Further Thoughts on Maximum Pressures for Rock Grouting and Lugeon WPT-PPT Presentation

PPT Presentation

Pdf Summary

The presentation questions conventional maximum-pressure rules for rock grouting, such as limits based on depth—typically around 20 kPa per metre of overburden and 25 or 50 kPa per metre of bedrock. It argues that no single pressure limit suits every project: appropriate pressure depends on rock type and condition, project circumstances, pump capabilities, and grout properties.<br /><br />Because the condition of fractures within each grouting stage is uncertain, fixed pressure limits may be inefficient. The presenter proposes setting a variable maximum pressure according to the fracture conditions in each stage, while avoiding hydrofracturing or jacking. Carefully increasing pressure could make better use of each grouting hole and reduce the need for repeated, costly drilling and treatment sequences.<br /><br />The presentation also distinguishes grouting pressure from the pressure used in Lugeon water pressure tests (WPT). Rather than routinely using the same maximum pressure for both, WPT pressure should be determined by hydraulic considerations and calculations.

Keywords

rock grouting

maximum pressure

fracture conditions

hydrofracturing

jacking

Lugeon test

water pressure test

grout properties

bedrock

pressure limits