Research On Characteristics Of Fluctuating Pressure And Its Similarity Law For Pervious Slab In High Dam Plunge Pool

Most hydropower stations were built in high-mountain gorge areas in China. The energy dissipation for releasing the flood is characterized as high head and large discharge in narrow valley, thus the problem of flood discharging and energy dissipation with high head and discharge power is critical and prominent. To consume enormous amounts of energy and prevent high-velocity flow to erode underwater bed, riverbed which was some distance from dam toe was lined with concrete and subsidiary dam in position to form of a certain depth of the stilling pond. The safety of protecting structure in plunge pool is the key to success of energy dissipation. The stability of lining structure in the plunge pool is one problem that needs to be solved in practice and also one of the subjects that many researchers have studied for years. Therefore, the study on safety of protecting structure in high dam plunge pool is still one of the front subjects in engineering hydraulics field. To improve the stability of protective structure, the researchers began to consider more effective ways to resist loads. More effective ways for resisting deformation under load have been explored to improve the stability of protective structure. From the concept of initiative protection, pervious slab can initiatively decrease the load acting on the pervious slab in plunge pool and improve the stability of protection structure. At present, pressure fluctuation similarity law in plunge pool should be studied in the first place to interpret the working principle and load characteristics of the new defensive structure, by which we could convert model test results in to fluctuating load of prototype.Secondly, due to the changing of own original structural style of active protection, it might completely change the pulse of the load transferring method. Therefore, analyzing the characteristics of the propagation of the reassure wave within the contraction joints plays an important guiding role in the rational determination of stress and stability design of the new kind of protection structure. The dissertation designed a series scale of hydraulic model test based on theoretical analysis and model test. Comparative analysis was carried out to study the characteristics of fluctuating pressure, the related spectrum and model similarity criterion between pervious slab and impervious slab in plunge pool. Furthermore, characteristics of the propagation of the pressure waves of pervious protecting structure were studied. The main achievements of the dissertation include:(1) It was analyzed in the paper of the characteristics of the amplitude value of the pressure recorded in the experiments. It consisted of the computation of average, standard deviation, skewness, kurtosis, probability density function and characteristic function of the pressure data, etc. From the results, a similarity law of the amplitude value of fluctuating pressure was discussed in the hydraulic model test.(2) The paper analyzed the characteristics of the correlation and spectrum of the pressure recorded in the experiments, which consisted of the computation of autocorrelation, spatial correlation and power spectral density function of the pressure data, etc. From the results, a similarity law of the correlation and spectrum of the pressure was discussed in the hydraulic model test.(3) The paper analyzed the propagation of the pressure wave within the contraction joints recorded in the experiments, which consisted of the characteristics of amplitude value of the pressure, correlated and related spectrum within the contraction joints.Above all, it could be drawn that in the hydraulic jumps and plunge pools, the similarity law of the pressure fluctuations of both the pervious slab and impervious in plunge pool obeyed the Froude law. Meanwhile the function of pervious holes was equivalent to increasing the gap width.