AASHTO R 8-1996 Standard Practice for Evaluation of Transportation-Related Earthborne Vibrations《运输相关土地产生的振动评价的标准规范》.pdf
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1、Standard Practice for Evaluation of Transportation-Related Earthborne Vibrations AASHTO Designation: R 8-96 (2015)1American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-5b R 8-1 AASHTO Standard Practice for Evaluation of
2、 Transportation- Related Earthborne Vibrations AASHTO Designation: R 8-96 (2015)11. SCOPE 1.1. This standard practice is to provide guidance for the assessment of potential or alleged structural damage due to earthborne vibrations related to transportation facility construction, maintenance, or oper
3、ation. 2. INTRODUCTION 2.1. The construction, maintenance, and operation of transportation facilities generate vibrations, which are transmitted through the air and earth and are subsequently received or “sensed” by structures or inhabitants. Only earthborne vibrations are addressed in this standard
4、 practice (see Section X2.8, Appendix X2). 2.2. Currently accepted practice in monitoring earthborne vibrations considers two parametersearth particle velocity and wave frequencydetermined at the site of concern (Siskind et al. , 1980; see Figure 1). Sensing instruments are usually set out on the gr
5、ound adjacent to the subject structure. For determination of safe vibration control limits, special concerns may dictate placement of sensors directly on specific parts of a structure such as the foundation, a supporting column, or a wall. 2.3. Much of the data concerning structural damage have been
6、 determined from blasting activities. Blasting is a commonly used construction-related procedure that produces vibrations characterized by a wide frequency range and potentially high intensities but of very short duration. Transportation-related activities, such as vehicular or rail traffic, may be
7、the source of repetitive, cyclical vibrations of much lower intensity than those caused by blasting. There may be concern in this regard because of potential for fatigue of structural components. Documentation of specific damage due to such transportation-related vibrations is scarce (Whiffin and Le
8、onard, 1971; Ames et al., 1976). 2.4. People “sense” or respond to a much broader range of vibration frequencies and intensities than do structures. Intrusive vibration levels can annoy humans at much lower intensities than levels considered critical for structures (see Figure 2). Such sensitivity c
9、auses concern for structural damage potential even at the extremely low levels of vibration that are a recognized nuisance to people. Various threshold limits have been recommended in standards aimed at minimizing damage to various structures. Recommended safe vibration limits are based upon the app
10、earance of “threshold cracks” or cosmetic cracking. Such cracks appear at lower vibration levels than do architectural or minor damage. The applicability of specific limitations is often the subject of litigation requiring expert witness opinion. 2016 by the American Association of State Highway and
11、 Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5b R 8-2 AASHTO Figure 1Safe Vibration Limit Recommendations for Residential Structures (USBM RI 8507) 2.5. Concerns of anticipated or perceived damage can be related to structures or their contents. Prac
12、tically all buildings contain fine cracks or imperfections that are not noticed until concern is stimulated by perception of abnormal vibrations. Evaluation of the potential effects of transportation-related earthborne vibrations requires documentation of the background or pre-existing condition of
13、the structure or component of concern. Such an evaluation should also include a determination of the intrusive vibration characteristics (amplitudes and frequencies) at the point of interest. Dowding (1992) reviews the various methods for determining ground vibration frequencies. Analysis of the res
14、ults may necessitate modification at the vibration source or mitigation of effects at the location of concern. 3. PROCEDURE 3.1. A survey of the site should be made by personnel capable of locating, evaluating, and documenting significant or apparent evidence of distress. Such surveys preferably sho
15、uld be made before the onset of any objectionable vibration-producing activity. The scope of the inspection should be appropriate for both the subject of concern and the intensity of the vibrations. Photographic or video documentation of the inspection is recommended. Any procedures requiring intrus
16、ion on property should be specifically permitted by the property owner, preferably in writing. Specialists in vibration monitoring are often contracted for survey services. Frequency (Hz)ParticleVelocity(in./sec)0.75 in./secDrywall2 in./sec0.008 in.0.03 in.0.50 in./secPlaster1010.10.011 10 100 2016
17、by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5b R 8-3 AASHTO Figure 2Safe Vibration Limit (USBM RI 8507) and Human Perception (Rathbone) 3.2. All vibrations arriving at the monitoring location within t
18、he selected sensitivity range of the seismograph are recorded. For comparison purposes, it is often useful to obtain recordings of the normal or background vibrations at the site when the specific objectionable source is not present. The sensitivity range of the instrument should be selected so that
19、 recording is initiated below the intensity of the objectionable vibrations and extends above the highest expected intensity. It may be necessary to estimate or predetermine the expected intensity level to be sensed in order to select the appropriate instrument range setting to be used during monito
20、ring. It is necessary to determine the time when the vibration source is active. Specific activities of the vibration source, such as driving of piles, as opposed to extraction, vibratory compaction, or pavement-breaking activities, should be indexed in time for proper correlation with the arrivals
21、on the vibration records. Because the determination of frequency is important, instruments that provide a time-history or waveform of each velocity component for a vibration event are preferred. 3.3. A field calibration procedure should be conducted before the start of monitoring and recording. The
22、incoming ground vibrations should be measured on the ground at foundation level, as close to the structure as possible, to be consistent with studies providing safe vibration limits (Siskind and Stagg, 1985). The transducer is positioned with the longitudinal axis (indicated by an arrow) toward the
23、vibration source or parallel to the structure. Transducers must be adequately coupled with the ground or the structural component being monitored (see Section X1.5, Appendix X1). Instrument manufacturers provide appropriate instructions and recommendations for special installations. Some published t
24、hreshold criteria are based on specific monitoring procedures. Consistent procedures in the placement and location of transducers during monitoring are recommended for comparison of results. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplicat
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