The Job
This Tampa thermal grouting project is for Duke Energy. As part of this extensive project, contractors mined a 184-linear-foot, 48-inch diameter microtunnel beneath an arterial roadway. This microtunnel serves as a conduit for high-voltage electrical cables. CJGeo performed the thermal grouting for the microtunnel's annular space.
CJTherm TM-5 grout venting at the far end.
The Challenge
The high-voltage transmission lines generate significant heat during operation. To ensure the cables operate at optimal temperatures without sacrificing performance or longevity, the installation must efficiently transfer this heat away from the conduit. The project required a specialized grout with specific thermal resistivity properties to facilitate this heat dissipation. The thermal resistivity requirement for this project was a maximum of 60 °C-cm/W at 6% moisture content.
The Solution
CJGeo determined that our CJTherm TM-5 thermal grout would be an ideal fit for this project. While performing continuous temperature & pressure monitoring within the tunnel during grouting operations, we placed the grout in a single lift. Confirmation of fill was uniform grout venting from the far end 12 o'clock vent port. After completing the work, CJGeo used Geotherm of Houston, Texas, to test the as-placed CJTherm TM-5 for thermal resistivity. The tests showed the grout had a wet cast rho of 52 and a 0% moisture rho of 90, well exceeding the specification.
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