| The safety of protecting structure in high dam plunge pool is the key to success or failure of energy dissipation, there is are many destructive examples in and abroad. Working and destruction mechanism of protecting structure in high dam plunge pool is very complicated, mechanism of transmission of fluctuating pressure in gap is invoved ,also corelationship of dynamic loads on up and down surface of slabs, so the uplift force is very hard to forecast. Model test and numerical analysis were studied in this paper, and hydrodynamic characteristics in high dam plunge pool is researched.fluctuating pressure in gap is studied by model test and numerical analysis, a simplified two-dimension model is build to reveal the characteristics of fluctuatingpressure in gap by model experiment data, then factors of uplift force are calculated using this simplified model. making the best use of the support vector machine characteristic of structure risk minimization principle, the upport vector machine safety monitoring model of slab-upliftforce is established. Main achievement is included as follows:(1)Two kinds of energy dissipation mode and their characteristics were introduced, fluctuating pressure in stilling basins was analyzed, including their amplitude characteristics, spectrum distribution and change law of spatial integral scales . some new kinds of energy dissipator and protective measures of stilling basins were introduced combining with engineering examples, by comparing data from model test,effect of these dissipater was showed.(2)Research models of fluctuating pressure in gap were studied, distribution law of pulsating pressure in gap was deduced based on oscilation model. Use cosine wave as an example, process of fluctuating pressure was caculated using transient flow model. Canculation results of these two different model were compared, characters of two method were analyzed.Fluctuations on upsurface and down surface were achieved by experiments of hydraulic jump in flume tank. Probability distribution and spectrum of fluctuating pressure were studied basing on the achieved data, and characters of fluctuations in gap was summarized. High and low frequency of experiment data were separated using wavelet decomposition. Corelationship between fluctuations in two ends of gap and conversion factor of fluctuations in gap Cg were researched.(3)Basing on conclusions of one dimension water oscillation model, a new simplified two dimension model is presented in this paper. It is considered that pressure fluctuation under slab can be determined by several points on the up surface, considering attenuation of pressure during transmission in gap,a attenuation coefficient K was introduced,and value range of K is calculated by experiment data. Corelation coefficient between fluctuations on the middle of up and down surface is verified using the simplified two dimension model. factors about uplift force were deduced using this model, and it is a new attempt to forecast uplift force by measuring fluctuating pressure on upsurface of slab using this model. Theoretical results and experiment results are compared by model test of hydraulic jump in flume tank.(4)BP neural network and support vector machine, which belong to machine learning theory, were used to forecast fluctuating uplift force by constructing forecast system, ability of the systems was test and compared by model test data. It is said that both these two uplift force forecast systems has good applied foreground for their good effect . a uplift force forecast model was construct by data from Guandi model test, and this model is precise to some extent in uplift force forecasting.
|
PDF Full Text Request