Details:

Creators:
Ivey-Burden, Lindsay ; Morris, Frank
Ivey-Burden, Lindsay ; Morris, Frank Less -
Corporate Creators:
University of Virginia
Corporate Contributors:
United States. Dept. of Transportation. Research and Innovative Technology Administration
Subject/TRT Terms:
[+]
Air Voids Boreholes Drilling Evaluation Ground Penetrating Radar Nondestructive Tests Pipelines Pipe Scanning Research Hub Trenchless Technology Underground Construction
Publication/ Report Number:
UVA 2013-05
Resource Type:
Tech Report
Geographical Coverage:
United States
Corporate Publisher:
Mid-Atlantic Universities Transportation Center
Abstract:
Trenchless Technology has become an increasingly popular underground utility construction method, beginning in the early 1900s with pipe jacking beneath railroad lines. One method, horizontal directional drilling (HDD), became more common in the 1990s and into the current day. The utilization of HDD is associated with the potential risk for ground subsidence, soil heaving, sinkholes and settlement after construction. This can damage existing infrastructure and cause safety hazards. Trenchless methods, requiring an annual overcut – such as HDD, disturb soil around the outer diameter of the utility being installed. While the annular overcut is necessary for feeding pipes through the borehole, when used in conjunction with a liquid lubricant, the likelihood for developing voids increases. The annular overcut is also a cause for concern because the consistency and void ratio of the overburden soil change after boring. Inconsistent and void-ridden soil can cause void propagation through the overlying soil until it reaches the surface, where it will become a sinkhole or crack. This paper addresses post-construction evaluation methods, especially pertaining to the annular space and void propagation region above and around a freshly installed utility in Southern Virginia. Two non-destructive evaluation methods are used to scan the surrounding soil: Ground penetrating-radar (GPR) and FutureScan. FutureScan, a radar device developed by Louisiana Tech University, is capable of being attached to pipe inspection robots and uses a means of penetrating radar to detect voids and inconsistencies in three dimensions. This study examines the difference between GPR and FutureScan, regarding the imaging techniques used and the measured void ratios. Relative elevations were recorded before, during, and after drilling, to measure surface movement caused by drilling efforts. The relative elevation was also recorded several months after utility installation, for comparison on a long-term scale. After the analysis was conducted using both FutureScan and GPR, representative soil samples of the test site were retrieved and transported to a geotechnical laboratory for further testing. Based on the GPR and FutureScan findings, the utility of the two post-construction evaluation methods was determined.
Format:
PDF
Collection(s):
US Transportation Collection University Transportation Centers
Main Document Checksum:
[+]
urn:sha256:f43b0a4f1d2afc72952bdf4496fc1e2bd9b32de459ee8d3f756f6e9f6c298000
Download URL:
https://rosap.ntl.bts.gov/view/dot/29049/dot_29049_DS1.pdf
File Type:

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