Influence Of W-OH On The Surface Soil Structure Of Pisha Sandstone

In recent years,the situation of soil erosion in China has been improved,but there is still a long way to go.The Pisha sandstone area is one of the most serious area of soil and water loss problem in our country.After years of exploration,the researchers developed the new material,W-OH,which is a type of water-soluble polyurethane,with the excellent properties like water-soluble,short-setting,and eco-friendly.And there have been some preliminary studies showing that the material can significantly improve the corrosion stability of Pisha sandstone slope.However,the relevant mechanism is still in exploration.Scanning electron microscope(SEM)was used to evaluate the micromorphology of surface soil structure of Pisha sandstone,observing the pore morphology,size and distribution of Pisha sandstone,and the particle morphology,size,arrangement and distribution,as well as the contact degree and bond form of particles.Then,water stability experiment of the structure of Pisha sandstone was carried out by using standard method of soil hydrostatic disintegration experiment,calculating the water stability index of Pisha sandstone with W-OH solution of different concentrations.On the basis of previous researches,the indoor simulated slope was improved and the erosion experiment of Pisha sandstone slope was carried out,measuring and comparing the runoff and sediment yield of Pisha sandstone slope with W-OH solution of different concentrations.The experiment on denudation rate was improved to measure and compare the denudation rates of Pisha sandstone slope with W-OH solution of different concentrations,as the denudation rate of Pisha sandstone slope was calculated by fitting the function of “section denudation rates-section positions”.In this dissertation,the influence of W-OH on the topsoil structure of Pisha sandstone was investigated from three aspects: the morphology change at micro level,the water stability change at medium level and the corrosion resistance change at apparent level.The results showed as follows:1)W-OH material modified the surface structure of Pisha sandstone particles: after the addition of W-OH solution,the soil particles became less sharp as wrapped by gel,the surface became soft and rough,the particle gap became fuzzy,and the large pores were filled by gel.These changes greatly enhanced the friction force and bonding force between the particles of soft sandstone.2)W-OH material improved the corrosion resistance of Pisha sandstone: the particle without W-OH material has poor water stability and weak water erosion resistance,and the K-value was as low as 0.07.However,the K-value of particles with W-OH material could reach 0.55.3)W-OH also changed the law of runoff and sediment yield on the slope of Pisha sandstone: the sediment yield on the slope significantly decreased,and the runoff on the slope tended to be stable.4)W-OH material improved the corrosion resistance of the slope: the average denudation rate of the slope with more than 2% concentration of W-OH solutionwas significantly reduced.And it's worth noting that the degree of reduction of denudation rate is also related to the slope and flow factors.The influence of W-OH on the surface soil structure of Pisha sandstone was evaluated from micro level,medium level and superficial level,including the experiments on micromorphological features,structural water stability,and erosion stability.The results may provide support for the research on the improvement mechanism of Pisha sandstone slope surface and basis for the application of W-OH material.