Laserfiche WebLink
<br />i5 ~ <br />~~~ <br /> <br /> <br />1 <br />1 <br />1 <br /> <br /> <br /> <br /> <br />~J <br /> <br />1 <br /> <br />LJ' <br /> <br />1 <br />1 <br />Southwestern Portland Cement <br />Mining Impacts on Montgomery School <br />SIIH AG1tA Project E93-7038 <br />Page 3 <br />Human occupancy is an additional source of vibration in the structure. As part of a rational <br />assessment of the response of structures to ground vibration, Siskind, et. al. (1980) evaluated <br />the level of building vibration associated with normal human activities in a swcture including <br />an individual walking, jumping, slamming doors or nail pounding. This was done in an <br />instrumented single-family residence by measuring the range of structure vibrations from various <br />activities. Table 2 summarizes the data compiled in this study. As indicated by the data, human <br />activities can generate vibrations in building floors and walls of over 1.0 in/sec, with vibration <br />levels frequently exceeding 0.5 in/sec. <br />Blasting operations at the existing Lyons Quarry also provides a source of ground vibration to <br />the Montgomery School Building. While there is no specific monitoring data at the Montgomery <br />School Building site, an analysis of the historic ground vibration data taken from blasting at the <br />Lyons Quarry site indicates maximum ground vibration levels at the site as a result of blasting <br />operations in the past two years could be as high as 0.18 in/sec. <br />3.0 LITERATURE REVIEW <br />A review was completed of the literature to determine ground vibration limits previously applied <br />to historical structures. <br />Siskind et al. (1980) presents vibratitm standards and criteria that have been applied to a variety <br />of conditions including values specifically addressing historical structures. These are summarized <br />in Table 3. It was noted that the German vibration standazd was so strict as to be unworkable <br />and reportedly not enforced for blasting. Further, it was noted there was no technical data <br />provided to justify any of the specified vibration limits and that some of the established criteria <br />account for the intrusive aspect of blasting in addition to the building damage aspects. For <br />example, blasting associated with British tunneling is restricted to maximum ground velocities <br />of 0.39 in/sec in densely populated azeas and 0.98 in/sec in spazsely populated azeas. Excluding <br />the German standard from this summary, the criteria previously applied to historic or sensitive <br />structures ranges from 0.2 to 0.71 in/sec. For comparison, Table 4 provides general levels of <br />structural distress resulting from various ground vibration magnitudes. <br />The U.S. Geological Survey has evaluated safe ground vibration levels for stone archeological <br />ruins (King and Algermissen,1985 and 1987; King, et.al., 1991) and an adobe structure (King <br />et al, 1988) subject to various forms of transient ground vibration caused by aircraft, vehicles, <br />construction equipment, trains, and blasting. A limiting level of vibration induced in the <br />structure of 0.079 in/sec (2 mm/sec) was recommended for compliance monitoring in each of <br />these studies. It was further noted that the structures amplified ground vibrations with a <br />frequency content near the resonant frequency of the structures <br />to 10. This resulted in a recommended peak allowable ground <br />in/sue velocity limit to be applied to the structures. <br />(1 to 20 Hz.) by a factor of 2 <br />velocity of one half the 0.079 <br />AG RA <br />Earth & Errvironmenta/ Group <br />