蓄水期和运行期库盆变形机制及对高拱坝安全的影响

发布时间：2018-12-07 13:49

【摘要】：目前我国高拱坝逐步进入蓄水期和运行期。锦屏一级、溪洛渡等高拱坝的蓄水过程引发了显著的库盆变形,蓄水完成后仍有持续的谷幅收缩,影响高拱坝当前工作性态和长期安全状况。拱坝设计方法中关于库盆变形的影响尚未有系统性的评价标准。本文研究了蓄水初期裂隙岩体变形机制,初步解释了谷幅收缩等库盆变形现象,并提出了基于极限分析思想的高拱坝长期稳定性评价方法。主要工作和创新性成果如下:(1)将变形加固理论拓展到含多裂纹结构体的稳定性分析,采用塑性余能评价整体稳定性,采用不平衡力分析裂纹起裂、贯通、破坏的过程。开展了含预置裂纹试块受压破坏和高拱坝超载破坏的数值研究,并与模型试验结果进行对比,分析了拱坝坝踵开裂以及坝身裂缝扩展的可能性。对比结果验证了该方法在拱坝稳定性和开裂破坏分析中的有效性,为蓄水期和运行期的高拱坝安全评价提供了理论基础。(2)总结了高拱坝蓄水期库盆变形规律和常规有限元计算难以模拟的原因。在弹塑性模型屈服条件中考虑静水压力作用,并应用于锦屏一级拱坝蓄水期库盆变形数值分析。计算结果与监测结果进行对比良好,初步解释了谷幅收缩、库盆沉降等现象。(3)探索了裂隙水压力作用的细观机制。非贯通裂隙中的水压力是自平衡力系,改变了岩体平衡状态,使库盆岩体产生塑性变形。通过多方文献、监测资料和计算结果论证了这一观点。在此基础上,分析了蓄水期库盆变形对锦屏拱坝安全的影响,并提出了岩体强度参数反演的初步思路。(4)针对运行期库盆时效变形作用下的拱坝安全问题,提出边界位移法和变刚度的强度折减法。边界位移法在模型边界解除约束,施加固定位移,模拟库盆长期时效变形;变刚度的强度折减法基于弹塑性模型和流变模型之间的内在联系,具有完备的理论基础。这两种方法分别采用超载法和强度折减法的研究思想,对库盆和高拱坝的长期极限状态进行分析和评价。(5)采用黏弹-塑性流变本构模型,对锦屏一级高拱坝运行期库盆变形及对坝体的影响开展数值研究。基于流变计算结果,应用边界位移法和考虑变刚度的强度折减法对拱坝进行极限分析。结果表明,库盆长期变形在一定范围内对拱坝整体稳定是有利的。
[Abstract]:At present, high arch dams in China gradually enter the water storage period and operation period. In Jinping stage, the storage process of Xiluodu isobarth arch dam has caused significant deformation of reservoir basin, and there is a sustained contraction of valley amplitude after the completion of storage, which affects the current working behavior and long-term safety condition of high arch dam. There is no systematic evaluation standard for the influence of reservoir basin deformation in arch dam design method. In this paper, the deformation mechanism of fractured rock mass in the early stage of water storage is studied, and the deformation phenomenon of reservoir basin with valley amplitude contraction is preliminarily explained, and a long-term stability evaluation method of high arch dam based on limit analysis is put forward. The main work and innovative results are as follows: (1) the theory of deformation reinforcement is extended to the stability analysis of multi-cracked structures, the whole stability is evaluated by plastic residual energy, and the process of crack initiation, transfixion and failure is analyzed by unbalanced force. The numerical study on compressive failure of test blocks with preset cracks and overloading failure of high arch dams is carried out, and the possibility of cracking of arch dam heel and crack propagation of dam body is analyzed by comparing with the results of model tests. The results show that the method is effective in the stability and crack failure analysis of arch dams. It provides a theoretical basis for the safety evaluation of high arch dams during the storage and operation periods. (2) the deformation law of reservoir basins in the storage period of high arch dams and the reasons for the difficulty in simulating the conventional finite element calculation are summarized. The hydrostatic pressure is considered in the yield condition of elastic-plastic model and applied to the numerical analysis of reservoir deformation in the storage period of Jinping arch dam. The calculated results are compared well with the monitoring results, and the phenomena of valley amplitude contraction and reservoir basin subsidence are preliminarily explained. (3) the mesoscopic mechanism of the pressure action of fissure water is explored. The water pressure in the non-penetrating fracture is a self-equilibrium force system, which changes the equilibrium state of the rock mass and causes plastic deformation of the reservoir basin rock mass. This view is demonstrated by various literatures, monitoring data and calculation results. On this basis, the influence of reservoir basin deformation on the safety of Jinping arch dam during storage period is analyzed, and a preliminary idea for inversion of rock mass strength parameters is put forward. (4) aiming at the safety problem of arch dam under the action of time-dependent deformation of reservoir basin in operation period, the paper analyzes the effect of reservoir basin deformation on the safety of Jinping arch dam. Boundary displacement method and variable stiffness strength reduction method are proposed. The boundary displacement method is based on the elastic plastic model and the rheological model, which is based on the inherent relationship between the elastic-plastic model and the rheological model, and has a complete theoretical basis for simulating the long-term aging deformation of the reservoir basin by applying the fixed displacement at the boundary of the model. The long-term limit state of reservoir basin and high arch dam are analyzed and evaluated by using overload method and strength reduction method respectively. (5) Viscoelastic-plastic rheological constitutive model is used. The deformation of reservoir basin and its influence on dam body during the operation period of Jinping first grade high arch dam are studied numerically. Based on the results of rheological calculation, the boundary displacement method and the strength reduction method with variable stiffness are used to analyze the limit of arch dam. The results show that the long-term deformation of the reservoir basin is beneficial to the overall stability of the arch dam.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV642.4

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