煤矿井下地质构造对地应力分布的影响

采用小孔径水压致裂地应力测量装置,在典型的急倾斜、特厚煤层矿区——甘肃华亭矿区的大型向斜构造附近进行14个测站地应力测量,以分析向斜构造不同部位的地应力变化。实测数据表明:华亭煤矿、砚北煤矿井下构造应力占绝对优势;在向斜翼部,水平应力较小;在向斜轴部,水平应力急剧增加,增加幅度远大于垂直应力;向斜构造对矿区地应力分布产生严重影响。基于山西晋城矿区的地应力实测数据,分析断层对地应力值与方向的影响。断层附近某些区域水平应力有所减小,大型断层会引起最大水平主应力方向的扭转。在实测数据基础上,采用FLAC3D数值计算软件,分析华亭矿区大型向斜构造周围地应力场分布,并与地应力实测数据进行对比。将地应力实测与数值模拟有机结合,是全面了解煤矿井下地应力场分布特征的有效途径。

EFFECT OF GEOLOGICAL STRUCTURES ON IN-SITU STRESS DISTRIBUTION IN UNDERGROUND COAL MINES

Using the hydraulic fracturing in-situ stress testing rig with small boreholes,stress measurements were carried out at 14 sites near the large syncline structure in the Huating coal mining area,where steep and extremely thick coal seams are typical in China,to analyze the in-situ stress variation in different parts.Measured data point out that the tectonic stress predominates in the Huating coal mine and Yanbei coal mine.Along the wing of the syncline structure,the horizontal stress is comparatively small;however,the horizontal stress near the axis of the syncline structure increases far more quickly than the vertical stress;and the syncline structure greatly influences the stress distribution in the coal mining area.Based on the in-situ stress data measured in the Jincheng coal mining areas in Shanxi Province,the effects of faults on the magnitude and orientation of in-situ stresses were analyzed.Some areas near the faults show the lower horizontal stress than the normal level,and large faults may alter the orientation of the maximum horizontal principal stress.On the basis of measured in-situ stresses,numerical models were built to analyze the stress distribution around the large syncline structure in the Huating coal mining area by means of FLAC3D code,and the numerical results were compared with the measured ones.The combination of in-situ stress measurement and numerical simulation will provide an effective approach to fully understand the characteristics of in-situ stress field in underground coal mines.