Exploring the Macroscopic Behavior and Microstructure Evolution of Lightly Cemented Sand in the Post-Liquefaction...

Area of Science:

• Geotechnical Engineering
• Soil Mechanics
• Material Science

Background:

• Liquefaction in cemented sands poses significant risks in geotechnical engineering.
• Understanding post-liquefaction behavior is crucial for infrastructure resilience.
• Microscopic factors influencing cemented sand's mechanical response require detailed investigation.

Purpose of the Study:

• To investigate the post-liquefaction monotonic undrained shearing behavior of cemented sand.
• To analyze the influence of cement content (CC) and cyclic stress ratio (CSR) on mechanical properties.
• To correlate macroscopic behavior with microscopic characteristics using the discrete element method (DEM).

Main Methods:

• Simulated cyclic undrained triaxial tests to induce liquefaction.
• Simulated post-liquefaction monotonic undrained triaxial tests on cemented sand.
• Utilized discrete element method (DEM) to model macro- and microscale behaviors, analyzing fabric, coordination number, energy, and bond breakage.

Main Results:

• The DEM model accurately captured the effects of CC and CSR on undrained shear strength, stiffness, and pore pressure.
• Increased CC in virgin specimens enhanced initial stiffness and shear strength due to higher coordination numbers and input work.
• Liquefied specimens exhibited very low initial stiffness, irrespective of CC, attributed to a smaller initial mechanical coordination number.
• For liquefied cemented sand, both mechanical coordination number and input work increment decreased with increasing CSR.

Conclusions:

• Microstructure evolution is the primary driver of post-liquefaction behavior in cemented sands.
• Cementation level and liquefaction history significantly dictate the macroscopic response.
• DEM provides a robust framework for understanding complex soil-structure interactions at particle scale.