| Due to the uneven thickness of the accumulation body of the barrier dam and the extremely uneven internal structure,it is of great significance to find out the compactness of the barrier dam to provide a basis for the treatment,reinforcement and development and utilization of the subsequent barrier dam.Based on the needs of practical engineering,this paper discusses the adaptability of natural source surface wave method to the compactness detection of large particle size barrier dam through the combination of forward and inversion of theoretical model and field test.The feasibility of natural source surface wave method is verified by the compactness detection of an actual barrier dam reconstruction project.The main research contents and achievements of this paper are as follows :(1)The present situation and existing problems of surface wave method for the compactness detection of barrier dam are analyzed.The dispersion equation of Rayleigh wave in layered media is summarized.The spatial autocorrelation method and its correlation function are summarized.The overall process of surface wave detection is briefly explained.(2)According to the causes of formation,the barrier body is divided into three categories,and the geophysical properties of the barrier body caused by collapse and landslide are analyzed.According to the structural characteristics of the dam body and the logging wave velocity,six dam body models with different compactness structures were established,and the model was numerically simulated and analyzed.The forward and inversion results verify the feasibility of surface wave exploration in the detection of extremely inhomogeneous media.(3)Through the on-site detection experiments of different arrays,the array combination suitable for the compactness detection of large-size barrier dam is clarified.Under the same number of detectors,the detection effect of triangular array is better than that of linear array.Under different number of detectors,the detection accuracy of the array increases with the increase of the number of detectors.Linear array is selected when affected by terrain fluctuation,and triangular array is selected for detection when terrain conditions are good.(4)The natural source surface wave survey line arrangement and detection of the barrier dam were carried out,for 11 velocity profiles,the relationship between apparent shear wave velocity and compactness was used to evaluate the compactness of the dam..By comparing the logging and elastic wave CT data,it is found that the natural source surface wave method has good accuracy in the compactness detection of large particle size barrier dam.(5)The relative relationship between the phase velocity of surface wave and the compactness of the dam is obtained by the results of the survey line and the logging data.Based on this,the three-dimensional model of the apparent velocity of surface wave and the distribution model of the phase velocity of surface wave are established according to the wave velocity information inverted by the survey line,and the compactness of the dam is evaluated and qualitatively partitioned. |
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