Abstract: The Bohai Sea, located in the northern part of North China, is an inland basin about 73 thousands km². Tectonically, it is one of the most active areas in eastern China since Late Tertiary. Meanwhile, it is also an area rich in oil and gas deposits. Previous studies have shown that faults and tectonic stress are important for oil and gas migration and accumulation. Based on the in-depth study on the tectonics of the Bohai Sea area and in the light of the geological and evolutional history, the authors simulate the stress field of the area using 2-D finite element method. In the simulation, the studied area is assumed as a rigid block that has been divided into 1347 finite elements, 1339 nodes. The tectonic field stress is calculated using SAP5 procedure. Some significant results are achieved. In light of the calculations and the evolutional history of the area, we firstly divide the Bohai sea tectonic stress field into four regions, namely the east Liaoning Bay, the central Bohai Sea, the east Bohai Sea and the west Bohai Sea. The stress characteristics are different in different regions, e.g. the central Bohai Sea has the maximum average normal stress value and shear stress value compared with other regions,while its minimum principal stress is lower. Secondly, the stress distribution of the whole study area shows that the faulting in the west is more intense than that in the east since Late Tertiary. The faults in the east Bohai Sea region have a higher degree of development and gaping along the Tanlu Fault belt, while in the middle Bohai Sea area, the faults have a low degree of displacement and development.

Key words: mathematical simulation, finite element model, stress field, Bohai Sea

摘要： 根据渤海海域的构造演化背景和地质构造特征建立了该区的二维地质模型,用二维有限元方法计算模拟了渤海海域现代构造应力场,获得了该区构造应力场的分布特征;同时,根据计算结果把渤海海域的构造应力场分为辽东湾、渤中、渤东和渤西等4个区域,并对这4个区域在构造应力场上的差异性进行了描述。从渤海海域整体的应力分布可以看出,该区新近纪以来的断裂活动总体水平上西部较东部强烈,海域东部沿郯庐断裂带仍有较高的断裂发育程度及断裂张开性,而海域中部地区的断层发育程度、活动位移均较低。

关键词: 数值模拟, 有限元, 应力场, 渤海海域