Causal Factors Associated with Hydraulic Fracturing During Foundation Grouting at TVA's Boone Dam-PPT Presentation

PPT Presentation

Pdf Summary

The presentation examines hydrofracture during grouting for the Boone Dam Internal Erosion Remediation Project. It reviews site and subsurface conditions, the grouting layout and methods—including low- and high-mobility grouting—and evidence observed during the work.<br /><br />Exploratory trenches revealed extensive planar grout seams in the area discussed. The presentation also documents ground displacements and a hydraulic-fracturing signature recorded during a grouting stage on January 27, 2017, alongside other manifestations of hydraulic fracturing and grouting-pressure profiles. Although it identifies hydrofracture mechanisms as a topic, the supplied slides do not detail the specific causal mechanisms.<br /><br />Changes were made to the specifications for a subsequent grouting program to reduce risk and improve control. These included using a more viscous mix with a longer set time, seating the minimum-point-of-seal packer deeper below the top of rock, increasing separation between nearby grouting activities, requiring instrumented packers, and limiting pressure targets at shallow depths. The changes also clarified mix-change triggers and restrictions on grout take, discontinued shallow water-pressure tests, and improved real-time grout monitoring.<br /><br />The presentation was delivered by Chris L. Saucier, P.E., of the Tennessee Valley Authority, who served as Technical Director of the Boone Dam remediation project.

Keywords

hydrofracture

grouting

Boone Dam

internal erosion remediation

hydraulic fracturing

grout seams

subsurface conditions

grouting pressure

instrumented packers

grout monitoring