Rock discontinuity characterization for TH53 relocation, Virginia, MN

摘要

The Minnesota Department of Transportation (MnDOT) is relocating a portion of T.H.53 between Eveleth and Virginia, MN. The preferred alignment crosses the existing Rouch-leau iron-ore pit on a 1,100-foot bridge. Two abutments and one pier of the bridge will be founded on bedrock. Future iron-ore mining adjacent to the alignment will create rock slopes up to 500 ft high. These factors require characterization of the rock discontinuities present, both bedding and jointing. This paper will focus on discontinuity orientation, spacing and persistence. Information was collected by two innovative methods: down-the-hole televiewer logging (both optical and acoustic) and photogrammetry using images acquired via remotely piloted aircraft (RPA). These two methods differ significantly in scale and locations measured. The results will be compared from this perspective. The televiewer logging was challenging because of down-the-hole blockages, and RPA missions were challenging to plan and execute for several reasons. The methods used to overcome these challenges will be presented.