筑坝堆石料的剪胀特性及其对高面板堆石坝静、动力变形的影响研究

The deformation behavior and contitutive relation of rockfill material are much significant theory foundation for the evaluating the stress and deformation of high rockfill dam. Compared with sand, it is obvious that the size of rockfill materials is much larger, the particle grading is highly un-uniform, and the particle breakage is more significant. These differences indicate that the well established theory of dilatancy and constitutive relation developed based on sand test should not be directly applied to rockfill materials without careful examinations. A series of large static and cyclic triaxial tests on the rockfills of Zipingpu dam will be performed to study the dilatancy and critical state which had been investigated to a very limited extent. The dilatancy relation and the expression of critical state line suitable for rockfill materials will be proposed. According to the research frame of sand, an elastic-plastic model for rockfill materials will be established to take into account particle breakage and stress path. On this basis, elastic-plastic static and dynamic analysis method and simulation software for high earth and rockfill dam will be developed. The stress and deformation of Zipingpu dam which was the highest concrete face rockfill dams (CRFDs) that have been ever subjected to strong shock will be simulated by elastic-plastic analysis method during construction period、operating period and earthquake period. The analysis method and rationality of constitutive model will be verified according to the field measured data. Finally the static and dynamic deformation behavior of 100-300m CFRDs will be studied. The sensibility of the parameters of dilatancy model will be analyzed to reveal the the effect mechanism of the dilatancy property of rockfill materials on the stress and deformation of high CRFDs.

堆石料的变形特性和本构关系是分析高土石坝应力和变形的理论基础。与砂土相比，筑坝堆石料具有颗粒尺寸较大、颗粒级配好及颗粒破碎较明显等特点，基于砂土试验建立的剪胀规律和本构模型是否适用于堆石料还不清楚。本项研究通过大型静、动三轴仪，对紫坪铺工程筑坝主堆石料进行大量的试验研究，重点分析堆石料剪胀和临界状态特性，考虑颗粒破碎和复杂加载条件，建议适合筑坝堆石料的剪胀关系和临界孔隙比关系，据此建立筑坝堆石料的静、动力弹塑性本构模型。在此基础上，发展高土石坝弹塑性静、动力分析方法和计算软件，对遭受强震考验的紫坪铺面板坝工程进行施工期、运行期以及地震时的应力和变形数值模拟，根据实测资料验证计算方法和本构模型的合理性，进而研究100m-300m的面板堆石坝静、动力变形特性，分析剪胀特性及其模型参数的敏感性，揭示堆石料剪胀特性对高面板堆石坝应力和变形的影响机理。

尽管现代面板堆石坝压实密度和变形模量较早期有很大提高，但坝体变形仍是面板堆石坝安全设计的主要问题。筑坝堆石料的变形特性是影响面板应力量值和分布规律的重要因素。此外，面板应力还与面板与垫层间的接触变形紧密相关。近年来，高面板堆石坝在填筑、蓄水以及地震过程中出现了面板挤压破坏和面板脱空等问题，这些问题与堆石体的变形以及面板与垫层间的接触变形均有着密不可分的关系。筑坝堆石料本构模型以及面板与垫层间接触面本构模型是计算分析面板堆石坝变形和面板应力分布规律的重要理论基础。近年来，面板堆石坝填筑和蓄水过程的弹塑性有限元分析已经有了较大的发展。但由于缺乏强震情况下的震害资料，面板堆石坝动力弹塑性分析方法的发展受到了一定的限制。目前，在面板堆石坝动力分析中广泛采用的等效线性分析方法可以较好的反映中、低强度地震的加速度反应，但不能满足大坝在强震环境中可能出现的强非线性乃至破坏全过程模拟的分析要求。强震下面板堆石坝较大的塑性(残余)变形，是引起面板挤压破坏和面板脱空等现象的主要原因，但等效线性分析方法不能考虑动力条件下塑性变形渐进发展过程，难以合理评价强震下堆石体变形对面板破坏的影响。为此，本文首先采用大型三轴仪对筑坝堆石料的颗粒破碎、临界状态及剪胀特性进行了试验研究，在此基础上提出了一个考虑颗粒破碎的状态相关堆石料广义塑性模型。然后提出了一个三维广义塑性接触面模型。最终建立了一套基于筑坝堆石料和面板与垫层间接触面弹塑性本构模型的面板堆石坝三维静、动弹塑性有限元分析方法，并应用于紫坪铺面板堆石坝填筑、蓄水及地震全过程的静、动弹塑性有限元实例分析。