干湿交替条件下花岗岩崩岗区土壤裂隙发育规律  

Development of Soil Cracks in Granite Benggang Area Under Wetting-drying Cycles

作　　者：韩杰欣 邓芷慧 王旌靡 邓羽松 黄智刚[1] 段晓倩 HAN Jiexin;DENG Zhihui;WANG Jingmi;DENG Yusong;HUANG Zhigang;DUAN Xiaoqian(Agricultural College of Guangxi University,Nanning 530004,China;Forestry College of Guangxi University,Nanning 530004,China)

机构地区：[1]广西大学农学院,南宁530004 [2]广西大学林学院,南宁530004

出　　处：《水土保持学报》2024年第5期262-271,共10页Journal of Soil and Water Conservation

基　　金：国家自然科学基金项目(42107350);中央引导地方科技发展资金项目(桂科ZY21195022)。

摘　　要：[目的]土体裂隙可以改变土壤结构,降低土体稳定性,进而加速崩岗发育。深入探究干湿交替条件下花岗岩崩岗区裂隙发育规律,具有重要的现实意义。[方法]以花岗岩坡面土壤的7个样点为研究对象,分别为坡上红土层(US)、坡中红土层(MS)、坡下红土层(DS)、崩壁红土层(RL)、崩壁过渡层(TL)、崩壁砂土层1(SL1)和崩壁砂土层2(SL2),进行干湿循环试验,结合数字图像处理技术对土体表观裂隙进行定量分析。[结果](1)花岗岩崩岗区土体R_(sc)、Na和土体破碎化程度随含水量的降低而增加,7个样点的R_(sc)、N_(a)、W_(a)、L_(a)均随干湿交替次数增加而逐渐降低;(2)集水坡面坡上、坡中红土层及崩壁砂土层裂隙连通度与砂粒呈显著正相关;各样点R_(sc)与饱和水含量、有机质、阳离子交换量、游离氧化铁呈显著正相关,黏粒/砂粒高的样点R_(sc)与黏粒/砂粒呈显著正相关。[结论]花岗岩崩岗区土壤不同土层之间的干缩裂隙发育存在差异,但发育规律基本为发育准备期、快速发育期、发育稳定期3个阶段;花岗岩土壤坡上红土层裂隙主要为干缩裂隙,坡下红土层干缩裂隙较少。[Objective]Soil cracks can change soil structure,reduce soil stability,and then accelerate the development of hill collapse.It is of great practical significance to study deeply the fracture development law of granite Benggang area under wetting-drying cycles.[Methods]7 samples of granite slope soil were taken as the research objects,including the upper part of the slope(US),the middle part of the slope(MS),the lower part of the slope(DS),the red soil layer of wall collapse(RL),the transition layer of wall collapse(TL),the sand layer1 of wall collapse(SL1)and the sand layer2 of wall collapse(SL2).The wetting-drying cycles experiments were carried out with these samples.Combined with digital image processing technology,the soil surface cracks are quantitatively analyzed.[Results](1)Soil R_(sc),Na and soil fragmentation degree in granite Benggang area increase with the decrease of water content,the R_(sc),N_(a),W_(a)and L_(a)of 7 sample points show a gradual decrease with the increase of dry and wet alternating times.(2)The connectivity of cracks in the red soil layer in the upper part of the slope,the middle part of the slope and the sand layer of the wall collapse are significantly positively correlated with the sand content.The R_(sc)at each sampling point is significantly positively correlated with saturated water content,organic matter content,cation exchange capacity,and free iron oxide content.Sampling points with high clay/sand content show a significant positive correlation with clay/sand content.[Conclusion]There are differences in the development of dry shrinkage cracks in different layers of soil of granite Benggang area,but the development rules are basically three stages:preparation stage,rapid development stage and stable development stage.The cracks of red soil layer on the upper part of the slope of granite soil are mainly shrinkage cracks,and the shrinkage cracks of red soil layer in the lower part of the slope are less.

关 键 词：崩岗侵蚀 花岗岩红壤 干湿交替 裂隙 

分 类 号：S157.1[农业科学—土壤学]