"water" Type Ground Fissure In Xi'an Region Paranormal Activity Analysis

The identified ground fissures in Xi'an run through the entire urban area of xi 'an,causing a lot of difficulties to the urban planning and construction of xi 'an and the utilization of land resources,as well as huge economic losses.Since the unreasonable exploitation of groundwater resources in the early stage of xi 'an city led to the abnormal activity of ground fissures in xi 'an,new fissures gradually emerged and the scope of disaster was continuously expanded,it is of great importance to understand the activity mechanism of ground fissures in xi 'an under pumping conditions to mitigate the occurrence of ground fissures and rationally utilize groundwater resources.Based on the existing field investigation data,this paper firstly summarizes the tectonic geological background of weihe basin and xi 'an area,and systematically summarizes the development,activity and disaster characteristics of ground fractures in xi 'an.Based on the bioreau consolidation theory and groundwater dynamics,this paper discusses the stress and strain in the stratum,the reason of differential subsidence and the characteristics of ground fissure activity when the confined water is extracted from the area with hidden underground fissures.In this paper,FLAC3 D finite difference numerical simulation software is used to simulate the influence of pumping underground confined water on ground fissure activity in Xi'an from different dip angles of buried ground fissures and different pumping modes.The main research results are as follows:(1)When the concealed ground fissure is in the condition of relative water isolation,the influence of its inclination and inclination on the area and shape of seepage area after pumping is the indirect cause of differential settlement,while the difference of permeability is the direct cause of differential settlement.(2)Under the condition of dead weight,differential subsidence will also be formed on both sides of the crack.No matter what the dip Angle of the crack is,the subsidence groove appears in the upper wall area,and the maximum subsidence value gradually increases with the increase of the dip Angle of the crack.(3)When pumping is carried out in the area with hidden fractures,it is assumed that the existence of hidden fractures will hinder the seepage of pore water to a certain extent,resulting in the discontinuous distribution of pore pressure in the ground fractures after pumping.As the pore water pressure changes the stress redistribution in the formation,the "steep" stress zone is located within a certain range near the ground fissure.The upper wall is a stress reduction zone and the lower wall is a stress enhancement zone.(4)In the process of pumping,the aquifer not only produces vertical displacement by releasing water in the vertical direction,but also accelerates the activity of ground fissures because the horizontal seepage of aquifer is larger than the vertical seepage.(4)In the process of pumping water,the aquifer will not only produce vertical displacement due to the release of water pressure in the vertical direction,but also accelerate the activity of ground fissures because the horizontal seepage of the aquifer is larger than that of the vertical seepage.(5)In combination with the actual pumping conditions,it is found that the upper wall settlement is always greater than the lower wall settlement no matter how much water is pumped or how long the pumping time is,when the upper wall and lower wall are simultaneously pumped,which is consistent with the characteristics of the surveyed ground fractures.