Study On Clearing Mechanism And Key Parts Of Removing Solid Ice-snow On Road

In winter, the most northern regions of China has been plagued by clearing snowproblems, snowfall in these areas has the characteristics of lasting a long period, a largeamount of snow and a wide range. The snow without clearing in time forms a hard solidice-snow with surface ice and containing impurities plate by the means of vehicles andpedestrians repeatedly rolling and temperature changing. The road coveredsolid ice-snow has not only caused great inconvenience to vehicles and people, but alsoincreases the probability of traffic accidents. According to the relevant results of globalsurvey in all large and medium-sized cities, the traffic accident caused by ice-snow on urbanroads accounted for more than20%of the total amount of traffic accidents in winter, and hasbeen recognized worldwide as "white" city harm. Therefore, it is very important to developthe new, rapid, efficient and environment friendly road solid ice-snow clearing equipment.The conversion process and form types of solid ice-snow were analyzed, thephysical property parameters of snow density, compressive strength, shear strength, frictioncoefficient were described, the surface structure of natural freezing ice-snowand compacted ice-snow were observed by using stereomicroscope. Based onthe microscopic description of the ice particles and Bazant thinking, the microstructure model of ice-snow was build, the microstructure deformation mechanism ofice-snow contacted with its macroscopic continuous behavior, constitutive model ofice-snow was constructed. The stress state and failure characteristics of ice-snow locatedin the edge of the road no lateral pressure and in the middle of the road confining pressurewas respectively analyzed through the ice-snow of unidirectional compression damage testand the three axle loading test. The test results proved that the constitutive modelof solid ice-snow was rationality and applicability. The model can correctly describethe macroscopic properties of solid ice-snow on stress-strain relationship, applied to thestrain rate greater than0.5×10-5/s of snow skiing, roller compacted snow with large density,which provide a theoretical reference for the theory establishing of solid ice-snow removal.It was found that the main damage type of solid ice-snow was brittle fracture by usinghigh speed camera to observe the solid ice-snow of cutting failure process. The failurereason was comprehensive effect of blade cutting and ice-snow tearing. Based onconstitutive model and cutting stripping process, the physical model of ice-snow critical statewas built when ice-snow appeared crack. Snow removal tool was conducted to mechanicscharacters analysis, the cutting fractured mathematical model of solid ice-snow has beengiven and the ice-snow failure criterion was established. The new failure criterion consideredthe constitutive characteristics of ice-snow, believing ice-snow occur local failure in the most weak parts, then growth for larger crack, resulting in ice-snow fracture, which provideda theoretical basis for road solid ice-snow quality clearing.A test rig was set up to measure the cutting resistance of ice-snow, solid ice-snow cutting damagetest was carried out on the test rig, which proved failure criterion rationality. the minimumcutting resistance as objective, installation angle, rake angle, cutting depth as influencingfactors, the three factors and five levels orthogonal rotation snow removal parameter analysistest was put into effect, which proved the mathematical model of the cutting resistancecorrectness and further showed the availability of failure criterion.According to the different characters and density of solid ice-snow, concave disc andmilling snow clearing key components were developed, the two parts adopt innovativelysplit combined with independent dynamic profiling mechanism, which have good copyingobstacle effect and high removing rate. Concave disc type snow removing components usedin cutting low density solid ice-snow, has the advantages of low energy consumption andhigh efficiency, which can be achieved the five functions that crushing, cutting, tilt, scrapeand push. The milling snow clearing key component is active the cutting method and hasextremely strong ice breaking capability used to high density ice-snow of frozen shape andice membrane shape, which can be achieved milling, crushing, profiling, obstaclenegotiation and other functions.The four groups of monomer combination concave type snow removing machine wasdesigned, marching speed, the snow depth, concave disk edge angle, the angle betweenthe disc and the direction of travel as influencing factors, two return interactive design offour factors and five levels was carried out and the optimal combination ofoperation parameters were determined. A comprehensive analysis of theory and experimentto determine the main parameters of concave disk snow removal key components: the angleis13degrees between the disc and the direction of travel, the concave wheel disk with adiameter of400mm and thickness of3.5mm, disc blade angle is20degrees, the curvatureradius of concave disk is650mm.The milling snow removal key component was conducted to movement analysis anddynamic simulation analysis, through the simulation and the actual movement of snowremoving machine motion trajectory consistency, to verify the correctness oftheoretical analysis and simulation analysis. The milling snow removal prototype wasdesigned, the installation angle, marching speeding and spindle speed of tools as the mainfactors, snow-free rate and snow pack volume as the objective function, the quadraticregression rotatable orthogonal design was conducted and the optimal combination ofoperation parameters were determined for the milling snow removal prototype. The performance and working quality of the concave disc and milling snow removalprototypes were comprehensive tested under three kinds of road conditions, the testresults showed that the concave disc and milling snow clearing prototype werewell-functioning, high working efficiency, removing rate was more than90%, parameterssetting and the indicators of clear working can meet the requirements. The concave disc keycomponents were suitable for the plate ice-snow which density below550kg/m3andthickness in the range of10to80mm. The key components of milling type were suitable forthe plate and ice membranous snow that density in range of300to750kg/m3, thickness lessthan50mm, especially applied to the solid ice-snow with ice membrane shapeof density greater than550kg/m3, the two snow clearing prototypes of tests provide atheoretical basis for the research of solid ice-snow clearing technology and the developmentof snow clearing equipment.