Experimental Research Of Homogeneous Earth Dam Overtopping Breaching Process Based On Resistor Matrix Measurement Technology

The effect of dam accident is fatal.International scholars attach great importance to the research of dam break problems.The number of earth dam is largest and the proportion of earth dam of dam-failure rate is biggest in all dams.But the break mechanism of earth dam is very complex and the tools measuring the dam break process have some defects,the break mechanism of earth dam is not very clear.Dam model test is the major means of studying dam failure mechanism.Dam failure process measuring tool directly influences the precision of the research result of dam model test,so the study of dam failure process measurement is of great significance.Based on the existing research results of domestic and foreign scholars,in view of the insufficient research of the present dam break mechanism and too single tools measuring the dam break process,the new measuring equipment based on resistance matrix positioning technology which can be used to measure earth dam overtopping breaching process especially the dam breach process is independently designed and developed from the perspective of improving dam-break measuring tool,detailed investigation is made on the previous dam failures,and in view of accident-prone dam type and common dam-break way,multi-group homogeneous earth dam overtopping dam-break model tests are carried out.The results are as follows:(1)Through the investigation and analysis of previous dam failures,we find that low standard for flood control and poor engineering quality are the main causes of the dam failures,and the major forms of earth dam break are overtopping and piping.The research of earth dam especially the homogeneous earth dam overtopping dam break has the typical significance,and it should be the focus of the research of dam break problems.(2)The measuring equipment based on resistance matrix positioning technology which can be applied to the dam break process measurement has been independently designed and manufactured,and a series of problems in the equipment design and production are solved.Through the actual dam-break test,waterproof and functionality of the equipment are well validated.It can be seen from the reverted dam break process by using dam break measurement process that after the water flow overtopping,first there is an obvious downcutting process on the dam body,and downcutting gradually develops to two sides after developing to a certain stage.It can be seen that the water erosion damage to the dam body is slower in the initial stage.But plenty of water flow drains through the dam breach when the dam breach develops to a certain stage.The erosion process to the earth dam aggravates accompanying the soil failure around the dam breach meanwhile,and the dropping speed of the resistor unit is significantly increased.The dam breach is covered with the muddy water and the slumping soil in the process;it is difficult to observe the development process of the dam breach only by the naked eye,so the advantages of the measurement equipment based on resistance matrix positioning technology rather than the optical principle are put forward sufficiently.(3)Dam slope and dam construction materials affect the dam-break duration,and the dam break process lasts longer when the overtopping dam break happens on the earth dam with slower dam slope and denser dam construction material.The construction materials can't be completely homogeneous even in the homogeneous earth dam,the weak parts of the dam will be damaged by water,and the shortcomings of the dam will accelerate the dam-break process.(4)The dam erosion damage caused by the overtopping dam break occurs in the downstream face first,then it is scoured gradually from the downstream face to upstream face,the dam-break process significantly speeds up after the extending dam breach is formed,and finally the damage degree of dam downstream face is more serious than that of the upstream face.For the dam breach development,the water erosion to the dam is naturally the main reason that can lead to the development of the dam breach,but the soil collapse along with the water flow action is also one of the important ways of dam breach extension.It is necessary to think highly of the slope instability theory when we analyzed the breach development way of the earth dam,and the impact and infiltration of the flow should be considered meanwhile.