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Inner Mongolia Agricultural University (2020)

Combined Action Mechanism of Ulan Buh Desert Sand Prevention Technology Measures and Its Optimal Configuration

闫敏;

Titre : Combined Action Mechanism of Ulan Buh Desert Sand Prevention Technology Measures and Its Optimal Configuration

Auteur : 闫敏;

Grade : Doctoral Dissertation 2020

Université : Inner Mongolia Agricultural University

Résumé
Engineering measures as the basis for sand and the necessary conditions for biological measures,it is widely used in road,railway and urban areas such as sand damage control,different measures to prevent sand complex mechanism of action and effective protection to determine the scope of the protection system structure design optimization is important.In this paper,through the wind tunnel experiment of different sand prevention technology measures,single and superimposed sand prevention measures in different directions of wind speed gradient horizontal airflow velocity field variation and vertical airflow velocity profile changes characteristics,analysis of the vertical sand flow around the measure and the surrounding sand blocking effect,the complex action mechanism of different sand prevention measures was discussed,and the compounding action law was verified in the field,and the different modes of sand prevention damage prevention were optimized with the economic cost.The results show that :(1)Different measures near-surface air flow with the horizontal distance are showing a "first to reduce,gradually stabilize,increase after" trend,and this variation is not interference by the indicative wind speed,but the air flow changes significantly inflection point difference.-10H is the point of air flow fluctuations,-5H is the inflection point of wind speed reduction,the airflow tends to stabilize the inflection point is different,the overall performance of the smaller the size,the higher the height of the air flow stability faster,the inflection point position more forward,while the effective protection of the leeward side.-4H and-2H is the point of air flow fluctuation and wind speed reduction with a single sand barrier respectively,and its air flow tends to be short.Double-row sand barrier windward side air flow changes the same inflection point and a single sand barrier,air flow into the sand barrier between gradually stabilized,after a certain distance from the leeward side began to recover.When the sand barrier superimposed in different ways,did not change the air flow in the windward side of the variation,"narrow front wide back" and "resistant front consolidated back" mode increases the distance of the air flow stable region,which extended airflow recovery point position,"high front low back”mode and double-row sand barrier difference was not significant.(2)The airflow velocity profiles at different positions on the windward side of different measures are not significantly affected by obstacle,the leeward side of the air velocity profile changes significantly different inflection points.Checkerboard barrier and single sand barrier leeward side near the surface 0~4cm height significantly reduced airflow,4-16cm airflow uplift significantly,4cm height of the inflection point of rapid changes in wind speed.Double-row sand barrier enhances the control of the near-surface air flow,8cm height of the inflection point of rapid changes in wind speed.When the superposition of different sand prevention measures to reduce and uplift the role of different heights appear different wind speed,4cm height is "resistant front fixed back"mode wind speed sharply reduced inflection,8cm height is "high front low back" and"narrow front wide behind" mode wind speed sharply reduced inflection,showing a variation of the upward movement of the inflection point with the increase of the height of the sand prevention measures.All modes indicate changes in wind speed only affect the scale of wind speed changes,does not affect the vertical air velocity profile change

Mots clés : Wind protecting efficiency; Sand blocking effect; Compound effect; Engineering sand-proof measures; Pattern optimization; Ulan Buh Desert

Présentation (CNKI)

Page publiée le 15 juin 2021