| Carbonate rocks are widely distributed along the section of D1K6+100 to D1K96+000 in constructing Nanning-Guangzhou railways, which is designed speed of 200km. This thesis takes the method of electromagnetic tomography in detection of the section karst grouting consolidation as the object of study. Through a large number of field tests, electromagnetic tomography analyzing and statistics of measured data, three typical methods of electromagnetic tomography in detection of grouting consolidation and the criteria are being analyzed and studied.Firstly, representative stratum models are built based on drilling data in test sections. Then, representative stratum models are analyzed and calculated by electromagnetic tomography method, and finally the conclusion is obtained in this thesis. Besides, a large number of on-site testing are carried out, and the conclusion is analyzed and explained referring to different typical section models. The measured data by electromagnetic tomography method in the sections are statistically analyzed, whose grouting tests have passed the examinations of over water pressure tests, coring and surface wave. Finally, the criteria are obtained, which can be used to examine the electromagnetic tomography in detection of Nanning-Guangzhou railway karst grouting consolidation.Through a great quantity of suit tests and analysis to the stratum models, and according to other ways of tests to known acceptable quality of grouting, it is considered that the electromagnetic tomography method can estimate grouting quality of Karst cave roadbed and cobble soil comprehensively, objectively and effectively. But the electromagnetic tomography method was not fit for grouting in clay and intact limestone and aquifer formed by debris line, because absorption difference of layer of clay and limestone before and after grouting is less than instrument error. The cement solidification conditions on the impact of the electromagnetic tomography absorption are analyzed by repeatedly testing at the same location in the suit test. Through statistical analysis of test data, the results of the electromagnetic tomography method can run to stability in 7 days after grouting. So it is thought that the.electromagnetic tomography in detection should be carried out 7 days after completion of grouting. Finally, through the statistical analysis to the massive measured data, the electromagnetic tomography method and its criteria in detection of Nanning- Guangzhou railway karst grouting consolidation is determined. The criterion of acceptability about quality of gravel soil grouting is that electromagnetic wave absorption coefficient difference is greater than 0.1dB/m after grouting, and the criterion of acceptability about quality of limestone cave and crushed zone grouting is that electromagnetic wave absorption coefficient difference is greater than 0.4dB/m after grouting... |
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