They have a frequency range of 0.1 to 500 Hz as utilized in this study (3). The B&K (Brüel and Kjaer) type 2209 and GR (General Radio) type 1933 instruments are type 1 precision sound level meters with impulse detection capability. Their low-frequency cutoffs are 2 and 5 Hz (±3 dB), respectively, when used in the "linear" mode.5 Some measurements were also made of the C-weighted peak and slow-response noise levels with the GR 1933. The B&K type 2631 is a microphone carrier system with a frequency range of 0.1 to 8 kHz. Structure and ground motions were measured with direct output particle velocity transducers manufactured by MB Corp., with a flat frequency response (±3 dB) of 5 to 850 Hz. All of these noise and vibration measuring devices have been described elsewhere in detail (1-3). Sites All the residences monitored were within 1,000 feet of the quarry property lines, and in one case, the structure was within 500 feet of the blasting. Table 1 describes the structures. Table 2 lists a few blast design parameters including a note on the bench location. The highwall shots had a collar elevation approximately corresponding to the level of the houses. All of the pit bottom shots were over 200 feet below the level of the structures and always out of direct line-of-sight. Weather conditions were only causally observed with Dwyer gage wind measurements made at ground level. Further studies of this type, particularly at larger shot-to-structure distances, will require more accurate weather measurements. Residences A through E are shown in figures 1 through 5. A sixth residential structure was also instrumented. However, blast records for this structure were inconclusive. Particle velocity gages were placed approximately in the center of floors and walls in order to measure maximum generated motions. The indoor noise resulted from direct airblast combined with structure-generated noise, and it was generally not possible to distinguish between these sources. Construction Basement Location from Shots quarry Wood frame.. Concrete block. SW from highwall, 13, 14, 17, 5dB (L) is used to designate linear frequency response of at least 5 Hz to 10 kHz. NW from pit.. 19. 19. and construction industries whose major concerns are development of reasonable and technically established damage and annoyance criteria and standardized measurement techniques for both noise and vibration. The Bureau of Mines is currently conducting several studies involving the establishment or modification of noise and ground vibration criteria for blasting, standardized measurement methods for both noise and ground vibrations, and methods to control noise generation and propagation. This paper describes measurements of noise and structural vibrations in six occupied residences generated by seven quarry production blasts. Both interiors and exteriors of residential structures were monitored during blasting as part of an overall effort to define and characterize the noise and ground vibration properties that are most critical in the generation of structural damage and human annoyance. Data are for informational purposes only, and the Bureau of Mines does not consider the few measurements presented here a basis for recommending changes in damage criteria. ACKNOWLEDGMENTS The authors wish to acknowledge the very capable assistance of the agencies, consultants, homeowners, and quarry operators whose contributions were essential for this work. Greg Zak of the Illinois Environmental Protection Agency and George W. Kamperman of Kamperman Associates, Inc., provided helpful suggestions and made the initial contacts with the private citizens involved. MEASUREMENT PROCEDURES Noise and vibration measuring devices were installed inside and outside six different residential structures for seven limestone quarry production blasts. Two residences were instrumented simultaneously for each of the last three blasts. Particle vibration measuring gages were placed on house walls and floors and also on the ground outside the structures. Microphones and other blast noise transducers were located inside and outside to determine the relative importance of the groundborne vibration and the airblast overpressure in producing vibrations in the buildings. Instrumentation A multichannel FM tape recording system was used to measure and record the blast noise and structure vibration (4).3 Previous work had shown that special ultra-low-frequency response is required to accurately characterize airblast overpressures (3). Noise from large-scale blasting is predominately around 1.0 to 1.5 Hz in the distance range of hundreds to thousands of feet. The DP-7 noise transducers are variable reluctance pressure gages manufactured by Validyne Corp. and adapted to measure airblast overpressures. 3 Underlined numbers in parentheses refer to items in the list of references at the end of this report. 4 Reference to specific brand names is made for identification only and does not imply endorsement by the Bureau of Mines. They have a frequency range of 0.1 to 500 Hz as utilized in this study (3). The B&K (Brüel and Kjaer) type 2209 and GR (General Radio) type 1933 instruments are type 1 precision sound level meters with impulse detection capability. Their low-frequency cutoffs are 2 and 5 Hz (±3 dB), respectively, when used in the "linear" mode.5 Some measurements were also made of the C-weighted peak and slow-response noise levels with the GR 1933. The B&K type 2631 is a microphone carrier system with a frequency range of 0.1 to 8 kHz. Structure and ground motions were measured with direct output particle velocity transducers manufactured by MB Corp., with a flat frequency response (±3 dB) of 5 to 850 Hz. All of these noise and vibration measuring devices have been described elsewhere in detail (1-3). Sites All the residences monitored were within 1,000 feet of the quarry property lines, and in one case, the structure was within 500 feet of the blasting. Table 1 describes the structures. Table 2 lists a few blast design parameters including a note on the bench location. The highwall shots had a collar elevation approximately corresponding to the level of All of the pit bottom shots were over 200 feet below the level of the structures and always out of direct line-of-sight. Weather conditions were only causally observed with Dwyer gage wind measurements made at ground level. the houses. Further studies of this type, particularly at larger shot-to-structure distances, will require more accurate weather measurements. Residences A through E are shown in figures 1 through 5. A sixth residential structure was also instrumented. However, blast records for this structure were inconclusive. Particle velocity gages were placed approximately in the center of floors and walls in order to measure maximum generated motions. The indoor noise resulted from direct airblast combined with structure-generated noise, and it was generally not possible to distinguish between these sources. A..... Stories 1. Construction Basement Location from Shots Wood frame.. Concrete block. SW from highwall, 13, 14, 17, 5dB(L) is used to designate linear frequency response of at least 5 Hz to 10 kHz. |