Effect Of Land Subsidence From Groundwater Pumping On Deformation Of Track Structure

With the strategy of the introduction,digestion,absorption and re-innovation changing into the going-out strategy,the high-speed rail industry has made remarkable achievements in China.However,the growing problem of land subsidence has been a major limitation to the rapid development of high-speed rail industry,Many scholars have been studying the effect of land subsidence on the safe operation of high-speed railway by numerical simulation method,but the theoretical studies about the effect of land subsidence caused by groundwater exploitation and excavation dewatering on deformations of track are relatively sufficient.Therefore,in this paper,a series of basic theory was conducted on the hot topics,which can lay the foundation for further research in future.In the process of groundwater exploitation and excavation dewatering,waterproof curtain is seldom employed in an open area.And many excavation shapes and distribution of pumping wells are close to circles.So we analyzed the regularity of land subsidence caused by pumping groundwater without waterproof Curtain in circular or nearly circular excavation.Based on the layered approach in vertical and the differential thought in horizontal,the governing partial differential equations were proposed for the soil layer in cylindrical coordinate with the assumption that the relation of soil deformation and the load is in one dimension and linear.Combining the functions of drawdown,we can get the approximate analytical solution.It shows that the relationship between soil subsidence and the logarithm of distance is linear,that iss=c₁-c₂lnr.Because of the complexity of track structure and necessity of simplified model in theoretical research,it is fundamental to study the deformation response of a beam affected by land subsidence.Therefore,a track structure can be considered as a concrete beam with a moderate distance,and the governing line of deflection differential equation based on the theory of beam on elastic foundation can be obtained too.Using the finite different method,we can get the numerical solution.Meanwhile,by writing programs with MATLAB,we can make the results visible.It indicates that with the development of land subsidence,the beam initially declines along with the land surface,and then the middle of the beam separates from the land surface,finally the void extends to the side of beam.In addition,we study the effect of parameters variation in land subsidence curve on void length by programs.Finally,a three-dimensional model of fluid-solid coupling was established by ABAQUS,in the meantime,the conclusions above were verified.