| Firstly, the thesis introduces the theory of water wave dynamic applied in the impulse wave. Then the wate wave dynamic computing model is built. The whole paper takes Gongjiafang rockfall and its surge for example. The Gongjiafang engineering geological condition and surge orginal condition are surveyed in field detailedly, analyzing its deformation and failure mode. Water wave dynamic model is employed to simulated Gongjiafang surge in a computing domain of23km length and10.4km width. The author analyse the wave interaction mechanism consistence character with the results of physical tests. The field survey information, formula results and tests values were used to check the simulation accuracy, and formula calculating system method is given based on whole process of impulse wave. At last, the prospect of water wave dynamic model given in the paper is discussed. In the above work, the paper studies on below three innovation points:(1) The computing theory on water wave dynamic model simulating landslide-surge is proposed. Introducing the water wave dynamic equations, the forecasting software of impulse wave is compiled, and analysis method on impulse wave generated by landslide in reservoir is built basically.(2) A experiment method on physically simulate impulse wave generated by cataclastic rockmass is proposed. The results of physical scaled model and numerical model is used to study the formation, propagation and run-up process of the surge.(3) Based on the understanding of impulse wave action process, one formula calculating system combined with empirical formula, theoretical formula and experimental formula is built, which can be used to assess the maxium wave height in the river, the maxium wave height and maxium run-up of some point rapidly.The main conclusion and progress obtained from the paper are following as below:1. The water wave dynamic model, FAST (Fast assessment system for tsunamis generated by geo-hazard) software is developed with the technology of GIS. This software is consisted of pre-process module, computing module and post-process module, it improve and enhance the source function with the character of easy operation, high efficiency and visualization. In FAST, the representive particle, the thalweg line, and river can show the history process of the impulse wave.2. As the application of case, Gongjiafang rocky slope of Three Gorges Reservoir is studied in emphasis. Because of the change of formation lithology, there is slightly soft and thin marl of T1d3group in the foot of slope, and there is thick dolomitic limestone of T1d4group in the middle of slope. More than10large structural planes are developed in the slope, two preferred structure plane groups and rock layers form cataclastic structural rockmass. The median size of the accumulation is25cm after field survey. Based on the survey on the Gongjiafang slope and around slopes, V shape toppling deformation, interlaminar shear and bank collapse are discoved. The Gongjiafang slope is one typical reverse rock slope with toppling deformation, and its failure mode is topple. The upper deformation part is basically stable segment, the middle part is toppling and the foot part is sliding. The stability of the whole slope is mainly affected by the lower slide section. When the lower section is failed or damaged, the overall structure is collapse and instability immediately.3. The surge orginal conditions of Gongjiafang landslide are studied. Because the Gongjiafang rockmass structure is cataclastic structure, the landslide sliding into water is granular clusters sliding into water with the volume of38×104m3. The underwater course is11.5%of the total section length in sliding direction. The water depth of Yangtz River of this course is140m, and the water way type is V sharp gorge reservoir.4. The water wave dynamic model FAST is employed to simulate the impulse wave generated by Gongjiafang rockfall in23rd Nov.2008, qualititatively analyzes the development of impulse wave in the Yangtze River and divides the prewarning risk region.5. The whole process analysis on the Gongjiafang vedio show that the impulse velocity of landslide was12m/s, the maxium amplitude of impulse wave was31.8m, its phase celerity was12-18m/s, the maxium run-up in the opposite bank is12m, and there were still1-2m run-up wave in the Wushan Town harbor after propagating to4.5km away upstream. When comparing with the FAST results, it is in good agreement with the field run-up value and the vedio.6. According to gravity similarity criterion, one model with24m length and1.3m width is built in the ratio of1:200to simulate the surge in4.8km river course. The marble coarse sand with the D50of1.47mm is used to simulate the collapse material, with the shape of isosceles trapezoid. The simulation river condition is peace and still with no flow. Six wave gauges are used to monitor the wave process in the sliding direction, and nine wave gauges are used to record the wave process in the river way. Fifteen run-up instruments are used to measure the maxium run-up, and two high-speed cameras are used to record the formation process of impulse wave and the run-up. The physical scale test reproduces Gongjiafang rockfall and its surge in the water level of172.8m, the maxium wave amplitude of17.4m is obtained. Compared the test data with the survey data, the relation coefficient is0.949with the average difference of10%. All these show that the physical test is valid and can be used to study on impulse wave rule. 7.145m,156m,172.8m,175m water level series of physical tests show that there are some rules in the process of impulse wave. In the generation phase, there are two bigger wave crest. The propagation, superposition and reflection of the two waves are recorded by the wave gauges, which present the interaction of waves in the propagation process. The data refinedly portray the difference of wave propagating decay in the water way. In the generation zone, the decay ratio is the biggest with the value of5O%o, in the slightly far zone, the decay ratio is about1‰, and the ratio is0.5‰in farther zone. As the extendence of river way, there exist rapid decay zone and gentle decay zone obviously. The cameras and run-up instruments record the run-up condition. The run-up data show that there also exist rapid decay zone and gentle decay zone as the river way, but the micro-topography has a great influence on the run-up, so it is not easy to quantify.8. In the micro perspective, the process lines of water gauges are in good agreement with the point history of simulation. The numerical simulation reproduces the wave chasing, superstition and reflection in the physical test. In the macro perspective, the wave amplitude and run-up value of the simulation are closed to the physical test results with good correlation. The simulation condition can quantitatively reflect the results of physical test and formulas; it has good validity and accuracy.9. One impulse wave calculating system combined with empirical formula, theoretical formula and experimental formula is built. It confirms the leading wave amplitude formula according to the sliding material. It use the cycling propagation formula and parallel propagation formula to calculate wave amplitude in rapid decay zone and gentle decay zone, and local head loss is taken into consideration for propagating calculation modification. The calculating results are very closed to FAST values.10. Water wave dynamic model method can offer technology basis on the prewarning on impulse wave hazard generated by landslide in long distance water region. In the future, varied impulse wave orginal model should be enhanced in ord to expand the usage range of the water wave dynamic model.The thesis systematically discusses the rockfall and its following surge in the reservoir, calculates and analyses rockfall and its surge key problem including rockfall deformation, rockfall dynamic, impulse wave generation, propagation and wave run-up. The water wave dynamic model is used to study impulse wave generated by rockfall, which supple and enrich the methods and theories in the side of impulse wave research and prediction. The paper takes the typical rockfall of the Three Gorges Reservoir for example, compares the simulation with the physical test, formula and field survey sufficiently, which has important theoretical and practical significance. |
PDF Full Text Request