Study On Causes Of Water Damage Of Expressway In Aeolian Sand Area And Scouring Mechanism Of Slope

Aiming at the problem of water damage to the highways in the aeolian sand area,a thorough investigation was conducted on the water damage of the subgrade,bridges,culverts and their associated structures on the Yu-Jia Expressway,and the data on the water damage of the Yu-Jia Expressway was also carried out.A large number of analysis and collation work were carried out,and the cause of the water damage of the expressway in the aeolian sand area was summarized.The relevant engineering characteristics tests of the aeolian sand sampled on the water destroyed site were performed,and the relevant parameters of the aeolian sand were determined.The theoretical analysis of the starting and scouring of the aeolian sand slope surface was carried out,and the starting velocity formula and the scouring strength formula of the aeolian sand slope surface were established based on the existing research results at home and abroad.Finally,the erosion test of the aeolian sand slope surface was carried out,and the starting velocity formula and the scouring strength formula of the aeolian sand slope surface were verified,which provided a certain reference for the road water damage control in the aeolian sand area.The main research work and achievements of this article are as follows:(1)Through comprehensive investigation on the water-damage project of the Yu-Jia Expressway,it was concluded that the majority of the water damage in the wind-swamping area was due to the direct contact of the concentrated water flow formed by the rainwater collected on the road surface after being discharged by the drainage ditches under the heavy rainfall.The exposure to unprotected aeolian sand slopes involves the starting and scouring strength problems of aeolian sand slopes under the effects of water flow.(2)The particle size composition,mineral composition,surface microstructure characteristics,density and compaction characteristics of aeolian sand sampled on the site of water damage were analyzed through experiments,and the relevant parameters of aeolian sand were determined.(3)From the point of view of statistics,the criteria for starting discrimination of aeolian sand on the slope are discussed,and the criterion for determining the start of aeolian sand can be determined based on the number of aeolian sand starts per unit area of the slope;The process of sediment accumulation in the water flow is subjected to force analysis,and the formula for the starting drag force of the aeolian sand on the slope is established;the relationship between the velocity field and the shear field on the aeolian sand slope surface is combined with the Gangcalov's empirical formula establishes the formula for the starting velocity of aeolian sand on the slope;discusses the erosion intensity of the aeolian sand slope from the perspective of energy balance,and combines the existing research results to establish a calculation formula for the erosion intensity of the aeolian sand slope.(4)Aeolian sand slope scouring test study was carried out,and the established formula for the starting velocity of the aeolian sand and the scouring strength formula were verified.After analysis of the test data,the formula for the starting velocity of aeolian sand established in this paper was verified.The accuracy and feasibility of the scouring strength formula.