Expansive soils, dominated by
montmorillonite and illite, feature “20% swelling when wet and 15% shrinkage when dry,” posing three major threats to water well drilling rig operations:
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Borehole wall rheological failure:
When water content rises, expansive soils become plastic-flowing, with borehole shrinkage at 5cm/h.
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Swelling-shrinkage cycle damage:
Wet-dry alternation creates network cracks in the borehole wall, increasing collapse risk by 40%.
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Drill tool viscous resistance:
Clay particles adsorb to drill pipes, making lifting resistance 3 times higher than in ordinary formations.water well drilling rig
Bangxin drilling rig