Experimental Study On Vibration Test Of Subgrade Compaction Degrees

As the government increased the infrastructure investment in the recent years,the construction of road is developing at a fantastic speed.Road density and traffic load is increasing and it is also a higher demand for the highway construction project on the quality and quantity.Compactness is one of the detection indicators to reflect the quality of the project.But the compactness testing methods have shortcomings of using more time and labor and destroying the roadbed.So it is an urgent requirement of the current situation in the construction of road to develop a rapid and convenient testing method to measure the compactness of roadbed.Based on the summarized relevant achievements both domestic and abroad,a new measuring method of compactness which combines with the transient Rayleight wave method and the frequency analysis of transient shock is put forward in this paper.The acceleration response signals are analyzed and it provides a experimental basis for the vibration test of compactness and the corresponding quantitative analysis method of the compactness is put forward.The tests of vibration which is according to vibration energy having different attenuation speed in different media and some combination of domestic design theory is a rapid testing methods to measure the compactness of roadbed.This paper uses the orthogonal experiment to combine the different control variables(compactness,water content,measuring distance) and puts forward the best vibration test program.We use different signal acquisition methods (detrimental to the collection and non-destructive acquisition)to collect the acceleration response signals,and measure the acceleration response signals which are produced in the hammer effect.First,the acceleration response signals are pre-processed,and then the damping ratio and RMS of the acceleration response signals are calculated.Using the Matlab software analyzes the correlation between the damping ratio and RMS and the compactness and gives the corresponding formula.Test results show that the soil damping ratio and RMS are the characteristics parameters to reflect the compactness.Through the correlation analysis between the two characteristics parameters and compactness,water content,the results show that it has a good linear relationship between the two characteristics parameters and compactness.And the water content did not significantly affect for the parameters.The test method is feasible,test results are reliable.The further study of the detection compactness's methods provide a theoretical basis for an accurate,rapid,non-destructive testing instrument of compactness,and it has the great significance for the actual measurement of the works.