Emergency Plans for Sudden Settlement in Expansive Soil Drilling

Sudden settlements in expansive soils often result from local water loss shrinkage, with four-level responses:

 

  1. Mild settlement (<10cm):
    Inject high-viscosity mud (45s viscosity) to fill voids.
  2. Moderate settlement (10–30cm):
    Drop graded sand-gravel mixed with quick-setting agent (initial setting in 15min).
  3. Severe settlement (>30cm):
    Adopt grouting pipe shed method to form a 1.2m-diameter reinforcement ring.
  4. Extreme settlement:
    Install backpressure devices at the hole opening combined with freezing for water stop.expansive soil