Fractal theory is introduced in fracture surface research of alkali-slag concrete (ASC) under freeze-thaw cycles; crack distribution of ASC fracture surface and freeze-thaw damage zone were calculated. Through fractal analysis of ASC sample fracture surfaces, relevance between section fractal dimension and fracture toughness and relationship between material composition and section fractal dimension are clarified. Results show that the specimen's cracks before freeze-thaw extend along force direction gently, and there are more twists and turns after freezing and thawing; the fractal dimension also grows from 1.10 to 1.33. SEM internal microcracks' of ASC internal microstructure after freezing and thawing is 1.37; 0 to 300 times ASC fractal dimension under freezing and thawing is between 2.10 and 2.23; with freeze-thaw times increasing, ASC fracture toughness decreases and fractal dimension increases, the fractal dimension and fracture toughness have a good linear relationship, and the fractal dimension can reflect the toughening effect of ASC. It is very feasible to evaluate ASC fracture behaviour under freezing and thawing with the fractal theory. Fractal dimension generally increases with activator solution-slag (A/S for short) or slag content. The greater the amount of A/S or slag content, the lower the dimension.

As a key indicator of airport concrete pavement, the durability of concrete is seriously affected by the jet flow generated by aircraft engines. In order to clarify the temperature field distribution of aircraft jet flow acting on the pavement surface, this paper obtained the temperature field distribution of pavement surface under the action of three types of aircraft jet flow by combining field test experiment and CFD simulation. CFD simulation adopts the shear stress transfer model which is often used in engineering problem calculation, and the field test experiment adopts the method of embedding temperature sensor in precast concrete slab. The paired two sample t test was used to test the difference between the experimental results and the simulation results. The experimental results show that the pavement temperature increases first and then decreases with the distance from the engine, and reaches the maximum at the intersection point of the jet flow and the airport pavement. The simulation curve is in good agreement with the experimental results. When the level of confidence is 0.01, there is no significant difference between the simulation value and the experimental value, which verifies the accuracy and feasibility of the simulation calculation model. The simulation results of the three aircraft showed that when type C aircraft is in the state of full afterforce, the maximum pavement temperature is the highest which is 22m away from the nozzle, and can reach 533.81K. The current work provides a new method for measuring the temperature distribution of airfield pavement under the action of jet flow and a basis for the application of fiber concrete in airfield pavement.INDEX TERMS Jet flow, pavement, CFD, test experiment, temperature field distribution.

It is a hot issue for airport users and researchers to pay attention to the influence of the hot air flow generated by the hot blowing snow thrower on the durability and service life of the pavement. In order to clarify the influence of hot air flow generated by hot blowing snow throwers on the temperature distribution of airport runway, this paper studies the temperature distribution of airport runway under the action of hot air flow generated by hot blowing snow throwers by CFD simulation and design of field measurement experiments. The results show that the maximum temperature of the surface obtained by the simulation method is 554.21K, the limit temperature of the surface is 539.75K and the average temperature difference is 22.64K, which verifies the accuracy of the simulation model. In view of the research results, in order to promote the application of this type of snow thrower in the airport, it is necessary to verify whether the airport roadway can withstand the action of high temperature airflow of 539.75K.

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Composite obstacle limitation surfaces are defined by overlaying the obstacle limitation requirements for departure and approach. Based on the assumption that airfield clearance zone consists of 3D lumps, adaptive algorithm for resolving 3D lumps is proposed, which can be used to design an airfield clearance condition evaluation procedure that can evaluate superelevation of topographical data. A programing method for airfield topography information collection based on Google Earth is proposed. By overlaying the three layers that include topographical information, obstruction information and image of airfield clearance zone, a stereoscopic display of airfield clearance condition management platform is established under ArcGIS. Thereby, an airfield clearance condition evaluation and management system is formed, which contains topographical information collection, evaluation and management of airfield clearance zone.