Activity structure and crustal stability in Beijing-Tianjin-Hebei collaborative development zone

Beijing-Tianjin-Hebei Collaborative Development Zone(BTHCDZ)is one of the strategic development zones in eastern China, and is also the active tectonic region in North China.Based on its strong neotectonic activity, many active faults and frequent earthquakes, it is sure that there are potential geological safety hazards.Based on the results of the investigation and research on Zhangjiakou area, Xiong'an New Area and neighboring area, Beijing area and its key tectonic sites, and combined with the comprehensive analysis of the existing research results, the features of the geometry, kinematics and dynamics of the main active fracture and as well as the engineering geology and geohazards are systematicly analyzed in the BTHCDZ.And then the assessment of crustal stability based on the spatial analysis function of ArcGIS platform in the BTHCDZ has been completed.The results show that: There are Xingtai-Hejian-Tangshan and Shijiazhuang-Tongzhou two NNE-trending, and Zhangjiakou-Bohai one NWW-trending activity tectonic belts existed in the BTHCDZ, and within the three belts, there are 11 Holocene fractures, 16 Late Pleistocene fractures and 23 major Quaternary fractures; The direction of the maximum horizontal principal stress of present tectonic stress field in the north and southeast regions of Hebei Province is near EW, while the southern section of the east edge of Taihangshan is NNE direction and the northern section is NW direction; The overall performance of NNE active fault belt is clockwise normal activity with SE tendency, while NWW active fault belt has obvious activity from Late Pleistocene, and the overall performance is anti-clockwise normal activity with SW tendency; The general crustal stability of the BTHCDZ is general good for the planning and construction of important towns and major projects, and the unstable zones and sub-unstable areas are mainly distributed in Xingtai, Tangshan, Yanhuai Basin and the Holocene active fault zone.The research results will provide geological support for the macro-development strategy of the BTHCDZ.