【摘要】 岩芯非弹性应变恢复法是近年来发展起来的比较经济有效的深部地应力测量方法,汶川5.12地震后,我国大陆首次将该方法应用于汶川地震断裂带科学钻的地应力测量.本文简述了该方法的原理、计算方法和汶川地震科学钻一号孔的典型结果.给出了一号孔在所测深度之处的三个主应力的大小和方向.三个主应力中,最大主应力和中间主应力近于水平,最小主应力近于直立.最大主应力方向为北西.在746m深度,三个主应力的大小为25.2MPa,21.5MPa,18.5MPa.这种应力状态可使龙门山断层产生逆冲兼右行走滑运动,与汶川5.12地震的断层运动一致.该方法得到的结果与震源机制解及其他地应力测量方法得到的结果吻合.测量结果表明,非弹性应变恢复法具有较大的实用价值.特别是在较大深度的钻孔和地层较破碎的复杂地质条件下,应力解除法、水压致裂法等难以实施时,此方法仍有可能获得较可靠的地应力数据,适应性更强.更多还原

【Abstract】 The principle and calculation procedures for a lower cost and effective core-based stress measurement technique called anelastic strain recovery(ASR) technique are described.And then an example of its application to the hole-1 of Wenchuan Earthquake Fault Scientific Drilling Project(WFSD-1) is shown.Three principal stress magnitudes and directions of the hole-1 at the tested depth were determined.The maximum σ1 and middle principal stress σ2 are nearly horizontal,and the minimum principal stress σ3 is nearly vertical.The azimuth of the maximum principal stress is NW.At the vertical depth of 746 meters,the magnitude is 25.2 MPa for σ1,21.5 MPa for σ2,and 18.5 MPa for σ3.This stress state can be interpreted as the same stress regime to make Longmen Shan fault to generate thrust and dextral strike-slip movement,which is consistent with fault movement of Wenchuan 5.12 Earthquake.The results obtained by ASR can be compared with that by focal mechanism solutions and other stress measurement methods.The example shows that,ASR method has great practical value.Especially in the larger drilling depth and complex geology conditions,stress relief method and hydraulic fracturing method can hardly be implemented,while ASR can obtain reliable data with good adaptability.更多还原