| There are carbonate rocks widely distributed along the section of Litang to Guiping in constructing Nanning-Guangzhou railways, where the distribution of carbonate rocks takes up 92.7% in the line. This thesis takes the method of transient Rayleigh wave in detection of the section Karsts grouting consolidation as the object of study. Through a large number of field tests before and after grouting, the forward analysis by ANSYS finite element numerical simulation, theoretic calculation and statistics of measured data, it has been analyzed and studied the method, time and criteria of transient Rayleigh wave in detection of grouting consolidation in three typical sections.Firstly, three kinds of different layered medium model are built and the corresponding dispersion curves are obtained by ANSYS finite element numerical simulation and theoretic calculation. It is shown that ANSYS finite element numerical method can be used to simulate the transient Rayleigh wave through analyzing dispersion curve shapes and wave velocity. Then, three typical sections are selected according to the borehole data and the model of numerical calculation is built. Analyzing and comparing the characteristics of dispersion curve shapes and wave velocity of field measured data and numerical simulation before and after grouting, which is to verify the reliability of the field measurement, is supplied the theory basis for data statistic analysis. Finally, the data of Rayleigh wave in the measuring points, where grouting is already checked qualified by the water pressure test, coring and other geophysical methods, have been statistically analyzed. The relation curves between wave velocity and buried depth are obtained, and further more the criteria are built, which can be used to examine the method of transient Rayleigh wave in detection of Nanning-Guangzhou railway karsts grouting consolidation.1.The criteria of grouting in karsts areas are obtained through analyzing and reaching, which include the follows:caves,V≥17.1H+236.9; rock mass,V≥23.0H+321.1;soil mass,V≥20.6H+130.3. Judging the key test areas and general test sections, it is turned out that the criteria can be used to examine the method of transient Rayleigh wave in detection of Nanning-Guangzhou railway karsts grouting consolidation. 2.The seriflux is gradually solidified as time passes in the period of grouting completion, so there is different wave velocity in the different testing time. Analysis shows that the wave velocity is steady after 28 days since grouting completed, therefore, it is considered that grouting detection should be start 28 days later. However, when it is need to detection ahead of time, the wave velocity after completely solidification can be calculated according to the changing regularity of the increase rate of wave velocity over time. |
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