Research On Prediction Model Of Soil Loss During Railway Construction In Northern Earth And Rocky Mountainous Area

The prediction of soil erosion during railway construction in northern earth-rocky mountainous area was often based on the analogous value of soil erosion modulus with similar engineering background.Sensitive units of water and soil loss during railway construction in northern earth-rocky mountainous area:construction access roads,filled embankments,excavated road cuttings,spoil（waste disposal）fields are the research objects,using theoretical analysis combined with data analysis as technical means,both SPSS and MATLAB software to analyze soil loss quantitatively.The relationship between the amount of loss and the influencing factors such as rainfall,soil and rock factor,and topography are used to build a prediction model of soil loss in the geomorphological unit disturbed by railway constructed,and calculate the soil erosion modulus value under the condition of rainfall.The main conclusions are as follows:（1）In the correlation analysis between rainfall factors and soil loss,except for the significant correlation between rainfall and soil loss,the other single factor have poor correlation with soil loss,indicating that it’s irrational to described by a single factor of rainfall.In the two-factor analysis,it is found that the fitting effect of the two-factor combination and soil loss was improved compared with the single-factor rainfall,and the fitting effect is PI₃₀≈PI₆₀>PI.In the multi-factor analysis,it is proposed that a multivariate regression multiplication model composed of three factors of rainfall,average rainfall intensity and maximum 30mins rainfall intensity as variables is established.Among them,the fitting effect of the multiplicative model is better,and its expression is A=24.191P ^0.008I ^0.127I₃₀⁰.⁵⁴¹,the adjusted R²is 0.834,and the significant value p is 0.003.（2）The power function curve relationship between slope and unit area soil loss is analyzed,and the functional formula is y=0.976x^1.236;the power function curve relationship between slope length and unit area soil loss is analyzed,and the functional formula is y=5.482x^0.75;the slope factor expression defined on the standard underlying surface is established as S=3.752sinθ-0.436,and the slope length factor expression is L=1.029（l/20）^0.804;the topographic factor conversion table is obtained by interpolation method,the reference topographic factor value LS can be obtained directly through the conversion table.（3）The prediction model of soil and rock factor of railway engineering slopes is proposed:K=0.0156e^{2.3304[SIL（1-CLA）]/ρ},and it is applied to the calculation of typical soil soil and rock factor in northern rocky mountainous area,and the obtained reference value of K value for 186 soil species.Through the analysis of the influence of gravel content on soil and rock factor,it is found that the overall trend of K value decreases with the increase of gravel content,and the soil and rock factor correction formulas suitable for clay,loam and sandy loam soil are proposed.（4）The prediction model and applicable conditions of soil and water loss prediction model for each construction disturbance during railway construction in northern earth-rocky mountainous area are constructed.The model formula of construction access road is A=P·I·I₃₀·K·L·S,the model formula of filling embankment is A=Q·K·L·S,and the model formula of excavation road cutting and spoil（waste disposal）field is A=(P·I·I₃₀+Q)·K·L·S.The soil erosion modulus value under the condition of rainfall for the newly built Chongli Railway is proposed.