某深厚覆盖层上的高心墙坝基础防渗墙采用顶部设置内置廊道的方式与砾石土心墙连接,在蓄水运行后发生廊道受损开裂现象。基于“南水”双屈服面模型和Goodman无厚度接触单元建立准三维有限元模型,考虑大坝填筑和水库蓄水过程,对该心墙坝及其内置廊道进行静力结构特性的研究,通过大坝变形监测值对数值模型参数与计算结果进行了验证。结果表明:由于受到底部防渗墙的支撑,内置廊道表现出不均匀变形、局部脱空以及压应力集中等结构特性;根据接触单元法向应力归纳了廊道在施工蓄水全过程中的围压分布的拟合公式,并通过与传统围压分析方法和规范的对比,说明基于塌落拱理论的围压计算方法无法适用于此类内置廊道结构的受力分析;提出了一种改进的柔性连接结构,以改善内置廊道应力状态并保证工程的安全运行。研究成果对于类似工程的结构设计和安全分析具有参考意义。
The anti-seepage wall of a high core dam foundation on thick overburden is rigidly connected with the gravelly-soil core wall by setting a built-in corridor at the top, and the corridor has been damaged and cracked after water storage operation. Based on the “Nanshui” double yield surface model and the Goodman zero-thickness contact element, a quasi-three-dimensional finite element model was established, and the static structural characteristics of the core dam and its built-in corridor were studied by considering the actual dam filling and reservoir storage process. The rationality of the model parameters and calculation results can be verified by the comparison of the calculated and monitored deformation values of the dam. The results indicate that due to the support of the bottom cut-off wall, the built-in corridor presents structural characteristics including uneven deformation, local separation and compression stress concentration; In addition, according to the normal stress of the contact element, the fitting formula of the surrounding pressure distribution of the corridor in the whole process of construction and water storage was summarized. By comparing with the traditional surrounding pressure analysis methods and specifications, it is illustrated that the surrounding pressure calculation method based on the collapse arch theory is not suitable for the stress analysis of built-in corridor with similar structures. Thus, an improved flexible connection structure was proposed to improve the stress state of the corridor and ensure the safe operation of the project. The above conclusions have reference significance for the structural design and safety analysis of similar projects.
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