Heave at Manufacturing Facility: Observations and Response

A manufacturing facility was completed in Loveland, Colorado in early 1993 on the clay shale Pierre Formation. As expansive subsurface materials were identified prior to construction, the facility was founded on drilled shaft foundations with a structurally supported basement underlain by a crawl space. The site was landscaped with bluegrass turf, and there were initially unlined ponds on the up-gradient side of the building. Significant heave of almost 9 inches occurred under portions of the building within three years of occupancy. Early responses included replacement of damaged concrete masonry unit (CMU) partition walls and other cosmetic repairs. In addition, the ponds were lined, the lawn removed adjacent to portions of the building, and deep dewatering wells installed on the up-gradient side of the building. Heave and distress continued in spite of these efforts, progressing slowly across the facility, and currently (2005) impact over three-quarters of the building. Maximum heave is almost 12 inches, and over half the building has heaved more than 6 inches. The locus of the maximum rate-of-heave is moving across the building at about 7 feet per year. Repairs have been performed over time as needed. Lateral heave has sheared a number of the 36-inch and 42-inch drilled shafts, which have been repaired by external banding with post-tensioned cables or carbon fiber wrap. Heave appears to be associated with depths of wetting greater than typically documented in the area. Both construction details and geology appear to have contributed to the heave. Manufacturing has continued uninterrupted with only moderate inconvenience to the building occupants. Interestingly, single-family residences that abut the site have little reported heave damage.