| Frequently occurring in mountain valley or sloping field, debris flow is one kind of solid-liquid two-phase flow which containing a mass of sand block and bowlder. It has many characteristics such as breaking out abruptly, time brevity, vigor ferocity, and fast calamity etc. Now it bas become one of the most active surface dynamic physiognomy processes. Impact force of debris flow is a sort of dynamic loading when debris flow goes forward to impact all the tings touched. It is the load gist to actualize controlling projects of debris flow. Based on the research of kinematics and dynamics of debris flow, the paper has studied impact force of debris flow with manifold numerical calculations. The main contents and conclusions include:First,the paper has established a experimentation model of debris flow and experimentalized according to 0.3~0.8cm,0.8~15cm,1.5~3.0cm three solid phase diameters, 0.02,0.08,0.16,0.20,0.25 five solid phase ratios. At the same time it attained more than 85000 data using bridge sensor, dynamic strain gauge and high-speed vidicon etc and established more than 40 dynamic impact signals at different states. Depending on the result of experimentation, the velocity is decreasing, but the impact of debris flow take on increscent current along with the augmentation of solid phase ratios.Second, based on water for carrier, the impact force curves of debris flow have been regarded as one kind of pressure fluctuation signals to be analyzed. By the research on every kind impact signal of debris flow, the paper has estimated and analyzed the average, standard deviation, maximum, normal distribution curves and the velocity of debris flow. So, the characteristic parameters relativing to the impact signals of debris flow have been picked-up.Third, based the characteristics of impact signals of debris flow, the paper has used different wavelet analysis methods to denoise the signals in order to finding more obvious trend of the impact signals. Taking the B-3 impact signal for object, the paper have make use of the time-frequency localization functions of wavelet analyse to distill the signal frequency of energy distributing. Then it's known that the main energy segment is among 0~10Hz.Fourth, grounded on the analysis to impact signals of debris flow, the paper found the congruous fluctuating pressure expression by constantly computing and data fitting. The correlation coefficients of A, B, C sets are 82.81%, 86.12%, 96.16% separately. It shows that the solid phase ratio is indispensable to fluctuating pressure calculation.Fifth, making use of the smoothness of de-noised data curves, the paper regarded them as liquid phase impact force of debris flow, expanded the smooth signals according to the interrelated and experiential theories and distilled the discrete solid phase impact force curves. Based on the contacting mechanics and momentum conservation law, impact effect of great blocks in debris flow to controlling structures was analyzed.Sixth, based upon the load curves analyzed with wavelet, according to the characteristics of fluctuation load of debris flow and reciprocity of solid-liquid two-phase, the paper generalized cyclic loading model of impact signals of debris flow and predigested the model into turbulent debris flow and viscous debris flow two load modes. It offered more effective account theories to design the load of controlling structures of debris flow.
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