基于多重分形的混凝土重力坝水平位移波动分析

Analysis of horizontal displacement fluctuation of concrete gravity dam based on multifractal

为了更好地掌握大坝变形的长期行为和演变规律,在考虑位移与环境量相关性的前提下,将多重分形理论应用到大坝变形实测数据分析中。以某混凝土重力坝的变形分析为例,利用多尺度滑动时间窗消除由传统多重分形子区间划分产生的伪波动,通过多重分形去趋势相关性分析法(MF-DCCA)刻画位移与环境量相关性的多重分形特征,进一步利用多重分形非对称去趋势相关性分析法(MF-A-DCCA)分别对位移原序列、正趋势、负趋势进行波动性、非对称性和长程相关性分析,从位移整体波动和局部趋势两个层面描述了位移在环境量影响下的多重分形特征。分析结果表明,坝体变形性态较好,且位移多重分形特征受环境量影响明显,其中库水位的变化是导致该混凝土重力坝水平位移多重分形特征的主要原因。

In order to better grasp the long-term behavior and evolution law of dam deformation,the multifractal theory was applied to the analysis of measured data of dam deformation under the premise of considering the correlation between displacement and environmental quantity.Taking the deformation analysis of a concrete gravity dam as an example,the multi-scale sliding time window was used to eliminate the pseudo fluctuation generated by the traditional multifractal sub interval division.The multifractal characteristics of the correlation between displacement and environmental quantity were characterized by the multifractal detrended cross-correlation analysis(MF-DCCA).Furthermore,the multifractal asymmetric detrended cross-correlation analysis(MF-A-DCCA)was used to further analyze the volatility,asymmetry and long-range correlation of the original displacement sequence,positive trend and negative trend.The multifractal characteristics of displacement under the influence of environmental factors were described from two aspects of overall fluctuation and local trend of displacement.From the analysis results,the deformation behavior of the dam is good and the multifractal characteristics of displacement are obviously affected by environmental factors.The change of reservoir water level is the main cause for the multifractal characteristics of the horizontal displacement.