Abstract

The success of the water-preserved mining technology is closely related to the stability of the aquiclude and the aquifer, in particular, which is made of weakly cemented rock mas. This paper starts with the tri-axial compression tests on the mudstone specimens obtained from the Ili mining area, followed by the systematic numerical simulation via the Particle Flow Code (PFC) program, aiming at obtaining an in-depth understanding of the response of weakly cemented mudstone under tri-axial compression loading state. The main outcomes obtained from this research indicated that: (1) the behavior of weakly cemented mudstone is closely sensitive to the confining pressure. As the confining pressure increases, both the peak strength and plastic deformation capacity of weakly cemented mudstone will be enhanced; (2) the main feature of weakly cemented mudstone after tests is its centrosymmetric “Z” shape, mainly attributed to the progressive separation of the particle element of mudstone; (3) the behavior of weakly cemented mudstone either in terms of the axial stress-axial strain or the failure mode is sensitive to the confining pressure. If the applied confining pressure is lower than 5 MPa, the micro-cracks are in the form of the single shear band, whereas the tested specimens will tend from brittle shear to plastic shear associated with the “X” shear when the confining pressure is higher than 5 MPa; and (4) The failure of weakly cemented mudstone is mainly attributed to the continuous expansion and penetration of internal microcracks under compression. The brittle failure mode of weakly cemented mudstone tends to ductile failure with the increase of confining pressure. The main contribution of this research is believed to be beneficial in deepening the understanding of the mechanics of weakly cemented mudstone under tri-axial compression and providing the meaningful reference to the practical application of water-preserved mining in the Ili mining area.

Highlights

  • The coal resources development strategy of China has been gradually shifted to the western region in recent years

  • Fan et al conducted a triaxial compression seepage test on the specimen, which discussed the influence of the mining process on the seepage mechanism of weakly cemented rock [11]

  • Considering the limitation of laboratory tests in exploring the mechanism response of weakly cemented mudstone under tri-axial compression, the numerical simulation is believed to be the effective method with the development of high-speed computers and mature commercial software

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Summary

Introduction

The coal resources development strategy of China has been gradually shifted to the western region in recent years. Fan et al conducted a triaxial compression seepage test on the specimen, which discussed the influence of the mining process on the seepage mechanism of weakly cemented rock [11]. Considering the limitation of laboratory tests in exploring the mechanism response of weakly cemented mudstone under tri-axial compression, the numerical simulation is believed to be the effective method with the development of high-speed computers and mature commercial software. As the extension of further research on weakly cemented rock in the Ili mining area, this paper presents the concise laboratory tests on another typical weakly cemented rock (i.e., mudstone from the Ili mining area) under tri-axial compression loading with three confining pressures (i.e., 1, 3, and 5 MPa). Based on the combined laboratory tests and numerical modelling, the deformation and failure mechanism of weakly cemented mudstone were well investigated

Specimen Preparation
Experimental Equipment and Process
Test Results and Discussions
Figures that:
Numerical Simulation
Establishment of Basic Model
Numerical
Verification of Basic Model
Failure Modes
Analysis of the Failure Mechanism
12.3 Stress-strain
Full Text
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