Development of a Mixing Index for Cutter Soil Mixing-PPT Presentation

PPT Presentation

Pdf Summary

The presentation proposes a new Mixing Index for Cutter Soil Mixing (CSM), arguing that the Blade Rotation Number (BRN), developed for single- and multi-axis mixing, does not adequately represent CSM’s different mechanics. CSM cutter wheels rotate on horizontal axes, cutting and disaggregating soil; slurry injection and shear plates help produce a semi-fluid, thoroughly mixed material.<br /><br />Although high-quality mixing has been observed across a range of soils, including organic soils, a reliable, practical way to assess mixing effort is still needed. An earlier energy-based method by Bellato et al. included cutter torque but is cumbersome to calculate and requires data processing. Analysis of 261 panels from 11 British Columbia sites also found no clear relationship between calculated mixing energy and 28-day unconfined compressive strength (UCS). This is consistent with earlier findings that BRN does not reliably predict UCS. One explanation is that strength may stop increasing once a soil-specific threshold energy is reached; most reviewed CSM data appear to exceed that threshold.<br /><br />The proposed alternative is the Cutter Wheel Rotation Number (CWRN), intended as a simple, field-friendly index. Comparisons with Bellato’s energy calculations show a general trend, suggesting CWRN may serve as a reasonable indicator of energy input.<br /><br />Preliminary CWRN targets, normalized to a 1 m panel thickness, are 200 for sand, 250 for silt, 300 for clay, 330 for organic clay, and 360 for peat. These values are provisional, particularly for clay and organic soils, and require validation. Further work should establish threshold energies across soil types, investigate less-conservative energy requirements, and determine how to account for cutting and disaggregation—especially during single-phase and bottom-up mixing.

Keywords

Cutter Soil Mixing

Mixing Index

Blade Rotation Number

Cutter Wheel Rotation Number

soil mixing

unconfined compressive strength

mixing energy

slurry injection

cutter wheels

threshold energy