三维机场净空应用模型研究

Research on Application Model of Three-Dimensional Airfield Clearance Zone

针对机场净空评定中的净空规定准确使用问题,依据规定分析了跑道纵坡构形对障碍物限制面组成的影响,提出了机场净空应用模型与理想模型的概念。为分析两种模型对机场净空评定的影响,认为机场净空区是由障碍物限制面平面和相应高度限制要求所围成的三维立体空间,提出了解算三维立体块的高度和平面限制范围的净空评价模型。参照此方法,先分析确定了应用模型升降带内坡面控制点以及升降带两侧过渡面与内水平面交点坐标,然后分别对升降带、端净空区与侧净空区构建了三维立体块净空评价模型,由此编写了机场净空评定程序,并应用到算例中。对比净空评定结果可以看到:理想模型是应用模型的特例,在使用时可以根据机场所处的寿命周期选用,在机场可行性研究阶段及以后,必须使用应用模型,而其中跑道两端高度不同引起的障碍物限制高度差异具有一定的规律性,应加以注意。

In view of the accurate use of airfield clearance rules in the evaluation of airfield clearance condition,and the impact of the longitudinal slope configuration of runway on obstacle limitation surfaces according to the regulations,concepts of ideal model and application model for airfield clearance zone are put forward.In order to analyze the influence of the two models on airfield clearance condition evaluation,airfield clearance zone of three-dimensional space enclosed by the plane of obstacle limitation surfaces and the corresponding limiting requirement of height is of consideration.An evaluation model of airfield clearance condition is proposed,calculating the limiting range of height and plane of three-dimensional lump.Referring to this method,the coordinates of the slope restraining points in runway strip and the points where transitional surface beside two sides of runway strip intersect inner horizontal surface are analyzed and confirmed,and then the calculation models of three-dimensional lump of clearance for runway strip,terminal clearance zone and side clearance zone are established.Thus,the procedure of airport clearance condition evaluation is written and applied to an example.The comparison of the results after evaluating airfield clearance condition can be seen:ideal model is a special case of application model,in which one can be selected based on the life cycle of the airport.The application model must be used after entering the stage of airport feasibility study.What’s more,there is a certain regularity to merit attention about the difference of obstacle limitation height caused by different height at both ends of the runway in application model.