基于离散元的CRCP冲断区域剥落机理研究

剥落是CRCP冲断区域常见病害,病害产生后将严重影响道路美观,危害行车舒适与安全。为揭示剥落产生机理,首先分析剥落产生原因,划分剥落类型,构建力学分析模型;然后,考虑到混凝土细观上是由集料、胶凝材料及其界面组成,运用离散元软件建立混凝土立方体试件,进行抗压强度数值模拟试验,结合室内试验,确定混凝土细观参数,并进行弯拉强度和抗剪强度试验;最后,以确定的细观参数为基础,建立路面数值模型,进行受力分析,研究混凝土剥落产生机理及其影响因素。研究结果表明:剪切剥落不易产生,分层剥落是混凝土剥落的主要类型;随着车辆荷载的增加,剪切剥落和分层剥落均更易产生,且剥落深度更大;钢筋的腐蚀对分层剥落基本无影响,但使浅层剪切剥落更易产生;随着混凝土强度的衰减,路面受力变化不大,但其本身强度的衰减将加快混凝土的剥落;随着裂缝宽度的增加,钢筋承受拉应力加大,浅层剪切剥落更易产生,分层剥落不易产生。

Spalling Mechanism for CRCP Punch-outArea based on Discrete Element Method

Spalling is one of the common defects in CRCP punch-out area,which will seriously affectthe road appearance andthe driving comfort and safety.In order to study the spalling mechanism of CRCPpunch-out area,firstly,the reasons for spalling is analyzed,the types of spalling is categorized,and themechanics analysis model is established.Then,considering that the concrete is composed of aggregate,binding material and their interface from the perspective of meso-structure,the concrete cubic testspecimen is established by discrete element software,and numerical simulation tests of compressionstrength are carried out.Combining the indoor test,the meso-structure parameters of concrete aredetermined and then subject to flexible tensile strength test and shear strength test.At last,based on theabove meso-structure parameters,the CRCP model is established by discrete element software,the stressis computed,and the influence factors and mechanism of spalling are analyzed.The results indicate thatshear spalling is hard to take place and delamination spalling is the main type of the spalling;with theincrease of vehicle load,shear and delamination spalling are easier to occur,and the depth of spalling isgreater;with the corrosion of the steel bar,the shear spalling of the shallow layer are more likely to beproduced,which has no effect on the delamination spalling;with the attenuation of concrete strength,thepavement stress changes not greatly,but the attenuation of its strength would accelerate the spalling;withthe increase of the crack width,the tensile stress of the steel reinforcement increases,the shear spalling ofthe shallow layer is more easily to occur,and the delamination spalling is harder to take place.