Research On The Vibration Detecting Method Of Subgrade Compaction Degree Based On Vritual Instruments

In the current highway construction, the traditional method to detect the degree ofcompaction can not meet the requirements: non-destructive, high speed and precision, in theprocess of engineering quality inspection. Hence, to develop a rapid and non-destructivemethod to detect the compaction degree has a very important engineering significance.This thesis is based on the test methods of compaction degree and research results athome and abroad, then we use the transient shock method, and combined with virtualinstruments and related software to develop a new system on testing the compaction degree.The hardware: heavy hammer, roadbed and sensor in this system has selected by scientificcalculation and design. The core of this system is PXI and SCXI platform from NationalInstruments, and then combined with the LabVIEW software to collect, display, save andreplay the signal. First, in the case of keeping certain water content in the roadbed specimens,we begin to measure the acceleration at the moment of the heavy hammer shocked with theroadbed specimens of different compaction degree in the laboratory conditions. Later, we fitthe data in Excel software by using the peak and peak to peak method. Then, according to theregression curve, to evaluate the quality of this two methods and select the plan which isadopted by the system. Finally, to test the regression equation wether it is reliable in the fieldtest and realize testing function of compaction degree for different subgrade specimens.Through the field test, we find the method is feasible and the result is reliable. Thevirtual testing platform of the SCXI, PXI architecture can be applied to the test system ofcompaction degree conveniently, quickly and effectively. It has provided a test basis forexploiting a kind of fast, nondestructive and precise method to test compaction degree in thefurther study.