高尾矿坝地震变形破坏机制与抗震性能评价方法研究

Earthquakes are one of the major causes of the tailings dam failure. Tailings dam failure mode under earthquake action, except for liquefied slippery flow and overall instability, is more commonly localized or overall finite deformation failure. In this project, a comprehensive research method of theoretical analysis, laboratory experiment and numerical simulation is used to study the seismic deformation and failure mechanism and seismic performance evaluation method of high tailings dam, based on three large-scale tailings pond in seismic regions. Considering the high stress level of the sedimentary tailings in the high tailing dam, dynamic characteristics tests of different tailings under high stress conditions are carried out to reveal the influence of tailings' own properties and external load conditions on its dynamic strength and deformation characteristic, and dynamic constitutive model of tailing under high stress conditions is established. The numerical simulation method is used to analyze the rules and mechanisms of the mechanical characteristics of tailings, structural characteristics of the dam, seismic load characteristics and seismic strengthening measures on the seismic deformation and failure of the tailings dam, and the conditions of the failure mode and its catastrophic mechanism are revealed. The seismic performance evaluation method of tailing dam with permanent deformation as the main evaluation index is established and applied to the seismic safety evaluation and reinforcement design of the actual project. The research results can provide scientific basis and technical support for the prediction and prevention of high tailing dam's earthquake disaster.

地震是导致尾矿坝失事的主要因素之一。尾矿坝在地震作用下的破坏模式，除液化流滑和整体失稳以外，更常见的是局部或整体的有限变形破坏。本项目以三座地震区的大型尾矿库为工程依托，采用理论分析、室内试验和数值模拟相结合的综合性研究方法，对高尾矿坝地震变形破坏机制和抗震性能评价方法进行研究。①考虑到高尾矿坝内堆积尾矿所处应力水平较高这一特点，开展高应力条件下不同尾矿的动力特性试验，揭示尾矿自身性质和外部荷载条件对其动强度和变形特性的影响规律，建立高应力条件下尾矿的动本构关系模型。②采用数值模拟的方法，分析尾矿力学特性、坝体结构特点、地震荷载特征和抗震加固措施等因素对尾矿坝地震变形破坏的影响规律和作用机制，揭示该破坏模式的产生条件和灾变机理。③构建以永久变形为主要评价指标的尾矿坝抗震性能评价方法，并应用于实际工程的抗震安全评价和加固设计中。研究成果可为高尾矿坝地震致灾的预测和防控提供科学依据和技术支撑。

尾矿库通过堆筑尾矿坝拦截尾矿和尾水而形成，不仅占用大量土地，而且是一个具有高势能的人造泥石流物源区。其一旦失事，将会造成严重生命财产损失和生态环境污染。我国是一个矿业大国，也是地震多发的国家。许多尾矿库位于地震区。目前对尾矿坝地震稳定性的研究多集中于液化破坏方面，而从变形稳定性的角度开展尾矿坝地震响应和破坏机制的研究十分少见。本项目运用理论分析、室内试验和数值模拟相结合的综合性研究方法，对高尾矿坝地震变形破坏机制与抗震性能评价方法开展研究，取得了多项研究成果：对常规条件和液化后再固结条件下尾矿的动力学特性开展了试验研究，分析了粒径、密度、围压、固结度等内外因素对尾矿动力特性的影响规律，获得了更符合原状尾矿结构和性质的重塑尾矿试件，提出了一种优化了的重塑尾矿试件的制样方法；对高围压条件下尾矿的静动力学特性开展了系统分析，获得了不同于常规围压条件下尾矿的静动力学非线性变形特征和强度演化规律，得到了能更准确描述高应力条件下尾矿力学特性的本构模型；获得了高尾矿坝地震反应特性和地震稳定性变化规律，揭示了堆积坝高度、干滩面长度、设计地震加速度、加固措施等内外因素对尾矿坝地震响应的影响规律；综合考虑尾矿坝在地震中可能破坏模式，从变形稳定性的角度出发，构建了一套较完整的、实用的尾矿坝动力稳定性计算方法，对多座尾矿坝的地震稳定性进行了分析预测。研究成果可为高尾矿坝地震致灾的预测和防控提供科学依据和技术支撑。