Theoretical Analysis On Density Measurement Of Rockfill Object By Additive Mass Method

In the21st century, as the world economy continues to grow, the demand ofelectricity is getting bigger and bigger, so there are more and more waterconservancy and hydropower facilities being under constructing now. In theconstruction of water conservancy and hydropower project, its quality is particularlyimportant. The density is a very important indicator in the process of detection ofwater rockfill dam（rockfill object）.The additive mass method is widely used in the rock-fill object densitymonitoring program. But most of the study on the additive mass method is based onthe assumption that the rockfill object system is elastic, and the influencing factorsabout the part of the vibration range rockfill case and frequency of the receivedsignal are not clear.In this paper, by establishing7kinds of medium parameters of the rockfillobject,6kinds of load parameters,2kinds of the offset of mass,2kinds of theradius of mass and under the effect of filtering detector, we have get factor of theshape and depth of the part of the vibration, the frequency of received signal and thepart of vibration qualitym0of method, through calculation and comparisonanalysis the range of rockfill part of the vibration and the speed curve of signal. Thespecific content and the results are as follows: by observation of the set of variousparameters, we identified the range of part of the vibration is semi-ellipsoid; theYoung’s modulus E affect the depth of the part of the vibration very much, thelarger Young’s modulus E is, the more depth of the part of vibration; the smallerattenuation coefficient β is, the smaller x-y direction range of the vibration of therockfill object. However, when β is small, the affect is not significant; as thenumber of mass increasing, the rockfill part of the vibration range is slightly smaller,but basically, there is no difference with the part of the vibration range with no mass;the bigger offset, the bigger frequency of reception signal, and it made the part ofthe vibration qualitym0smaller, so we suggested to set a appropriate offset in theactual project; the decrease of the mass radius would greatly reduce the part of thevibration quality, so we suggested to set a appropriate radius of mass.As the detector in the practical engineering is speed detector, which ishigh-pass, so the low frequency wave would be distortion. Because of this, we madea brief description of the selection of the speed detector, and provided theoreticalsupport for practical engineering operations. This paper theoretically studied the relationship of frequency between thesource and received signal, then derived their equation, also got the relationshipbetween the part of the vibration quality and the frequency of the received signal.This is meaningful to select the frequency of load in the actual operation.