Alternative Title

NCKRI Symposium 2: Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst

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Publisher

University of South Florida

Publication Date

May 2013

Abstract

pg(s) 79-88 Induced sinkholes are a known geologic hazard and may be associated with construction activities that cause alteration of ground water flow patterns or induce rapid loads and/or vibrations on karst-affected soils and rocks. This study describes the geophysical and geotechnical investigation of a site in northern Hillsborough County, Florida, where a large diameter underground high-pressure natural gas pipeline was installed utilizing horizontal directional drilling (HDD) methods. Objectives of the investigation were to evaluate the impacts of: 1) pipeline installation on existing ground-collapse features, 2) potential induced ground subsidence and 3) possible effects on water bodies and building structures. The site was investigated utilizing geophysical testing (electrical resistivity), standard penetration test (SPT) borings, and ground vibration monitoring during pipeline construction. In the investigation, subsurface conditions indicative of possible preexisting weakened soil and rock materials associated with incipient raveled zones in overburden soils and soil-filled conduits in limestone bedrock were found in proximity to the pipeline corridor. During the HDD boring and pipeline installation, noticeable ground vibrations occurred, along with formation of several ground settlement/collapse features. The data suggest two mechanisms of induced sinkhole formation: erosion of weak zones in overburden soils by the high pressure drilling mud and/or erosion of weak, soil-filled conduits in limestone bedrock. In addition to current settlement impacts to the property, the investigation found a potential for future ground subsidence associated with undetected eroded and raveled zones that may in the future propagate to the land surface. Open Access - Permission by Publisher See Extended description for more information.

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1 online resource

Type

Conference Proceeding

Genre

Conference Proceedings; Serials

Format

application/pdf

Identifier

K26-01561

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