季冻区高性能橡胶混凝土路面结构的损伤机理及力学响应研究

Crumb rubber concrete (CRC) can achieve the recycling of waste rubber，such properties as crack-resistance, fracture resistance, vibration damping, and noise reduction performance of concrete materials are improved. It is expected to be used in road engineering. At present, most researches focus on the physical and mechanical properties of rubber reinforced concrete materials, but lack the understanding of the connection between materials, components and structure, while the damage mechanism and mechanical response of rubber concrete pavement structure under load and environment are still not determined. In view of the climatic characteristics and traffic conditions in Inner Mongolia, the research group will carry out research on the damage mechanism and mechanical response of high performance concrete pavement structure in seasonally frozen region. High performance rubber concrete mix and preparation methods are to be proposed which can meet the bearing requirements of the rubber concrete pavement panel under heavy traffic load, with high flexural strength, high bending fracture toughness, high fatigue resistance and high durability properties. The calculation method of the fracture toughness and the instability toughness of the high performance rubber concrete pavement are studied, and the judgment criterion of the crack propagation stability is to be established. The nonlinear finite element analysis of tensile and flexural properties of high performance rubber concrete will be carried out from the microscopic level, while the initiation, development and fracture process of high performance rubber concrete pavement structure cracks are to be demonstrated. The fatigue stress calculation method of high performance rubber concrete pavement structure under the action of temperature gradient or driving load will be established.

橡胶混凝土（CRC）可实现废旧橡胶的循环利用，还可改善混凝土材料的抗裂、抗折、减振、降噪等性能，有望用于道路工程。目前的研究多集中在橡胶混凝土材料的物理力学性能，缺少材料、构件与结构之间的联系，荷载与环境作用下橡胶混凝土路面结构断裂损伤机理和力学响应还不明确。针对内蒙古的气候特点及交通状况，本课题组将开展季冻区高性能橡胶混凝土路面结构的损伤机理及力学响应研究。提出满足季冻区重载交通的橡胶混凝土路面面板承载要求，具有高弯拉强度、高弯曲断裂韧性、高抗疲劳性能和高耐久性能的高性能橡胶混凝土的配合比及制备方法。研究高性能橡胶混凝土路面起裂韧度、失稳韧度的计算方法，建立其裂缝扩展稳定性的判断准则。从细观层次上对高性能橡胶混凝土的抗拉、抗折性能进行非线性有限元分析，揭示高性能橡胶混凝土路面结构裂缝的萌生、发展及断裂过程。建立温度梯度和行车荷载分别作用下，高性能橡胶混凝土路面结构的疲劳应力计算方法。

橡胶混凝土（CRC）可实现废旧橡胶的循环利用，还可改善混凝土的抗裂、抗折、减振、降噪等性能，适用于道路工程。为研究季冻区CRC路面结构的破坏机理及力学响应，本课题开展了高性能CRC动、静力性能及其路面结构的设计方法研究。结果表明，通过优化配比，可制备具有高强度、高韧性、高抗疲劳性能和高耐久性能的CRC，满足季冻区重载交通的路面面板承载要求。常温下，随着橡胶掺量的增加，强度逐渐下降，下降趋势加快。橡胶掺量相同时，水胶比越小，CRC抗折强度越大。低温下，橡胶掺量相同时，随着水胶比的增大，低温下CRC的抗折强度值较常温下CRC的抗折强度值越大，此时的折压比受水胶比的影响更加明显。从强度及峰值应变两方面上看，低温下CRC中橡胶掺量宜控制在10%~15%，随着橡胶粒径减小，动态抗压强度略有降低，而峰值应变略有增大。低温作用后，CRC材料压-压滞回曲线趋于饱满，耗能性能明显增大；加载力幅值水平越大，CRC的阻尼损耗因子越大，低温下的提高幅度小于常温情况。基于细观层次，将CRC看作由砂浆、粗骨料、橡胶颗粒、砂浆－粗骨料界面和砂浆－橡胶颗粒界面组成的多相复合材料。砂浆与橡胶颗粒的界面区域对CRC强度和破坏过程影响较大，骨料和砂浆界面性能约为砂浆的65%，橡胶和砂浆界面性能约为砂浆的35%。温度梯度作用下，与普通混凝土路面结构相比，CRC路面在纵缝边缘、横缝边缘、板角和板中的面层板底最大拉应力减小了50~70%。标准行车荷载作用在CRC在路面纵缝边缘、横缝边缘、板角和板中位置，面板层底最大拉应力减小约25~30%。运用弹性薄板理论和功的互等定理，可求解静力荷载作用下CRC路面挠度。在温度梯度92℃/m和轴载250kN的共同作用下，CRC路面各结构参数取值范围为：面层厚度不应小于26cm，基层厚度宜取24cm，地基反应模量不应小于50MPa/m。在行车荷载以及温度梯度作用下，以面层厚度、模量等为参数，对CRC路面板底最大拉应力敏感性分析结果进行拟合，建立了疲劳应力计算公式。