移动非均布荷载下的交叉口路面剪应力分析

Analysis on pavement shear stress at intersection under a moving non-uniform distributed load

交叉口、停车场和长大下坡路段等城市道路受力区域,行车荷载复杂,且加速、制动、转向等不同的车辆行驶状态带给路面极其复杂的受力状态。利用ANSYS进行移动非均布荷载下的路面剪应力有限元分析,并采用解耦的方法来解决轮胎与路面接触的复杂问题,即把轮胎与路面的相互作用分解为2个阶段来模拟。首先把路面简化成刚性面来近似处理,建立轮胎与刚性面接触的静载模型,并通过实测试验对模型进行验证,进而得到接触面的应力分布,然后把该应力结果施加到半刚性路面模型上。该路面模型考虑荷载分布形状和轮胎花纹的影响,采用移动的横、纵都非均布的加载形式,针对不同速度、加速度分析路面最大剪应力的分布规律。轮胎对路面的作用可以产生垂直、横向和纵向3个方向的应力,接触面的横向力会显著影响近路表的路面应力情况。研究结果表明：匀速状态下,路表最大剪应力出现在第2花纹的两侧边缘,比中点处的剪应力大了约50%;减速状态下,路表最大剪应力在中间花纹;匀速状态下,路面最大剪应力出现在距路表约2~6cm的沥青上面层中,比路表剪应力大20%;减速状态下,最大剪应力移动到路表;速度和减速度都会影响路面的最大剪应力,而减速度的变化对剪应力影响显著。

Complex road conditions such as complex traffic,complex acceleration,braking,steering and other different driving conditions of the urban road,such as intersection,parking lot and long downhill sections,bring extremely complex stress state to road surface.The pavement shear stress was analyzed under moving non-uniform load using ANSYS.The decoupling method was used to solve the complex issue of tire contact with road surface.Decoupling decomposed the tire-road interaction into two phases.A pavement was simplified to a rigid surface with thedecoupling method,a static load model about a tire contacting with the rigid surface was established and validated by indoor tests to obtain the stress distribution of the contact surface,and then the stress was applied to the semi-rigid pavement model.The influence of load distribution shape and tread pattern were considered in this model,and the maximum shear stress of pavement was analyzed for different speeds and decelerations under the moving horizontal and vertical non-uniform loads.Considering the effect of load distribution and tread pattern,the pavement model was used to analyze the distribution law of maximum shear stress of pavement for different speeds and accelerations.The effect of tire on road surface could produce vertical,horizontal and lateral stress in three directions,and the contact surface of lateral force will significantly affect the road near the road surface stress.The results show that the maximum shear stress of road surface occurs at the edge of both sides of the second pattern under the uniform speed state,which is about 50% higher than that at the midpoint.The maximum shear stress of road surface occurs in the middle of pattern under the deceleration state.The maximum shear stress of pavement occurs at the top layer of asphalt pavement with a distance of about2-6cm to road surface under the uniform speed state,which is 20%greater than the shear stress of road surface.The maximum shear stress occurs at the road surface under the deceleration state.The speed and deceleration may both affect the maximum shear stress of pavement,but the influence of deceleration on the shear stress is significant.