Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings (2013) / Chapter Skim
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4C h a p t e r 2 Introduction According to data provided by the Federal Highway Administration, the vast majority of tunnel linings in the United States use cast-in-place (CIP) reinforced concrete, with a significant number using CIP unreinforced concrete, steel/iron liner plate, or shotcrete.
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5section on I-20 in Fort Worth, and an airport runway section at the George Bush Intercontinental Airport. • Field validation testing of NDT devices using actual tunnels.
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6with concrete/shotcrete during construction so as not to puncture the plastic. Table 2.1 provides a summary of the specimen details.
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7levels of lumps of documented sizes corresponding to three regions of interest: (1) lumps below the reinforcement that represent typical lumps dense enough not to be quickly displaced toward the surface via vibration, (2)
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8sheets.
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9Table 2.3. Summary of Simulated Defects in Concrete Bridge Deck Simulated Defect Defect Material Actual Dimension (mm)
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10 Interstate highway system. Both bores of the tunnel were built using multiple-face drill and blast methods.
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11 air-coupled GPR system collecting data in the tunnel. Plan sets were not available.
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12 download; the user's manual is provided in a separate publication.) The researchers also mounted a FLIR T300 camera on the GPR boom and the TTI data collection system collected images from this camera along with the GPR data.
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13 The tomograph, shown in Figure 2.14 (left) , uses a 4-by-12 grid of mechanically isolated and dampened transducers that can fit the profile of a rough concrete testing surface with a variance of approximately 10 mm (0.4 in.)
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14 (assuming or knowing the ultrasonic wave velocity in the test medium)
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15 The modulus from surface wave velocity, VR, first converted to shear wave velocity, can be determined by using ( ) = − ν1.13 0.16V VS R In the USW method, the variation in velocity with wavelength is measured to generate a dispersion curve.
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16 Figure 2.20 compares typical USW dispersion curves from an intact area and a defective area. The dispersion curve shifts to lower moduli in defective areas.
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17 of railway and roadway tunnels (mostly railway) in various countries but was never used in the United States before this project.
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