Slope Plant Protection Technology And Quality Assessment Of Highway Engineering In Red Soil Area

In the past ten years,a lot of road construction has been carried out in our country.The formation of a national road network based on the expressway as the skeleton,the ordinary trunk as the vein and the rural roads.But at the same time,the construction of roads has brought serious destruction to the ecological environment in surrounding areas.Aiming at the ecological restoration work of road construction in one of the eight ecologically fragile regions in China,an appropriate ecological restoration technology research system is proposed to form a technical quality scheme of plant protection for road slopes in red soil region.In this paper,the roadside slope of Changqi expressway red soil area is taken as the research object,through the preliminary investigation,the highway slope engineering wound disease investigation and disease cause analysis in red soil area,select plants suitable for planting in southern acid red soil area,in the form of combination of shrubs and grasses to protect the highway slope in acid red soil area.By analyzing the effects of different plant protection combinations on plant recovery,soil recovery,tensile strength of plant roots,shear strength of root-soil complex and numerical simulation analysis of slope stability,a quality evaluation system of plant protection technology for highway engineering slope in red soil area was established.The main research results are as follows:(1)Based on the analysis of the characteristics of Changqi Expressway slope,the influence of highway construction on plant and engineering in red soil area was clarified.Acid soil has a negative effect on plant root formation,plant nutrient absorption,plant growth status,plant seed survival rate,and aggravate the highway slope weathering and spalling,fragmentation,collapse,collapse,erosion,landslide and other diseases.(2)The herbs manilla grass,vetiveria zizanioides,tritolium repens L and shrub plants magnolia multiflora and amorpha fruticosa were selected to form six different plant combinations.According to the characteristics of the slope,soil and terrain of the experimental site,the ecological protection method was adopted as the planting plant protection.From the two aspects of plant restoration and soil restoration,the influence of different combination protection on the ecological restoration of plant slope was explored.(3)Three growth time points(30th day,60th day and 120th day)of different plant combinations were selected for tensile test and direct shear test.The results showed that the maximum tensile strength and shear strength of each plant combination increased with the extension of time,and the root tensile strength of each plant combination had significant differences at different growth time points.The increase of internal friction Angle of different plant composite root soil is significantly less than that of cohesion,indicating that the increase of soil shear strength mainly depends on the increase of cohesion.(4)The strength reduction method was used to analyze the stability of the rootless soil slope and the slope with different plant combinations.It was found that the plant combination could effectively improve the stability of the subgrade slope.The safety factor of the rootless soil slope was 0.977,and the safety factor of the slope with magnolia multiflora and vetiveria zizanioides was 1.504.The slope protection effect of plants was analyzed from three aspects:root length,planting position and root orientation.It was found that the slope safety factor increased first and then decreased with the increase of root length or root orientation.The slope safety factor was the highest when plants were planted at the foot of the side slope,followed by the middle slope,and the worst was at the top of the slope.(5)Plant recovery,soil environment and mechanical properties were used as first-order indexes,and plant growth status,plant coverage,plant taproot length,soil moisture content,soil pH,soil organic matter,soil aggregates,available phosphorus content,alkali-hydrolable nitrogen content,available potassium content,root tensile strength,root soil shear strength and slope stability were used as second-order indexes.The quality assessment system of roadside slope ecological protection in red soil area was established.Combining subjective and objective methods to determine the weights of all levels of the evaluation system,the AHP-entropy method and fuzzy comprehensive evaluation method of ecological protection quality assessment model were constructed.The weight analysis results show that the weight of mechanical properties is the highest among first-order indexes,which is 0.539 6.Among the secondary indexes,the weight of slope stability is the highest,which is 0.182 468.The results showed that the evaluation value of the combination of magnolia multiflora and vetiveria zizanioides with the highest score was 0.682,and that of the combination of amorpha fruticosa and manilla grass with the lowest score was 0.554.The research results of this paper transform the single highway engineering slope protection construction into the slope protection construction of highway ecological engineering,which can play a dual role in improving the quality of engineering construction,beautifying and protecting the ecological environment,and provide important technical support and data support for the establishment of highway slope ecological protection technology and system in the red soil area.