图  1  钻孔应力释放引起岩芯膨胀示意图

S_max—水平最大主应力；S_min—水平最小主应力；d₀—变形前钻孔直径；d_max—钻孔变形后长轴直径；d_min—钻孔变形后短轴直径；d_θ—参考方向直径；θ—参考方向角度a—取芯前直径；b—取芯后钻孔直径；c—取芯过程；d—取芯后岩芯直径

Figure  1.  Schematic diagram of core expansion caused by drilling stress release

(a) Diameter before coring; (b) Diameter after coring (borehole); (c) Coring process; (d) Diameter after coring (core)S_max–Maximum horizontal principal stress; S_min–Minimum horizontal principal stress; d₀–initial diameter of the borehole before deformation; d_max–long-axis diameter of the borehole after deformation; d_min–short-axis diameter of the borehole after deformation; d_θ–diameter in the reference direction; θ–angle of the reference direction

图  2  变形速率分析法示意图

σ_p—峰值轴向应力；σ₀—历史最大主应力；∆ε_axial—轴向应变差；∆ε_lateral—横向应变差a—应力−时间曲线；b—应力−应变曲线

Figure  2.  Schematic diagram for deformation rate analysis

(a) Stress–time curve; (b) Stress–strain curveσ_p–Peak axial stress; σ₀–Historical maximum principal stress; ∆ε_axial–Axial strain difference; ∆ε_lateral–Lateral strain difference

图  3  RCAE法测量步骤（Ma et al.，2020，2022a）

Figure  3.  Measurement procedure of the RCAE method (Ma et al., 2020, 2022a)

图  4  饼化的岩芯分类（闫绍坤等，2024）

a—破碎状岩饼；b—薄饼状岩饼；c—厚饼状岩饼；d—短柱状岩饼

Figure  4.  Classification of core discing (Yan et al., 2024)

(a) Fragmented rock disk; (b) Thin rock disk; (c) Thick rock disk; (d) Short cylindrical rock disk

图  5  使用各种成像设备拍摄的深孔不规则特征图像

a—德国KTB钻孔孔壁形态；b—不规则钻孔形态

Figure  5.  Images of the irregular features of a deep borehole, acquired with various imaging equipment

(a) German KTB borehole wall morphology; (b) Irregular borehole morphology

图  6  深钻孔中4种典型的不规则钻孔

红色虚线代表完美圆形的钻孔形态，蓝色实线代表圆形钻孔变形后的形式a—粗糙；b—冲蚀；c—键槽；d—崩落

Figure  6.  Four typical irregular cross sections of a deep borehole

(a) Roughness; (b) Washout; (c)Key seat; (d) BreakoutThe red dashed line represents the perfectly circular borehole shape, while the blue solid line represents the deformed shape of the circular borehole.

图  7  微小震震源机制解联合应力多边形反演地应力场

NF—正断层；SS—走滑断层；RF—逆断层；k_max和k_min—最大水平侧压力系数、最小水平侧压力系数；R_max，min—最大、最小差应力比

Figure  7.  Inversion of the in-situ stress field from focal mechanism solutions of micro-earthquakes combined with stress polygons

NF–normal fault; SS–strike-slip fault; RF–reverse fault; k_max and k_min–maximum and minimum horizontal pressure coefficients; R_{max, min}–maximum and minimum differential stress ratios

图  8  基于数据驱动的人工智能方法（ML/NNP/Intelligent Anti-Analysis）工作原理图

Figure  8.  Working principle flow chart of the data-driven artificial intelligence method (ML/NNP/Intelligent Anti-Analysis)