摘要
为了探究非等压应力场下充填钻孔主应力差分布规律并评估其稳定性,采用理论分析、数值模拟和工程实例方法,分析了不同钻孔直径、垂直主应力σV、最大水平主应力σH、水平主应力比λ′下钻孔主应力差和塑性区的分布规律。结果表明:平行于最小水平主应力σh方向的钻孔内壁处均是主应力差最大区域;建立了不同λ′下钻孔主应力差最大位置计算模型,可为预测不同围岩深度下钻孔破裂发展方位提供理论指导;钻孔主应力差分布的数值模拟结果与理论计算结果基本一致,验证了理论分析的正确性。当围岩参数一定时,不同钻孔直径、σH、σV下主应力差分布均为类“8”字形,不同λ′下主应力差的分布形态转变历程为圆形→椭圆形→类“8”字形;围岩塑性区先出现在主应力差最大方位,即平行σh方向,后向平行σH方向发展;塑性区的存在可能导致围岩失稳,并使得钻孔横截面由圆形向椭圆形发展。以国外某铜矿充填钻孔为例,分析了围岩主应力差和塑性区分布规律,并计算了钻孔加固的最小泥浆压力,可为提高钻孔稳定性提供工程指导。
To explore the distribution law of principal stress difference(PSD)and evaluate its stability for backfilling boreholes in unequal stress field,the distribution laws of principal stress difference and plastic zone for borehole at various diameters,vertical principal stressσV,maximum horizontal principal stressσH,and horizontal principal stress ratioλ′were analyzed through theoretical analysis,numerical simulation and engineering case methods.The results show that the area of maximum PSD lies in the inwall of the borehole parallel to the direction of minimum horizontal principal stressσh.A calculation model was established for the position of maximum PSD,which can provide theoretical guidance for predicting the development direction of borehole fracture at different depths of surrounding rock.The numerical simulation results of the distribution of PSD in the borehole are consistent with the theoretical calculation results,verifying the correctness of the theoretical analysis.When the rock parameters are constant,the distribution of PSD is like an“8”shape at various borehole diameters,σH andσV,while the transition of the PSD shape at variousλ′is from round→ellipse→similar“8”shape.The plastic deformation zone in the surrounding rock initially emerges in the direction with the largest PSD,that is,the direction ofσh,and subsequently progresses in the direction ofσH.The presence of the plastic zone may lead to instability in the surrounding rock and result in the transition of the borehole cross-section from round to ellipse.Taking the backfilling boreholes from a foreign copper mine as an example,the distribution law of PSD plastic zone in the surrounding rock was analyzed.Additionally,the minimum mud pressure for boreholes was calculated.This analysis can provide engineering guidance for improving borehole stability.
作者
刘春康
王洪江
李浩
LIU Chunkang;WANG Hongjiang;LI Hao(Key Laboratory of Ministry of Education for High-efficient Mining and Safety of Metal Mines University of Science and Technology Beijing,Beijing 100083,China;School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China)
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2024年第5期1743-1756,共14页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(51834001,52130404)。
关键词
充填钻孔
非等压应力场
主应力差
稳定性
最小泥浆压力
backfilling borehole
unequal stress field
principal stress difference(PSD)
stability
minimum mud pressure
