Abstract

The stability and safety of rock mass in underground constructions are influenced by the damage processes of cracks evolution caused by the excavation under coupled hydro-mechanical loading conditions. In this paper, to understand the crack development and damage evolution of sandstone under different seepage conditions, a series of triaxial compression tests with acoustic emission under different water pressures (5, 10, 15 MPa) are carried out. The stress-strain behavior, crack stress thresholds, failure mode, AE characteristics and micromechanical mechanisms are analyzed and discussed. The experimental results demonstrate that the crack stress thresholds and the mechanical property of studied sandstone decrease with the increase of water pressure. Moreover, the water pressure has an important influence on and deformation behavior of sandstone, for instance, the elastic modulus and deformation modulus decreased when the water pressure increased. Based on the result of accumulated ring counts, the damage evolution of sandstone gradually increased with increasing water pressure. Finally, the micro-structural evolution under the coupling effects of water pressure and applied stress is discussed. The obtained results can be used to identify the initiation and propagation of studied sandstone in the engineering applications.

摘要

地下工程岩体的稳定性和安全性受到水力耦合荷载条件下开挖裂隙演化破坏过程的影响。本文为了解砂岩在不同渗流条件下的裂纹发育和损伤演化，开展了一系列不同水压（5、10、15 MPa）下的声发射三轴压缩试验。分析和讨论了应力-应变行为、裂纹应力阈值、失效模式、AE 特征和微观机械机制。实验结果表明，所研究砂岩的裂纹应力阈值和力学性能随着水压的增加而降低。此外，水压对砂岩的变形行为有重要影响，例如，当水压增加时，弹性模量和变形模量降低。从累计环数结果来看，随着水压的增加，砂岩的损伤演化逐渐增大。最后，讨论了水压和外加应力耦合作用下的微观结构演变。所获得的结果可用于识别所研究砂岩在工程应用中的起裂和扩展。