What’s All the Buzz - Construction Vibration Mitigation Helps Laboratory Research Animals

06.19.18   Christopher G. Naida, PE | More by this Author

What’s All the Buzz - Construction Vibration Mitigation Helps Laboratory Research Animals

When a major university planned new construction near three existing buildings that house more than 100,000 mice enclosures (pictured below), they feared that construction vibrations would cause undue stress to the animals, and subsequently compromise research projects. Previous observation had demonstrated that mice become distressed at certain levels of vibration, which impacts the validity of research.

The university called upon SME to develop a plan to avoid vibration distress. Portable seismographs were installed and programed for continuous reading of the incoming vibrations.

First, vibration data was recorded prior to construction activities. Vibration data was again recorded during construction scenario tests prior to the full project start, with the intent to evaluate acceptable vibrations levels and mitigation techniques for excess vibrations. Since construction plans required use of large excavators, vibratory soil compaction equipment was used to densify backfill.

Vibrations from this equipment, traveling through the soil from the construction site to where the mice were housed, could have caused distress. A test using typical compaction equipment on the adjacent site was used to measure vibration levels, and SME measured the resulting vibration levels in the building where the mice were housed.

The vibration measurements at the locations where mice were housed were generally within the “not perceivable” to “barely noticeable to persons” range. However, some behavioral issues were reported with the mice despite these low vibration levels. The vibration measurement findings were shared with the university research team and SME suggested using a damping system (e.g., rubber pads) between the metal racks and the floor slab to absorb some of the vibration felt by the mice.

With the damping system in place, SME’s team returned to the site and performed additional vibration measurements. The racks with the rubber pads showed a 47 to 70 percent reduction in the already barely perceivable PPV levels. With the addition of these damping pads, university staff reported favorable behavior of the mice in those racks. SME’s assessment and recommended mitigation techniques resulted in both happier mice and uncompromised research future results.

For more information on vibration testing, contact Christopher G. Naida, PE.

TAGS: Geotechnical

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