1、CECW-EG 3535789 0025250 3YO 9 1- 3/-) 7 DEPARTMENT OF THE ARMY ETL 1110-8-3(FR) US Army Corps of Engineers Washington DC 20314-1000 Engineer Technical Letter NO. 1110-8-3(FR) 15 February 1991 Engineering and Design UNDERWATER INSPECTION OF CONCRETE STRUCTURES 1. Purpose This engineer technical lette
2、r (ETL) provides information on the techniques and procedures for underwater inspection of civil works concrete structures. 2. Applicability This ETL is applicable to all USACE elements and USACE Commands having civil works responsibility for the design of civil works projects. 3. References. a. Ale
3、xander, A. M. 1980 (Apr). “Development of Procedures for Nondestructive Testing of Concrete Structures; Feasibility of Sonic Pulse-Echo Technique,“ Miscellaneous Paper C-77-11, Report 2, US Army Engineer Waterways Experiment Station, Vicksburg, MS. b. Alexander, A. M., and Thornton, H. T., Jr. 1988.
4、 “Developments in Ultrasonic Pitch-Catch and Pulse-Echo for Measurements in Concrete,“ SP-112, American Concrete Institute, Detroit, MI. c. Alongi, A. V., Cantor, T. R., Kneeter, C. P., and Alongi, A., Jr. 1982. “Concrete Evaluation by Radar Theoretical Analysis,“ Concrete Analysis and Deterioration
5、, Transportation Research Board, Washington, DC. d. Arcone, S. A. 1989 (Oct). “Analysis of a Short Pulse Radar Survey of Revetments Along the Mississippi River,“ Technical Report REMR-CS-26, US Army Engineer Waterways Experiment Station, Vicksburg, MS. e. Busby Associates, Incorporated. 1987. “Under
6、sea Vehicles Directory,“ Arlington, TX. f. Clausner, J. E., and Pope, J. 1988 (Nov). “Side-Scan Sonar Applications for Evaluating Coastal Structures, Technical Report CERC-88-16, US Army Engineer Waterways Experiment Station, Vicksburg, MS. g. Department of Labor. 1977. Occupational Safety and Healt
7、h Operations, Vol III, washington, DC. h. Headquarters, US Army Corps of Engineers. 1 Oct 1987. “Safety and Health Requirements Manual,“ EM 385-1-1, US Government Printing Office, Washington, DC. i. Keeny, C. A. 1987 (Nov). “Procedures and Devices for Underwater Cleaning of Civil Works Structures,“
8、Technical Report REMR-CS-8, US Army Engineer Waterways Experiment Station, Vicksburg, MS. j. Keeney, C. A., and Pollio, S. E. 1984 (Aug). “Evaluation of Nondestructive Underwater Timber Inspection Techniques,“ Report No. TN-1703, Naval Facilities Engineering Command, Port Huenme, CA. 2613 Provided b
9、y IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3515789 0025251 287 k. Kucharski, W. M., and Clausner, J. E. 1990 (Feb). “Underwater Inspection of Coastal Structures Using Commercially Available Sonars,“ Technical Report REMR-CO-11, US Army Engineer Waterways
10、Experiment Station, Vicksburg , MS. 1. Morang, A. 1987 (Dec). “Side-Scan Sonar Investigation of Breakwaters at Calumet And Burns Harbors on Southern Lake Michigan,“ Miscellaneous Paper CERC-87-20, US Army Engineer Waterways Experiment Station, Vicksburg, MS. m. Morey, R. M. 1974 (Mar). “Application
11、of Downward Looking Impulse Radar,“ Proceedings of 13th Annual Canadian Hydrographic Conference, Canada Centre for Inland Waters, Burlington, Ontario. n. Popovics, S., and McDonald, W. E. 1989 (Apr). “Inspection of the Engineering Condition of Underwater Concrete Structures,“ Technical Report REMR-C
12、S-9, US Army Engineer Waterways Experiment Station, Vicksburg, MS. o. Smith, A. P. 1987 (Apr). “New Tools and Techniques for the Underwater Inspection of Waterfront Structures,“ OTC 5390, 19th Annual Offshore Technology Conference, Houston, TX. p. Thornton, H. T., Jr. 1985 (Mar). “Corps-BuRec Effort
13、 Results in High-Resolution Acoustic Mapping System,“ The REMR Bulletin, Vol 2, No. 1, US Army Engineer Waterways Experiment Station, Vicksburg, MS. q. Thornton, H. T., Jr., and Alexander, A. M. 1987 (Dec). “Development of Nondestructive Testing Systems for In Situ Evaluation of Concrete Structures,
14、“ Technical Report REMR-CS-10, US Army Engineer Waterways Experiment Station, Vicksburg, MS. r. Thornton, H. T., Jr., and Alexander, A. M. 1988 (Mar). “Ultrasonic Pulse-Echo Measurements of the Concrete Sea Wall at Marina Del Rey, Los Angeles County, California,“ The REMR Bulletin, Vol 5, No. 1, US
15、Army Engineer Waterways Experiment Station, Vicksburg, MS. s. US Army Engineer Waterways Experiment Station. 1985. “Underwater Cameras for Inspection of Structures in Turbid Water,“ REMR Technical Note CS-ES-3.2, The REMR Notebook, Vicksburg, MS. t. US Army Engineer Waterways Experiment Station. 198
16、8. “Underwater Nondestructive Testing of Metal Structures (Training for Divers),“ REMR Technical Note CS-ES-1.6, The REMR Notebook, Vicksburg, MS. u. US Army Engineer Waterways Experiment Station. 1988. “Video Systems for Underwater Inspection of Structures,“ REMR Technical Note CS-ES-2.6, The REMR
17、Notebook, Vicksburg, MS. v. US Department of Transportation. 1989 (Nov). “Underwater Inspection of Bridges,“ Report No. FHWA-DP-80-1, Federal Highway Administration, Washington, DC. 4. Background Dewatering many civil works projects or appurtenant structures to perform inspections and repairs is dif
18、ficult, very expensive, and, in some cases, practically impossible. Disruption of operations at some projects cannot be tolerated for lengths of time sufficient to conduct detailed surveys and inspections. Obviously, there is a need for improved techniques for examining structural features in detail
19、 in underwater environments. Consequently, a study was conducted as part of the Repair, Evaluation, Maintenance, and Rehabilitation (REMR) Research Program to evaluate the available underwater 2614 inspection techniques for concrete structures. The results of this REMR study Provided by IHSNot for R
20、esaleNo reproduction or networking permitted without license from IHS-,-,-are summarized in this ETL. m 3535789 0025252 113 rn 2 L13 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3535789 0025253 05T 5. Underwater Survey Techniques A variety of proc
21、edures and equipment for conducting underwater surveys is described herein. Included are several nondestructive techniques which can be used in dark or turbid conditions that preclude visual inspection. Some techniques originally developed for other purposes have been adapted for application in unde
22、rwater inspections. Prior to conducting an underwater survey, it is sometimes necessary to clean the surface of the structure. A number of procedures and devices for underwater cleaning of civil works structures are described by Keeny in “Procedures and Devices for underwater Cleaning of Civil Works
23、 Structures.“ a. Visual Inspection by Divers (1) Underwater surveys by divers are usually either scuba or surface- supplied diving operations. Basic scuba diving equipment is an oxygen tank, typically weighing about 75 lb, which is carried by the diver. Surface- supplied diving, where the air supply
24、 is provided from the surface or shore, is a more elaborate operation in terms of equipment, safety concerns, diver skills, etc., especially when the diver approaches maximum allowable depths. Diver equipment for surface-supplied diving includes air compressors, helmets, weighted shoes, air supply l
25、ines, breastplates, etc., which can weigh as much as 200 lb. The free-swimming scuba diver has more flexibility and maneuverability than the surface-supplied diver. However, he cannot dive as deep or stay underwater as long as a surface-supplied diver. (2) Underwater inspections performed by divers
26、offer a number of advantages: they are (a) applicable to a wide variety of structures, (b) flexible inspection procedures, (c) simple (especially the scuba diver in shallow-water applications), and in most cases, (d) relatively inexpensive. Also, a variety of commercially available instruments for t
27、esting concrete above water have been modified for underwater use by divers. These instruments include a rebound hammer to provide data on concrete surface hardness, a magnetic reinforcing steel locator to locate and measure the amount of concrete cover over the reinforcement, and direct and indirec
28、t ultrasonic pulse velocity systems which can be used to determine the general condition of concrete based on sound velocity measurements (“New Tools and Techniques for the Underwater Inspection of Waterfront Structures“). Information concerning the training required for divers performing underwater
29、 nondestructive tests on metal structures is provided in “Underwater Nondestructive Testing of Metal Structures (Training for Divers).“ (3) Limitations on diver inspections include the regulations (“Occupational Safety and Health Operations“ and Engineer Manual 385-1-1) that restrict the allowable d
30、epths and durations of dives and the number of repeat dives in a given period. Also, in turbid water a divers visibility may be reduced to only a few inches, or in extreme cases, a diver may be limited to a tactile inspection. Also, cold climates tend to reduce the divers ability to perform at norma
31、l levels. In any case, a divers visual, auditory, tactile, and spatial perceptions are different underwater than in air. susceptible to making errors in observations and recording of data. Therefore, he is b. Manned and Unmanned Underwater Vehicles (1) Underwater vehicles can be thought of as platfo
32、rmed, underwater camera systems with manipulator and propulsion systems. a power source for propulsion, vehicle controllers (referred to as “joysticks“), and a display monitor. Available accessories which allow the vehicles to be more functional include angle lens, lighting components, instrumentati
33、on for analysis, attachments for grasping, and a variety of other capabilities. They consist of a video unit, (2) There are five categories of manned underwater vehicles: (a) untethered, Lbb (b) tethered, (c) diver lockout, (d) observation/work bells, and (e) atmos- Provided by IHSNot for ResaleNo r
34、eproduction or networking permitted without license from IHS-,-,-m 35115789 0025254 Tb m pheric diving suits. All are operated by a person inside, have viewports, are dry inside the pressure hull(s), and have some degree of mobility. (3) There are six types of unmanned underwater vehicles: (a) tethe
35、red, free swimming, (b) towed, midwater, (c) towed, bottom- reliant, (d) bottom crawling, (e) stru (f) untethered (“Undersea Vehicles Directory“). These remotely operated 3 2617 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3515789 0025255 922 vehi
36、cles (ROVs) are primarily distinguished by their power source. All include a TV camera to provide real-time or slow-scan viewing and have some degree of mobility. They are controlled from the surface via operator-observed video systems. the ROV and accessory equipment. which are self-propelled and o
37、perate without any connection to the surface. Most ROVs are capable of accommodating various attachments for grasping, cleaning, and performing other inspection chores. Specially designed ROVs can accommodate and operate nondestructive testing equipment. Joysticks are used to control propulsion and
38、manipulation of Exceptions are the untethered types of ROVs (4) Underwater vehicles can compensate for the limitations inherent in diver systems because they can function at extreme depths, remain underwater for long durations, and repeatedly perform the same mission without sacrifice in quality. Al
39、so, they can be operated in environments where water tempera- tures, currents, and tidal conditions preclude the use of divers. (5) Manned underwater vehicles are usually large and bulky systems which require significant operational support (special boats for transporting, placement and retrieval of
40、 equipment, large generators or other power sources, trained operators, etc.). Therefore, they are used less frequently than the smaller unmanned ROVs (Figure 1). Although the dependability of ROVs has steadily increased, some limitations remain. Most ROV systems provide Figure 1. ROV with video cam
41、era system. PHOTO NOT INCLUDED. two-dimensional views only and, therefore, may not project the full extent of any defects. Murky water limits the effectiveness of ROV systems. In some situations, it may be difficult to determine the exact orientation or position of the ROV, thus impeding accurate id
42、entification of an area being observed (“Underwater Inspection of Bridges“). Also, ROVs do not possess the maneuverability offered by divers. As a result, controlling the ROV in “tight“ areas and in swift currents is difficult and can result in entanglement of the umbilical (“Video Systems for Under
43、water Inspection of Structures“). (6) Underwater vehicles are being increasingly accepted as a viable means to effectively perform underwater surveys in practically all instances where traditional diver systems are normally used. Manned underwater vehicles have been used in the inspection of stillin
44、g basins, in direct support of divers, 4 2618 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-W 3515789 002525b 869 W and in support of personnel maintaining and repairing wellheads. Applications of ROVs include inspection of dams, breakwaters, jetti
45、es, concrete platforms, pipelines, sewers, mine shafts, and ship hulls, etc. (“Undersea Vehicles Directory“). They have also been used in leak detection and structure cleaning. c. Photography Systems (i) Photography systems used in underwater inspections include still- photography equipment, video r
46、ecording systems, video imaging systems, and any accessories. (2) Still-photographic equipment includes cameras, film, and lighting. Most above-water cameras ranging from the “instamatic” type to sophisticated 35-mm cameras can be used underwater in waterproof cases (“Underwater Inspection of Bridge
47、s). There are also waterproof 35-mm cameras designed specifically for underwater photography (“Underwater Cameras for Inspection of Structures in Turbid Water”). These cameras usually include specially equipped lens and electronic flashes to compensate for the underwater environment. Most film, colo
48、r and black and white, can be used in underwater photography if ample lighting is provided. High-speed film that compensates for inherent diffi- culties in underwater photography is available. (3) Adequate lighting is important for quality underwater photography. Suspended particles in water tend to
49、 absorb and reflect projected light back into the camera lens, thereby distorting the photograph. Placing the lights at 45-deg angles with respect to the target area will significantly reduce these reflections. (4) The limited visibility in extremely turbid water can make normal photographic techniques useless. In such cases, a clear-water box constructed of clear acrylic plastic and filled with clean water can be used. box against the subject displac
