某拱坝坝基坝体承载力评价及右岸坝肩稳定性分析

发布时间：2018-06-24 05:06

  本文选题：右岸坝肩 + 拱坝承载力　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：拱坝整体承载力及坝肩抗滑稳定一直是拱坝工程所关注的重要问题。本文以某代表性拱坝为例,利用有限差分软件FLAC3D,通过多种分析方法对该拱坝的整体承载力及坝肩抗滑稳定进行了分析和评价,并对不同分析方法的适用性进行了探讨。(1)利用超载法评价拱坝整体承载力。水容重超载法评价拱坝整体承载力,分别从超载过程中拱端推力的变化规律、坝体坝基变形及塑性区的发展、右岸坝肩的位移及塑性区变化特点等五方面进行了分析。(1)拱推力在建基面上的分布,随着超载系数的增大,呈现出了向坝体中部高程位置转移的特点。从法向与切向拱推力比值tanφ可看出超载对坝肩岩体的稳定性不利。(2)断层的错动量曲线在超载系数为7.75时发生突变。(3)在水容重超载过程时,右岸坝肩岩体屈服区由低部高程逐渐向中高高程部位发展,并在超载系数为7.75时,屈服区贯通。(4)对前人提出评价拱坝整体承载力指标K1、K2、K3、K4进行了探讨,认为K3不仅要考虑坝体特征点位移超载系数关系曲线拐点,还需综合考虑坝肩变形与屈服规律。通过本拱坝水容重超载分析,得到K1=1.0,K2=1.75,K3=6.75,K4=8.75。库水位超载法在超载过程中,拱推力变化规律与水容重超载法类似,超载系数为2.1时,断层错动量曲线出现拐点。但坝肩岩体塑性区分布远小于水容重超载法,且只在中高高程上有一定发展。水容重超载法得到的K1=1.0,K2=1.4,K3=2.1,K4=2.2。拱推力超载法由于没考虑坝肩坝体之间的协调变形,分析拱坝整体承载力时,效果不理想,认为不适合评价拱坝整体稳定性。(2)强度折减法评价右岸坝肩整体稳定性,得出的安全储备系数为2.4。从失稳模式来看,是坝肩边坡自重情况下的稳定性,而不能反映坝肩抗力体在拱推力作用下的抗滑稳定问题,不能回答工程所关注坝肩抗力体特定失稳模式的稳定性,有一定的局限性。(3)为评价右岸坝肩关键块体稳定性采用了四种计算方法,方法I为折减关键块体,方法II为折减形成关键块体的结构面,方法III为折减构成关键块体的结构面及III岩体,方法IV为基于应力变形的块体极限平衡法等。(1)方法I时,右岸坝肩失稳模式为浅层滑动。(2)方法II和方法III时,坝体拱推力影响范围内的岩体随着折减系数的增大而不断产生朝向坡外的变形,能较为客观地体现关键块体的失稳趋势。(3)方法IV物理意义明确,所得安全系数与刚体极限平衡法具有一致性,说明此种方法评价坝肩关键块体稳定性较为理想。
[Abstract]:The overall bearing capacity of arch dam and the stability of dam abutment against sliding stability have been an important issue in arch dam engineering. This paper, taking a representative arch dam as an example, uses a finite difference software FLAC3D to analyze and evaluate the overall bearing capacity of the arch dam and the stability of the dam abutment against sliding and the applicability of the different analysis methods. (1) to evaluate the overall bearing capacity of arch dam by overloading method. Water bulk density overload method is used to evaluate the overall bearing capacity of arch dam. The variation of arch end thrust in overloading process, the deformation of the dam foundation and the development of the plastic zone, the displacement of the right bank's abutment and the change of the plastic zone, etc. are analyzed. (1) the separation of the arch thrust on the building base. With the increase of overloading coefficient, it presents the characteristics of the position shift toward the middle elevation of the dam body. From the ratio of the normal to the tangent arch thrust, Tan Phi can be seen that the overloading is unfavorable to the stability of the abutment rock mass. (2) the fault momentum curve is abrupt when the overload coefficient is 7.75. (3) the yield area of the right bank abutment rock mass during the overloading process of the water bulk density From the low elevation to the middle and high elevation, the yield area penetrates through the overloading coefficient of 7.75. (4) the previous evaluation of the overall bearing capacity of the arch dam K1, K2, K3 and K4 has been discussed. It is considered that K3 should not only consider the overloading coefficient of the dam's displacement, but also consider the deformation and yield law of the abutment. In the overloading analysis of water bulk density of this arch dam, the variation of arch thrust in the process of overloading of water level of K1=1.0, K2=1.75, K3=6.75 and K4=8.75. is similar to that of water density overload method. When the overloading coefficient is 2.1, the fault momentum curve appears inflection point. But the plastic zone distribution of the abutment rock mass is far less than the water bulk overload method, and only one of the middle and high elevation is in the middle and high elevation. The K1=1.0, K2=1.4, K3=2.1, K4=2.2. arch thrust overloading method obtained by the method of water bulk density overload is not suitable for the overall stability of arch dam, because it does not consider the coordination deformation between the dam body and the overall bearing capacity of the dam, and thinks that it is not suitable for evaluating the overall stability of the arch dam. (2) the strength reduction method is used to evaluate the overall stability of the right bank abutment, and the safety reserve system is obtained. The number of 2.4. is the stability under the gravity condition of the abutment slope, but it can not reflect the stability of the dam abutment resistance body under the action of the arch thrust, and can not answer the stability of the specific instability mode of the abutment resistance body. (3) it is used to evaluate the stability of the key block body of the right bank abutment. The four method of calculation is that I is the key block to reduce the key block, and the method II is to reduce the structure surface of the key block. Method III is the structure surface of the key block and the III rock mass, and the method IV is the block limit equilibrium method based on the stress and deformation. (1) when I, the right bank abutment instability mode is shallow sliding. (2) II and method III, when II and method III The rock mass within the influence range of the thrust force increases with the increase of the reduction factor, which produces the deformation towards the slope outside. (3) the physical meaning of the method IV is clear, and the safety factor is consistent with the rigid body limit equilibrium method. It is said that the stability of the key block body of the abutment is better than that of the method. Ideal.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223
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本文编号：2060154