Velocity analysis on CMP sections based on the smearing paradigm

Macedo, Daniel Leal; Figueiredo, José J. S. de; Portugal, Rodrigo de Souza

doi:10.1190/sbgf2009-079

Cited by 1 publication

(1 citation statement)

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“…The velocity analysis is an accurate way, which originated from seismic exploration [14] . However, there exist special problems in the process of applications.…”

Section: Introductionmentioning

confidence: 99%

Detection of railway subgrade moisture content by GPR

Liu¹,

Jia-qi²,

Fu³

et al. 2016

Proceedings of the 7th International Conference on Environment and Engineering Geophysics &Amp; Summit Forum of Chinese Academy

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Abstract-In cold regions, heaving of the railway subgrade is an important security risk to high-speed railway. It is necessary to find out the moisture content of the subgrade to secure the normal railway operation. Common Mid-Point (CMP) measurement using Ground Penetrating Radar (GPR) was carried out to estimate the moisture content of railway subgrade. As the subgrade is layered medium typically, CMP method is suitable for moisture content measurement. At first, the CMP data is analyzed through velocity spectrum to obtain the stacking velocity, from which the vertical interval velocity profile can be calculated by Dix's formula. The moisture content can be obtained by Topp's formula from dielectric constant which depends on the velocity. However, the velocity analysis has lots of problem for the shallow and thin layers like rail subgrade. With the help of FDTD simulation by gprMAX, we find that there are many multiples and refracted waves which cause much false results during velocity analysis as the offset is large. Under the guidance of the simulated result, we use optimized data gathers for velocity analysis to the real data. It is found that the final result is good and in accordance with the result of induced polarizability (IP). It is proven that it is indeed feasible to use GPR to detect moisture content of subgrade. This method can be widely applied in subgrade moisture detection.

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“…The velocity analysis is an accurate way, which originated from seismic exploration [14] . However, there exist special problems in the process of applications.…”

Section: Introductionmentioning

confidence: 99%