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飞机起降过程中主起落架移动荷载引起的跑道道基土体循环动应力是导致跑道沉降和差异沉降的主要原因。本文采用移动荷载作用下跑道动力响应半解析有限单元法,基于叠加原理分析了B747-400和A380-800客机主起落架轮组移动荷载作用下道基土体动应力响应规律。分析结果表明:在B747-400和A380-800客机主起落架移动荷载作用下,道基浅层土体竖向正应力沿横向呈倒锅底型分布,荷载影响深度可达13m;主起落架机轮分布对浅层道基土体竖向正应力影响较大,对深层土体影响不大;飞机移动速度对浅层道基土体竖向正应力分布影响较小,但对深层土体影响较明显,当飞机滑行速度达到60~80m/s时,荷载影响深度达静力分析时的1.5~1.7倍;采用柔性道面板时,浅层土体竖向正应力较刚性道面结构时增加约50%,荷载影响深度增加约10%。
The main reason for the runway settlement and differential settlement is the cyclic dynamic stress caused by the moving load of the main landing gear during the take-off and landing of the aircraft. In this paper, the semi-analytical finite element method for dynamic response of runway under moving loads is used to analyze the dynamic response of soil under the moving loads of the main landing gear wheels of B747-400 and A380-800 passenger aircraft on the basis of superposition principle. The analysis results show that the vertical normal stress of the shallow soils of the B747-400 and A380-800 under the moving gear of the main landing gear is in the shape of an inverted pot at the bottom and the influence depth of the load is up to 13m. The main landing gear The wheel distribution has a great influence on the vertical normal stress of shallow soils and has little effect on the deep soils. The movement speed of aircraft has little effect on the vertical normal stress distribution of shallow soils, The effect is obvious. When the taxiing speed reaches 60 ~ 80m / s, the influence depth of the load reaches 1.5 ~ 1.7 times of the static analysis time. When the flexible slab is used, the vertical normal stress of the shallow soil is higher than that of the rigid slab An increase of about 50%, the load impact depth increased by about 10%.