基于非结构网格三维有限元堤坝隐患时移特征分析

Time-lapse characteristics analysis of hidden dangers of three-dimensional finite element levees based on unstructured grids

土石堤坝的内部隐患是造成堤坝事故的主要因素,严重威胁到坝体的安全和稳定。由于堤坝隐患会随时间发生形态与尺寸的改变,表现出明显的电性结构变化,因此通过时移电阻率成像方法可以实现对土石堤坝的实时监测,进而达到堤坝隐患快速预警的目的。目前的时移电法堤坝隐患监测技术主要基于一维或二维介质模型,无法准确描述三维堤坝结构的时移电性变化特征,为此,基于高密度直流电阻率法探测理论,利用三维非结构有限元数值模拟正演方法,精细模拟典型堤坝隐患模型直流电场的时移变化特征,分析响应变化规律。数值模拟结果表明,时移监测结果对堤坝隐患变化趋势具有良好的反映,堤坝隐患尺寸、位置和形态的改变能够引起监测异常幅值和位置的规律性变化。本文的研究成果可为堤坝隐患时移监测异常识别和灾害预警提供理论指导。

The internal hidden danger of earth-rock dams is the main cause of dyke accidents,which seriously threatens the safety and stability of the dam.Since the hidden danger of the dam will change with the shape and size over time,it shows obvious electrical structural changes.Therefore,the real-time monitoring of the earth dam can be realized by the time-lapsing resistivity imaging method,so as to achieve the purpose of rapid warning of hidden dangers of the dam and avoid them in time.The damage is caused by hidden dangers.However,the current time-lapsing electric dam hidden danger monitoring technology is mainly based on one-dimensional or two-dimensional medium model,which cannot accurately describe the time-lapse electrical characteristics of three-dimensional dam structure.For this reason,based on high-density DC resistivity detection theory,the authors used the three-dimensional non-structural finite element numerical simulation forward modeling method to simulate the time-lapse variation characteristics of the DC electric field in a typical dam hidden danger model and analyzed the response change law.The results of time-shift monitoring have a good reflection of the trend of hidden dangers of dams.The changes in the size,location and shape of dams can cause regular changes in the amplitude and location of the monitoring.The research results of this paper can provide theoretical guidance for the anomaly identification and disaster warning of time-lapse monitoring of dams.