基于弹塑性模型参数反演的高土石坝地震响应预测

Seismic response prediction of high earth rockfill dams based on elasto-plastic inverse analysis

合理准确描述堆石料的力学特性是高土石坝地震响应预测和安全评价的重要前提。以特高心墙坝填筑期变形的监测结果为目标值开展了三维反演分析,获取了反映大坝真实状态的坝料广义塑性模型和邓肯张E-B模型的参数,探讨了两种本构模型描述高土石坝变形的精度,随后采用反演的广义塑性模型参数开展了高土石坝的地震响应预测及安全评价。结果表明:目前反演分析常用的邓肯张E-B模型无法兼顾竖向和水平变形,且反演参数无法用于动力分析;静动统一的广义塑性模型计算的竖向和水平位移均与实测结果吻合良好,并可直接用于大坝的动力响应预测。所建立的一整套基于弹塑性模型参数反演的高土石坝地震响应预测分析方法,可为高土石坝的安全评价和风险预警提供可靠的技术支撑。

Reasonable and accurate description of the mechanical properties of rockfill is an important prerequisite for seismic response prediction and safety evaluation of high earth rockfill dams.In this paper,3D inverse analysis is carried out using the deformation monitoring results of an extra-high rockfill dam during the filling period.The generalized plastic model and Duncan E-B model parameters of dam material are obtained,which can reflect the real state of the dam.In addition,the accuracy of two constitutive models is discussed.And the seismic response prediction and safety evaluation of high earth rockfill dams are performed using the inversed generalized plastic model parameters.Compared with the measured results,the vertical and horizontal displacements calculated by the generalized plastic model coincide well,and the inversed parameters can be applied to predict the dynamic response of dams directly.However,the conventional Duncan E-B model cannot take into account both vertical and horizontal deformation,and the inversed parameters cannot be used for dynamic analysis.The vertical and horizontal displacements calculated by the proposed static-dynamic unified generalized plastic model are in agreement with measured data,demonstrating that it can be applied in seismic prediction.The results show that the proposed analytical methods for seismic response prediction based on the elasto-plastic inverse analysis can provide a reliable technical support for safety evaluation and risk warning of high earth rockfill dams.