Impacts And Solutions Of The Regional Land Subsidence To The Subgrade Of(Beijing-Shanghai)High-Speed Railway

Land subsidence is an environmental geological phenomenon with regional ground elevation decreasing slowiy caused by the compressibility of soil on the crust surface.The Beijing-Shanghai high speed railway is a passenger railway with busier passenger and freightage transportation and larger growth potential across the country and it is across the region where the Chinese socio-economic develops actively.Most areas along the railway exist regional land subsidence in different degrees and lead to a series of problems affecting the safe and reliable operation of the train.As a result,we should on one hand carry out researches on the influencing factors to the regional land subsidence and settlement pattern characteristics to find out the factors and characteristics which affect regional subsidence,and on the other hand,develop researches about the impacts of regional subsidence to the engineering of high speed railway subgrade with the theories of regional subsidence,and analyse the rules and degree.Then launch relevant engineering measures researches.This paper analysed and investigated the characteristics of the regional subsidence and the impacts on the engineering of high speed railway subgrade.and proposed relevant controlling measures combining with Beijing-Shanghai high speed railway.The main results are as follows:1. By material investigation and theoretical analysis.this paper investigated the settlemented distribution,characteristics,formation mechanism and development trend of major subsidence areas along the Beijing-Shanghai high speed railway and the research status of mathematical models caused by groundwater withdrawal comprehensively.And analysed the deposition model,characteristics and mian influencing factors of sandy soil and clay layer by analogue simulation.Then proposed the characteristics and influencing factors of land subsidence in the two key areas——Tianjin-Dezhou and Changzhou-Shanghai high speed railway.2. Based on relevant theoretical calculation with data monitored in the field of Beijing-Shanghai high speed railway.this paper analysed the impacts on regional even and uneven settlement to the engineering of (Beijing-Shanghai) high speed railway subgrade respectively.and evaluated the degree of various impacts. Furthermore,taking engineering cases along the railway as research objects,simulating calculation to the subgrade settlement of Beijing-Shanghai high speed railway caused by shallow groundwater exploitation was carried out and analysed the influence models and rules of the engineering of high speed railway subgrade owing to shallow groundwater.3. This paper proposed the corresponding engineering measures based on the origins,characteristics and impacts on the engineering of high speed railway subgrade,which mainly includ foundation consolidation during construction period,automatic monitoring system for land subsidence in time of operational period,grouting and relevant controlling measures for groundwater exploitation.