根土复合体加固露天矿山排土场边坡研究

Study on Reinforcement of Open-pit Mine Dump Slope by Root-Soil Composite

露天矿山开采损毁大量土地资源,并引发植被受损和山体滑坡等一系列生态环境问题,植被修复是解决露天矿山排土场边坡生态环境和自然灾害的优选方法。通过开展室内单根拉伸和拉拔试验,分析根径、土壤压实度和根系埋深对根—土界面抗拔拉力的影响,并探究紫花苜蓿根系在拉拔作用下的力学性能与破坏机理。结果表明:(1)紫花苜蓿的抗拉拔力与根径呈正相关,抗拉拔强度与根径呈负相关,相关系数高达0.9以上;(2)紫花苜蓿的抗拔力随压实度的增加呈现出先增大后趋于平稳的变化趋势;(3)压实度越大,埋置深度对抗拔力的影响程度越小;根径越大,埋置深度对抗拉力的影响程度越大。根系拉拔特性研究为加固露天矿山排土场边坡提供了理论依据。

The mining of open-pit mines destroys a large amount of land resources and causes a series of ecological and environmental problems such as vegetation damage and landslides.Vegetation restoration is the preferred method to solve the ecological environment and natural disasters of open-pit mine dump slopes.Aiming at the tensile properties of the interface between herbaceous plant roots and soil,alfalfa was taken as the research object,and the reinforcement effect of herbaceous plant roots on the shallow soil was used to improve the stability of open-pit mine dump slope.The effects of root diameter(0~2 mm),soil compaction(65%~95%)and root depth(8~15 cm)on the pull-out resistance of root-soil interface were analyzed by carrying out indoor single-root tensile and pull-out tests,and the mechanical properties and failure mechanism of alfalfa roots under pull-out were explored.The results show that:(1)The tensile and pull-out force of alfalfa increase with the increase of root diameter,while the tensile and pull-out strength decrease with the increase of root diameter.There is an obvious non-linear relationship between pull-out strength and root diameter,and the correlation coefficient is more than 0.9.The pull-out failure occurr when the pull-out failure reach the critical value of 0.73 mm.(2)With the increase of the degree of compaction,the pull-out resistance of alfalfa shows a trend of first increasing and then smoothly,indicating that after the peak of pull-out resistance,the friction force at the root-soil interface is greater than the tensile force of the root system,and the root system is broken.The greater the degree of compaction,the higher the probability of tensile failure.(3)The influence of buried depth on the pull-out resistance of alfalfa roots is related to the degree of compaction and root diameter.The greater the degree of compaction,the smaller the influence of buried depth on the pull-out resistance,and the greater the root diameter,the greater the influence of buried depth on the pull-out resistance.In Summary,root diameter,soil compaction and root burial depth are the main factors affecting the pull-out resistance of the root-soil interface.By studying the influence of root diameter,soil compaction and root buried depth on the pull-out resistance of root-soil interface can improve the stability of open-pit dump mine slope.