| The ground fissure has become the main type of geological disaster that currently affects the construction of the Longyao area in Hebei and the production and life of the masses.In order to grasp the specific development and distribution of ground fissures and the width of disasters caused by ground fissure activities,it provides a scientific basis for local engineering construction and disaster prevention.Based on the investigation of the field geological survey and the trenching project,combined with the indoor physical simulation and numerical analysis,the research on the development characteristics and the influence width was carried out,and the following main results and conclusions were obtained:1.Field survey results show that the total length of the Longyao ground fissure is about 35 km,which can be divided into east and west sections.Among them,the western section is near EW and is about 20 km long.It is distributed in the area from Zhoucun to Xidianzi Village,and it is characterized by a positive left-lateral strike and slip.Where the crack passes,the surface forms an east-west steep ridge with obvious north high and low south,the relative vertical dislocation amplitude is up to 30 cm,the maximum horizontal opening distance of the ground fissure is 20 cm,the maximum slip distance of the slip is 10cm;the east section is near the direction of NE60°.About 15 km long,is distributed in the area of Dongdian Macun to Maoerzhai Village.The ground fissures are intermittently exposed and are characterized by a right-handed right-lateral slip.The vertical displacement of the ground fissure is not obvious,the maximum horizontal opening distance is 30 cm,and the maximum slip distance of the slip is 6cm.The trench revealing and drilling engineering shows that the Longyao ground fissure zone has a multi-branch,multi-period activity characteristic on the section,and the fault distance of the main fracture surface increases with the depth.2.According to the regional tectonic setting,the geometric relationship between active faults and ground fissures,and the similarity of motion characteristics,and the relationship between them and the ground fissures induced by seismic activity,The Longyao ground fissure is controlled by the Neiqiu-Julu fault.The ground fissure spreads and expands along the Neiqiu-Julu fault.Under the influence of the sudden impact of an earthquake or concentrated precipitation,the fissure penetrates the surface,The over-exploitation of groundwater and farmland irrigation further expand the scale of the ground fissure.The development of the Longyao ground fissure is closely related to the regional tectonic activity,and the fault activity is the main controlling factor of the development of the ground fissure.The excessive exploitation of groundwater is the predisposing factor.The genetic mechanism can be summarized as the model of “fracture-controlled ground fissure activity + rapid occurrence of surface fissures induced by earthquake or concentrated precipitation + pumping to promote the accelerated expansion of fissures”.3.Field investigations show that the impact width of the Longyao ground fissure activity is 74 m,the maximum is 46 m on the upper plate and 28 m on the lower plate.Among them,the main deformation zone of the ground fissure activity zone is 0~15m on the upper plate and 0~11m on the lower plate;the micro-deformation zone is 15~46m on the upper plate and 11~28m on the lower plate.4.Physical simulation experiments show that the width of the main deformation zone of the ground fissure activity is 19.5~30m,the maximum is 12.18~17.49 m,and the maximum is 7.32~12.51 m.5.The numerical simulation results show that the impact width of the ground fissure activity is 78 m,the maximum on the upper plate is 50 m,and the maximum on the lower plate is 28 m.Among them,the main deformation zone of the ground fissure activity zone is 0~18m on the upper plate and 0~10m on the lower plate;the micro-deformation zone is 18~50m on the upper plate and 10~28m on the lower plate.6.According to the field investigation,combined with the indoor physical simulation and numerical analysis results,refer to "Xi'an Ground Crack Site Investigation and Engineering Design Regulations"(DBJ61-6-2006,J10821-2006),the width of the impact zone of the Longyao ground fissure is 74 m,and the influence width of the upper plate is large.The maximum influence width of the upper plate is 46 m,and the maximum influence width of the lower plate is 28 m.According to the active belt of the Longyao ground fissure,the deformation affected zone can be divided into the main deformation zone and the micro-deformation zone according to the degree of deformation.Among them,the influence width of the upper plate of the main deformation zone is 0~15m,the influence width of the lower plate is 0~11m;the influence width of the upper deformation zone is 15~46m,and the influence width of the lower plate is 11~28m;the influence of the building The degree is negatively correlated with the distance from the center of the ground fissure activity belt,that is,the damage degree and damage area of the building,which increases significantly with the decrease of the distance between the center of the building and the ground fissure activity belt;the building damage in the main deformation zone Seriously,the degree of damage to buildings beyond this range is drastically reduced,especially after leaving the micro-deformation zone. |
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