青藏高原腹地现今地应力测量与应力状态研究

The recent state of stress in the central Qinghai-Tibet Plateau according to in-situ stress measurements

青藏高原腹地现今构造活动强烈,为了解强烈构造活动下的应力背景,我们在五道梁、风火山、雁石坪和安多不同构造部位的四个测点采用压磁应力解除法进行了现场应力实测工作,测量深度12～2 0m .测量结果表明,最大主应力方向总体为北东向,与地质、地震以及大地测量等方面的研究成果基本吻合;最大主应力量值为3 6～6 8MPa(安多测点除外) ,与其他地区测量结果相比,属于中等偏高;安多测点最大主应力方向为北西西向,最大主应力量值为8 1MPa,与其他测点有较大差别,反映了板块缝合带附近现今应力状态的复杂性.

Qinghai-Tibet Plateau is most intensive in tectonic activity. In order to understand the recent state of stress, ground stress surveys were carried out at different structural positions and depths and in different rocks using piezomagnetic stress gauge overcoring method in the central Qinghai-Tibet Plateau. The results of stress measurements indicate that the direction of maximum principal stress is NE. This agrees with the result of the study of geology and earthquake and deformation. The values of maximum principal stress are 3.6～6.8MPa which are high as compared with those obtained elsewhere in China from a viewpoint of regional stress analysis. But the value and the direction of Amdo stress measurement site are different with those of other sites. The direction of maximum principal stress is NWW. The value of maximum principal stress is 8.1 MPa. This also indicates that the recent state of stress is complex near the plate suture zone. These results of stress measurements can provide important basic data as well for study of fault activity and geological hazard and engineering stability evaluation in Qinghai-Tibet railway, as also for continental dynamic study.