Regional characteristics and evolutionary trend prediction of land subsidence caused by groundwater over exploitation in North Shandong of the North China Plain

As an important part of ground subsidence in north China plain, the problem of land subsidence in North Shandong is becoming more and more serious. Boxing County was taken as the engineering background, the characteristics of dynamic distribution of groundwater and evolution of land subsidence in the study area was systematically analyzed based on the detailed hydrogeological and engineering geological data and the monitoring data of land subsidence over the years. A three-dimensional fluid-solid coupling numerical model of land subsidence was established by adopting the Biot's consolidation theory of porous media to reflect the development process of land subsidence and predict the subsidence evolution law under different groundwater extraction schemes. The results show that the decrease of shallow groundwater level in Boxing County is large in the south and small in the north, and an oval deep groundwater descend funnel is formed taking the urban area of Boxing County as center; three small land subsidence areas have gradually formed with the subsidence centers of Boxing county, Hubin town and Dianzi town, which have the tendency of interrelated expansion; the three-dimensional fluid-solid coupled numerical model of land subsidence in Boxing County is reasonable to reconstruct the development process of land subsidence in the study area, according to the prediction by simulation, the land subsidence will continue to grow at a relatively high rate in the next 10 years under the existing groundwater exploitation scheme, and the area with the accumulated subsidence exceeding 500mm will continue to expand, a 20% reduction in existing groundwater exploitation is a reasonable and effective way to slow down land subsidence hazards. © 2020, Science Press. All right reserved.