Study on the Characteristics of Shear Stress in Debris Flow with Mixed Grain size

• Main Authors: Chen, Bryan, 陳柏安
• Other Authors: Yu Fan Chieh
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/93437875662720256626

碩士 === 國立中興大學 === 水土保持學類 === 84 === The purpose of this paper was going to measure the total shear stress in order to understand the flowing characteristics of debris flow. Twenty-one kinds of soil materials which were composed with different grain size were used to conduct the flowing experiments in flume channel. And the results were concluded as follows: 1. A shearmeter which was made with strain gage could measure the total shear stress during debris flowing. But the output signals still could not regulated perfectively because of the restriction of recorder. 2. The bore height is an important factor to affect the shear stress in debris flow.Measured shear stress would increase with the bore height, so does the volumetric concentration. 3. Velocity had an inverse tendency to the measured shear stress. The velocity gradient might be play the main role rather than the velocity to affect the shear stress. 4. In the viewpoint of dynamic friction, the inner dynamic friction cofficient would increase with H/D50 and the flume channel slope but in inverse of the volumetric concentration. For the surface friction of shearmeter, the friction cofficient would have the inverse tendency to H/D50 and the flume channel slope. 5. Comparing with Takashi''''''''s velocity equation, Yu''''''''s equation might comparatively match with the measured velocity. The measured velocity could not match well with the theoretical velocity, because some parts of observations for flowing velocity were not in the state of steady flow. 6. Synthetic roughness on the channel bed made the shear stress higher than the theoritical shear stress. The observed shear stresses could not confirm whether the real shear stress was or other stress effects were contained.