Application of CCHE2D Numerical Model on Deposion Fan of Debris Flow

• Main Authors: Kun-Ting Tsai, 蔡坤廷
• Other Authors: Huei-Bang Lian
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/62805392748582597209

碩士 === 逢甲大學 === 水利工程與資源保育學系 === 104 === A study was use CCHE2D numerical model, set up of movable-bed of open channel numerical terrain, and according to debris flow’s characteristic to adjustment sediment transport factor, input triangular discharge hydrograph and Equilibrium sediment to numerical terrain, when discharge hydrograph arrive peak, we increase volumetric sediment concentration to debris flow scenario simulation,and let sediment transport to be overload in channel to simulation debris flow,and to do sensitivity analysis about factor. According to the study and analysis of the test, hereby list the following result: 1.SEDTRA model is the best result in sediment transport formula of the sensitivity analysis about debris flow simulation. 2.The solid particles size didnt affect thickness of the Deposion Fan ,if big size particles is more,the Deposion Length is long and diffusion amplitude is broad.If little size particles is more,the Deposion Length is short and diffusion amplitude is narrow. 3.Adaptation Length is a sediment transport factor of the CCHE2D numerical model,influences of the deposion concentrated degree . If Adaptation Length is long , thickness of the Deposion Fan is thick and slop of Deposion Fan is slow. If Adaptation Length is short , thickness of the Deposion Fan is thin and slop of Deposion Fan is steep. If want fairish of the slop and diffusion area , the Adaptation Length should between 80m to 189m. 4.Mixing layer is a sediment transport factor of the CCHE2D numerical model, If Mixing layer thickness is thick,diffusion area of the Deposion Fan is broad,and have a triangular deposio at valley downstream. If Mixing layer thickness is thin,diffusion area of the deposion fan is narrow,and have a sector deposio at valley downstream. The results show mixing layer between 0.001m to 0.5m can showing deposion fan of the debris flow, Therefore recommended use default value 0.01m. 5.Adjust volumetric sediment concentration of debris flow when fixed discharge ,is adjust inflow volume of the solid particle . The results show Adjust volumetric sediment concentration of debris flow can showing deposion fan, diffusion amplitude is along with volumetric sediment concentration increase. 6. According to previous studies,with particle size 2mm, 2% and 80% of the limit. The three types of debris flow in the bulk segment generated Jieke fan piled earth and sand particle size composition has no significant effect on the accumulation of thickness variations. Three, to the accumulation of mud flow length of the longest, followed by debris flow, debris flow accumulation length of the shortest, a simulation result of this trend, and the particle size of the study the test results match. Keyword : CCHE2D、Debris Flow、Deposion Fan、Sensitivity Analysis