高寒矿区排土场边坡土体抗剪强度特征

为研究高寒矿区排土场边坡草本植物根-土复合体抗剪强度特征及其影响因素，以青藏高原东北部天骏木里煤田江仓矿区排土场为研究区，对组合种植垂穗披碱草（Elymus nutans Griseb.）和冷地早熟禾（Poa crymophila Keng）的排土场边坡，测得边坡地表以下不同深度根-土复合体密度、含水率和含根量等指标，通过室内直剪试验获得素土和复合体黏聚力c和内摩擦角φ；采用灰色关联法得到密度、含水率和含根量与抗剪强度指标c和φ间的关联度。试验结果表明:排土场边坡相同取样点位置和层位，根-土复合体密度和含水率均小于素土，且第二层（地表以下10~20 cm）根-土复合体含根量显著小于第一层（地表以下0~10 cm），第二层含根量较第一层平均降低幅度为31.66%；此外，根-土复合体c值较素土大，第一层和第二层根-土复合体c值较素土其平均增加幅度为32.69%、13.42%，两者的φ值则未表现出显著性变化规律；根-土复合体抗剪强度指标c和φ与密度关联度相对较高，与含水率关联度次之，与含根量关联度相对较小。研究结果对高寒矿区采用种植植物方式开展排土场边坡生态恢复，科学有效地防治坡面水土流失、浅层滑坡等地质灾害，具有一定的理论研究价值和实际指导意义。 

Shear strength characteristics of slope soil in dumping site in high-cold mining area

The paper aims to study the shear strength characteristics and the influencing factors of the root-soil composite systems of herbs in the dump slope of the high-cold mining area. The dumping site of Jiangcang mining area of Muli Coalfield, located in the northeastern Qinghai-Tibet Plateau, was selected as the study area. For the dump slope which was planted with Elymusnutans Griseb., combined with Poacrymophilakeng, density, moisture content and root content of different depths of root-soil composite systems below the surface of slope were tested; the cohesion and the internal friction angle of soil without roots and root-soil composite systems were obtained by indoor direct shear test. The correlation among density, moisture content and root content and the shear strength indexes(cohesion and internal friction angle) were obtained by the grey correlation method. The test results show that the density and moisture content of root-soil composite systems are smaller than those of soil without roots at the same sampling position and horizon of dump slope, the root content of the second layer(10-20 cm below the surface) of root-soil composite systems is smaller than that of the first layer (0~10 cm below the surface) significantly, and the average reduction amplitude of root content in the second layer is 31.66% compared with the first layer; moreover, the cohesion of root-soil composite systems is larger than that of the soil without roots, the average increment amplitude of cohesion of root-soil composite systems in the first layer and the second layer are 32.69% and 13.42% respectively compared with soil without roots, while the internal friction angle does not show obvious change law; the correlation between strength indexes(cohesion and internal friction angle of root-soil composite systems) and density is higher, the next is moisture content, the last is the root content. The results of this study have certain theoretical research value and practical guiding significance for ecological restoration of the dump slopes in the alpine mining area, which can scientifically and effectively prevent geological disasters such as soil erosion on slope and shallow landslides.