露天煤矿废弃地植物根系抗剪强度试验

Experimental study on shear strength of plant roots in open-pit coal mine wastelands

为探讨煤矿废弃地植被恢复时的保水固土效果,分析根-土复合体含水率和含根量对抗剪强度的影响机制,比较含水率和含根量对土壤黏聚力和内摩擦角的作用效果,从而为煤矿废弃地的生态修复提供理论依据。以新疆呼图壁县西沟煤矿废弃地为研究区,选取黑麦草、披碱草、新麦草、高羊茅、早熟禾、冰草和紫羊茅7种植物进行根-土复合体的抗剪强度试验,并测量其土壤含水率和含根量。结果表明:根-土复合体的含水率和含根量主要通过影响土壤黏聚力来影响抗剪强度,对内摩擦角的影响并不显著;多数根-土复合体的土壤黏聚力随含水率增加而减小(除紫羊茅),随含根量的增加而增大;抗剪强度与法向压力呈线性相关关系,但不同根-土复合体随法向压力的增加抗剪强度的增量不同,抗拉强度的大小表现为高羊茅>冰草>早熟禾>紫羊茅>黑麦草>披碱草>新麦草。该研究结论为:高羊茅和冰草具有良好的土壤加筋作用和固土性能,黑麦草和早熟禾能够更好地适应研究区环境,且具有较强的抗拉性能,可以作为研究区生态恢复的优选草种。

[Background]Plant roots play an important role in maintaining moisture,fixing soil and preventing soil erosion in the process of ecological restoration of abandoned coal mines.With the application of soil-reinforcement by roots technology and the promotion of ecological engineering,the contribution of plant roots to soil stability has attracted extensive attention from scholars around world.In order to investigate the effect of water retention and soil consolidation during the restoration of herb in abandoned coal mine,the influence of water content and root amount of root-soil composite on shear strength was analyzed,comparing the effect of soil moisture and root with soil cohesion and internal friction angle respectively,thus providing a theoretical basis for the ecological restoration of coal mine wasteland.[Methods]Taking the abandoned land of Xigou Coal Mine in Hutubi county,Xinjiang as the research area,7 plant species of Lolium perenne L.,Elymus dahuricus Turcz.,Psathyrostachys juncea(Fisch.)Nevski,Festuca elata Keng ex E.Alexeev,Poa annua L.,Agropyron cristatum(L.)Gaertn.and Festuca rubra L.were selected for root-soil complex shear strength test and measurement of soil moisture content and root amount.[Results]The moisture content and root content of the root-soil complex mainly influence the shear strength by affecting the soil cohesion,and the effect on the internal friction angle is not significant.The soil cohesion of most root-soil complexes is negatively related to moisture content(except for F.rubra L.),which increases with the root content.The shear strength is linearly related to the normal pressure,but the shear strength of different root-soil composites increases in different account.The tensile strength is as follows:F.elata Keng ex E.Alexeev>A.cristatum(L.)Gaertn.>P.annua L.>F.rubra L.>L.perenne L.>E.dahuricus Turcz.>P.juncea(Fisch.)Nevski.Among them,F.elata Keng ex E.Alexeev has better soil-fixing performance,and A.cristatum(L.)Gaertn.has better soil reinforced effect.Therefore,they are recommended as the first choice for soil-reinforcement plants in the study area.Secondly,P.annua L.and L.perenne L.can be considered.P.juncea(Fisch.)Nevski.has the worst soil-fixing properties;E.dahuricus Turcz.and F.rubra L.are more suitable as solid soil plants in the moister areas.[Conclusions]The results of this study provide theoretical basis for the restoration of abandoned land in Xigou Coal Mine and other similar environments,and have theoretical and practical significance for further discussion on effective prevention and control of soil erosion and soil erosion in abandoned coal mines.