Experimental Research Of Landslide Induced Wave In Shallow Water Area

The key in impulse wave study is to predict the maximum wave height,further predicting its degree of disaster,analyzing its propagation regulation in order to evaluate its potential risk.Deeply analyzing the formation mechanism of landslide impulse wave through physical simulation test,discussing its propagation feature,verifying and analyzing the applicability of the existing equation have significant theoretical and practical meaning for prediction and forecast of impulse wave generated by landslide in reservoir.This paper first analyses the formation and impulse wave feature of four typical landslide induced wave in shallow water area,they are Qianjiangping landslide,Xintan landslide,Jiguanling landslide and Tangjiaxi landslide.Taking the scale feature of four typical landslide case into consideration synthetically and on the basis of following similarity criterion,the indoor physical model is established.In terms of many indoor model tests,the maximum wave heigh,run-up and impact force are measured.The formation mechanism,wave feature and impact force changing regulation are deeply analysed.Finally taking Daling potential landslide point as an example,the maximum height of impulse wave,run-up and impact force after the deformation of landslide are calculated and analysed.Based on the analysis and research above,the main conclusions acquired in this paper are listed as follows:(1)summarization of typical landslide induced wave disaster cases in shallow water area and establishment of related modesBy analyzing the topography,formation mechanism,movement process and degree of disaster of Q ianjiangping landslide,Xintan landslide,Jiguanling landslide and Tangjiaxi landslide,these four typical landslide induced wave cases in shallow water area,the impulse wave features are concluded.That is,landslide slipping into shallow water has a great influence on watercourse and it may result in barrier lake or river blocking.Slipping mass entering water with high speed will generate higher impulse wave than it in deep water area under the same circumstance.According to scale of the four typical landslide case and based on Froude similarity criterion,the physical model of landslide induced waves in shal ow water area is established.(2)analysis of the interaction process between sliding mass and water bodyDuring the process of sliding mass sliding down,the sliding mass couples with water body and the sliding mass conveys its energe to water body continuously.The water tongue and landslide induced waves are generated.There are three stages during the process of its sliding down,namely violent acceleration,slow acceleration and violent deceleration.When the barycenter passes the water surface,the accelerated velocity starts to decrease as a reault of resistance and flotage from the water.The sliding speed decreases to zero rapidly after it reaches the maximum value when the sliding mass touches the bottom.While the speed reaches certain value,the water tongue is generated when the sliding mass touches the water surface.(3)Come up with the calculation model of landslide induced waves in shallow water areaRange and variance analysis method is used to analyze the experiment result,studying the sensibility that each influence factor has to the highest wave height and the maximum wave impact force.The results indicate that each influence factor affecting the highest wave height in sequence is thickness of the sliding mass,angle of sliding surface,water depth and length of the sliding mass.Regression method is adopted and calculation model of the highest wave height that is fit for shallow water area is put forward.And landslide examples in shallow wate r are used to verify the validity of the calculation model.(4)analysis of wave run-upWave run-up will straightly account for the surging force influence region caused by landslide induced wave.Wave run-up is mainly connected to the height of wave and angle of opposite bank.The first column wave will generate the highest run-up and the run-up height of the following wave will decrease gradually.Through the analysis of the experiment data,wave run-up decreases as the angle of the opposite bank increases.(5)analysis of water tongue impact force and wave surging forceThe sliding mass slides with a high speed and the water tongue is generated after it strikes the water.Water tongue propagates with high speed and flaps the opposite bank.Water tongue impact force and wave surging force will have an influence on trees and buildings on the opposite bank.The impact force value carried by the water tongue is one to six times as it of the surging force carried by the landslide induced waves.As the increasing o f opposite bank angle,water tongue impact force increases while wave surging force decreases.In overall consideration of the influence that water tongue impact force and wave surging force have on opposite bank,the angle between fending groin and horizontal plane should be 40-45° when establishing it on the opposite bank.(6)stability analysis of daling landslide potential pointThrough calculation,daling landslide potential point is basically stable under the condition of 175 m water level and rainstorm.Rainstorm will increase the sliding force and is adverse to its stability.The slope is influenced by the environment and human factors and it is in development of deformation.(7)the disaster degree prediction and analysis of daling landslide potential pointThrough analysis,the highest wave height will reach 18.4m after its deformation with run-up of 13-17 m and surging force of 226-304 Kpa.If large-scale slide happens to daling landslide potential point,it will threaten 260 persons of 76 families,citrus economic forest of 55 acres,400-meter length of G348 national highway,high voltage tower and cable,communication optical fiber cable and fishery zone in luogudong river.The probable direct economic loss will be over 60 billion.