Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Abstract

The development of a site for a power plant was complicated by the presence of pinnacled karst bedrock located beneath more than 24 meters (80 feet) of intermediate geo-materials (IGM). Shallow mat foundations had been planned in the conceptual design. Detailed subsurface investigations included an extensive supplemental drilling phase that identified a complex layer of pinnacled karst lying beneath a hard, nearly inelastic layer of residual IGM. In an effort to keep the site on shallow foundations, the design team attempted a preload approach to pretest the load-bearing capacity of the potentially karst prone site. Project schedule constraints required the preload be removed and abandoned in lieu of more positive, fast-track solutions after detection of collapse-like movements. With schedule milestones fast approaching, the project moved to conventional H-piles to expedite foundation construction. The pile design effort included an indicator pile program with confirmation borings, a static load test and PDA testing. Pile installations were installed up to a depth of 101 meters (332 feet) and rejections penetrated over 125 meters (410 feet). Predicted averages for the project were met at 30 meters (100 feet). Project evolution included settlement plots for 28 shallow settlement plates and three deep anchors reflecting not consolidation, but small shear movements as the overburden crushed the underlying pinnacles.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Site Development in Deep Karst Terrain

New York, New York

The development of a site for a power plant was complicated by the presence of pinnacled karst bedrock located beneath more than 24 meters (80 feet) of intermediate geo-materials (IGM). Shallow mat foundations had been planned in the conceptual design. Detailed subsurface investigations included an extensive supplemental drilling phase that identified a complex layer of pinnacled karst lying beneath a hard, nearly inelastic layer of residual IGM. In an effort to keep the site on shallow foundations, the design team attempted a preload approach to pretest the load-bearing capacity of the potentially karst prone site. Project schedule constraints required the preload be removed and abandoned in lieu of more positive, fast-track solutions after detection of collapse-like movements. With schedule milestones fast approaching, the project moved to conventional H-piles to expedite foundation construction. The pile design effort included an indicator pile program with confirmation borings, a static load test and PDA testing. Pile installations were installed up to a depth of 101 meters (332 feet) and rejections penetrated over 125 meters (410 feet). Predicted averages for the project were met at 30 meters (100 feet). Project evolution included settlement plots for 28 shallow settlement plates and three deep anchors reflecting not consolidation, but small shear movements as the overburden crushed the underlying pinnacles.