考虑防洪风险的混凝土坝变形双控指标拟定方法研究

Study on Formulation Method of Double Control Index of Concrete Dam Deformation Considering Flood Control Risk

针对基于典型小概率法拟定大坝监控指标时的失效概率取值偏经验性以及目前变形监控指标未考虑变形变化速率的问题,将大坝变形失效风险与大坝防洪风险(上游来水和泄洪能力)相结合,将失效概率取设计防洪风险,采用典型小概率法拟定了关键测点变形监控指标,再基于设计洪水调洪演算库水位及其对应的变形分量变化速率,从而确定变形速率监控指标,提出了考虑防洪风险的混凝土坝变形和变形速率双监控指标的拟定方法。以某服役期高拱坝为例,拟定了典型测点实测变形和变形速率双监控指标,实测变形数据及其变化速率均小于拟定的变形监控指标和变形速率监控指标,这表明该大坝当前变形性态安全可控。

In view of empirical for the failure probability value of the dam monitoring index based on the typical small probability method and the problem that the current deformation monitoring index does not consider the deformation change rate,the dam deformation failure risk is combined with the dam flood control risk(upstream inflow and flood discharge capacity),and the failure probability is taken as the design flood control risk.The typical small probability method is used to formulate the deformation monitoring index of the key measuring points.Based on the water level of the design flood routing reservoir and its corresponding deformation component change rate,the diformation rate monitoring index is determined.A method for formulating the dual monitoring index of deformation and deformation rate of concrete dam is proposed considering flood control risk.Taking a high arch dam in service as an example,the double monitoring indexes of measured deformation and deformation rate of typical measuring points are proposed.The measured deformation data and its rate of change are less than the proposed deformation monitoring index and deformation rate monitoring index,showing that the current deformation state of the dam is safe and controllable.