锦屏一级拱坝黏弹性工作性态反演分析

Back analysis of viscoelastic working behavior for Jinping-Ⅰ Arch Dam

针对锦屏一级拱坝历年1 880 m高水位稳定期坝体向下游侧位移持续增大的异常变形性态,基于现场位移监测数据和坝体混凝土徐变试验数据,对该拱坝当前运行性态进行了反演分析。结果表明:坝体目前处于黏弹性工作状态,监测发现的短期趋势性变形是由水压荷载作用下黏弹性滞后变形效应和年周期环境温降效应所共同引起。混凝土黏弹性力学参数之间具有较好的线性关系,基于弹性水压分量反演得到的坝体混凝土弹性模量实际是瞬时弹性模量与延迟弹性模量的等效值,对于锦屏一级拱坝,该反演值为35.5 GPa,与前期反演值和试验值较为接近;而基于黏弹性水压分量反演得到的广义Kelvin模型中瞬时弹性模量、2延迟弹性模量和2黏滞系数分别为47.3 GPa、189.4 GPa、132.3 GPa、383.8 GPa·d和20 574.6 GPa·d。建议今后对锦屏一级拱坝建立变形监控模型时,应在HST模型中引入黏弹性滞后水压分量。

Aiming at the annually measured continuous growth phenomenon of the dam body deformation towards the downstream direction for Jinping-I Arch Dam when the reservoir keeps stable at the normal water level elevation of 1 880 m, back analysis was conducted for the viscoelastic working behavior of the dam based on the measured displacement data and the concrete creep data. The results show that the dam body is in a working state of viscoelastic at present, and the measured short-term trend deformation is jointly caused by the hysteretic hydraulic deformation and the ambient temperature drop effect. Good linear relationships exist between the viscoelastic mechanical parameters of the dam concrete. The elastic modulus of the dam concrete through back analysis according to the elastic hydraulic component is actually an equivalent value of the instantaneous and delayed elastic modulus. For Jinping-Ⅰ Arch Dam, this inversion value is 35.5 GPa, which is close to the earlier back-analysis value and experimental value. The instantaneous elastic modulus, two delayed elastic moduli and two viscosity coefficients in the generalized Kelvin model are 47.3 GPa, 189.4 GPa, 132.3 GPa, 383.8 GPa·d and 20 574.6 GPa·d, respectively. To establish deformation monitoring models for Jinping-I Arch Dam, it is recommended that a new viscoelastic hysteretic hydraulic component should be added to the traditional hydraulic, seasonal and time(HST) model.