Study On Environmental Impacts And Prevention Of Soil And Water Loss In Mountainous Highway Construction

The construction of expressways,especially the construction of highways in mountainous areas,will seriously affect the original landforms and vegetation along the highways,and disturb the topsoil cover structure,resulting in a decrease in soil stability and further exacerbation of regional soil erosion.Taking the Xishang Expressway project as an example,this study analyzes the characteristics of new soil erosion and its influencing factors during the construction period of Xishang Expressway by means of field survey,field survey,fixed point monitoring,data collection and risk assessment of soil erosion.Based on the prevention and control of soil erosion,the water and soil loss of each sub-area was estimated.According to the results of soil and water loss risk assessment,the soil erosion control measures were rationally laid out,and the dynamic process of soil erosion in different stages of Xishang Expressway was clarified.The implementation effect of prevention and control measures for soil erosion in the commercial highway project.The main research results obtained in the paper are as follows:(1)This study explains the characteristics and its causes of soil erosion in mountainous area.The characteristics of soil erosion of Xishang Expressway are linear distribution,various types,large differences in temporal and spatial distribution,and concentrated occurrence periods.The main reasons for soil erosion in mountainous highways include:mechanical construction rolling and road cutting,tunnel excavation,embankment filling,soil slag,bridge mulching,etc.,which were used in highway construction,destroyed the original landform and vegetation as well as the topsoil structure along the expressway,resulting in soil stability and corrosion resistance;at the same time,the soil protection measures will be exacerbated by inadequate protection measures such as borrow pits,waste slag yards,construction access roads and construction and construction sites.(2)This study puts forward the different soil and water loss prevention and control subregions of the mountainous highway project and evaluates the risk of soil erosion in each subregions.According to the topography and geomorphology,the Xishen Expressway Soil and Water Loss Prevention Zone can be divided into two first-level sub-areas of the step area and the middle and low mountain areas.According to the construction and prevention measures,this area is based on the first-level division of the soil erosion control area of the Xishang Expressway.The refinement is divided into five secondary divisions,namely,the main line engineering prevention area,the auxiliary facilities prevention area along the line,the borrowing ground prevention area,the abandoned slag yard prevention area and the temporary engineering prevention area.It is estimated that the background value of soil erosion in the West China Expressway Soil and Water Loss Prevention and Control Zone is 70,700 tons,and the soil erosion after disturbance is 228,300 tons.The total amount of new soil erosion during the construction period is 157,600 tons,of which the area is 108,700 tons.The middle and low mountain areas are 48,900 tons.According to the risk assessment results of soil erosion,the risk of soil erosion in the main road engineering area is the highest,and the risk of soil erosion in the main line engineering area is higher than that in the middle and low mountain areas;the auxiliary engineering area,borrow pit,spoil ground and temporary construction area in the terrace area The risk of soil erosion is less than that of low and medium mountains.(3)This study puts forward countermeasures for soil erosion control in mountainous highways.The main control project of the Xishang Expressway,the control area of the borrow pit,and the control area of the waste slag yard are mainly based on engineering protection measures,assisting with plant protection measures and temporary protective measures;plant measures and temporary protective measures are in the auxiliary facilities mainly along the line;temporary engineering prevention and control areas are mainly based on temporary engineering protection measures.The engineering protection measures for the borrow pits,waste slag yards and land remediation of Xishang Expressway were designed,and the types of supporting soil and water conservation plants were optimized.The slopes and scenes of the soil erosion control areas should be shrub or joss.The combination of grass protection and typical design.(4)The article clarifies the dynamic process of soil erosion in different stages of highway engineering in mountainous area.The estimation results show that the soil erosion modulus of the middle and low mountainous areas is higher than that of the terraced areas;the soil erosion modulus of the waste slag yard after construction period,vegetation restoration period and soil erosion prevention measures are the largest,followed by the borrow pit and the main line engineering area.The ancillary project area is the smallest;the total amount of soil erosion after the implementation of the Xishang Expressway construction,vegetation restoration period and soil erosion control measures are 85,199t,46,727t and 5,621t respectively.With the gradual exertion of the benefits of soil erosion control measures,the soil erosion intensity of the soil erosion control areas of the Xishang Expressway has gradually decreased.