Experimental study on the pore and solid structures of municipal solid waste under compression based on computed...

Area of Science:

• Geotechnical Engineering
• Environmental Engineering
• Materials Science

Background:

• Municipal solid waste (MSW) is a complex, heterogeneous porous medium.
• Macroscale experiments inadequately capture MSW's hydraulic and mechanical properties, particularly preferential flow and solid reinforcement.
• Understanding microscale structure is crucial for accurate modeling.

Purpose of the Study:

• To investigate the microscale structure of MSW using CT scanning.
• To quantify pore size distribution and structural solid angle under varying stress conditions.
• To analyze the mechanical behavior of different pore sizes in MSW.

Main Methods:

• CT scanning of laboratory and landfill MSW samples.
• Image processing including dynamic threshold segmentation and morphological denoising.
• Maximum inscribed sphere (MIS) algorithm for pore size distribution.
• Angle statistical algorithm for structural solid angle analysis.

Main Results:

• Pores classified as large (>1 mm), medium (1-0.1 mm), and small (<0.1 mm).
• Under 50 kPa vertical stress, porosities were 35% (large), 12% (medium), and 26% (small).
• At 400 kPa, large pore porosity decreased to 15%, while medium and small pores remained stable. Structural solid angle distribution approximated a Gaussian function, concentrating around 30-32°.

Conclusions:

• Vertical stress significantly reduces large pore porosity in MSW.
• Medium and small pores exhibit greater stability under compression.
• Microscale structural analysis provides critical insights into MSW's mechanical and hydraulic behavior.