Study On The Mechanism Of Typical Fracture Clusters In The Middle Reaches Of The Yellow River Basin

The special geographical environment,complex geological conditions and frequent human activities in the middle reaches of the Yellow River Basin have led to the extensive development of ground fractures,and the concentrated clustering and extensive multiple effects of ground fractures are particularly typical,causing serious natural disasters.In this paper,based on in-depth research and field investigation,we systematically summarize the spatial and temporal distribution characteristics of ground fractures along the middle reaches of the Yellow River basin for the first time,and reveal the combined characteristics of planar spreading and profile structure,movement and activity behavior,and disaster damage forms of ground fracture clusters based on three typical clustering patterns;carry out a numerical simulation study on the evolution of ground fracture development under multi-factor conditions using FLAC3 D finite difference software to reproduce The study is intended to provide a theoretical basis for proposing ecological disaster mitigation and management measures from the perspective of mutual feedback mechanisms between fracture hazards and ecological and geological environment,which can contribute to disaster prevention and mitigation,habitat security,urban and rural planning and construction in the middle reaches of the Yellow River.The study can provide a scientific basis for disaster prevention and mitigation,habitat security,urban and rural planning and construction,as well as ecological protection and high-quality development of the river basin.The main conclusions of this paper are as follows:(1)Based on field investigation and extensive data collection,the spatial and temporal distribution characteristics of ground fracture development in the middle reaches of the Yellow River are systematically studied,and it is found that the spatial distribution has strong correlation with topography and geomorphology,active fractures,ground subsidence and seismic activities;three typical patterns of concentrated clusters of ground fractures in the transition zone of basin and mountains,basin fault blocks and large and medium-sized cities along the route are proposed,and their planar distribution pattern,three-dimensional rupture structure,The patterns of planar distribution,three-dimensional rupture structure,motion activity behavior and disaster damage are explained,and the activity and evolution characteristics of typical basin margin fractures are compared and analyzed in terms of development history time dimension.(2)A three-dimensional geological model was established by Rhino,and the numerical simulation of fracture development and evolution with different cluster patterns was carried out by FLAC3 D finite-difference software,and the cluster patterns of fractures in the transition zone of basin and mountain under the action of tectonic stress field,the fracture boundary and internal fractures under the action of mid-crustal flow spreading and fracture activity,and the fractures in the urban area under the action of building load and groundwater extraction were studied respectively.The development of urban fractures and the development process of fractures are compared and verified with the prototype fractures,and the simulation results are consistent.(3)Based on the characteristics and behaviors of ground fracture clusters in the middle reaches of the Yellow River,we analyzed the effects of various factors on the occurrence of ground fracture clusters based on the characteristics of deep dynamic structure,basin evolution mechanism,present-day tectonic stress field,relative motion of land masses,fracture activity mode,fracture activity intensity and seismic activity in the middle reaches of the Yellow River and the characteristics of soil tectonic stress change,groundwater extraction,loess wetting and surface water action in the area of ground fracture clusters.The influence and contribution of each factor on the occurrence of ground fracture clusters are analyzed,and the coupling mechanism of ground fracture clusters in the middle reaches of the Yellow River is discussed from the viewpoint of system integrity and dynamic equilibrium,and a preliminary decoupling theory is constructed.