Traditionally, closure criteria and control of grouting effectiveness for bedrock permeation grouting has always relied on "final stage" confirmatory water pressure testing of the grouted rock mass using classic Lugeon-style testing. However, increasing industry-wide acceptance of real-time grout monitoring using electronic data acquisition can allow adoption of closure criteria using grouting data alone, without recourse to additional water pressure testing. This use of electronic data is facilitated by three other advances: grout stability and properties (rheology); understanding of grout penetration; and monitoring technology to control grout injection. Drawing upon these advances, and supported by modelling of grout flow in fractured rock (presented as a companion paper, Carter et. al., 2012), procedures are proposed to allow reliable rock grout curtain construction using cement-based grouts.
Fractured rocks, specifically sedimentary sequences, present a particular challenge for grouting, as major connected fractures that must be sealed will rarely be intersected by vertical groutholes. The aperture controlled grouting (ACG) method can be readily applied using discrete fracture network (DFN) analysis approaches to understand the pattern of fractures that need to be grouted. Aperture controlled grouting then utilises a combination of the principles of fracture grouting and grouting intensity number (GIN) grouting for practical and cost-effective grouting of tunnel, dam, shaft, or environmental restoration projects. This paper illustrates the application of DFN techniques for fracture assessment for grouting design and then compares the ACG approach to more conventional grouting approaches based on recent grouting experience.
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