| The ground-based microwave interference radar integrates Stepping Frequency Continuous Wave technology,Synthetic Aperture Radar technology and Interference Measurement technology.It uses non-contact measurement method to obtain real-time dynamic monitoring data and becomes a new monitoring technology in deformation monitoring field.Based on the IBIS system of ground fault radar produced by IDS Company in Italy,this paper studies that the system performance test,Hilbert-Huang transform theory and its application in the data processing of foundation radar.The main contents are as follows:1-IBIS system comprehensive performance test.The accuracy of the IBIS system is simulated by the combination of corner reflector and the spiral micrometer.The results show that the accuracy is better than that of the sub-millimeter.In order to ensure the accuracy of IBIS system monitoring,the influence of instrument placement error and atmospheric error is further studied.The influence of elevation angle and distance on observation accuracy is proved by experiment and data simulation method.The atmospheric data The observation results have an effect,and the atmospheric parameters model needs to be corrected.2-IBIS system dynamic monitoring application.The IBIS system is used to study the deformation dynamic of a high-speed railway bridge.The key structures of the continuous-supported box girder,the long-span continuous cast-in-place beam,the pier and the acoustic barrier are measured and the measurement objects are obtained.Dynamic displacement sequence.In addition,the application of IBIS system to complete the Tongzhou Dipamkara Tower monitoring project,designed a high-rise building monitoring program and data processing methods.Combined with the bridge monitoring dynamic monitoring program summed up the complete IBIS dynamic monitoring system.3-Based on the Hilbert-Huang transform(HHT)theory,the non-linear and unsteady vibration signals obtained from the IBIS system of ground-based radar are analyzed and analyzed.(1)Empirical modal decomposition(EMD)vibration signal reconstruction.For the dynamic measurement results are affected by high frequency noise,the adaptive signal processing method EMD is used to denoise the ground radar original signal.The original signal is decomposed into a series of intrinsic modal functions(IMF)from high frequency to low frequency.The correlation coefficients are used to determine the noise boundary,and the IMFs are reconstructed into noise sequences,periodic sequences and trend sequences.Compared with the original signal,the reconstructed periodic sequence can more accurately reflect the vibration detail and periodicity of the building.(2)HHT modal parameter identification.In order to obtain the load frequency of the high-speed railway bridge under the train excitation,the original signal is decomposed into the intrinsic mode function(IMF)which expresses the vibration response by HHT theory.The main mode of the vibration response is investigated by Fourier spectrum,(RDT),the deterministic signals in the response of the main mode are extracted,and the Hilbert transform is performed to identify the natural frequency and damping ratio of the vibration of the building under the excitation.In the process of ground radar data processing,combined with the HHT theory,it can effectively eliminate the noise effect,obtain the real displacement data,accurately identify the building modal parameters,and provide the scientific and accurate basis for the health assessment of the building,so as to It is proved that HHT theory has good applicability to the application of ground radar data. |
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