Experimental study on shear strength of plant roots in open-pit coal mine wastelands
MAO Xurui;XU Penghai;CAO Yue'e;FAN Mengcheng;YANG Jianjun;College of Resource and Environment Sciences,Xinjiang University;Key Laboratory of Oasis Ecology,Ministry of Education;Shanxi Zhongsheng Environmental Technology Development Limited Company;Development and Reform Commission of Xinjiang Uygur Autonomous Region;
[Background] Plant roots play an important role in maintaining moisture,fixing soil and preventing soil erosion in the process of ecological restoration of abandoned coal mines. With the application of soil-reinforcement by roots technology and the promotion of ecological engineering,the contribution of plant roots to soil stability has attracted extensive attention from scholars around world. In order to investigate the effect of water retention and soil consolidation during the restoration of herb in abandoned coal mine,the influence of water content and root amount of root-soil composite on shear strength was analyzed,comparing the effect of soil moisture and root with soil cohesion and internal friction angle respectively,thus providing a theoretical basis for the ecological restoration of coal mine wasteland. [Methods]Taking the abandoned land of Xigou Coal Mine in Hutubi county,Xinjiang as the research area,7 plant species of Lolium perenne L.,Elymus dahuricus Turcz.,Psathyrostachys juncea(Fisch.) Nevski,Festuca elata Keng ex E. Alexeev,Poa annua L.,Agropyron cristatum(L.) Gaertn.and Festuca rubra L. were selected for root-soil complex shear strength test and measurement of soil moisture content and root amount. [Results] The moisture content and root content of the root-soil complex mainly influence the shear strength by affecting the soil cohesion,and the effect on the internal friction angle is not significant. The soil cohesion of most root-soil complexes is negatively related to moisture content(except for F. rubra L.),which increases with the root content. The shear strength is linearly related to the normal pressure,but the shear strength of different root-soil composites increases in different account. The tensile strength is as follows: F. elata Keng ex E. Alexeev A. cristatum(L.)Gaertn. P. annua L. F. rubra L. L. perenne L. E. dahuricus Turcz. P. juncea(Fisch.) Nevski. Among them,F. elata Keng ex E. Alexeev has better soil-fixing performance,and A.cristatum(L.) Gaertn. has better soil reinforced effect. Therefore,they are recommended as the first choice for soil-reinforcement plants in the study area. Secondly,P. annua L. and L. perenne L. can be considered. P. juncea(Fisch.) Nevski. has the worst soil-fixing properties; E. dahuricus Turcz. and F.rubra L. are more suitable as solid soil plants in the moister areas. [Conclusions] The results of this study provide theoretical basis for the restoration of abandoned land in Xigou Coal Mine and other similar environments,and have theoretical and practical significance for further discussion on effective prevention and control of soil erosion and soil erosion in abandoned coal mines.