水工隧道施工过程中围岩的高应力场容易引发岩爆现象，对工程安全造成威胁，围岩的钻孔卸压是岩爆主动防治措施中一类较为经济的方法。为研究不同钻孔数量和钻孔深度组合下水工隧洞砂岩力学性质和破坏特征，基于单轴压缩试验机和VIC-3D非接触式全场应变测量系统对8种不同钻孔组合的砂岩进行了单轴压缩试验，分析了8种钻孔组合下砂岩抗压强度、弹性应变能积聚及释放特征，拟合了砂岩剩余体积率与砂岩抗压强度之间的回归关系; 通过数字图像相关法(DIC)和断裂相场模拟分析了8种钻孔组合下砂岩裂纹演化与破坏特征，并基于有限元数值模拟对比分析了直孔和10°斜孔对砂岩应力重分布的影响。结果表明：1) 钻孔半径相同时，钻孔越深砂岩抗压强度越低; 2) 钻孔半径和钻孔深度相同时，随着钻孔数量增加，砂岩抗压强度非持续下降，钻孔布置亦可能影响砂岩抗压强度; 3) 砂岩弹性应变能与抗压强度呈高度正相关，损失能与弹性应变能的比值越接近0，砂岩破坏越剧烈; 4) VIC-3D系统测量和数值模拟结果均证实了单轴压缩下砂岩的蝶形破坏趋势，且非对称结构3个钻孔的方案砂岩抗压强度低，远场应力下降多，破坏时间早，经济可行; 5) 在岩性和钻孔深度相同时，直孔和10°斜孔对砂岩最大主应力重分布的影响相近，但施工时要结合现场实际和需求进行钻孔。研究为水工隧洞钻孔卸压方案的优化设计提供了一定参考。

Objective: The construction of hydraulic tunnels in high-stress surrounding rock environments often leads to the occurrence of rock bursts, thereby posing a substantial threat to engineering safety. Among the various active prevention and control measures for rock bursts, drilling pressure relief in surrounding rocks is considered a relatively economical and effective method. By creating drilled holes in the rock mass, stress concentration can be redistributed, thereby reducing the likelihood of sudden failures and improving the overall stability of the tunnel structure. Methods: In order to investigate the mechanical properties and damage characteristics of sandstone in hydraulic tunnels under different combinations of drilling numbers and drilling depths, a series of uniaxial compression tests were conducted. These tests utilized an advanced uniaxial compression testing machine and the VIC-3D noncontact full-field strain measurement system. The experiment involved eight different combinations of drilling holes in the sandstone specimens. This study comprehensively analyzed key parameters such as compressive strength, the accumulation and release characteristics of elastic strain energy, and the residual volume rate of sandstone. A regression analysis was conducted to establish a quantitative relationship between the residual volume rate of sandstone and its compressive strength. In addition, the crack evolution and damage characteristics of sandstone under different drilling hole configurations were studied using digital image correlation (DIC) technology and fracture phase field simulation. Furthermore, numerical simulations based on finite element methods were performed to compare the effects of straight holes and 10° inclined holes on stress redistribution within the rock mass. Results: The experimental and numerical results led to the following key findings: (1) when the radius of the drilled holes remains constant, an increase in the drilling depth leads to a decrease in the compressive strength of sandstone. This finding indicates that deeper drilling can effectively weaken the rock mass and facilitate stress relief. (2) Under the condition of identical hole radius and depth, an increase in the number of drilled holes results in a discontinuous reduction in the compressive strength of sandstone. Moreover, the arrangement of the drilled holes plays a crucial role in determining the overall strength of sandstone. For instance, the specimens with asymmetrical three-borehole configurations exhibited lower compressive strength than those with symmetrical four-borehole configurations. This finding suggests that asymmetrical arrangements can enhance energy dissipation efficiency and reduce the overall stress level within the rock. (3) The elastic strain energy of sandstone exhibits a strong positive correlation with compressive strength. Moreover, as the ratio of loss energy to elastic strain energy approaches zero, the intensity of sandstone destruction considerably increases. This outcome highlights the role of energy release in the failure process of rock materials. (4) DIC strain field analysis and numerical simulations confirm that sandstone under uniaxial compression follows a characteristic butterfly-shaped damage pattern. The three-borehole asymmetric configuration showed lower compressive strength, greater far-field stress reduction, earlier failure onset, and higher economic feasibility for pressure relief applications than the four-borehole symmetric configurations. (5) Under identical rock formation and borehole depth conditions, the impact of straight and 10° inclined boreholes on stress redistribution is found to be similar. However, practical construction decisions should be made, considering site-specific conditions and operational requirements. Conclusions: This study provides valuable insights for optimizing the design of borehole pressure relief schemes for hydraulic tunnels. The findings provide a reference for engineers seeking to improve tunnel stability through effective stress redistribution strategies. By systematically evaluating different drilling configurations, this study contributes to the development of more efficient and cost-effective methods for mitigating rock bursts in high-stress environments.