Analysis of Typical Rock Physical Characteristics, Mechanical Properties, and Failure Modes of the Laoheba Phosphate Mining Area in the Sichuan Basin, China

Abstract

The Laoheba Phosphate Mine Area in the Sichuan Basin stands as one of China’s primary locations for phosphate extraction, boasting a diverse array of rock types and complex rock layers. In recent years, frequent geological disasters, notably landslides, have occurred in the mining area. The safe extraction of phosphate rock faces significant challenges, necessitating an in-depth exploration of the physical and mechanical properties of the rocks within the mining area. This study employs nuclear magnetic resonance (NMR) and X-ray diffractometer (XRD) testing on six typical rock specimens, contrasting and analyzing their physical traits, thus unveiling the impact of rock composition and microstructure on their mechanical properties. The MTS815 Flex Test GT rock mechanics testing system was employed to perform uniaxial compression, triaxial compression, Brazilian disk splitting, and triaxial penetration tests. The study systematically examined the mechanical characteristics of typical rocks in the mining area. The correctness of the experiments was mutually validated by four types of tests. Finally, an analysis of rock failure modes and patterns was conducted. Research suggests that phosphate ore exhibits the highest porosity and permeability. Phosphate ore exhibits significant development of original joints and cracks internally, along with numerous defects, leading to its minimal compressive and tensile strength. Phosphate ore is typically situated in regions of weakened rock mass strength. Real-time monitoring of confining pressure is essential during mining operations to prevent the collapse of surrounding rock formations. The findings of this study offer theoretical backing for secure mining operations in the Laoheba Mining Area of the Sichuan Basin while also furnishing fundamental physical and mechanical parameters for regional geomechanical analysis.