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<p>With continuous resource development, engineering failures resulting from heterogeneous stress distributions within rock masses often cause significant economic losses and casualties. In this study, high-quality hydraulic fracturing (HF) in situ stress measurements were integrated with ultrasonic borehole television image-logging and borehole rock mechanics tests to develop a methodology for constructing stress profiles that reflect the heterogeneity of stress fields in rock masses. High-resolution image-logging data were utilized to determine the principal stress orientation at the study site, and high-quality HF in situ stress measurements were conducted to quantify the minimum horizontal principal stress. The magnitude of the maximum horizontal principal stress was determined by combining borehole breakout stress polygons with traditional HF techniques. To investigate the mechanisms governing stress heterogeneity, the lithological characteristics of the rock mass and distribution of fractures were incorporated with depth information obtained from boreholes, regional focal mechanism solutions, and finite element simulations of the study area. Application of this methodology to the Hami YD copper mining area revealed that, despite localized variations, the overall stress distribution aligned with the regional stress pattern. Within the shallow strata (&lt; 450&#xa0;m), the maximum horizontal stress (<i>S</i><sub>H</sub>) was consistently observed in the northeast region (N53.34° ± 11.72°E). At greater depths (&gt; 450&#xa0;m), <i>S</i><sub>H</sub> was observed in the northwest region (N50.61° ± 14.22°W). Notably, a distinct high-stress anomaly (up to 41.32&#xa0;MPa) was observed at a depth of 550–600&#xa0;m in borehole ZKBC-2. These results suggest that minor fluctuations in stress conditions at shallow regions primarily stem from variations in rock mass integrity. By synthesizing multiple datasets and analytical approaches, this study elucidated the processes driving stress heterogeneity. First, rock mass integrity is closely linked to both the magnitude of local stress and the deflection of stress orientation: when rock mass integrity is low and the orientations of structural planes are favorable for shear sliding, the magnitude of <i>S</i><sub>H</sub> decreases, accompanied by a simultaneous deflection of the stress orientation. Second, a substantial disparity in lithological strength caused by magmatic intrusion fundamentally alters the stress orientation and magnitude. These findings offer a foundation for the accurate identification and mitigation of hazards caused by heterogeneous stress distributions in deep underground structures.</p>

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Insights into the Characteristics and Mechanism of Heterogeneous In Situ Stress: A Case Study from the YD Copper Mine, China

  • 期刊论文

  • 发表日期：

    2026年6月30日

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  • Jikun Liu,
  • Chenghu Wang,
  • Guiyun Gao,
  • Zengzhen Qian,
  • Shibo Yu,
  • Chengwei Yang,
  • Wei Li

摘要

With continuous resource development, engineering failures resulting from heterogeneous stress distributions within rock masses often cause significant economic losses and casualties. In this study, high-quality hydraulic fracturing (HF) in situ stress measurements were integrated with ultrasonic borehole television image-logging and borehole rock mechanics tests to develop a methodology for constructing stress profiles that reflect the heterogeneity of stress fields in rock masses. High-resolution image-logging data were utilized to determine the principal stress orientation at the study site, and high-quality HF in situ stress measurements were conducted to quantify the minimum horizontal principal stress. The magnitude of the maximum horizontal principal stress was determined by combining borehole breakout stress polygons with traditional HF techniques. To investigate the mechanisms governing stress heterogeneity, the lithological characteristics of the rock mass and distribution of fractures were incorporated with depth information obtained from boreholes, regional focal mechanism solutions, and finite element simulations of the study area. Application of this methodology to the Hami YD copper mining area revealed that, despite localized variations, the overall stress distribution aligned with the regional stress pattern. Within the shallow strata (< 450 m), the maximum horizontal stress (SH) was consistently observed in the northeast region (N53.34° ± 11.72°E). At greater depths (> 450 m), SH was observed in the northwest region (N50.61° ± 14.22°W). Notably, a distinct high-stress anomaly (up to 41.32 MPa) was observed at a depth of 550–600 m in borehole ZKBC-2. These results suggest that minor fluctuations in stress conditions at shallow regions primarily stem from variations in rock mass integrity. By synthesizing multiple datasets and analytical approaches, this study elucidated the processes driving stress heterogeneity. First, rock mass integrity is closely linked to both the magnitude of local stress and the deflection of stress orientation: when rock mass integrity is low and the orientations of structural planes are favorable for shear sliding, the magnitude of SH decreases, accompanied by a simultaneous deflection of the stress orientation. Second, a substantial disparity in lithological strength caused by magmatic intrusion fundamentally alters the stress orientation and magnitude. These findings offer a foundation for the accurate identification and mitigation of hazards caused by heterogeneous stress distributions in deep underground structures.