Hybrid Grouting for Remediation of Taupo Control Gate, Waikato River-PPT Presentation

PPT Presentation

Pdf Summary

The Taupo Control Gates regulate flows in the Waikato River for flood control. Built in 1941, the six underflow gates can pass peak flows of 320 m³/s. High-velocity water has caused scour and erosion in the easily eroded volcaniclastic and alluvial ground, creating voids around the sheet piles and threatening the structure’s service life.<br /><br />The remediation approach was designed to address uncertainty about the extent of the voids while preventing grout from entering the river. A grid of drilled holes was used to map voids and flow paths on the way down, then inject grout on the way up. The mapping informed ground models for analysis and helped guide the grouting operation.<br /><br />The hybrid grout comprised Part A, a cement–fly ash blend, and Part B, an activator that produces calcium hydroxide ions and triggers rapid gelation. The setting time was controlled by adjusting the mix ratio, with set times as short as five seconds.<br /><br />During grouting, pressure and flow data were used to track grout migration and assess ground response, including heave and volumetric expansion. Secondary holes provided verification of grout distribution. The presentation also noted that TAM grouting pipes could support future work.<br /><br />The project was carried out collaboratively with McConnell Dowell and Mercury.

Keywords

Taupo Control Gates

Waikato River

flood control

scour and erosion

sheet piles

ground voids

hybrid grout

TAM grouting

volumetric expansion

McConnell Dowell