The stress concentration of pipe structure or cavity defect has a great effect on the mechanical properties of the high-performance concrete (HPC) members in deep underground locations. However, the behaviour of HPC with cavities under triaxial compression is not understood, especially when pressurized liquid flows into the fractures from the cavity. This study aims to investigate the effect of the cavity and the confining pressure on the failure mechanisms, strengths, and deformation properties of HPC with a new experimental scheme. In this experiment, the pressurized liquid can only contact the surface of the sample in the cavity, while the other surfaces are isolated from the pressurized liquid. To further explore the effect of the cavity, the same experiments are also conducted on sealed and unsealed intact samples without a cavity. The failure modes and stress-strain curves of all types of the samples are presented. Under various confining pressures, all the samples with a cavity suffer shear failure, and there are always secondary tensile fractures initiating from the cavity sidewall. Additionally, it can be determined from the failure modes and the stress-strain curves that the shear fractures result from the sidewall failure. Based on the different effects of the cavity on the lateral deformations in different directions, the initiation of the sidewall fracture is well predicted. The experimental results show that both the increase of the confining pressure and the decrease of the cavity size are conducive to the initiation of sidewall fracture. Moreover, the cavity weakens the strength of the sample, and this study gives a modified Power-law criterion in which the cavity size is added as an impact factor to predict the strength of the sample.

管道结构或空腔缺陷的应力集中对地下深处高性能混凝土（HPC）构件的力学性能有很大影响。然而，在三轴压缩下具有空洞的 HPC 的行为尚不清楚，特别是当加压液体从空洞流入裂缝时。本研究旨在通过新的实验方案研究空腔和围压对 HPC 失效机制、强度和变形特性的影响。在本实验中，加压液体只能接触腔内样品的表面，而其他表面与加压液体隔离。为了进一步探索空腔的影响，同样的实验也在没有空腔的密封和未密封的完整样品上进行。给出了所有类型样品的失效模式和应力-应变曲线。在各种围压下，所有带空腔的试样均发生剪切破坏，且始终存在由空腔侧壁引发的二次拉伸断裂。此外，可以从失效模式和应力-应变曲线确定剪切断裂是由侧壁失效引起的。基于空腔对不同方向横向变形的不同影响，很好地预测了侧壁断裂的起始。实验结果表明，围压的增加和空腔尺寸的减小都有利于侧壁断裂的萌生。此外，空腔削弱了样品的强度，