• 文章目录 •

### 三峡工程库首区及狮子口重力滑动构造系统的构造应力场研究

1. 中国地质大学
• 收稿日期:1995-06-20 修回日期:1995-06-20 出版日期:1995-12-20 发布日期:1995-12-20

### STRESS FIELD OF THE EASTERN AREA OF THE YANGTZE GORGE RESERVOIR AND THE SHIZIKOU GRAVITATIONAL GLIDING SYSTEM

Song Lihao, Yang Sennan, Wu shuren, Ren Jianye

1. China University of Geosciences, Wuhan 430074
• Received:1995-06-20 Revised:1995-06-20 Online:1995-12-20 Published:1995-12-20

Abstract: Systematic Study on the regional Stress field in the eastern area of the Yangtze Gorge Reservoir and the local stress for the Shizikou gravitational gliding system has been carried out by stereographic and statistical analyses on numerous conjugate joints, slickensides, styolites and micostructures including fractures with their veinlets, pressure solution seams and tectonic lenses. The regional principal compressive stress (σ1 )is determined to be horizontal with two stress groups directed S-N and NEE75°－SWW250°respectively. Based upon quantitative analysis on regional paleostress field by rock rupture criterion combined with e-twin ratio and dislocation density methods, the differential stress during S-N compressive deformation is estimated at 200Mpa, whereas that during NEE75°-SWW250°compression at 80-120MPa. The cross-cutting relationships between conjugate joints, fault striae, microstructures and regional faults and folds indicate that the S-N-and NEE75°-SWW250°oriented compressions were active during the main stages of the Yanshanian and the Himalayan movements respectively. It is shown by finite-element simulation that the Yanshanian differential stress in the southern area has higher strength than that in the northern section In contrast, no significant spacial variations in differential stress have been found for the Himalayan compression. Stereographic and statistical analyses on minor structures inside the Shizikou gravitational gliding system reveal that the stress field of that system is generally characterized by front-edge compression and hack-edge extension with gently dipping σ3 towards NE SW and moderately dipping to nearly vertical σ1 at the back edge, and gently dipping σ1 towards NE-SW and moderately dipping to nearly verticalσ3 at the front edge. The strss field of the Shizikou gravitational gliding system is defined to be the local one superimposed on the regional field yielded by the main stage of the Yanshanian movement．