| China’s highway construction has gradually shifted from the plain area to the mountainous area.The highway construction in the mountainous area has caused high filling of roadbeds or deep excavation of slopes,which has destroyed the original slope vegetation and played an important role in the external environment such as rainfall.Under the slope,there are hidden dangers such as soil erosion,landslides and other geological diseases,which seriously threaten the safety of driving.At present,high-steep slopes of expressways often use engineering protection with strong slope protection.However,they are expensive and difficult to maintain,and cannot effectively restore the damaged vegetation.Therefore,the ecological protection technology of high-steep slopes of expressways is studied has an important meaning.Firstly,through a large number of investigations,the causes of slope diseases are analyzed.The cumulative frequency method is combined with literature data to define the definition of high and steep slopes.The comparative analysis method is used to analyze the structural stability and landscape characteristics of slope protection Based on this,the protection technology for the geotechnical network to increase the steep slope is determined;based on the mechanical and hydrological effects of vegetation,an ecological protection mechanism is proposed.Then,based on the analysis of factors affecting the ecological performance of high and steep slopes,topography,and other factors,the rough set theory was used to determine the main indicators of the stability of the slopes affected by the high and steep slopes and the root tensile strength.Based on extenics theory,a high-slope slope ecological evaluation model was constructed based on factors such as slope ecological grade,slope angle,and root pull strength.Through the root tensile strength test,it is obtained that the plant root tensile strength and tensile strength are related to the diameter of the plant root;through the direct shear test,it is obtained that the growth of the plant root is proportional to the cohesion of the soil and the internal friction angle.In addition,the soil cohesion of plant roots increased by 27% and the internal friction angle increased by 1.1% compared to the soil without plant roots.According to the indoor scour test,the soil loss of the plant slopes was reduced by 60%compared with the plant slopes.A composite model of root and soil was established by finite element method,and the relationship between different plant roots and shear stress was analyzed.The shear stress difference method was used to propose a solid soil range cam model(SRCM)for trees,shrubs,and herb roots under different slopes and heights To determine the range of soil consolidation for different soil qualities.Finally,the slope ecological protection construction technology is proposed by analyzing the terrain,landform,climatic conditions and other factors of the Yanchong Expressway test road slope,combined with the solid soil range cam model.To sum up,the thesis builds an ecological evaluation system and evaluation model for high and steep slopes based on a large number of field investigations,starting from the factors of mechanics,terrain,soil,vegetation,environment,vision,and landscape,using rough set theory and extenics theory;Based on this,through the root tensile strength test,direct shear test,scour test,the plant root soil interaction was analyzed,and the relationship model between the plant root growth and the cohesion and internal friction angle of the slope soil was obtained;The finite element simulation method was used to construct a cam model of the range of soil fixation of plant roots.Finally,the recommended value of the range of soil consolidation under different soil quality,plants,slope heights,and slope ratios was finally determined.The thesis embodies the scientific concept of "Lucid waters and lush mountains are invaluable assets." and provides theoretical support for ecological protection of high and steep slopes. |
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