Mountain Rivers Scattered Riprap Dam Anti Destroyed Measures

Loose rock dams are often destroyed due to rapid flow velocity in mountain streams. In this thesis, first, reasons and factors for the stability of loose rock dams were summarized according to the field surveys and certain expert's experiences. Then, researches on block stability problems were reviewed, and according to the relationship between grain size and incipient velocity, it is found that the block weight is in direct proportion to 6-9 power of incipient velocity, and 50% increase of the velocity willresult in about 40 times change of the block weight. After that, experiments were conducted in a flume, focusing on the relationship between incipient velocity and some main factors including block weight, water depth over the dam, cross-section size, block material and river bed material. The result shows that it is not appropriate to improve the stability of loose rock dams by simply increasing the block weight. Finally, a flexile concrete gemel was suggested to protect loose rock dams.