| Characterized by sudden outbreak and strong destructive power, the debris flow is the main type of water damage of highway. As one of the main debris flows, water-rock flow has the feature of wide distribution, fast formation and serious destruction. Based on the failure characteristics of water-rock flow and liquid rock impact of water-rock flow, the dissertation tries to explore into the negative influence of water-rock flow on highway, bridge and culverts and its impact on deformation characteristics of channel topography. Through theoretical analysis and experimental studies, the relationship among instantaneous flow spectrum, instantaneous acceleration spectrum, fluctuation pressure spectrum and channel topography has been studies based on interdisciplinary research such as fractal stochastic process, fluid dynamics, stochastic analysis theory, probability theory and mathematical statistics, applied statistics and mechanics of debris flow transport. The main contents and innovation achievements are as follows:First, after applying random process theory into water-rock flow, it has been demonstrated that instantaneous velocity of water-rock flow liquid can be measured; meanwhile, it can satisfy stable random process and is characterized by ergodicity.Second, based on water-flow model experiment, distribution of instantaneous velocity of water-rock flow liquid along the section of water depth has been obtained; the relationship between average turbulence intensity of water-rock flow liquid section and water depth has been analyzed; strong turbulence intensity has been verified; the signal of the liquid velocity is low in frequency or stable with the frequency within20HZ and intensity within10HZ. If the frequency band is within1HZ, the velocity signal is within1HZ.Third, on the basis of instantaneous velocity signal of water-rock flow liquid, random probability model of instantaneous velocity signal of water-rock flow liquid has been established with random process theory. Simulation analysis has been conducted to60group experiment signals; based on time-frequency transformation, analysis of amplitude, circular frequency and distribution of random phase angle probability, establishment principle of weight coefficient and equivalent simulated determination principle have been built; statistic eigenvalues and of spectral density function simulation signals and those of original signals are identical.Fourth, according to analysis of velocity probability model of water-rock flow liquid random particle, acceleration probability model of water-rock flow liquid particle and probability model of random particle fluctuation pressure have been established after constant computation and data fitting; fluctuation velocity spectrum obtained from known fluctuation pressure spectrum by inverse process has verified the accuracy and reliability of deduction and simulation process.Fifth, according to fluctuation pressure spectrum, lateral distribution law of fluctuation pressure has been obtained by entropy method; compared with topography isopleth, it has been found that if water-rock flow has fast velocity and large fluctuation pressure, there will be deep section scouring and larger groove variation.Sixth, the influence of water-rock flow on bridges and piers has been analyzed; increasing scouring, deeper scouring and decreasing load of base will lead to unsteadiness of piers; besides, strong force of impact will result in weaker overturning resistance property of piers.Seventh, on the basis of transformation relationship between random particle instantaneous flow pattern and fluctuation pressure spectrum, it has been found after comparing groyne measured topography data and fluctuation pressure signals: development rule of fluctuation pressure isopleth tallies with scouring topography variation; meanwhile, after analyzing the difference between variation of force of impact of water and fluctuation pressure variation, energy equation of random flow has been established which lays a solid foundation for the following study of fluid-structure interaction. |
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