Mapping Voids, Debonding, Delaminations, Moisture, and Other Defects Behind or Within Tunnel Linings (2013)

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209 a p p e N D I x p Introduction A survey of several tunnels linings was carried out with a por- table seismic property analyzer (PSPA) within the framework of the SHRP 2 Renewal Project R06G. The main objectives of the research project are summarized in the Executive Sum- mary of the main report. Two tunnels in Colorado and one tunnel in Virginia were involved in this study. The Eisenhower Memorial Tunnel in Colorado was investigated on October 3 and 4, 2011, and the Hanging Lake Tunnel in Colorado was assessed on October 5 and 6, 2011. The evaluation of the Chesa- peake Channel Tunnel in Virginia was performed October 11 through 12, 2011. The scope of the University of Texas at El Paso study was to evaluate the performance of the PSPA in locating defects behind or within tunnel linings. This appendix describes the tests executed and the results obtained. Description of pSpa and testing Methods PSPA is a portable device that can perform two tests— impact echo (IE) and ultrasonic surface wave (USW)— simultaneously. The PSPA consists of two receivers and a source packaged into a handheld portable device. The near and far receiver spacing from the source are 4 in. and 10 in., respectively. The impact duration (contact time) is about 60 µs, and the data acquisition system has a sampling fre- quency of 390 kHz. The advantage of combining these two methods in a single device is that once the test is performed, the variations in the modulus (an indication of the quality of concrete) and return resonance frequency (an indication of the full thickness or depth of delamination) of a slab can be assessed concurrently. The following sections discuss the principles of the two seismic methods, along with interpre- tation approaches. Impact Echo Method The IE method is one of the most commonly used non- destructive testing (NDT) methods for detecting delamination in concrete (Carino et al. 1986). This method works by striking a plate-like object such as a tunnel lining with an impactor that generates stress waves at frequencies up to 20 kHz to 30 kHz and collecting signals with a receiver (Figure P.1a). By using a fast Fourier transform (FFT) algorithm, the recorded time domain signal is converted into a frequency domain function (amplitude spectrum) and the peak frequency is monitored. For an intact point on a slab or an intact portion of a slab, the thickness (h) is then determined from the com- pression wave velocity (Vp) and the return frequency ( f ) as shown in Equation P.1: 2 (P.1)h V f p = α where a is about 0.96 for concrete slabs. For a deep and relatively small delaminated location in a concrete slab, the return frequency may shift to a higher fre- quency corresponding to the depth of the delamination. As shown in Figure P.1b, a shallow or a deep but extensive and severely delaminated area is usually manifested by a low peak frequency, indicating that little or no energy propagates toward the bottom of the deck, and a flexural mode domi- nates the frequency response. In this case, Equation P.1 is not applicable to measure the depth of delamination since it is influenced by several factors. Ultrasonic Surface Waves Method The USW method is used to estimate the average velocity of propagation of surface waves in a medium, based on the time at which different types of energy arrive at each sensor (Figure P.1b). The velocity of propagation, VR, is typically Portable Seismic Property Analyzer Field Tests in the United States

210 Figure P.1. Schematic illustration of the test methods. (a) IE method (b) USW method Source: Gucunski and Maher 1998. 1000 1200 1400 1600 1800 2000 2200 2400 0.05 0.1 0.15 0.2 D e pt h, m Phase Velocity, m/s Intact Severe delamination Intact Condition Shallow Severe Delamination Deep Onset of Delamination h 1 2 determined by dividing the distance between two receivers, DX, by the difference in the arrival time of a specific wave, Dt. Knowing the wave velocity, E, the modulus can be deter- mined from shear modulus, G, through Poisson’s ratio (ν) by using Equation P.2: 2 1 (P.2)E G( )= + ν Shear modulus can be determined from shear wave velocity, VS, by using Equation P.3: (P.3)2= γ G g VS The modulus from surface wave velocity, VR, first converted to shear wave velocity, can be determined with Equation P.4: 1.13 0.16 (P.4)( )= −V V vS R In the USW method, the variation in velocity with wave- length is measured to generate a dispersion curve. For a uniform or intact concrete slab, the dispersion curve shows more or less a constant velocity within the wavelengths no greater than the thickness of the slab. When a delamination or void is present in a concrete slab or the concrete has deterio- rated, the average surface wave velocity (or modulus) becomes less than the actual modulus because of interference from the defect. In this case, the velocity or modulus obtained may be called an apparent velocity or modulus. description of Sites The three tunnels visited in this study are described below. Eisenhower Memorial Tunnel An outside view of the Eisenhower Memorial Tunnel is shown in Figure P.2. The tunnel was originally designed as a twin bore tunnel—the Eisenhower bore and the Edwin C. Johnson bore. This two-bore tunnel is located approximately 60 mi

211 west of Denver, Colorado, on I-70. The tunnel is about 1.7-mi long, and the plenum is up to 18-ft high, with a nominally 2-ft-thick liner. Some sections of the ventilation plenum were investigated in this study. Hanging Lake Tunnel Hanging Lake Tunnel also consists of two bores and is located approximately 10 mi east of Glenwood Springs, Colorado, on I-70. The tunnel is about 0.7-mi long, and the ventilation plenum is 7-ft high, with a nominally 15-in.-thick liner, as shown in Figure P.3. Some sections of the plenum were evaluated. Chesapeake Channel Tunnel This one-bore subsea tunnel is part of a 17-mi-long bridge- tunnel connecting southeastern Virginia to the Delmarva Peninsula on U.S. Hwy 13. The tunnel is about 1-mi long with a nominally 2-ft-thick liner. An outside view of the tunnel is shown in Figure P.4. A section of about 2,600 ft of the ventila- tion plenum and a section of 200 ft on the wall of the roadway were involved in this study. Data Collection process In the Eisenhower Memorial Tunnel, data were collected point by point, mostly every 5 ft, along a line in each selected section. The selection was based on the detected anomalies with infra- red thermography. In the Hanging Lake Tunnel, besides the line testing, data were collected along a test grid. The selection of test sections was based on visual inspection and previous investigation of the tunnel. In the Chesapeake Channel Tunnel, both the ventilation plenum and roadway wall were evaluated with NDT. All tests, including those with PSPA in this study, were con- ducted at or within a number of areas. The selection was based on the distribution of major anomalies with a dielec- tric constant. The testing schedules and locations for the tunnels are presented in Table P.1. Table P.2 lists the selected areas on the plenum ceiling of the Chesapeake Channel Tunnel, which include three spots one an area and 10 selected anomaly areas characterized by a high dielectric constant (greater than 15, compared with 4.5 for typical dry concrete) and, for most of them, by cracking with more or less water dropping. Eisenhower Memorial Tunnel In the Eisenhower Memorial Tunnel, each bore was investi- gated in 1 day. Six 50-ft-long sections (from Section 8 to Sec- tion 13) were tested on October 3 in the eastbound bore. About Figure P.2. Outside view of Eisenhower Memorial Tunnel. Figure P.3. Outside view of Hanging Lake Tunnel. Figure P.4. Outside view of Chesapeake Channel Tunnel.

212 19 sections (from Section 148 to Section 166) were investigated on October 4 in the westbound bore. The selection of sections was based on visual inspection and a preliminary infrared test- ing. In both bores, the investigation was mostly performed every 5 ft at the center of each block. Several extra points were tested around the cracked and delaminated areas. It took about 10 min for each 50-ft section to be tested. The rest of the time was allotted to documenting the data collection information and taking some pictures. The main challenge while using the PSPA device was the dirt on the wall that caused an occasional slip of the device during testing. Therefore, some points had to be tested several times to get a clear signal. Hanging Lake Tunnel In the Hanging Lake Tunnel, five 50-ft-long sections (from Section 57 to Section 61) were investigated on October 5 in the westbound bore. Similar to the Eisenhower Memorial Tunnel, the selection of sections was based on visual inspec- tion and the severity of visible cracks. The data were collected at the center of each block as well as around the cracks and delaminated areas. In addition to 10 min of testing for each block, extra time was allotted to documenting the data collec- tion information and taking pictures. On October 6, two blocks in Section 57 were tested in more detail with denser measurements. These two blocks were investigated through seven horizontal and six vertical lines (see Figure P.5). It took about 2 h to test the two blocks. The main challenge while using the PSPA was the areas with large curvature, which pre- vented the device from maintaining full contact with the sur- face in some places. Chesapeake Channel Tunnel Because this tunnel has been previously evaluated by other NDT methods, the focus of this study was on a number of areas or spots on the plenum and the roadway wall where high dielectric constants were measured. Forty-six points within seven areas on the ceiling of the plenum were evalu- ated on October 11. Thirty-eight points within six areas on the ceiling of the plenum and 14 points at 11 spots on the wall of the roadway were evaluated on October 12. All tests were stopped at midnight that day because the traffic lane had to be reopened due to foggy weather. test results Because the IE and USW methods used in this study are point inspection methods, the results are best visualized using a contour map rather than evaluating them individually. How- ever, typical IE and USW results for an intact area and defec- tive area are shown for each tunnel. Eisenhower Memorial Tunnel IE Method The amplitude spectra for an intact point and two defective points along with the photograph taken through visual inspection are shown in Figure P.6. Compared with the intact point, either lower or higher peak frequencies con- trol the response at defective points, as discussed above. Based on an average compression wave velocity of 13,800 ft/s measured for the concrete and Equation P.1, a nominal Table P.1. Testing Schedules and Locations of the Tunnels Location and Schedule Eisenhower Memorial Tunnel Hanging Lake Tunnel Chesapeake Channel Tunnel Location Glenwood Springs, Colorado Dillon, Colorado Cape Charles, Virginia Date October 3 October 4 October 5 October 6 October 11 October 12 Direction Eastbound Westbound Eastbound Eastbound Plenum Plenum and wall Section tested 8 to 13 148 to 166 57 to 61 57 Not applicable Number of blocks (areas) tested 60 190 50 2 7 14 Number of points tested 57 151 42 42 46 52 Table P.2. Approximate Locations of the Areas Tested with PSPA in the Plenum of the Chesapeake Channel Tunnel Area Intact Defective Location 470+50 to 470+75 473+56 474+27 477+60 478+85 481+76 486+67 486+81 491+25 493+15 496+25

213 frequency of around 3.5 kHz approximately corresponds to the thickness of the liner (2 ft), whereas the frequency of 6.8 kHz for the shallow delamination approximately corresponds to a thickness of 1 ft. The response from the severely delaminated area corresponds to the flexural mode of vibration. Figures P.7a and P.7b show the spectral B-scan of the IE results along several blocks in the eastbound and westbound bores, respectively. At some points, a frequency of about 3 kHz to 3.5 kHz governs the response, which indicates the thickness of the liner. On the remaining areas, either a low- or high- frequency amplitude governs the response. The low- frequency flexural mode results from a shallow or a deep but extensive delamination. Therefore, its peak frequency does not correspond to any thickness measurement, and the depth of defect can be estimated from a USW B-scan. However, the high-frequency response could be attributed to the onset of delamination. In that case, the depth of delamination is esti- mated from Equation P.1 and confirmed with the USW B-scan. In the presence of a crack, data analysis is more com- plicated. Multiple frequencies are present in the response when a crack is between the source and receiver in an IE B-scan, and the crack is recognized through high average moduli in the USW B-scan. USW Method Figure P.8 shows a typical USW dispersion curve for an intact area and a defective point along with actual photographs. The dispersion curve shifts to lower moduli where severe flaws are present. The cross sections of variation in modulus with wave- length, which can be viewed qualitatively as a scaled variation in modulus with depth, are shown in Figure P.9 for the east- bound and westbound bores. The problematic areas manifest themselves as areas with lower average moduli. Combining the IE and USW results builds confidence in the interpretation of the location and depth of the problem- atic areas. In other words, the combined tests allow for a bet- ter delineation between shallow/deep and initial/extensive defects. For instance, a low-frequency dominant frequency in the IE results in Figures P.7a and P.7b is an indication of a shallow or a very deep and extensive delamination, and the depth can be estimated from USW B-scans (Figures P.9a and Joint (a) The actual photograph (b) Plan of the tested blocks Figure P.5. Tested blocks with denser grid measurement in Hanging Lake Tunnel.

214 (a) Good condition (b) Poor condition (c) Severe condition 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 X: 3050 Y: 1 Frequency (Hz) (d) Representative amplitude spectrum for intact and defective points N or m a liz e d A m pl itu de X: 6862 Y: 1 X: 1525 Y: 1 Good Condition Poor Condition Severe Condition Figure P.6. Amplitude spectra along with actual photographs for intact and defective points in Eisenhower Tunnel showing good, poor, and severe conditions, and representative amplitude spectrum for intact and defective points.

215 Longitudinal Axis Fr eq ue n cy (H z ) 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.2 0.4 0.6 0.8 1 Longitudinal Axis Fr eq ue n cy (H z ) 1 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100105110115120125130135140145150 0.5 1 1.5 2 x 104 0 0.2 0.4 0.6 0.8 1 N o rm alized A m p litu d e Sec 9/10 Sec 8/9 Sec 13/14 Sec 12/13 Sec 10/11 Sec 11/12 crack delaminated crack crack 148/147 167/166 164/163 161/160 157/156 154/153 151/150 crack crack crack deteriorated crack deteriorated N o rm alized A m p litu d e (a) Eastbound Bore (b) Westbound Bore Figure P.7. IE spectral B-scans along Eisenhower Memorial Tunnel.

216 Figure P.8. Photographs of intact and defective points along with representative dispersion curve for both points, in Eisenhower Memorial Tunnel. 3 4 5 6 7 8 9 10 11 0 1000 2000 3000 4000 5000 6000 7000 Modulus (ksi) (c) Representative dispersion curve for intact and defective points Defective Point Intact Point A ve ra ge M od ul us = 5 04 k si A ve ra ge M od ul us = 5 ,7 34 k si D ep th (in ch es ) (a) Intact location (b) Defective location

217 Figure P.9. Variation of modulus with depth, in Eisenhower Memorial Tunnel. Longitudinal Axis De pt h (in ch es ) 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 3 4 5 6 7 8 9 10 11 2500 3000 3500 4000 4500 5000 5500 6000 Longitudinal Axis De pt h (in ch es ) 1 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 3 4 5 6 7 8 9 10 11 2500 3000 3500 4000 4500 5000 5500 6000 Sec 9/10 Sec 8/9 Sec 13/14 Sec 12/13 Sec 10/11 Sec 11/12 crack delaminated crack crack 148/147 167/166 164/163 161/160 157/156 154/153 151/150 crack crack crack deteriorated crack deteriorated Apparent M oduli (ksi) Apparent M oduli (ksi) (a) Eastbound Bore (b) Westbound Bore

218 P.9b). The areas with high-frequency dominant amplitudes (around 16 kHz) in Figures P.7a and P.7b are deep delamina- tion, with the depth of the delamination around 5 in. (accord- ing to Equation P.1). At several points in Figures P.9a and P.9b, the manifestation of defect starts at 6 in. On the major- ity of testing areas, multiple frequencies control the response in the IE B-scans indicating the presence of cracks. Compa- rable results are obtained from the USW B-scans. When the crack is between the source and first receiver, the USW mod- ulus is typically greater than normal because of the travel path of the wave. Similarly, when the crack is between the two sensors, the reported USW modulus is lower than normal. The results for these points agree well with the actual condi- tion that was documented during visual inspection. Hanging Lake Tunnel IE Method The actual condition of liners at the time of testing is shown in Figures P.10a and P.10b. The amplitude spectra for selected intact and defective points are shown in Figure P.10c. Based on an average compression wave velocity of about 14,000 ft/s measured for the concrete, the dominant frequency corre- sponding to the tunnel thickness (15 in.) is around 5.4 kHz. Compared with the intact point, higher peak frequencies mostly control the response at the defective points. Figure P.11 shows the spectral B-scan of the IE results along several blocks in the westbound bore. At some points, a frequency of 5.4 kHz dominates the response, which 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 X: 8387 Y: 1 Frequency (Hz) N or m al ize d A m pl itu de X: 5337 Y: 1 Intact Point Defective Point (a) Intact location (c) Representative amplitude spectrum for intact and defective points (b) Defective location Figure P.10. Photographs of intact and defective points, along with representative amplitude spectrum for both points, in Hanging Lake Tunnel.

219 indicates intact areas. On the remaining areas, mostly high frequency governs the response, which is an indication of a deep (but not extensive) delamination or crack. A better delineation between delamination and crack can be obtained through the USW B-scan. Figure P.12 presents the contour map of the peak frequency on the defined test grid. As mentioned earlier, the thickness frequency is around 5.4 kHz. The threshold in color index is set according to the dominant frequency on intact areas. Fre- quencies lower than 4 kHz and higher than 8 kHz are consid- ered as the dominant low and high frequency, respectively. The spectral B-scan of the IE results along Line 2 is shown in Figure P.13. The red stripe around 5.4 kHz corresponds to the tunnel thickness and indicates echo mode. The rest of the spectral B-scans of IE results are shown in Appendix P1, at the end of this appendix. USW Method Figure P.14 compares typical USW dispersion curves from an intact area and a defective area with their actual conditions, as was documented during visual inspection. In defective areas, the dispersion curve shifts to lower moduli. The variation in modulus with wavelength (or depth) along several blocks of the eastbound bore of the Hanging Lake Tunnel is shown in Figure P.15. The problematic areas are marked with red, which indicates a lower modulus. The IE B-scan (Figure P.11) and the USW B-scan (Figure P.15) Longitudinal Axis Fr eq ue n cy (H z ) 1357911131517192123252729313335373941 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.2 0.4 0.6 0.8 1 N orm alized Am plitude 60/61 59/60 58/59 57/58 56/57 61/62 Crack Crack and leakage crack Figure P.11. IE spectral B-scan along Hanging Lake Tunnel. Longitudinal Axis Tr an sv er se A xi s P1P2P3P4P5P6 L1 L2 L3 L4 L5 L6 L7 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 D om inant Frequency (Hz) Figure P.12. Planar variation of the dominant frequency on meshed block, in Hanging Lake Tunnel.

220 Longitudinal Axis Fr eq u en c y (H z ) P1P2P3P4P5P6 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.2 0.4 0.6 0.8 1 N orm alized Am plitude Figure P.13. IE spectral B-scan along L2 on meshed block, in Hanging Lake Tunnel. 2 3 4 5 6 7 8 9 10 11 12 2000 2500 3000 3500 4000 4500 5000 5500 Modulus (ksi) Defective Point Intact Point A ve ra ge M od ul us = 4 ,5 27 k si A ve ra ge M od ul us = 2 ,6 27 k si D ep th (in ch es ) (a) Intact location (c) Representative dispersion curve for intact and defective points (b) Defective location Figure P.14. Photographs of intact and defective points, along with representative dispersion curve for both points, in Hanging Lake Tunnel.

221 Figure P.15. Variation of apparent modulus with depth along Hanging Lake Tunnel. Longitudinal Axis De pt h (in .) 1357911131517192123252729313335373941 2 3 4 5 6 7 8 9 10 11 12 2000 3000 4000 5000 6000 Apparent M oduli (ksi) 60/61 59/60 58/59 57/58 56/57 61/62 Crack Crack and leakage crack result in similar defect maps (both for location and depth). The points with multiple peak frequencies in Figure P.11 are recognizable in Figure P.15 through a low modulus starting at the surface (indication of crack). Other defective points that manifest themselves by high frequency (between 15 kHz and 17 kHz) in the IE B-scan might be delamination at the depth of 5 in. to 5.5 in. (calculated using Equation P.1). Similarly, the indication of lower moduli starts at a depth of around 5 in. in the USW B-scan at those points. The planar contour map of the variations of the average modulus on the meshed blocks is presented in Figure P.16. The defective areas manifest themselves as the areas with lower moduli and are marked in red. Another way to represent the USW outcomes is through a line scan, which is shown in Figure P.17 for Line 2. The depths of suspected delamination areas can be approximated through the B-scan. The line scans from the remaining lines are pre- sented in Appendix P1. As shown in Figure P.17, the defective areas manifest themselves as areas with lower average moduli. The planar variations in modulus, obtained by the USW method at two different depths, are shown in Figure P.18. All planar variations of modulus are presented in Appendix P1. Chesapeake Channel Tunnel Ceiling of Plenum Figure P.19 shows the results from the IE and USW analyses of the data collected in the intact areas where no cracks or other surface damages were observed and with low dielectric constants (significantly less than 10). Figure P.16. Planar variation of average apparent modulus on meshed block, in Hanging Lake Tunnel. Longitudinal Axis Tr an sv er se A xi s P1P2P3P4P5P6 L1 L2 L3 L4 L5 L6 L7 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Apparent M oduli (ksi)

222 Longitudinal Axis De pt h (in ch es ) P1P2P3P4P5P6 2 4 6 8 10 12 2000 3000 4000 5000 6000 Apparent M oduli (ksi) Figure P.17. Variation of apparent modulus with depth along L2 on meshed block, in Hanging Lake Tunnel. Tr an sv er se A xi s Longitudinal Axis P1P2P3P4P5P6 L1 L2 L3 L4 L5 L6 L7 (a) At depth of 5 inches Longitudinal Axis Tr an sv er se A xi s P1P2P3P4P5P6 L1 L2 L3 L4 L5 L6 L7 (b) At depth of 10 inches 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Figure P.18. Planar variation of apparent modulus at depths of 5 in. and 10 in. of meshed block, in Hanging Lake Tunnel.

223 The data used in Figure P.19 were actually from three sep- arated intact spots within a distance of about 20 ft. Since they have the similar feature, the results are represented together. As shown in Figure P.19a, a clear and almost constant peak frequency of about 3 kHz represents the thickness echo of the concrete liner. This frequency results in a thickness of 2 ft for the concrete liner with an average compressive velocity of 13,800 ft/s per Equation P.1. However, Figure P.19b indi- cates that the concrete liner at these spots is quite uniform, with an average modulus of more than 4,000 ksi up to 12-in. penetration. The very high modulus values (indicated in blue in Figure P.19b) may reflect the high-velocity surface conditions. The results from the PSPA tests for the 10 defective areas are shown in Figures P.20 through P.29. In general, the IE method exhibited higher peak frequencies compared with the thickness frequency, and the USW method showed lower moduli compared with the modulus of normal con- crete at those defective areas or spots. For instance, in areas 477+60, 481+76, and 486+81, higher peak frequencies dom- inated the responses at several points in the IE B-scans. The calculated depths of delamination (by Equation P.1) agreed well with the depths of delamination in the USW B-scans. The anomalies or defects mainly distributed along the transverse cracks on the plenum ceiling. Some exceptions occurred, such as in areas 473+56 and 491+25, where the IE and USW analyses were not consistent. That result can be attributed to the edge effect near the crack and placement of the PSPA sensor unit relative to the crack. When the crack is between the source and first receiver, the USW modulus is typically greater than normal because of the travel path of the wave. However, when the crack is between the two sensors, the reported USW modulus is lower than normal. The interpretation of the existence of the crack agrees well with the actual condition that was documented during visual inspection. Wall of the Roadway Tests with the PSPA on the wall of the roadway covered a dis- tance of approximately 150 ft from Station 485+6 to Station 486+54 with uneven intervals, following the blue marks on the wall. Results are shown in Figure P.30. Test points 9 to 12 were actually restricted in a very small area about 2 ft by 2 ft. This area was characterized by an extremely low modulus and higher IE peak frequencies compared with the thickness fre- quency of the liner, indicating that a severe delamination or void was just behind the tile of the wall.

224 (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus Longitudinal Axis Fr eq ue nc y (H z) 473+56 1 2 3 4 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 2 3 4 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 2000 2500 3000 3500 4000 4500 5000 5500 6000 Crack 473+56 Crack Apparent M oduli (ksi) N orm alized Am plitude D ep th (in ch es ) Figure P.20. PSPA results on plenum ceiling in area 473+56, in Chesapeake Channel Tunnel. 1 2 3 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis D ep th (in ch es ) intact 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) N orm alized Am plitude Longitudinal Axis (b) B-scan of apparent modulus(a) B-scans of amplitude spectrum Fr eq ue nc y (H z) intact 1 2 3 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Figure P.19. PSPA results in an intact area on plenum ceiling, in Chesapeake Channel Tunnel.

225 (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus N orm alized Am plitude Longitudinal Axis Fr eq ue nc y (H z) 474+27 1 2 3 4 5 6 7 8 9 10 11 12 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Crack 1 2 3 4 5 6 7 8 9 10 11 12 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 474+27 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) D ep th (in ch es ) Crack Figure P.21. PSPA results on plenum ceiling in area 474+27, in Chesapeake Channel Tunnel.

226 Figure P.22. PSPA results on plenum ceiling in area 477+60, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus N orm alized Am plitude Longitudinal Axis Fr eq ue nc y (H z) 477+60 1 2 3 4 5 6 7 8 9 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Crack 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 477+60 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) Crack D ep th (in ch es )

227 Figure P.23. PSPA results on plenum ceiling in area 478+85, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus Longitudinal Axis Fr eq ue nc y (H z) 478+85 1 2 3 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 2 3 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 478+85 2000 2500 3000 3500 4000 4500 5000 5500 6000 Crack Apparent M oduli (ksi) N orm alized Am plitude Crack D ep th (in ch es ) Figure P.24. PSPA results on plenum ceiling in area 481+76, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus 1 2 3 4 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 481+76 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) N orm alized Am plitude Longitudinal Axis Fr eq ue nc y (H z) 481+76 1 2 3 4 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Crack Crack D ep th (in ch es )

228 Figure P.25. PSPA results on plenum ceiling in area 486+67, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus N orm alized Am plitude Longitudinal Axis Fr eq ue nc y (H z) 486+67 1 2 3 4 5 6 7 8 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 2 3 4 5 6 7 8 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 486+67 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) D ep th (in ch es )

229 Figure P.26. PSPA results on plenum ceiling in area 486+81, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus N orm alized Am plitude Longitudinal Axis Fr eq ue nc y (H z) 486+81 1 2 3 4 5 6 7 8 9 10 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 486+81 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) D ep th (in ch es )

230 Figure P.27. PSPA results on plenum ceiling in area 491+25, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus N orm alized Am plitude Longitudinal Axis Fr eq ue nc y (H z) 491+25 1 2 3 4 5 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Crack 1 2 3 4 5 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 491+25 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) Crack D ep th (in ch es )

231 Figure P.28. PSPA results on plenum ceiling in area 493+15, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus 1 2 3 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 493+15 2000 2500 3000 3500 4000 4500 5000 5500 6000 Apparent M oduli (ksi) N orm alized Am plitude Longitudinal Axis Fr eq ue nc y (H z) 493+15 1 2 3 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 D ep th (in ch es ) Figure P.29. PSPA results on plenum ceiling in area 496+25, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus 1 2 3 4 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis 496+25 2000 2500 3000 3500 4000 4500 5000 5500 6000 Longitudinal Axis Fr eq ue nc y (H z) 496+25 1 2 3 4 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Crack Apparent M oduli (ksi) N orm alized Am plitude Crack D ep th (in ch es )

232 Figure P.30. PSPA results on wall of roadway, in Chesapeake Channel Tunnel. (a) B-scans of amplitude spectrum (b) B-scan of apparent modulus Longitudinal Axis Fr eq ue nc y (H z) Roadway 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 N orm alized A m plitude 1 2 3 4 5 6 7 8 9 10 11 12 13 14 2 3 4 5 6 7 8 9 10 11 12 Longitudinal Axis Roadway 2000 2500 3000 3500 4000 4500 5000 5500 6000 A pparent M oduli (ksi) D ep th (in ch es )

233 Appendix P1 The remaining line scans and planar variations of modulus are presented here. Longitudinal Axis Fr eq u en cy (H z ) Line 1 123456 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Longitudinal Axis Fr eq u en cy (H z ) Line 2 123456 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Figure P1.1. IE Spectral B-scans on meshed blocks, in Hanging Lake Tunnel. (Continued on next page.)

234 Longitudinal Axis Fr eq u en cy (H z ) Line 3 123456 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Longitudinal Axis Fr eq u en cy (H z ) Line 4 123456 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Longitudinal Axis Fr eq u en cy (H z ) Line 5 123456 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Longitudinal Axis Fr eq u en cy (H z ) Line 6 123456 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Figure P1.1. (Continued.)

235 Longitudinal Axis Fr eq u en cy (H z ) Line 7 123456 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 104 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Figure P1.1. (Continued.) Figure P1.2. Variation of apparent modulus with depth on meshed block, in Hanging Lake Tunnel. (Continued on next page.) Longitudinal Axis Line 1 123456 2 4 6 8 10 12 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Axis Line 2 123456 2 4 6 8 10 12 D ep th (in ch es ) D ep th (in ch es )

236 Figure P1.2. (Continued.) 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Axis Line 5 123456 2 4 6 8 10 12 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Axis Line 6 123456 2 4 6 8 10 12 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Axis Line 7 123456 2 4 6 8 10 12 D ep th (in ch es ) D ep th (in ch es ) D ep th (in ch es ) 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Longitudinal Axis Line 3 123456 2 4 6 8 10 12 D ep th (in ch es ) Longitudinal Axis Line 4 123456 2 4 6 8 10 12 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 D ep th (in ch es )

237 references Carino, N. J., M. Sansalone, and N. N. Hsu. 1986. A Point Source–Point Receiver, Pulse-Echo Technique for Flaw Detection in Concrete. ACI Material Journal, Vol. 83, No. 2, pp. 199–208. Gucunski, N., and A. Maher. 1998. Bridge Deck Condition Monitoring by Impact Echo Method. Proc., International Conference MATEST ’98—Life Extension, Brijuni, Croatia, pp. 39–45. Figure P1.3. Planar variation of apparent modulus at different depths for meshed block, in Hanging Lake Tunnel. 123456 1 2 3 4 5 6 7 123456 1 2 3 4 5 6 7 123456 1 2 3 4 5 6 7 Tr an sv er se A xi s Longitudinal Axis 123456 1 2 3 4 5 6 7 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Depth 2 inches Depth 3 inches Depth 4 inches Depth 5 inches 123456 1 2 3 4 5 6 7 123456 1 2 3 4 5 6 7 Tr an sv er se A xi s 123456 1 2 3 4 5 6 7 Longitudinal Axis 123456 1 2 3 4 5 6 7 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Depth 6 inches Depth 7 inches Depth 9 inches Depth 8 inches 123456 1 2 3 4 5 6 7 123456 1 2 3 4 5 6 7 Longitudinal Axis Tr an sv er se A xi s 123456 1 2 3 4 5 6 7 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Depth 10 inches Depth 11 inches Depth 12 inches