Research On The Development Characteristics And Control Of Debris Flow Along Gannan Zhuohe Expressway

Under the background of rapid economic growth in China,domestic infrastructure construction is also constantly improving,especially the rapid development of highways and railways,and the scale of construction is constantly expanding.In the construction and operation of highways and railways,geological disasters often occur along the railway,which seriously endangering people's lives and property and sustainable economic and social development.Among them,debris flow is one of the most serious geological disasters that endanger highway safety.The proposed Zhuoni-Hezuo Section of Fengxian(Shaanxi)to Hezuo(Gansu)Expressway is an important part of the expressway in Gansu Province.The debris flow geological hazards along the expressway greatly threaten the safety construction and later operation of the proposed highway.Taking the debris flow along the proposed expressway as the research object,this paper comprehensively collects the geological data of the area,studies its distribution characteristics,formation characteristics and movement characteristics,summarizes its formation conditions and mechanism,evaluates its susceptibility,and selects the typical debris flow in the study area for specific analysis.Then the typical debris flow in the study area is selected for specific analysis,and finally the prevention and control measures of debris flow are discussed.The main research results of this paper are as follows:(1)Through collecting data and field investigation,the statistical analysis of 44 debris flows along the proposed Expressway shows that the debris flows in the study area are all rainstorm-type debris flows,and most of them are Valley-type debris flows,which are unevenly distributed in space as a whole and relatively concentrated in the area,showing seasonal,sudden and periodic characteristics in time distribution.The main hazards are siltation and erosion.(2)The topographic characteristics of debris flow in the study area are composed of high mountains and deep valleys,steep topography,large vertical gradient of valleys,and the shape of valleys is convenient for water flow convergence.The debris flow in the study area is composed of debris flow residues on the valley slope,slope diluvial deposits at the gully,mountain bedrock and its weathering substances,aeolian deposits on the gentle slopes on both sides of valleys and adverse geological effects on both sides of the gully.Source characteristics of internal debris flow,concentrated precipitation,short duration and high intensity rainstorm constitute the water source characteristics of debris flow in the study area.(3)Denudation gully topography is the basic condition for the formation of debris flow in this area,abundant loose solid material is the important condition for the formation of debris flow in this area,abundant precipitation is the necessary condition for the formation of debris flow in this area,active human engineering activities create favorable conditions for the formation of debris flow in this area,and the four factors complement each other,forming conditions of debris flow in this area.(4)By analyzing the susceptibility of 44 debris flows in the study area,the main types of debris flows in the study area are moderate and mild.There are 32 moderately prone debris flows,accounting for 73% of the total,and 12 mildly prone debris flows,accounting for 27% of the total.However,under rainstorm conditions,the probability of occurrence of debris flow is more than 85%,and the possibility of recurrence of debris flow is greater,reflecting that water is an extremely important factor in triggering the occurrence of rainstorm-type debris flow.(5)According to the formation,movement and hazard characteristics of debris flow in the study area,according to the basic ideas of debris flow prevention and control,the prevention and control measures of debris flow are discussed.The overall governance mode is mainly based on blocking and drainage,supplemented by prevention.The gully-type and slope-type debris flows developed in the study area are also discussed.Gully-type debris flow treatment is mainly based on gravity dam or grille dam and drainage channel.The treatment of slopetype debris flow in the study area is mainly based on check dam group and intercepting ditch.(6)Based on the above analysis and study,a typical debris flow along the proposed highway is selected and its causes,types,susceptibility and hazard characteristics are concretely analyzed.It is concluded that the debris flow is a viscous debris flow of rainstorm valley type and a medium-susceptible debris flow gully.The main hazards are silting and scouring.Suggestions on harnessing measures are put forward from five aspects: blocking,drainage,channel regulation,crossing engineering and biological prevention.