北川县典型林分根-土复合体抗剪强度

Shear Strength of Typical Stand Root-soil Composites in Beichuan County

[目的]探讨不同林分根—土复合体的抗剪强度特征和其差异性,为更好地解决当地的水土流失问题提供理论依据。[方法]以四川省北川县为研究区,对当地几种典型林分的原状根—土复合体进行直剪试验,测量其抗剪强度、土壤性质及根系特性等相关指标,并利用主成分法进行抗剪强度影响因素的分析。[结果](1)不同林分根—土复合体抗剪强度差异明显。30年辛夷林(XY)抗剪强度最大,斑竹林(BZ)抗剪强度次之,5年柳杉林抗剪强度最小;(2)植物根系固土效果显著,根—土复合体的抗剪强度较素土增加值为0.13~0.99 kPa,平均增幅为350.0%;同时,根—土复合体的峰值点位移、软化段长度、残余剪切强度均得到增强,平均增幅分别为75.0%,66.7%,262.5%;不同林分类型根—土复合体的能量消耗总值出现不同程度的差异,但与其抗剪强度的大小变化基本保持一致;(3)通过主成分分析法对抗剪强度影响因素进行综合分析得出,除土壤容重与5~8 mm根系的干湿重外,其余指标均与之密切相关。[结论]植物根系可以很好地发挥固土效果,不同林分之间根—土复合体抗剪强度差异明显。

[Objective] The aims of this study are to explore the characteristics and disparities in shear strength of root-soil complexes in different forest stands,and to provide a theoretical basis for addressing local soil erosion issues more effectively.[Methods] This study focuses on Beichuan County,Sichuan Province.Direct shear tests were conducted on intact root-soil complexes of several typical forest stands in the area,measuring relevant indicators such as shear strength,soil properties,and root characteristics.Principal component analysis was utilized to analyze the influencing factors of shear strength.[Results](1) There were significant differences in shear strength among root-soil composites of different forest stands.The shear strength of 30-year-old Magnolia liliiflora forest(XY) was the highest,followed by Spotted bamboo Phyllostachys bambusoides forest(BZ),while the shear strength of 5-year-old Cryptomeria forest was the lowest.(2) The plant root system significantly contributed to soil stabilization,with an increase in shear strength of root-soil composites ranging from 0.13 kPa to 0.99 kPa,with an average increase of 350.0%.Additionally,the peak displacement,softening segment length,and residual shear strength of root-soil composites were enhanced,with average increases of 75.0%,66.7%,and 262.5%,respectively.The total energy consumption of root-soil composites varied among different forest types but generally correlated with their shear strength.(3) Comprehensive analysis through principal component analysis revealed that,apart from soil bulk density and the dry and wet weights of 5~8 mm roots,all other indicators were closely related to shear strength.[Conclusion] Plant roots play a significant role in soil stabilization.The notable differences in shear strength of root-soil complexes were observed among different forest stands.