Analysis And Prevention Of The Influence Of Ground Subsidence Caused By Groundwater Exploitation On The South Shandong High-speed Railway

Land subsidence caused by over-exploitation of groundwater is a relatively common type of geological hazard,which is characterized by a long duration and a wide range of influence.At present,the land subsidence caused by large-scale groundwater resource overexploitation in my country mainly occurs in central and eastern provinces and regions such as Tianjin,Beijing,Shanghai,Jiangsu,Shandong,and Shanxi,China.The total land subsidence caused by the total land subsidence exceeds 200mm is about 80,000 km2.When constructing linear projects such as high-speed railways and underground oil pipelines in such areas,project safety is bound to be affected by ground subsidence,especially uneven settlement.Settlement control is very strict.The Heze-Qufu section of the Lunan high-speed railway,which is the main body of this study,starts from Qufu City in Jining City in the east,and to Mudan District in Heze City in the west.It is located in the alluvial plain of the Yellow River.After preliminary geological surveys,it is found that there are different levels of groundwater extraction along the line.The problem of land subsidence,especially near urban areas,has also appeared in the past 20 years,and has now developed into multiple settlement funnels of different sizes.Therefore,in order to evaluate the impact of groundwater extraction along the Lunan high-speed railway and provide a reliable basis for subsequent safe operations,it is of great significance to carry out quantitative analysis and research on the uneven ground settlement and its evolution characteristics along the Lunan high-speed railway.This paper takes the Heze-Qufu section of the South Shandong high-speed railway as an example,cross-fuses groundwater seepage theory and soil consolidation theory,establishes a groundwater numerical model and a three-dimensional fluid-solid coupling numerical model of land subsidence in the study area,and carries out quantitative evaluation of uneven land subsidence in the study area And research on the evolution of settlement.The established three-dimensional fluid-solid coupling numerical model of land subsidence is used to analyze and calculate the future development trend of uneven land subsidence along the high-speed railway under different groundwater exploitation scenarios,and evaluate and determine the relatively serious area of land subsidence in the line section.At the same time,from the perspective of settlement control,targeted settlement prevention measures are proposed,The main research work and conclusions are as follows:1.This article uses groundwater numerical simulation software GMS to create a deep groundwater numerical model to simulate the flow field in the process of groundwater exploitation.After identifying and verifying the model,a highly reliable numerical model is obtained,and finally the deep groundwater in the area is summarized The dynamic distribution law of the flow field:due to the large-scale development and utilization of deep groundwater,there has been a serious imbalance in supplementary extraction.The water level continues to drop,which changes the natural flow field in the study area and forms a large-scale groundwater level drop funnel,resulting in Groundwater flows from the surrounding area to the funnel area.2.Based on groundwater seepage theory and soil consolidation theory,the multiphysics analysis software COMSOL Multiphysics is used to establish a three-dimensional fluid-solid coupling numerical model of ground settlement along the South Shandong high-speed railway.After calibration with InSAR data and monitoring point data,the calibrated Numerical model,and in accordance with the existing mining methods,by comparing the development trend of the current groundwater mining in the next 20 years,reducing mining by 10%and reducing the subsidence of 30%mining,to predict the subsidence and subsidence rate under different working conditions.Change the value,and finally conclude that reducing groundwater extraction can effectively control the occurrence of land subsidence and slow down the rate of land subsidence.3.This article uses the curvature calculation method of the settlement curve along the line to quantitatively describe the uneven settlement by comparing the curvature of each point along the line.After comparing and calculating the curvatures under the three working conditions,it is found that reducing groundwater extraction can effectively reduce ground subsidence and curvature,and ensure the safety of line operation.