高寒矿区草本植物根系增强排土场边坡土体抗剪强度试验研究

为研究草本植物根系对增强高寒地区露天煤矿排土场边坡土体抗剪强度的贡献以及相关因素对边坡土体抗剪强度的影响，以青海境内祁连山北缘江仓露天煤矿排土场为试验区，在排土场边坡组合种植垂穗披碱草(Elymus nutans Griseb.)和冷地早熟禾(Poa pratensis L.)2种草本植物，在边坡3个不同位置处分别制取不含根系素土和根-土复合体试样进行直剪试验，探讨土体物理力学性质以及植物根系数量与根-土复合体抗剪强度之间的关系。结果表明:（1）随着边坡海拔升高，坡面浅层素土和根-土复合体试样的密度和砂粒含量呈显著增加，含水率、粉粒和黏粒含量显著降低；（2）与边坡素土试样抗剪强度相比，坡底、坡中和坡顶位置处根-土复合体抗剪强度增幅分别为4.09%、18.92%和0.69%；（3）在素土和根-土复合体试样中，含水率与黏聚力之间呈显著负相关关系，相关系数分别为-0.943和-0.969；土体中砂粒含量与内摩擦角之间呈显著正相关关系，相关系数分别为0.940和0.926；（4）坡底至坡顶位置处根-土复合体的黏聚力与素土相比，增幅分别为29.23%,54.40%,26.45%。

An experimental study of the soil shear strength reinforcement of a mine dump slope by herbaceous root systems in alpine regions

The contribution of herbaceous root systems to increase the shear strength of slope soil in open-pit coal mine dumps in alpine regions is examined in this study, and the influence of relevant factors on the shear strength of slope soil is also studied. The dump of the Jiangcang open cast coal mine located in the northern edge of the Qilian Mountains in Qinghai Province is taken as the test area. The mixture of two herbs (Elymus nutans Griseb., Poa pratensis L.) were planted in the slope of the dump and the samples of soil without roots and root-soil composite systems from the dump slope were prepared. The direct shear tests were carried out on the samples. Physical mechanics properties of soil at three different positions of the slope and the relationship between the root number and the shear strength of the root-soil composite systems are analyzed. The results indicate that (1) with the increasing elevation of the dump slope, the density and sand content of the samples of soil without roots and root-soil composite systems significantly increase at the shallow layer of the slope soil, but the content of water, powder and clay decrease significantly. (2) Compared with the samples of soil without roots, the increment amplitudes of the shear strength of the samples of the root-soil composite systems at the slope bottom, slope middle and slope top are 4.09%, 18.92% and 0.69% respectively. (3) In the samples of soil without roots and the root-soil composite systems, the correlation between the moisture content and the cohesion force is significantly negative, with the correlation coefficients (R2) of -0.943 and -0.969, respectively, while the correlation between the content of sand and the internal friction angle is significantly positive, with the correlation coefficients (R2) of 0.940 and 0.926, respectively. (4) Compared with the samples of soil without roots, the increment amplitudes of the cohesion value of the samples of the root-soil composite systems from the slope bottom to the slope top of the dump are 29.23%, 54.40% and 26.45% , respectively.