Research On Snowdrifts And Snow Disaster Simulation Technology Of Road

Snowdrifts are a natural hazard which widely distribute in our country. The areaof snowdrifts covers 55.2 percent of all area in China. According to the informationof statistic, there are 6,891 km highways and 660,000 km roads which are affectedby snowdrifts and their disasters only in the Northeast, North China and Southwest.Therefore, snowdrifts and their disasters are an important sort of traffic disasters.Snowdrifts not only bring plenty of serious traffic accidents, but also bring enormousproperty loss and many social problems. Especially, with carrying out the "GreatWestern Development"strategy, the increase of the fund of construction and thedevelopment of construction of roads, the areas affected by snowdrifts willnecessarily increase and the harm caused by snowdrifts will further expand. So, it isgreatly significative of doing some researches on the formation mechanism ofsnowdrifts and methods of the prevention technique for snow-drifted road. It is thekey part to study the relations between the types of transect structure of road and theformation of snowdrifts in order to resolve above-mentioned problems.To the question of snowdrifts around roads, this dissertation is based on theitem of West Traffic Building "Research on the formation mechanism and theforecast of snowdrifts and their disaster round roads". It elementarily discussed thetheory and means of numerical simulations of snowdrifts and confirmed thesimulation idea of snowdrifts round roads, which is based on analyzing theformation mechanism of snowdrifts. The numerical simulations employed thecommercial CFD code, FLUENT and the technology of dynamic mesh, withadditional user C coding added to simulate accumulation or erosion of snow andtransient snow surface changes. At the same time, it designed the structure frame andtechnology platform of the simulation system of snowdrifts around roads.The dissertation is divided into six chapters.1) The first chapter illustrates the basis, the background and the necessities ofthe research and compares the advantages and disadvantages among four researchmethods of snowdrifts. After that, it analyzes the current research actuality and newdirection of formation mechanism and simulation technology of snowdrifts at homeand overseas. Finally, it expatiates on the configuration of the dissertation and thecontent of each chapter. 2) In the second chapter, from the point of visibility obstacle and snow obstacle,it analyzes many serious problems that snowdrifts cause on roads such as trafficaccidents, traffic jams, poor visibility and removal snow when snowdrifts ishappening or snow is accumulated on roads. Finally, it explains four basic principleof prevention technique and methods and applications of some measures forpreventing snowdrifts on roads. 3) In the third chapter, firstly, it studies the property and characteristic ofsnowdrifts. Secondly, it analyzes the distribution rule of the vertical wind profile,threshold wind velocity of formation snowdrifts and its factors of influence. Fromthe point of hydrodynamics, it expatiates the theory of snowdrifts transport, theturbulent diffusion theories of snow particles, and then analyzes the relation betweenaccumulation, erosion and wind velocity or surface roughness. Finally it explains thestructure of wind field and the processes of snow accumulation over section diagramof many kinds of roads. 4) In the fourth chapter, we do some researches on the technologies ofnumerical simulation of snowdrifts. The dissertation discusses the numericalsimulation theory and means of snowdrifts on roads and determines the wholesimulation ideas of snowdrifts based on the current simulation technologies about it.According to the development of two-phase flow hydrodynamics, it brings forwardthe assumptions and governing equations about simulating the process of snowdrifts.From the point of simulation, it discusses erosion and deposition models ofnumerical simulation of snowdrifts. And it employs the commercial CFD code,FLUENT, with additional user C coding to model the snow accumulation or erosionof snow and temporal snow surface changes and achieves two-dimensionalsimulation of snowdrift on typical roads. The simulation ideas and simulationtechnologies are innovative in the dissertation. The difficulties of numericalsimulation of snowdrifts and the solutions for those are discussed, which are causedby the limit and the development of hydrodynamics about multiphase and thetechnology of computer simulation 5) In the fifth chapter, the design of the numerical simulation system ofsnowdrifts is discussed and the example is given. It employs the technology ofobject-oriented design, the technology of system design and the technology ofobject-oriented database system to design the system frame of numerical simulations...