河间构造地裂缝应力场二维剖面模型研究

Study on two-dimensional profile model of stress field of ground fissures in Hejian structure

华北平原是我国地裂缝发育较为密集的地区,河北沧州河间地裂缝具有典型构造影响特征。为分析沧州河间地裂缝发育特征、成因机制,通过求解平面应力问题的有限单元方法反演了沧州河间区域构造应力场,确定了最大主应力场和最大剪应力集中区,从而探索分析构造地裂缝的潜在危险区,建立了地裂缝二维剖面模型,计算分析河间地区区域构造应力场及区域应力集中区与地裂缝的对应关系。研究了二维状态下区域构造应力场的总体特征和规律以及活动断裂对地裂缝的成生、扩展和发育分布的控制关系。分析认为,河间地区地裂缝是由下伏基底延展变形及随之产生的断裂活动提供内动力使应力集中区域发育,具有构造型地裂缝的典型发育特征,是河间地裂缝形成及发展的主要因素。

The North China Plain is a region with dense distribution of ground fissures in China,and there are typical tectonic characteristics of Hejian ground fissures in Cangzhou,Hebei Province. In order to analyze the development characteristics and genetic mechanism of the Hejian fissure,the finite element method of solving the plane stress problem is used to reverse the tectonic stress field in Hejian. Consequently,the maximum principal stress field and the maximum shear stress concentration area are identified,thus to analyze the potential dangerous zone of tectonic fissure,and establish the two-dimensional profile model of ground fissure. The corresponding relationship between regional tectonic stress field and regional stress concentration area and the ground fissure in Hejian area is calculated and analyzed. The general characteristics and regularity of regional tectonic stress field under two-dimensional condition and the controlling relation of genetics,expansion and development distribution of active faults to ground fissures are studied. It is concluded that Hejian ground fissures,featuring typical tectonic fissures,are caused by stress concentration region development powered by the internal dynamic stress resulting from the extension deformation of the underlying basement and its subsequent tectonic fractures.