【作者】 郭航忠；

【导师】 彭新民；

【作者基本信息】 天津大学 ， 水利水电工程， 2004， 硕士

【摘要】 水垫塘内防护结构的安全问题是实现消能和防冲目的的关键，对河床和大坝的安全至关重要。如何判别水垫塘内底板的稳定，这是实际工程所面临的亟待解决的课题之一，也是国内外许多学者长期致力于研究的课题之一。本文就这一问题，设计了一模型试验，对底板失稳时所受上举力与底板抗力间的关系以及水垫塘内底板稳定的安全水垫深度这两方面的问题进行了分析研究，提出了底板稳定的判别标准。具体研究内容如下：1.底板的失稳过程、失稳方式以及与入水单宽流量、水垫深度等的关系。2.底板失稳时上举力最大值与底板抗力间的关系。3.对上举力的最大值进行回归分析，利用底板稳定的控制准则，推导了底板稳定安全水垫深度的计算公式。4.对实测的上举力时程线进行了概率统计分析得出上举力超过底板抗力的超过概率。5.对底板所受上举力的时均值和标准差进行了回归分析，并在假定上举力服从正态分布的基础上，推导了底板稳定安全水垫深度的计算公式。小波分析是一种新的变换分析方法，同时具有时域和频域的良好的局部化性质。本文提出了一种利用小波分析水流脉动压力的方法，并利用该方法对试验实测的脉动压力进行了分析，同时探讨了信号采样长度和采样频率对该方法分析结果的影响。更多还原

【Abstract】 The safety of the protective structure in the plunge pool is the key to theachievements of energy dissipation and erosion protection. It is vital to the safety ofthe riverbed and the dam. How to judge the safety of apron slabs is one of theproblems that need to be solved in practice and also one of the subjects that manyresearchers have studied for years. According to this, a model experiment is designed.The relationship between the uplift loads and the resisting forces of apron slabs andthe safe water-cushion depth are studied in this paper. Based on the researches above,the criteria for judging the safety of apron slabs is put forward. The main researchwork details are as follows: 1.The process and the mode of the destabilization of the apron slabs underdifferent unit discharge, water-cushion depth and etc are analyzed. 2.The relationship between the maximum of uplift loads and the resisting forcesof apron slabs is analyzed. 3. The regression analysis on the maximum of uplift loads is conducted. Basedon the control criterion for the stabilization of apron slabs, the formula of the safewater-cushion depth is deduced. 4.Using probabilistic method, signals of uplift loads are analyzed and theprobability that uplift loads are greater than the resisting forces of apron slabs isobtained. 5.The regression analysis on the time average and standard deviation of upliftloads is conducted. Under the assumption that uplift loads are subject to normaldistribution, the formula of the safe water-cushion depth is deduced. Wavelet analysis, a new analysis method, has good local properties in both timeand frequency domains. A wavelet analysis method, which is applied to analysis onflow fluctuating pressure, is put forward. The impact of the sampling time andfrequency on this method is studied.更多还原