生态防护技术对稀土矿山边坡的固坡效果

Effects of Ecological Protection Technology on Slope Reinforcement of Rare Earth Mine

[目的]探讨以狗牙根系和竹格为主要材料组成的生态护坡模式对离子型稀土矿山原地浸矿采场边坡的固坡效果及加筋效应,为赣南地区稀土矿山采场边坡防治技术提供新的思路。[方法]使用狗牙根与稀土矿砂质黏土构成的根—土复合体为研究对象,通过直剪试验分析土壤含根量和含水率对抗剪强度的影响,采用二维有限元法分析“竹格+狗牙根”的生态护坡模式对边坡稳定性的增强作用,利用正交试验的直观分析法对竹桩间距、长度和直径支护参数进行优化。[结果]植物根系可以显著提升土壤的黏聚力,但对内摩擦角的影响较小。当含根量达到0.5%及以上时,根—土复合体的抗剪强度增幅呈下降趋势,即存在最优含根量。根系对25%含水率条件下的土体加筋效应最显著。该生态护坡模式能够显著增强边坡的稳定性,当竹桩长度取3m,间距2.5m,直径8cm时,其防护效果最佳。[结论]狗牙根根系在不同含水率、不同含根量条件下其加筋效果存在差异,“竹格+狗牙根”的生态护坡模式能够有效防止边坡浅层土的滑移。

[Objective] The slope protection and reinforcement effect of ecological slope protection model consisting of Cynodon dactylon and bamboo lattice as the main material on the slope of ion-absorbed rare earth mines by in-situ leaching were explored in order to provide a new idea for the stope slope control technology of rare earth mines in Southern Jiangxi Province.[Methods] Root-soil composite systems of C. dactylon and rare earth mineral sandy clay were used as the research object. The influences of root amount and water content on shearing strength were analyzed by direct shear tests. The effect of ecological slope protection mode of “bamboo lattice+ C. dactylon ” slope stability was analyzed by two-dimensional finite element method. The support parameters of spacing,length and diameter of bamboo piles were optimized by visual analysis method of orthogonal experiment.[Results] Plant roots could significantly enhance soil cohesion,but had little effect on internal friction angle. When root weight reached 0.5% or more,the shear strength of root-soil composite decreased,there was an optima root content. Root system had the most significant effect on soil reinforcement under 25% water content. The ecological slope protection model could significantly enhance the stability of slope. When the length of the bamboo pile was 3 m,the spacing was 2.5 m and the diameter was 8 cm,the protection effect was the best.[Conclusion] The reinforcement effect of C. dactylon root systems is different under different water content and root amount. The ecological slope protection mode of “bamboo lattice+ C. dactylon ” can effectively prevent the slippage of shallow soil of slope.