STUDY ON THE MECHANICAL EFFECT OF VEGETATION PROTECTION OF THAW SLUMPING SLOPE IN PERMAFROST AREA OF BEILUHE RE-GION ALONG THE QINGHAI-TIBET HIGHWAY
This study selected a thaw slumping slope in the Beiluhe region along the Qinghai-Tibet Highway as the research area,to evaluate the mechanical contribution of alpine meadow and artificial planting plants to soil rein-forcement and slope protection in permafrost region.The native meadow plants such as Carex myosuroides Vill.and Kobresia tibetica Maxim.and 6 kinds of herbs with growth period of 1 a such as Elymus nutans Griseb.,Puccinellia tenuiflora(Griseb.)Scribn.& Merr.,Agropyron cristatum(L.)Gaertn.,Poa annua L.,Puccinellia distans(L.)Parl.,Festuca sinensis Keng ex S.L.Lu were used as the main research objects.Based on the shear test of root-soil compos-ite system in laboratory,the contribution of herbs roots to enhance the shear strength of thaw slumping soil was dis-cussed,and the stability of thaw slumping slope was evaluated by static equilibrium method.The main results are as follows:by conducting the root-washing experiments,the average root content of the root-soil composite system sam-ple from high to low is as follows:native meadow(33.33 mg·cm-3),Elymus nutans Griseb.(16.95 mg·cm-3),Poa annua L.(13.12 mg·cm-3),Festuca sinensis Keng ex S.L.Lu(5.80 mg·cm-3),Agropyron cristatum(L.)Gaertn.(3.89 mg·cm-3),Puccinellia tenuiflora(Griseb.)Scribn.& Merr.(3.15 mg·cm-3)and Puccinellia dis-tans(L.)Parl.(2.86 mg·cm-3).The average height of plant in the study area from high to low is Elymus nutans Griseb.(10.93 cm),native meadow(9.64 cm),Agropyron cristatum(L.)Gaertn.(6.88 cm),Poa annua L.(5.22 cm),Festuca sinensis Keng ex S.L.Lu(3.90 cm),Puccinellia distans(L.)Parl.(3.86 cm)and Puccinellia tenuiflora(Griseb.)Scribn.& Merr.(2.90 cm).The shear strength of native meadow and 6 kinds of artificial herbs root-soil composite system in the study area was significantly higher than that of plain soil.The increase of the shear strength of the soil enhanced by the roots of the native meadow(42.17％)and the artificial planting Elymus nutans Griseb.(30.96％)is relatively larger than the others.The safety factor of the slope with roots calculated by the static equilibrium method is higher than that of the plain soil slope.The safety factor of slope from large to small is native meadow(1.47),Elymus nutans Griseb.(1.39),Poa annua L.(1.38),Agropyron cristatum(L.)Gaertn.(1.37),Puccinellia distans(L.)Parl.(1.36),Puccinellia tenuiflora(Griseb.)Scribn.& Merr.(1.32),Festuca sinensis Keng ex S.L.Lu(1.32)and plain soil(0.96).The results of this study provide theoretical basis and practi-cal guidance for the effective prevention and treatment of thaw slumping slopes in the Beiluhe region and the soil e-rosion,grassland degradation and other disasters caused by thaw slumping along the Qinghai-Tibet Highway.
Qinghai-Tibet HighwayPermafrostThaw slumpingVegetation slope protectionRoot-soil compos-ite system
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