| In order to further strengthen the railway planning network in Northwest China,geku Railway(Golmud Korla)was built in 2014.In order to enhance the construction engineering service of the concrete in the windblown sand area,solve the abrasion problem of the concrete components in the windblown sand environment,improve the applicability of the concrete to the windblown sand environment and the safety during the use period,and reduce the diseases of the concrete components in the project and the maintenance costs in the future,it is necessary to carry out the relevant research on the erosion abrasion.According to the survey and statistics,the distribution of natural sand size is similar to the normal distribution,and the largest proportion of sand size is 250-280 μ M.In the study area,there are 3417 times of wind speed of more than 6m / s in a year,which accounts for 39% of the maximum wind speed in the whole year.In the study area,the first dominant wind direction is WNW,the second dominant wind direction is w,and the third dominant wind direction is NW.Based on the high wind speed of more than 10 m / s,the wind direction has the highest frequency between WNW,NW and W.The temperature difference in the study area is large,and the difference between annual average maximum temperature and minimum temperature is 29.4 ℃.For humidity,there is no regular increasing or decreasing rule between the minimum and maximum humidity in each month.The rainfall is mainly concentrated in June,July and August,accounting for 68% of the annual rainfall.According to the test regulations,the erosion and wear tests are carried out in the erosion and wear test system of the sand and wind two-phase flow sandblasting machine under the influence of different parameters.The results show that the mass peeling off of the concrete specimen increases with the increase of the wind speed,and the faster the mass peeling off of the concrete specimen is,the radius and depth of the peeling off increase with the increase of the wind speed;the impact of the concrete specimen at different angles The area of 0 ° angle erosion surface is the largest.With the increase of the angle,the area of erosion surface decreases,so does the erosion quality of the specimen.The radius and depth of the peeling off decrease with the increase of the angle.The mass of the specimen decreases with the increase of the erosion time,and the speed of the mass reduction of the specimen slows down.The erosion wear of the concrete material is influenced by the particle size of the erosion particles It has a great influence,and the mass peeling,peeling radius and peeling depth of the concrete specimen increase with the increase of the erosion particle size.The particle size increases,the impact kinetic energy of the concrete specimen increases,and the peeling of the specimen material increases.The strength of the concrete specimen decreases after the erosion.The mechanism of erosion and wear is analyzed through experiments: when the cement stone on the surface of concrete is eroded by the wind carrying sand,the mortar layer is exposed,and when the fine aggregate mortar on the surface is eroded gradually,the sand particles in the mortar are constantly exposed on the surface,while the strength and hardness of the cement slurry are lower than the sand particles with small particle size,and the sand particles can better resist the impact of sand particles With the continuous erosion,the cement slurry on the upper surface layer of the concrete specimen will fall off,revealing the coarse aggregate in the concrete.The stone in the coarse aggregate is particularly critical.Its strength and hardness are higher than that of the small particle size erosion particles,resulting in the slow reduction rate of the specimen quality.Through ANSYS Fluent has carried on the numerical simulation to the indoor erosion and wear concrete component test,found that with the increase of erosion angle,the displacement of the two-phase flow of sand and wind is decreasing,and the velocity of the outlet is increasing,and has analyzed the overall test pressure situation,obtained that the pressure of the sand impacting the object is related to the radius,mass and erosion velocity of the erosion particles during the test,and at the same time,according to the results of the test,it is found that The distribution of particle trajectories is analyzed by particle trajectories.It is proposed that the evaluation method of erosion wear is erosion wear rate.The erosion rate nephogram on the test erosion surface is made by Tecplot software,and the erosion wear rate(erosion rate)is calculated according to fluent.It is concluded that with the increase of the initial velocity of particles,the erosion rate will increase,and the increase range will be larger;when the erosion angle is 60 °,the erosion rate will be larger;when the erosion angle is 30 °,the erosion rate will be smaller With the increase of particle size,the erosion rate is increasing,and the increasing range of erosion rate is also increasing.The three-dimensional bridge model is built for the field bridge,and the finite element ANSYS In fluent software,the whole bridge is calculated and the concrete pier is analyzed according to the parameters such as the actual wind speed,sand flow and sand particle size.It is found that the flow field structure of the pier is composed of six parts: the deceleration area on the windward side of the pier,the wind speed collection area on the beam surface,the highpressure high-speed area,the low-speed area on the bridge deck,the low-speed area on the leeward side of the pier and the wind speed stability area.The erosion particles are caused by the void The air resistance and gravity factors are parabolic trajectories,and the critical speed to reach the pier is calculated according to the finite element method;the pressure on the erosion surface of the pier is gradually reduced from the center to the surrounding,and negative pressure is generated at some positions to form suction;finally,the field sand velocity is calibrated as 6m / s,and the finite element ANSYS is simplified at the same time According to the formula of erosion rate given by fluent,the material quality of the concrete pier peeled off due to the sand erosion in one year is calculated,and the distribution of the erosion on the windward sand side of the concrete pier is given,which provides the theoretical basis for the area where the concrete pier is protected due to the sand erosion on site. |
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