根土复合体增强矿区排土场边坡抗剪强度试验研究

Experimental Study on Shear Strength of Dump Slope in Mining Area Enhan-ced by Root-Soil Composite

为研究矿区排土场边坡沙柳根—土复合体的固土护坡机理,对根系如何增强土体的抗剪强度进行了量化分析。以内蒙古鄂尔多斯市伊金霍洛旗纳林陶亥镇矿区排土场作为研究区,设置了试样主根含量为0根、5根、10根和15根共4个梯度,对沙柳根—土复合体进行50 kPa、100 kPa和150 kPa垂直应力下的大型直剪试验。结果表明:(1)随着主根含量的逐渐增加,根—土复合体的抗剪强度也相应提高,剪切破坏时,含根试样的黏聚力相较素土增大了3.28~5.43倍;(2)对主根含量、垂直应力、黏聚力和内摩擦角进行Pearson相关分析,并构建回归方程,结果显示根—土复合体的黏聚力与主根含量呈显著正相关关系(P<0.05,r=0.953),主根含量和垂直应力与内摩擦角均不存在显著相关关系(P>0.05);(3)由于根系与土颗粒之间的摩擦力与根系周围大量土颗粒团聚体的积聚,共同形成一种锚固加筋结构,使得黏聚力显著增大。研究结果为矿区排土场边坡通过种植植物来进行生态修复,以及有效地预防浅层滑坡和水土流失等灾害提供了理论基础。

With the rapid expansion of China’s economy,the demand for coal mining resources has significantly increased,predominantly utilizing low-cost open-pit mining methods.This approach results in the formation of numerous slopes within the discharge field.Under conditions of sustained rainfall,these slopes are highly susceptible to various geohazards,including landslides and soil erosion.Therefore,it is imperative to implement effective protective measures to ensure the safety of coal mine operations and the surrounding regions.To investigate the soil consolidation and slope protection mechanisms of salal root-soil complexes on the slopes of mine discharge sites,a quantitative analysis was conducted to assess how the root system enhances soil shear strength.This study focuses on the mine discharge site in Nalin Taohai Town,Yijinholo Banner,Erdos City,Inner Mongolia.Four gradients of main root content(0,5%,10%,and 15%)were established,and large-scale direct shear tests were performed on salix root-soil composites under vertical stresses of 50 kPa,100 kPa,and 150 kPa.(1)As the content of primary roots gradually increased,the shear strength of the root-soil composite correspondingly improved,with the cohesive force of root-containing specimens exhibiting an increase of 3.28 to 5.43 times compared to that of plain soil during shear failure.(2)When the shear failure of the salix root-soil composite adhered to the Moore-Cullen strength failure criterion,the cohesive force of the root-containing specimens increased by 3.28 to 5.43 times relative to that of vegetative soil.(3)Pearson’s correlation analysis and regression equation were constructed.The results indicate a significant positive cor-relation between the cohesive force of the root-soil composite and the primary root content(P<0.05,r=0.953).However,neither the primary root content nor the vertical stress exhibited a significant correlation with the angle of internal friction(P>0.05).The friction between the root system and soil particles,coupled with the accumulation of numerous soil particle agglomerates around the root system,collectively forms an anchoring and reinforcing structure that significantly enhances cohesive force.The findings of this study offer a robust theoretical foundation for the ecological restoration of slopes at discharge sites in mining areas through plant cultivation,as well as for the effective prevention of disasters such as shallow landslides and soil erosion.