Study On Related Rules Of Regional Land Subsidence From Groundwater Withdrawl

Land subsidence from groundwater withdrawal has been a global geological hazard.At present,the methods of studying land subsidence include empirical model,the theoretical model,the numerical model for prediction and inversion and monitoring technique.These methods can be used to measure or calculate a certain point on the ground.However,there are none study on spatial geometry features and laws on land subsidence contours.Based on the linear law of s-lnr,a serious of related laws has been carried and proved by several measured data.These rules of land subsidence will help to understand the land subsidence and its development more deeply and help the transformation and application of remote sensing monitoring data.The rule of the ground subsidence funnel,that is,the circular settlement funnel has been verified to conform to the law of the linear relationship s-lnr.In addition to the circular subsidence funnel,a more common and regular funnel is ellipse subsidence funnel.Permeability coefficient anisotropy has a significant effect on the ground subsidence funnel from groundwater withdrawal.The anisotropy of permeability in the vertical plane affects the slope of the funnel surface.The anisotropy in the horizontal plane affects the shape of the ground subsidence funnel to tend to ellipse.In this paper,the mechanism of the elliptical distribution of the water level descending contours is proved to be a function of the elliptical surface.At the same time,the characteristics of the function are verified by the monitoring data at home and abroad.On the basis of linear s-lnr relation of land subsidence of single well pumping,equation of land subsidence from group wells pumping distributed as line and area were derived applying the method of integration.For the observation point far away from the center of group wells,after simplification the equations above,the result of formula reveal that the linear s-lnr relation was satisfied too.The result is proved by the monitoring data of 3 land subsidence from classical theoretical solutions,numerical solution and engineering example.Based on previous research findings,relationship between c1 and c2 was studied in this paper.The study helps to determine the values of c1 and c2 and further determine the subsidence value s for every distance.Compared with one-dimension linear s-lnr relation for regional land subsidence,the newly founded linear relation between c,and c2 in this paper reveals a two-dimension law for subsidence funnel,which interprets the characteristic of land subsidence more deeply.It has important theoretical significance and comprehensive applications in engineering.Using the concrete expression of c1 and c2,it was found that the constant c1 and c2 and pumping discharge Q accord to the linear equation.The rules were proved by measured data from literature.Furthermore,based on the above series of laws,the volume formula of circular and elliptical subsidence funnels is simply deduced applying mathematic theory,after simplification the equations,it was found that the volume of the circular subsidence funnel and pumping discharge accord to the linear equations.The finding of this paper is simple and applicable,and then provides reference and basis for future ground subsidence prediction and groundwater exploitation planning.