Segmented constitutive relationship of weakly cemented sandstone and numerical implementation based on homogeneity

Area of Science:

• Geotechnical Engineering
• Rock Mechanics
• Mining Engineering

Background:

• Understanding the mechanical properties of weakly cemented sandstones is vital for safe coal mining.
• These rocks are prevalent in coal-bearing strata and pose unique challenges to mine stability.

Purpose of the Study:

• To investigate the deformation characteristics of weakly cemented sandstones.
• To develop and validate a novel constitutive model for predicting rock behavior.
• To provide a theoretical basis for assessing mine stability in these formations.

Main Methods:

• Triaxial compression tests were conducted on weakly cemented sandstone samples.
• A new piecewise constitutive model was developed, integrating the Double-strain Hoek model (TPHM) and statistical damage theory.
• The model was incorporated into FLAC3D for numerical simulations of stress field migration and damage evolution.

Main Results:

• A distinct compaction stage was observed in weakly cemented sandstones, shortening with increased confining pressure.
• The developed piecewise constitutive model accurately captured compaction, elastic deformation, and post-damage phases, showing excellent agreement with experimental data.
• Numerical simulations successfully predicted stress field migration and the evolution of damaged zones under various confining pressures.

Conclusions:

• The study enhances the understanding of weakly cemented sandstone mechanical behavior.
• The validated constitutive model provides a robust tool for predicting rock mass response.
• Findings offer a theoretical framework for improving the stability assessment of coal mines, particularly roof and floor slabs.