基于黏塑性理论的碾压混凝土动态剪切本构模型

DYNAMIC SHEAR CONSTITUTIVE MODEL OF RCC INTERFACE BASED ON VISCOPLASTICITY THEORY

由于碾压混凝土大坝是逐层碾压而成,坝体层面处的静动抗剪强度均低于其本体强度,在地震、振动或冲击作用下,坝体层面(包括坝基界面)有可能发生沿层面的动态滑移失稳破坏。基于Perzyna黏塑性连续理论,提出了一个用于描述碾压混凝土层面动态剪切断裂行为的本构模型。该模型的特点有:混凝土材料的软化塑性和扩容特性直接与界面处断裂失效过程相联系;使用Carol率相关界面方程作为屈服判据来描述碾压混凝土材料的率相关性;使用经典塑性断裂理论来描述剪切面上的断裂失效和摩擦滑动过程,并且只需要较少的模型参数。利用该模型与含层面碾压混凝土的动态强度试验结果进行了对比分析,包括在不同的应力路径如单轴拉、压和压剪状态下和不同加载速率下的试验结果。结果表明模型与试验得出的结论吻合较好,这种弹-黏塑性动态剪切本构模型对预测包含薄弱层面的碾压混凝土动力破坏性能是有效的,这为相关工程问题的研究提供有益的思路和有效的工具。

Due to the layer-by-layer compaction effect in dam construction, the static and dynamic shear strength of RCC(Roller Compacted Concrete) layer is less than its body strength. Discontinuous deformation and dynamic slip instability may occur along the RCC interface(including foundation interface) under the action such as earthquake, vibration or shock effect. Based on the Perzyna's viscoplasticity constitutive theory, a dynamic shear constitutive model is presented in which the shear fracture behavior of RCC interface can be described. Characteristics of the model proposed herein are: plastic softening and dilatancy behavior are directly related to the fracture process of interface; improved rate-dependent interface model by Carol is used as yield function to capture the strain effect of RCC; the process of decohesion coupled with frictional sliding is described by classic plastic-fracture mechanics and much less material and model parameters are required. The proposed model is applicable to dynamic strength experiments of RCC containing interface with different loading path including uniaxial tension and compression, compression-shear under various loading rates. The result shows, the proposed elastic-viscoplastic dynamic shear constitutive model can describe the failure processes and mechanisms of RCC structures with weak layers effectively, and can be a suitable numerical tool for the related practical engineering.