荷载-温度-水共同作用下脱空水泥混凝土路面板力学响应分析

Analysis on Mechanical Response of Void beneath Cement Concrete Pavement Slab under Load-temperature-water Interaction

为了得到脱空水泥混凝土路面板在考虑荷载、温度梯度、水共同作用下的应力随脱空发展的规律,利用ABAQUS建立了三维有限元模型分析力学响应。脱空部位选取板边中部及板角,设置不同的温度梯度、不同轴载、不同板厚、不同弹性模量以及考虑脱空部位有水和无水情况,定义了3场共同作用的弯拉应力值与不考虑动水作用的弯拉应力值之比S,分析动水对路面板的力学响应。结果表明:对于板边脱空,其不同温度梯度、不同轴载、不同面层弹性模量条件下,应力比S普遍大于1,动水主要表现为直接不利影响,另外,随着板厚的增加,S值逐渐小于1,表明增加板厚可以降低动水对路面板的直接影响;为避免路面板加速破坏,在脱空0.2 m^(2)之前进行早期维护,可有效延长道路服役时间;通过控制轴载可以减小动水对路面板应力的直接影响,增大板厚可以有效降低脱空敏感性,路面板的模量控制在27 GPa,有利于降低动水对板边的不利影响;对于板角脱空,动水并不会直接表现为不利影响,动水的存在降低了路面板应力对板角脱空的敏感程度,在脱空0.25 m^(2)之前进行早期维护,可有效减少板角的极限断板;板厚0.3 m可有效降低脱空及动水的不利影响;模量的增加有利于降低板角对脱空的敏感程度,但是模量的增加会不利于板边的应力,因此应该综合考虑板的模量。

In order to obtain the rule that the stress of voided cement concrete pavement slab develops with voiding under the combined action of load,temperature gradient and water,a 3 D finite element model is established by ABAQUS to analyze the mechanical response.Selecting the middle part of slab edge and slab corner at the void location,setting different temperature gradients,different axle loads,different slab thicknesses and different elastic moduli,and considering whether there is water or no water at the void location,the ratio S of the flexural stress under the combined action of the 3 fields to the flexural stress without considering hydrodynamic action is defined,and the mechanical response of dynamic water to pavement slab is analyzed.The result shows that(1) The stress ratio S is generally greater than 1 for slab edge void under different temperature gradients,different axial loads and different elastic moduli,and the dynamic water mainly shows direct adverse effect.In addition,with the increase of slab thickness,the value S is gradually less than 1,indicating that increasing slab thickness can reduce the direct effect of dynamic water on pavement slab.(2) In order to avoid the accelerated damage of pavement slab,early maintenance before 0.2 m^(2) void can effectively prolong the service time of road.The direct influence of dynamic water on pavement slab stress can be reduced by controlling axle load.Increasing slab thickness can effectively reduce the void sensitivity.Controlling the modulus of the pavement slab at 27 GPa is beneficial to reduce the adverse effect of dynamic water on the slab edge.(3) For slab corner void,dynamic water does not directly show adverse effect,and the existence of dynamic water reduces the sensitivity of pavement slab stress to slab corner void.Early maintenance before 0.25 m^(2) void can effectively reduce the limit breakage of slab corner angle.(4) The plate thickness of 0.3 m can effectively reduce the adverse effect of void and dynamic water.(5) The increase of modulus is beneficial to reduce the sensitivity of slab corner to void,but the increase of modulus will be detrimental to the stress of slab edge,so the modulus of slab should be considered comprehensively.