【摘要】 为获得矿山深部开采和设计所需要的地应力基础资料,中国地质科学院地质力学研究所于2012—2013年在冀东地区滦县一乐亭大断裂附近开展了3个钻孔水压致裂的应力测量工作,钻孔孔深为500 1000 m.地应力测量结果初步揭示了研究区地壳浅表层现今地应力的分布规律.实测结果表明:现今研究区域应力场优势方向为NW70°;3个测点的最大剪切应力与平均应力的比值u_m范围为0.24-0.48,平均值分别为0.30,0.40和0.30,均未达到地壳应力摩擦极限状态(u_m=0.6)的水平,而唐山大地震后不久研究区浅层获得的u_m则较大,个别点大于0.6,平均值为0.44,表明唐山大地震后研究区应力积累程度较低,应力释放较为充分;依据断层摩擦准则及拜尔利定律可知,研究区发生较大地震活动的危险性较低.更多还原

【Abstract】 In order to obtain the required basic information of crustal stress for exploitation and design of deepmine,Institute of Geomechanics of Chinese Academy of Geological Sciences carried out hydrofracturing in-situ stress measurements in three boreholes near Luanxian and Laoting fault in east of Hebei area successively in 2012 and 2013.The three boreholes are between 500—1000m in depth.The results of the stress measurements preliminarily revealed the distribution regularity of current in-situ stress in shallow crust of study area.The measured data show that the dominant direction of regional stress field is NW70°;the ratio of the maximum shear stress to the average stress of the three boreholes is in the range of 0.24—0.48 and the average values of the ratio are0.30,0.40,0.30 for the three boreholes,which are less than 0.6,that is the friction limit state of earth’s crust stress.But the ratio got shortly after the Tangshan M_s7.8 earthquake is large,few of them are greater than 0.6,and the average value is 0.44,which reveals that the stress accumulation degree in the study area was low and stress has been completely released.According to the friction criterion of faults and Byerlee law,the risk of a large seismic activity in the study area is in low risk.更多还原