Research On The Technology Of Slope Protection By Herbaceous Plant Root System On The Slope Of Dumping Groun

As a comprehensive slope protection technology involving multiple disciplines,vegetation slope protection technology has been increasingly used in slope protection projects of mine dumping sites in recent years.Herbaceous plants have become the preferred species for slope protection projects because of their easy cultivation,low economic cost,short growth cycle and vigorous development.However,there are few studies on the effect of herbaceous plant roots on slope reinforcement of dumping site.Therefore,this study takes the slope of open pit copper mine dumping site as the research object,based on indoor experiments and software analysis,combines the existing root structure theory and root-soil interaction theory,classifies the herbaceous plant root type species selected in this study,combines the root-soil composites characteristic analysis data,innovates the root-soil composite discrete element modeling analysis method,and uses numerical simulation software to analyze the reinforcement effect of herbaceous plant roots on the slope of dumping site.The main research results are as follows:(1)The configuration of the plant root system determines its role on slope stability.The single plant root system selected for this experiment is a representative root system type,which can be classified into three types based on the basic theory of plant root skeleton and configuration: inverted triangular distribution type of Poa annua L.,exponential distribution type of Galinsoga parviflora Cav.and uniform distribution type of Trifolium repens L..The root system’s fractional dimensional values of Poa annua L.was 1.598,that of Galinsoga parviflora Cav.was 1.599,and that of Trifolium repens L.was 1.521.(2)By conducting indoor direct shear tests with plain soil and inverted triangular distribution type,exponential distribution type,and uniform distribution type root-soil composites,the results showed that the presence of root system mainly increased the cohesion C value of root-soil composites with the increase of 7.66%～58.13%.While the enhancement of friction angle within the root-soil composites were not significant,and the increase were much smaller than the cohesion C,which were only0.82%～1.07%.(3)Compared with traditional engineering reinforcing materials,the complex distribution morphology of the root system enriches its function of soil consolidation,and the plant roots play three main roles in strengthening the soil: prevent cracking,increase strength,and increase toughness.The strength of its constituent root-soil composite is influenced by the strength of the soil,root-soil contact,and root strength together.(4)When shear occurs in the composite,the herbaceous root system shows three states of pull-out,pull-off and slip,and the internal stress is mainly concentrated in the root system part located near the shear plane.There the lateral roots of the inverted triangular distribution root system all have stress concentrations,and the local force chain breakage damage occurs on the side of the central axis.The strong taproot of the exponentially distributed root system bears the greater stress,and the dense root whisker above the shear zone provides part of the tensile force.The lateral roots of the uniformly distributed root system located in the shear zone were the densest,and their force chains fractured were the most.The presence of the root system significantly improved the integrity of the soil.The range of improvement of the inverted triangular distribution decreased uniformly with depth,the range of improvement of the exponential distribution varied more with depth,and the range of improvement of the uniform distribution varied least with depth.(5)After herbaceous plant protection,the root-soil composite formed by the reinforcing effect of root system is stronger than that of plain soil,which reinforces the whole shallow surface layer of slope,and the safety coefficient of the slope will be improved to some extent.The safety coefficients of the inverted triangle distribution,exponential distribution,and uniform distribution of root-type herbs on the studied slope are improved by 2.07%,0.64%,and 3.75% respectively.The herbaceous plant roots not only reduce the maximum plastic strain generated inside the slope,but also delays the expansion of the plastic strain area on the slope surface to the inside of the slope,which plays a good role in slope protection.This study demonstrates the mechanical effect of plant roots consolidation on slope protection,and adopts an innovative numerical simulation method to explore the root consolidation mechanism,which provides reliable theoretical and technical support for the practice of ecological slope protection technology.