Study on urban ground collapse induced by defective pipelines based on physical model experiments and numerical...

Area of Science:

• Geotechnical Engineering
• Environmental Engineering
• Computational Mechanics

Background:

• Seepage erosion from underground defective pipelines destabilizes surrounding soil strata.
• This instability can result in significant urban ground collapses, posing risks to infrastructure and safety.

Purpose of the Study:

• To investigate the failure mechanisms and mechanical characteristics of soil erosion caused by defective pipelines.
• To analyze the microscopic soil-water interactions during the seepage erosion process.

Main Methods:

• A large-scale physical modeling experiment was conducted.
• A coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) numerical model was developed and utilized.

Main Results:

• Groundwater seepage accelerates soil movement, with defective pipelines providing space for erosion.
• Seepage erosion rate escalates with flow velocity, leading to strata disintegration above a threshold (Vmax).
• Overlying strata thickness influences cavity progression time but not initial erosion rates; defect and particle sizes have minor impacts on erosion area.

Conclusions:

• The study elucidates the critical role of groundwater seepage in pipeline-induced ground erosion and collapse.
• Mechanistic analysis reveals that stress-strain changes are most pronounced during cavity development, highlighting the importance of this phase in failure progression.