COMPARISON OF PROPAGATION EFFICIENCY BETWEEN TUBE-A-MANACHETTE AND MULTI-STRAINER CHEMICAL GROUTING METHODS IN GRANULAR SOILS-Paper

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The study compares Tube-A-Manchette (TAM) and multi-strainer (MS) chemical grouting for ground improvement around a TBM cutter head in dense, water-bearing granular soils in Taiwan. The work aimed to stabilize the ground and prevent water and sand ingress during cutter maintenance, including in a congested area where conventional grout-hole spacing was difficult.<br /><br />TAM uses injection stages spaced about 33 cm apart, while MS uses approximately 100 cm intervals and a longer cylindrical injection source with additional outlets. Both methods allow repeated injections and use the same grout materials. MS is intended to spread grout farther and accommodate larger grout volumes without increasing flow rate. Field limit-injection tests indicated effective critical injection rates of about 13–16 L/min for both methods; the recommended operating rate was below 13 L/min.<br /><br />Estimated penetration radii in the granular layer were greater for MS than TAM. For cement-bentonite grout, estimates were 2.53 m for MS and 1.86 m for TAM; for silicate grout, they were 5.53 m and 3.26 m, respectively. These estimates suggest MS can cover a wider zone with fewer injection points.<br /><br />Post-grouting permeability tests recorded values of approximately 4.7 × 10⁻⁸ to 5.3 × 10⁻⁶ cm/s, meeting the project requirement of less than 1 × 10⁻⁵ cm/s and substantially reducing permeability from the original gravel-layer value of 1.4 × 10⁻¹ cm/s. No groundwater leakage occurred during cutter maintenance, and tunneling resumed successfully.<br /><br />The authors conclude that MS is a productive, cost-effective option for large spacing and space-constrained sites, while retaining key TAM capabilities, including repeated injections of different grout materials at the same point.

Keywords

Tube-A-Manchette

multi-strainer grouting

chemical grouting

TBM cutter head

ground improvement

dense granular soils

water-bearing soils

grout penetration radius

permeability reduction

Taiwan tunneling