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三维应力场中不同空间角下钻孔稳定性研究

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为了探究不同空间角对钻孔稳定性的影响,基于单轴和三轴试验探究了不同钻孔角度的岩体力学特性,建立了三维应力场中不同空间角度钻孔力学计算模型,基于欧拉变换建立了地应力坐标系、空间直角坐标系和钻孔柱坐标系之间的相互关系,结合Mohr-Coulomb强度准则的三维表达式推导出三维应力环境中不同空间角下钻孔围岩的塑性区边界隐式方程,寻求了描述钻孔周围应力分布特征的综合应力指标偏应力张量第二不变量J2,通过变化井斜角和方位角研究了不同方案下的钻孔孔周偏应力J2大小及形态分布特征,分析了不同空间角下的塑性区分布范围及形态.建立了偏应力J2与塑性区之间的相互对应关系,揭示了钻孔围岩的变形破坏本质,并基于理论分析提出了工程应用指导.研究结果表明:不同空间角下钻孔周边产生不同程度的应力集中,导致岩体的强度特性与声发射特征存在较大差异;不同井斜角和方位角条件下,钻孔孔周各处的偏应力集中程度存在较大差异,井斜角和方位角的改变对孔周J2最大集中位置所在的角度具有重要影响,不同方案下的J2应力扩展角与钻孔周边的J2最大值所对应的极角完全一致,且J2应力偏转角基本稳定在38°～42°;不同井斜角和方位角条件下钻孔塑性区破坏程度、破坏扩展最大尺寸以及破坏形态存在较大差异;偏应力J2等值线形态演化规律与塑性区形态演化规律具有一致性,在不同空间角下J2及塑性区形态均呈现"蝶形单翼扩展"的非对称扩展特征,且不同方案下塑性区最大破坏位置与偏应力J2最大集中位置所在的角度差值为3°～5°.研究结果对煤层瓦斯抽采和钻孔卸压具有重要的理论意义和参考价值.
Study on borehole stability under different spatial angles in three-dimensional stress field
In order to explore the influence of different spatial angles on the stability of bore-holes,the mechanical properties of rock masses with different borehole angles were investigated based on uniaxial and triaxial tests.The mechanical calculation models of boreholes with different spatial angles in three-dimensional stress field were established.Based on the Euler transformation,the relationship between the in-situ stress coordinate system,the spatial rectangular coordinate system and the borehole column coordinate system was estab-lished.Combined with the three-dimensional expression form of Mohr-Coulomb strength crite-rion,the implicit equation of plastic zone boundary of borehole surrounding rock under different spatial angles in three-dimensional stress environment was derived.The second invari-ant J 2 of the deviatoric stress tensor of the comprehensive stress index describing the stress distribution characteristics around the borehole was sought.By changing the inclination angle and azimuth angle,the size and shape distribution characteristics of the borehole circumferential deviatoric stress J2 under different schemes were studied,and the distribution range and shape of the plastic zone under different spatial angles were analyzed.The corre-sponding relationship between deviatoric stress J 2 and plastic zone was established,and the es-sence of deformation and failure of surrounding rock was revealed.Based on the theoretical a-nalysis,the engineering application guidance was put forward.The results show that there are different degrees of stress concentration around the borehole under different spatial angles,which leads to great differences in the strength characteristics and acoustic emission character-istics of rock mass.Under different inclination angles and azimuth angles,there are great differences in the degree of deviatoric stress concentration around the borehole.The change of inclination angle and azimuth angle has an important influence on the angle of the maximum concentration position of J 2 around the borehole.The J 2 stress expansion angle under different schemes is completely consistent with the polar angle corresponding to the maximum J 2 around the borehole,and the J2 stress deflection angle is basically stable at 38°-42°.There are great differences in the degree of damage,the maximum size of damage expansion and the fail-ure mode of the plastic zone of the borehole under different well inclination angles and azimuth angles.The morphological evolution law of the deviatoric stress J2 isoline is consistent with the morphological evolution law of the plastic zone.At different spatial angles J 2 and the plastic zone morphology,the asymmetric expansion characteristics of'butterfly single wing expansion'are presented,and the angle difference between the maximum failure position of the plastic zone and the maximum concentration position of the deviatoric stress J 2 under dif-ferent schemes is 3°-5°.The research results have important theoretical significance and refer-ence value for coal seam gas extraction and borehole pressure relief.

borehole stress distributionthe stability of surrounding rockplastic zonethe second invariant of deviatoric stress J2coordinate transformationdrilling inclination

刘洪涛、韩子俊、韩洲、郭林峰、韩向阳、刘勤裕、陈子晗、张荣光

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中国矿业大学(北京)能源与矿业学院,北京 100083

煤炭行业巷道支护与围岩控制工程研究中心,北京 100083

中国煤炭工业协会,北京 100013

钻孔应力分布 围岩稳定性 塑性区 偏应力第二不变量J2 坐标转换 钻孔倾角

国家自然科学基金联合基金项目国家自然科学基金项目中央高校基本科研业务费(中国矿业大学(北京)博士研究生拔尖创新人才培育基金)

U22A2016552004289BBJ2024001

2024

10.13247/j.cnki.jcumt.20240072

中国矿业大学学报
中国矿业大学

中国矿业大学学报

CSTPCD北大核心
影响因子：1.83
ISSN：1000-1964
年,卷(期)：2024.53(5)