基于Bodner-Partom模型的水泥乳化沥青混合料黏弹塑压实特性

为揭示水泥乳化沥青混合料压实过程中的黏弹塑性变形特性及其变形机理，结合现场路面压路机的施工工艺参数，采用万能试验机压缩试验模拟该混合料的压实过程。针对试验循环荷载力学响应曲线变形特征，引入有效平均应力构建混合料压实变形的Bodner-Partom本构模型。通过对应变-时间的非线性拟合识别出该混合料的B-P模型参数值，进而揭示压实过程中混合料的黏弹塑性动态流变特性及变形机理。试验结果表明：压缩试验可充分反映混合料压实过程中的力学响应变形特性；随着循环荷载次数的增加，混合料塑性和黏塑性变形减小而弹性和黏弹性变形增大。据混合料复压阶段的黏塑性变形规律导出试样空隙率的计算式，进而获得有效平均应力随试样空隙率的变化规律。B-P本构模型分析结果表明：黏性参数η随荷载作用次数的增加而逐渐增大，说明混合料在压实过程中黏性增强；应变率敏感系数n₁基本保持不变，表明压实过程中混合料温度相对稳定；参数值Z，D₀随荷载作用次数的增加分别呈递增、递减的规律，前者显示随着混合料被进一步压实其非弹性变形抵抗力增大，进而导致塑性和黏塑性应变逐渐减小，后者显示塑性应变率减小，表明单次循环荷载下塑性变形占总变形量的比例逐渐减小。B-P模型参数值可准确表征水泥乳化沥青混合料与时间和荷载相关的黏弹塑性流变特性，重构后的B-P本构模型可有效揭示混合料压实过程中的黏弹塑性变形机理，可为深入研究其压实流变性能和路面压实工艺奠定基础。

Viscoelastoplastic Compaction Properties of Cement-emulsified Asphalt Mixture Based on Bodner-Partom Model

In order to reveal the viscoelastoplastic deformation properties and mechanism of cement-emulsified asphalt mixture, universal testing machine compaction test was employed to simulate the compaction process in combination with the construction process parameters of the pavement roller. According to the deformation characteristics of mechanical response curve under loading cycles, the effective mean stress was introduced into the Bodner-Partom (B-P) model to construct a compaction deformation constitutive model of the mixture. Through nonlinear fitting analyses of the strain-time data, the parameter values of the constitutive model in the process of load cycles were identified, and furthermore, the viscoelastoplastic rheological properties and dynamic deformation mechanism in the compaction process of the mixture were revealed. The results show that the universal testing machine compression test fully reflects the deformation characteristics of the mixture. With the increase of loading cycles, plasticity and viscoplasticity deformation of the mixture decreases, and elastic and viscoelastic deformation of the mixture increases. According to viscoplastic deformation rule of the mixture, the expression for calculation of the void fraction in the compaction process is derived, deducing the changing rule of effective mean stress with the void fraction. The changing rules of B-P model parameters are listed as follows. Viscosity coefficient η increases with the increase of the load times and indicates that viscous property of the mixture increases after further compaction process. Strain rate sensitivity coefficient n₁ remains the same and demonstrates that mixture temperature in the compaction process is relatively constant. Internal validity Z and stress limit D₀ show an increasing and decreasing trend, respectively, with an increase in the load times. The former indicates that the inelastic deformation resistance increases, and plasticity and viscoplasticity deformation decrease with further compaction. The latter implies that the plastic strain rate decreases and plastic deformation proportion of the total deformation decrease gradually under a single cyclic loading. In conclusion, the B-P model parameters accurately describe viscoelastoplastic rheological properties of the mixture, which are associated with time and loading cycles. It can be verified that the reconstructed B-P constitutive model can effectively reveal viscoelastoplastic deformation mechanism in the compaction process. This can provide a theoretical foundation for further research on compaction rheological performance and pavement compaction techniques of the mixture.