Mechanical Damage and Failure Behavior of Shaft-Lining Concrete after Exposure to High Pore-Water Pressure

In order to investigate the effects of high pore-water pressure on the mechanical damage and failure behavior of mine shaft-lining concrete, specimens were immersed in a high-water-pressure container (up to 10 MPa) to form a high hydraulic gradient similar to that present in shaft-lining concrete in deep aquifers. The acoustic-wave velocity, strength, elastic modulus, and microcrack propagation were correlated through a mixed orthogonal experimental scheme in which the water pressure, exposure time, and concrete strength, were varied over 16 tests. The experimental results indicate that high pore-water pressure accelerates the damage process of shaft-lining concrete, resulting in increased modulus of elasticity, decreased peak strength with increasing water pressure and exposure time, and greater microcrack propagation in lower-strength-grade concrete (e.g., C60). In addition, most of the specimens failed by shear cracking. A damage evolution equation and constitutive model of shaft-lining concrete under uniaxial compression considering the effects of high pore pressure is established. The model shows good agreement with the experimental results.