埂土壤抗剪強度衰減-恢復效應。采用根系挖掘法、室內(nèi)直剪試驗和土壤理化性質(zhì)分析等綜合性研究手段,全面研究了桑樹生物埂根系分布、在次降雨前后(降雨第0~9天)干濕循環(huán)過程中生物埂土壤理化變化及抗剪強度響應特征、根系對土壤抗剪強度增強效應。結(jié)果表明:(1)不同徑級根系隨土層深度變化顯著,根徑級≤1mm的根系集中于土層深度較淺(0~20cm)位置,而2mm根徑級≤5mm的根系在較深層次(20~40cm)土壤中穿插生長。(2)桑樹生物埂土壤垂直層次土壤容重、土壤孔隙在次降雨前后均存在顯著差異(P0.05)。除30~40cm土層外,土壤容重在經(jīng)過一次干濕循環(huán)作用后有所增加,增加幅度為5.47%~5.88%,且在第5天時土壤容重達到最大值(各層次依次為1.39,1.37,1.44g/cm3);土壤總孔隙度、毛管孔隙度隨干濕作用時間呈現(xiàn)先增大后減小的趨勢,在第1天(峰值點)發(fā)生轉(zhuǎn)折變化。(3)生物埂土壤粘聚力和內(nèi)摩擦角隨著含水率增加呈現(xiàn)出一階指數(shù)衰減變化,各層次土壤粘聚力和內(nèi)摩擦角在干濕作用過程呈現(xiàn)出先衰減后恢復的"V"型變化趨勢;粘聚力與含水率的相關系數(shù)為0.68,內(nèi)摩擦角與含水率的相關系數(shù)為0.73。(4)桑樹生物埂不同根系徑級土體的粘聚力、內(nèi)摩擦角和抗剪強度與根長密度和根表面積密度呈正相關關系,相關系數(shù)在0.30~0.79之間。土壤粘聚力和內(nèi)摩擦角隨含水率增加呈線性衰減的趨勢,在次降雨前后生物埂土壤容重、土壤孔隙特征表現(xiàn)為顯著性變化;土壤粘聚力和內(nèi)摩擦角的變化與根長密度、根表面積密度呈正相關關系。生物埂能夠改善土壤結(jié)構(gòu)及其土壤通氣性,提高土壤養(yǎng)分含量,降低土壤容重,增加土壤孔隙度,為坡耕地耕層作物的生長發(fā)育、產(chǎn)量的提高創(chuàng)造有利的條件。
[Abstract]:In the process of rainfall, the soil of biological ridge experienced dry-wet-re-drying cycle, which had a potential impact on the shear strength and stability of the soil. In this paper, the effects of dry and wet effects on soil shear strength attenuation and recovery of mulberry biological ridges after rainfall were studied. The methods of root excavation, indoor direct shear test and physical and chemical properties analysis of mulberry soil were used to study the effects of drying and wetting on mulberry soil. The root distribution of mulberry biological ridge was studied comprehensively. The soil physical and chemical changes and shear strength response characteristics of the biological ridge during the dry and wet cycle before and after the second rainfall (the 9th day of rainfall) were studied. The effect of root system on soil shear strength was enhanced. The results showed that the root system of different diameter grade varied significantly with the depth of soil layer, and the root system with root diameter of 鈮，

本文編號：1572458