基于两尺度模型的CRCP冲断区域剥落研究

Study on spalling of CRCP punch-out area based on two scale model

为研究连续配筋混凝土路面(continuous reinforced concrete pavement,CRCP)冲断区域混凝土剥落机理,细观上采用离散元方法,宏观上采用有限元方法,基于宏观、细观两尺度模型对混凝土剥落展开研究。首先在分析混凝土剥落形成原因的基础上将剥落分为分层剥落和剪切剥落,并建立剥落力学分析模型;然后考虑水泥混凝土细观上由集料、胶凝材料及其界面组成,进行水泥混凝土抗压强度数值模拟试验,通过调试获得不同强度等级下混凝土的细观参数,以所得细观参数为基础,进行混凝土弯拉强度和抗剪强度细观数值模拟试验,得到其弹性模量、弯拉强度和抗剪强度,并将数值模拟试验结果与室内试验结果进行对比,将所得参数用于路面有限元建模和混凝土剥落机理分析;最后考虑冲断区域特点,建立CRCP宏观力学分析有限元模型,对车辆荷载、湿度梯度和温度梯度作用下的冲断区域剥落进行研究,并对混凝土细观参数(水泥掺量、水泥强度、界面强度等)和宏观影响因素(脱空、基层模量、路基模量等)的影响进行研究。研究结果表明:细观数值模拟试验结果与室内试验结果拟合良好;车辆荷载、湿度梯度和温度梯度作用下,剪切剥落不易发生,分层剥落较易发生;车辆荷载和外界环境作用下混凝土强度衰减、车辆超载和路基模量偏小是剥落产生的主要原因;路面设计选择材料时,适宜的集料类型及高强的水泥可有效减少剥落。

In order to study the spalling mechanism of concrete in continuous reinforced concrete pavement （CRCP） punch-out area, two-scale model of discrete element method on macro-scale and finite element method on a meso-scale was applied. Firstly, based on the analysis of concrete spalling reasons, spalling was classified into delamination spalling and shears spalling, and mechanics model of spalling was built. Secondly, under the consideration that cement concrete was consisted by aggregates, binding materials and their interface on a meso-scale, numerical simulation test of the compressive strength was made. Meso-structure parameters of concrete of different strength grades were obtained by continuously debug. Based on its parameters, concrete flexural tensile strength test and shear strength test were simulated numerically on a meso-scale.Elastic modulus, flexural tensile strength and shear strength were obtained, and the numerical simulation results were compared with laboratory test results, and the obtained parameters were used in finite element model and analysis of spalling mechanism of concrete. Finally, considering the characteristics of CRCP punch-out area, the mechanics model of CRCP on a macro-scale was established through finite element method to study spalling of CRCP punch-out area under vehicle load, moisture gradient and temperature gradient. Influence of meso-structure parameters concrete （such as cement content, cement strength, and interface strength） and macro influence factors （such as bottom void of pavement, modulus of base course, and modulus of subgrade） on spalling of CRCP punch-out area was analyzed. The results show that the simulated test results on a meso-scale fit well with the laboratory test results. Shear spalling is hard to take place and delamination spalling is easy to take place under vehicle load, moisture gradient while temperature gradient. Concrete strength attenuation under the influence of outside environment, overload and low modulus of subgrade are the main reasons for spalling. Sustainable material types and high strength cement can effectively reduce spalling. 5 tabs, 13 figs, 22 refs.