EXPERIMENTAL STUDY ON EFFECTS OF VEGETATION RESTORATION ON PHYSICAL AND MECHANICAL PROPERTIES OF DUMP SLOPE SOIL IN ALPINE COAL MINE AREAS

This paper aims to assess the contribution of roots of inter-planted herbaceous in reinforcing dump-slope soil in alpine mining areas and improving slope stability. It selects Jiangcang mining sites in Muli mining area as the testing area,where herbs of Elymus nutans Griseb. and Poa crymophila Keng are inter-planted. It uses a series of mechanical experiments to rooted soil as well as soil without root and determines,the physical and mechanical indices of the rooted soil as well as soil without root. It further conducts the Pearson correlation analysis to identify the correlation among cohesion of soil samples(rooted soil and soil without root),soil density,soil moisture content and root content. Results shows that the soil density of rooted soil,can decline from 0.13 to 0.21g ·cm^-3 with the corresponding declining percent of 6.31%~11.05%,while moisture content and cohesion can increase from 0.40% to 2.91%(with the increase percent of 4.47%~26.11%) and from 1.18 to 10.58 kPa(with the increase percent of 5.77%~62.11%),respectively. In contrast to the soil without root,indicating inter-planted herbs roots are more capable in reinforcing loose soil and improving slope stability. Pearson correlation analysis shows cohesion in vegetated slopes is positively correlated with its root content(P<0.05). Its correlation coefficient value is absolutely higher than the counterparts of soil density,and moisture content,which suggests a closer relationship between root content and soil cohesion. This conclusion can be used as a reference in the projects of alpine mining area ecological restoration and has a theoretical and practical values in geo-hazards prevention and control.