Research on permeable pores in collapse column fillings with different gradation structures

Area of Science:

• Geotechnical Engineering
• Mining Engineering
• Hydrogeology

Background:

• Particle loss in collapsed columns is a primary driver of catastrophic water inrush events.
• Understanding the relationship between particle loss and pore structure is crucial for mitigating these risks.

Purpose of the Study:

• To investigate the influence of particle migration on the seepage parameters of graded rock samples.
• To analyze the impact of varying water pressures and axial loads on particle loss and pore structure evolution.

Main Methods:

• Experimental determination of seepage parameters under different hydrostatic pressures (P) and axial loads (F).
• Analysis of particle loss, collapse, and silting behaviors in graded rock samples (n=0.3, 0.5).
• Correlation analysis between sample gradation, damaged area, and water inrush channel characteristics.

Main Results:

• Rock samples with gradation values of n=0.3 and n=0.5 exhibited dominant particle loss behaviors.
• Porosity (φ) showed an exponential relationship with bearing load (F), decreasing as load increased.
• Water inrush characteristics were primarily turbulent, with potential for slurry and splashing, especially after 1.2 MPa.

Conclusions:

• Sample gradation (n) strongly correlates with the damaged area and water inrush channel size.
• Permeable pores can be categorized into digging/collapse, water inrush gaps, and scouring holes.
• The pore seepage process involves four distinct stages: inoculation, rapid adjustment, rapid scour, and steady flow.