Analysis Of Crustal Stress Field And Regional Crust Stability Nearby Pingwu

In-situ stress, as one of the internal force factors that drive numerous geological disasters, is significant in the evaluation of regional crustal stability. In order to study the geostress distribution and the regional crustal stability in the northern region of earthquake fault zone after Wenchuan earthquake, the region of Jiangyou, Beichuan and Pingwu across Longmen Mountain fault zones is chosen as research area of this paper, according to the materials of focal mechanism solutions and experimental results of stress measurement data before and after the earthquake of Wenchuan, and inversed the stress field in the regions, as a basis for the analysis of the distribution of stress field in the study area, faults and geological rock group introduced on the stress field, assessed regional crustal stability combined with geological characteristics what is significant for this study.The results showed that the stress has been released in this region after Wenchuan earthquake, but the overall level is still more than 4Mpa, which is an adverse effect of regional crustal stability; in the study area, the principal stress direction of the stress field changed NW to NE after the earthquake that was compared with the measurement results before earthquake; the current stress field of the study area showedσ_hmax>σ_hmin>σ-υ, what was proved the characteristics of thrust fault motion after the earthquake in the east of fault zone, the plate that is on north of the fault zone continue to move, strike-slip trend has weakened; the stress on both sides of the fault zone is often not continuous, indicating the fault barriered the transmission of the stress significantly; lithological characteristics affected the distribution of stress, the stress of hard rock would be greater than the weak rock generally; the stress on the composite parts of fault are often weakened, primarily because of the dominant role of shear stress, which is showed stress concentration in the direction of X, Y. Based on fuzzy mathematics theory, the results of regional crustal stability evaluation showed that the main instability zones were always along the faults. In addition to a Small partial regions in Jiangyou, and a small area between the central fault zone and the behind fault zone of Longmen Moutain are the stable regional crustal stability zones, the other parts of the regional crustal stability were poor, were not appeared relatively stable areas throughout the study area.Although due to the limitations of the data and objective factors in the current experimental technology of hydraulic fracturing, some areas of the research results with the actual situation may be different, this paper studies the distribution of stress field and the results of regional crustal stability division that had some significance in selecting location for the major projects.