【作者】 余小孔；

【导师】 王正中；

【作者基本信息】 西北农林科技大学 ， 水工结构工程， 2010， 硕士

【摘要】 混凝土面板堆石坝以其安全性好、适应性广、施工方便、投资省、工期短等优点,近几十年来得到了广泛应用。随着面板堆石坝技术的发展和新技术的不断应用,面板堆石坝正逐渐成为一种极具竞争力的土石坝坝型,其高度也在不断增高,已经建成的水布垭混凝土面板堆石坝坝高233m,国内外正在研究建设300m级的面板堆石坝。坝高的不断增加,对高面板坝的设计提出了更为严格的坝体安全性要求,我们需要对以往适用于百米级面板坝的研究方法进行检验,同时对300m级高面板坝的工程特性及关键技术问题进行深入的分析和研究。其中,超高面板坝的坝体边坡稳定问题和断面分区优化设计是极为关键的技术问题。长期以来设计者认为面板坝由于堆石料的非冲蚀性和地质适应性,具有良好的稳定性,当筑坝材料为硬岩堆石料时,上、下游坝坡坡比大多采用1:1.3或1:1.4,但是以往适用于百米级面板坝的坝坡坡比不一定适合于高面板堆石坝,坝体稳定性分析应该充分考虑坝高和坝坡这两个因素对其稳定性的影响。库克提出的面板坝的典型分区模型没有明确指出“死区”的范围,也没有给出可参考的主次堆石变形模量关系,高面板坝的应力变形特性更为复杂,需要对这一问题进行更为详细的探讨。本文就坝高和坝坡对高面板坝的稳定性的影响进行分析,分别采用极限平衡法和有限元强度折减法,得到了坝高和坝坡对稳定性的影响的表达式;研究了面板坝断面分区优化中主次堆石分界线坡度和主次堆石变形模量比值对大坝变形特性的影响,提出了主次堆石分界线坡度和主次堆石变形模量比值的合理取值范围,使得坝体应力变形和稳定性满足要求的同时,实现充分利用当地材料、挖填平衡的经济性原则。主要内容如下:(1)采用基于极限平衡法的STAB软件,分别取不同的坝高(150m、200m、250m、300m)和上、下游坝坡坡比(1:1.4、1:1.5、1:1.6、1:1.7),计算不同工况下的坝体稳定系数,通过线性回归,得到坝高及坝坡与稳定性的关系表达式,为高面板坝的坝高和坝坡设计提供了很好的借鉴。(2)采用有限元强度折减法,以摩尔-库伦等面积圆屈服准则为屈服准则,取坝高为300m,上、下游坝坡坡比均为1:1.4的混凝土面板堆石坝,计算不同工况下的坝体稳定系数。结果发现该屈服准则计算的结果与传统的极限平衡法计算的结果十分接近。也进一步验证了上述公式的合理性。(3)通过研究坝体最大断面的主次堆石分界线坡度的变化对坝体稳定性的影响;不同主次堆石分界线坡度、不同主次堆石变形模量对面板堆石坝变形、应力特性的分析,研究了主次堆石分界线坡度及主次堆石变形模量比值的合理取值范围,为面板堆石坝的断面分区优化和合理利用开挖料提供参考。更多还原

【Abstract】 Concrete Faced Rockfill Dam (CFRD) was widely adopted in the recent decades because of its good security, extensive adaptability, convenient construction, small investment, short construction period. With the development of techniques and continuous application of new technologies about CFRD, it is becoming a competitive dam type among earth and rockfill dams and the height of CFRD is increasing. Shui Buya CFRD (dam height 233m) is the highest one among all the established CFRD in the world, and 300m level-CFRD is designed at home and abroad.The increase of dam height raises a more strict claim about the security for the design of CFRD. The research approach adequate for 100m level-CFRD needed to be revaluated while the engineering characteristics and other key technologies of 300m level-CFRD are also requiring deep analysis, among which the slope stability and section division optimization are the critical technical issues. For a long time, the CFRD was considered it has a good stability due to the rockfill’s erosion-resistance and geology adaptability, and the slope ration adopted 1:1.3 or 1:1.4 with experience. But this empirical design ratio might not be suitable to high CFRD, and the analysis of slope stability should consider the effect of dam height and slope ratio. In the typical division of CFRD proposed by Cooke, the scale of“dead zone”was not exactly designed, and there was no referable deformation modulus ratio between main and secondary rockfill zone. Owning to the complex stress-deformation characteristics of high CFRD, this question should also be discussed particularly.The effect of dam height and dam slope to slope stability were analyzed in this article with the limit equilibrium method and strength reduction method based on FEM and the expressions of dam height & stability factor and slope ratio & stability factor were proposed; the effects of the boundary ratio and the deformation modulus ratio between main and secondary rockfill zone to stress-deformation characteristics were studied and the reasonable scale of the boundary ratio and the deformation modulus ratio were suggested, which both meet the stability requirement and make full use of the rockfill materials to achieve the economical efficiency. The main content are as follows:(1) With the STAB program based on the limit equilibrium method (LEM), the stabilities of typical height dams (150m、200m、250m、300m) and slope ratios (1:1.4、1:1.5、1: 1.6、1:1.7) were analyzed under different operating times, the expressions of dam height & stability factor and slope ratio & stability factor was obtained by linear regression with a favorable correlation, which provides reference to the slope and dam height design of high CFRD.(2) Through strength reduction method based on FEM, the stabilites of dams (dam height 300m, dam slope 1:1.4under different operating times) were studied, according to the Mohr– Coulomb equivalent area circle yield criterion . The results implied that the stability factor were close to the results of LEM, which also proved the rationality of expression in content 1.(3) The effect of boundary ratio between main and secondary rockfill to stability for the maximum section, the effect of typical boundary ratio and the deformation modulus ratio between main and secondary rockfill to stress-deformation characteristics of high CFRD were studied. The rational range of boundary ratio and the deformation modulus ratio were pointed out to provide some references for the section division optimization and rational utilization of excavated materials for CFRD.更多还原