徐变是水泥基材料的固有性质，对混凝土结构物的应力和变形具有重要的影响。影响混凝土徐变的因素繁杂，不仅包括材料组成，还包括环境温度和湿度等外部因素。为了进一步阐明混凝土的徐变机理，提高混凝土徐变模型预测的准确性，论文对水泥基材料徐变与力学性能开展多尺度研究，主要的研究成果如下： (1) 采用仪器化压入技术对工程上常见水灰比水泥净浆的微观徐变、弹性模量和压痕硬度进行测试，为弹性模量和徐变多尺度预测模型提供准确的输入参数，同时分析微观结构、龄期、水灰比、加载速率等因素对水泥净浆微观徐变和力学性能的影响，提出基于动态连续刚度测试的分析结果确定水泥净浆微观均匀性质的试验方法。 (2) 分析不同应变率下水泥净浆微观粘塑性压深与压入荷载曲线，结果表明，不同应变率下水泥净浆的粘塑性压深与压入荷载关系具有土体的Isotache蠕变模型的特征，可采用Isotache蠕变模型表征水泥净浆微观尺度上的徐变行为，说明水泥净浆微观徐变行为与土体徐变行为类似，可能与外部荷载作用下颗粒的滑移与重排列有关。 (3) 建立水泥基材料弹性模量和徐变多尺度预测模型，分析均匀化方法、夹杂形状、夹杂大小、夹杂空间分布和界面性质等因素对多尺度预测结果的影响。结果表明，界面性质是影响水泥基材料弹性模量和徐变预测结果的重要因素，考虑基体与夹杂之间非理想界面的影响可以提高水泥基材料徐变与弹性模量多尺度预测模型的准确性。 (4) 基于四点弯曲试验设计混凝土宏观徐变测试装置，采用顺序耦合分析方法通过分析梁挠度测试结果得到混凝土徐变本构参数。该装置利用对称性减小混凝土收缩变形对徐变测试的影响，提高混凝土徐变测试的准确性。采用该装置研究混凝土在不同干燥条件下的徐变行为，验证其可行性和可靠性。 (5) 将考虑徐变、环境温湿度、混凝土龄期等因素影响的混凝土力学本构模型植入有限元软件用户子程序，采用顺序耦合分析方法模拟多场作用下地下通道大体积混凝土结构早期内应力发展和水泥混凝土路面板长期湿度翘曲变形与应力发展，为评估徐变对结构物服役状态的影响和混凝土结构物的施工提供参考。

Creep is an inherent property of cement-based materials, which has a great impact on the stress and deformation of concrete structures. Many factors can affect the creep property of cement-based materials, which include not only the mixture proportion, but also the external factors such as the environmental temperature and relative humidity. In order to further explore the creep mechanism and to improve the predicting accuracy of creep model for cement-based materials, this study conducted experimental and theoretical investigations on the creep and mechanical properties of cement-based materials at multiscale scales. The main conclusions can be drawn as follows: (1) The microscopic properties including the creep, elastic modulus, and contact hardness of cement pastes with common water-to-cement ratios in practice were investigated by instrumented indentation, which will be served as input parameters for the multiscale model to predict the elastic and creep properties of cement-based materials. The effect of microstructures, curing age, water-to-cement ratio and loading rate on the micro creep and mechanical properties of cement pastes were studied, then an experimental method to determine the homogenous property of cement pastes was proposed based on the results of dynamic continuous stiffness measurement. (2) The viscoplastic indentation depth and the indentation force curves under different strain rates were analyzed. It is found that the viscoplastic indentation depth and indentation force curves under different strain rates share the same feather with the isotache creep model of soil materials. The micro creep behavior of cement pastes can be characterized by the isotache creep model, which suggests that both cement pastes and soils may share the similar creep mechanism. The creep behavior of cement pastes at micro scale may be related to the shear sliding and rearrangement of granular particles under the external load. (3) A multiscale model was established to predict the elastic modulus and creep of cement-based materials. The influence of the homogenization schemes, the geometry and size of inclusion, the spatial distribution of the inclusion, and the interfacial property on the prediction of elastic modulus and creep of cement-based materials was analyzed. It is found that the interfacial property between the matrix and the inclusion is a key factor that affects the multiscale prediction of elastic and creep properties of cement-based materials. The results show that the predicting accuracy of the multiscale model can be improved by considering the imperfect interface effect. (4) A flexural creep set-up to measure the macroscopic creep of concrete was designed using a four-point bending configuration. The creep constitutive parameters of concrete were derived based on the measured deflection of concrete beam by conducting sequential coupling analysis. The set-up was designed to reduce the influence of shrinkage deformation on the creep measurement of concrete, which can provide an accurate measurement of concrete creep. In this study, the creep behavior of concrete under different drying conditions was studied by the flexural creep set-up, which verifies the feasibility and reliability of the flexural creep set-up. (5) The constitutive model of concrete considering the effect of creep, environmental temperature and relative humidity, and the curing age was developed in the user subroutine of finite element software. Two cases including the mass concrete road underpass and the cement concrete pavement under multi-physical fields were analyzed in terms of the stress and the deformation by conducting the sequential coupling analysis. The numerical analysis will provide references for the evaluation of effect of creep property on the service condition of concrete structures and the construction of concrete structures.