常态-碾压混凝土联合筑坝材料变形特性与抗剪强度准则研究

联合筑坝形式下坝体的多个部位往往存在大体积常态与碾压混凝土材料共用的情况。坝体结构中两种材料分布部位的多样性和力学性能的差异性是导致坝体出现变形协调问题的主要原因。为分析筑坝材料的变形协调特性,建立了常态-碾压混凝土复合试件细观数值模型,基于实际工程材料性能数据,采用非均质有限元法计算分析了复合试件的细观强度特性,评价了粉煤灰掺量、材料界面倾斜角对联合筑坝复合材料力学性能的影响,结果表明:混凝土复合试件强度介于两种材料之间且随粉煤灰掺量的增加而降低,侧向压应力对复合试件的强度提升较大,根据数值试验数据,提出了联合筑坝形式下复合试件的破坏准则,分析了复合试件斜剪破坏产生机制,验证了剪切破坏准则的有效性与可靠性,研究结果可为联合筑坝材料设计提供参考。     

Deformation coordination analysis of CC-RCC combined dam structures under dynamic loads

A combined dam structure using different concrete materials offers many practical benefits. There are several real-world cases where largevolume heterogeneous concrete materials have been used together. From the engineering design standpoint, it is crucial to understand the deformation coordination characteristics and mechanical properties of large-volume heterogeneous concrete, which affect dam safety and stability. In this study, a large dam facility was selected for a case study, and various design schemes of the combined dam structure were developed by changing the configurations of material zoning and material types for a given dam shape. Elastoplastic analysis of the damfoundation-reservoir system for six schemes was carried out under dynamic conditions, in which the concrete damaged plasticity(CDP)model, the Lagrangian finite element formulation, and a surface-to-surface contact model were utilized. To evaluate the mechanical properties of zoning interfaces and coordination characteristics, the vertical distribution of the first principal stress at the longitudinal joint was used as the critical index of deformation coordination control, and the overall deformation and damage characteristics of the dam were also investigated.Through a comparative study of the design schemes, an optimal scheme of the combined dam structure was identified: large-volume roller-compacted concrete(RCC) is recommended for the dam body upstream of the longitudinal joint, and high-volume fly ash conventional concrete(CC) for the dam body downstream of the longitudinal joint. This study provides engineers with a reference basis for combined dam structure design.