机场水泥混凝土道面板脱空评价方法与应力影响分析

Analysis on Evaluation and Mechanical Performance of Voids beneath Airport Cement Concrete Pavement Slab

为了研究机场水泥混凝土道面板接缝传荷能力对脱空评价体系的影响,分析道面板接缝传荷能力和脱空对道面板所受最大主应力的影响,基于三维有限元方法对不同道面板厚度、不同接缝传荷能力工况下的板边中点/板中弯沉值及其弯沉比变化进行了分析,得到了道面板接缝脱空系数与传荷系数之间的关系曲线(脱空判定的弯沉比临界关系曲线)。提出了基于接缝传荷系数的脱空评价方法,并经实际工程验证评价方法判断道面板脱空状况的可行性与准确性。结果表明:道面板厚度、脱空尺寸、脱空形态(接缝单侧/两侧脱空)以及飞机类型对道面板在飞机荷载作用下所受最大弯拉应力影响甚微,道面板接缝传荷能力对道面板应力影响显著;当接缝传荷能力作为唯一变量时,道面板在荷载作用下所受最大主应力随接缝传荷系数的递减呈二次方指数增加,当道面板接缝传荷系数下降至31%以下时,道面板所受弯拉应力最大增长率可达到25%;通过对不同接缝传荷能力、脱空尺寸、脱空形态、飞机类型对道面板所受弯拉应力的影响分析,得出基于接缝传荷系数的道面板在飞机荷载作用下所受最大弯拉应力计算公式,可用于道面板应力分析或判断道面板是否存在所受最大弯拉应力超过其自身极限应力而产生开裂的风险。

In order to study the influence of slab joint load transfer capacity of airport cement concrete pavement slab on void evaluation system, and analyze the influence of load transfer capacity and voids on the maximum principal stress on the pavement slab, the variations of slab’s edge midpoint/middle deflection and deflection ratio under different slab thicknesses and different joint load-transfer capacities are analyzed by using 3 D finite element method to obtain the correlation between slab joint void coefficient and load-transfer coefficient(deflection ratio critical relation curve for void determination). The void evaluation method based on joint load-transfer coefficient is proposed, and the feasibility and accuracy of using the evaluation method to judge the void condition of the pavement slab are verified by the actual project. The result shows that(1) the pavement slab thickness, void size, void form(unilateral/bilateral voids of joint), and aircraft type have little influence on the max flexural-tensile stress of pavement slab under aircraft load, while the load transfer capacity of pavement slab joint has significant influence on the pavement slab stress;(2) when the joint load transfer capacity is the only variable, the maximum principal stress of pavement slab under load increases exponentially with the decrease of joint load transfer coefficient, and the maximum growth rate of the flexural tensile stress on the pavement can reach 25% when the load transfer coefficient of pavement joint drops below 31%;(3) by analyzing the influences of different joint load transfer capacities, void sizes, void forms and aircraft types on the suffered flexural tensile stress of pavement slab, the calculation formula of the slab’s max flexural tensile stress based on joint load transfer coefficient under aircraft load is obtained, which can be used to analyze the stress of the pavement slab or judge whether the pavement slab has the risk of cracking due to the maximum flexural tensile stress exceeding its own limit stress.