Abstract:

For limitations of the present nondestructive detection methods in testing the quality of backfill grouting, by integrating the advantages of ground penetrating radar (GPR) method and seismic imaging method,reliability test of the grouting quality is carried out. The finite difference numerical simulation method is used to simulate the grouting quality testing of the two methods respectively, which verifies the theoretical detection effect of the methods. On the basis of the theoretical detection results, the predictive deconvolution filtering method is to effectively filter multiple waves in the results of two methods, which improves the accuracy and reliability of the detection results. Finally, according to the numerical simulation results, the comprehensive geophysical methods and data filtering technology is applied to the quality testing of backfill grouting behind lining segment of a double shield TBM construction tunnel in Tibet and are evaluated with the results of the borehole endoscopy. The testing results show that: (1) Predictive deconvolution filtering method can efficiently filter multiple waves caused by reinforcing bars, and increase resolutions of methods; (2) GPR method has a high resolution but limited to the dense steel mould contained in the lining segment, the effective detection depth is about 1 meter with 400 MHz antenna. While the depth of the seismic imaging method can reach about 5 meters, but the resolution is lower than the GPR method. These two geophysical methods are complementary to each other. (3)The comprehensive use of the two methods can effectively solve the quality testing of backfill grouting behind lining segment of TBM construction tunnel, and ensure safety of tunnel construction.

Key words: tunnel engineering, TBM, lining segment, quality inspection of grouting, comprehensive geophysical methods, predictive deconvolution