超高土石坝心墙孔压不均匀分布特征及其机理研究

Characteristics and mechanism of inhomogeneous pore pressure of core wall in super-high rockfill dam

两河口超高心墙坝填筑期监测发现,心墙孔压最大值明显高于同类工程,并且呈显著不均匀分布的现象,超出了以往的认识,引起了工程界对超高心墙坝安全的担忧。本文将饱和度作为初始材料参数引入到广义塑性本构模型中以反映心墙孔压与饱和度的耦合效应,建立了不排水条件下简化、高效的流固耦合分析方法并对其进行了验证。在此基础上,根据心墙初始饱和度的实测分布随机取值,开展了两河口心墙坝三维流固耦合分析,发现心墙实测孔压不均匀分布与饱和度随机性是直接相关的,揭示了实测高孔压及其分布特征的形成机理和影响,成果为超高土石坝心墙安全评价提供了理论支撑和技术手段。

Monitoring data shows that the pore pressure of core wall exhibits a significant inhomogeneous distribution and the maximum is far greater than that of other projects during the construction period of Lianghekou super-high core-wall rockfill dam.The phenomenon exceeds previous knowledge and arouses the concerns of engineering community about the safety of the core wall of the dam.In this paper,the degree of saturation S is introduced into generalized plastic constitutive model as an initial material parameter.To reflect the coupling effect of pore pressure and S,a simplified and efficient fluid-solid coupling method under undrained conditions is established and proved.According to the measured distribution rule of S,the 3D fluid-solid coupling analysis for Lianghekou dam shows that the inhomogeneous distribution of pore pressure is directly related to the randomness of S.Meanwhile,the formation mechanism and influence of the high pore pressure are revealed.The results can provide theoretical support and technology for safety assessment of core wall in super-high rockfill dams.