Study On The Characteristics And Genetic Mechanism Of Typical Ground Fissures In Beijing Plain

North China is a high incidence area of ground fissures,which has a serious impact on urban development and people's production and life.Beijing as the capital of China,after the reform and opening up in the past 30 years,resulting in the rapid expansion of population influx into the city of Beijing,The extensive use of water resources,water resources shortage in the supply situation,extraction of groundwater resources increased year by year,land subsidence intensified,resulting in formation of subsidence center,the ground fissures of significantly strengthened,become the important geological problems of development planning of Beijing city.The formation and expansion of cracks will not only lead to the transformation of surface,ground subsidence and other secondary geological disasters,will bring damage to roads,bridges,pipelines,buildings and other infrastructure,so the research on crack formation mechanism has very important practical significance and engineering.Based on the distribution and development characteristics of the ground fissures in Beijing plain,the paper studies the types of cracks in Beijing as well as the specific distribution and genetic mechanism of the Huangzhuang-Gaoliying fissures.The main research contents and results are as follows:(1)Through the data collection and reading literature,find out the natural condition of Beijing City,topography,lithology,geological structure,hydrogeological conditions and frequent geological disasters,based on this situation,determine the crack distribution and development of Beijing city.Comprehensive analysis shows that the Beijing plain ground fissure advantage in NE direction,strong activity of ground fissure and fracture belt are concomitant;distribution in the plain areas of Beijing ground fissures have obvious regional characteristics,it is divided into 6 regional distribution of earth fissure.The strongest activity of Beijing ground fissures is Huangzhuang-Gaoliying fissures induced by Huangzhuang-Gaoliying fault fracture zone,followed by Shunyi district and Beixiaoying fissures caused by Shunyi-Liangxiang fault leading.Those two fissures are all belonging to the active fault caused by excessive pumping cracks caused by pumping cracks.Based on this,an article ?the distribution and development of ground fissures in Beijing? published in the ?Journal of engineering geology?.(2)An in-depth study of the typical crack Huangzhuang-Gaoliying fissures,analysis the hazard and development characteristics,at the same timeborehole sampling in Huangzhuang-Gaoliying fissures to do laboratory test including density,moisture content,shear strength and shear strength test.Huangzhuang-Gaoliying fissures developed along the Huangzhuang-Gaoliying crack,through the test record we can find the available Viscosity-sand interbedding.In this Viscosity-sand interbedding,because sand has the higher cohesive,so the consolidation velocity of sand and clay is different in the process of pumping.Therefore,in the process of pumping,the consolidation velocity of sand and clay is different.The upper and lower plates are prone to differential settlement.(3)By using the finite difference software Flac3 D create the fault plane and fault body through model test,and as aid of the simulation about the bedrock movement during Huangzhuang-Gaoliying cracks concealed period,the role of tectonic movement and water seepage in the formation of ground fissures is analyzed.Through the numerical simulation,it can be seen that the cracks on both sides of the hidden fault gradually spread upward to the surface,then extend to both sides due to the expansion of water seepage.The seepage of water has a great effect on the expansion of the surface rupture.Through the numerical simulation of the hidden fault period,it can be seen that the existence of pre-existing faults can't be ignored.