Studies On Subgrade Settlement Monitoring And Prevention Technology In Jun Ma Chang-minle Of Lanzhou-Xingjiang High-speed Railway

The Lanzhou-Xinjiang High-speed Railway was opened and operated in December 2014.After investigation,as of January 2016,roadbed deformations and diseases have occurred in various degrees since the operation of some sections.Among them,settlement diseases have concentrated on the military horse farm to the folk music section.The 41 settlement sites of ballastless track line,the displacement of some settlement point beyond the adjustment of the fastener,the subgrade settlement has threatened the normal speed and safety of the train operation,therefore,urgent need to research and control measures to ensure the normal operation of the railway.This paper investigates in detail the physical and geographical conditions(topography and geomorphology),meteorological conditions(temperature,rainfall(snow)),engineering geology and hydrogeological conditions,subgrade forms,foundation treatment methods,and landfilling of the subgrade settlements from the Junmachang to Minle Section.(or excavation)heights,subgrade fillings,moisture content,subgrade protection and drainage facilities;analysis of dynamic inspections and static inspections of deformation data since the operation of key disease paragraphs;analysis of the subgrade under load and moisture changes through numerical simulation Stress field,displacement field,etc.The research content and research results of this paper are as follows:? There were 41 settlements in this section,which corresponded to the same amount of settlement in both the upper and lower levels.A total of 16 places with a total settlement of more than 26 mm.The subgrade at the subsidence is in the form of embankment.Most of the embankment is between 3 and 6m in height,and individual is over 6m.There is no form of road.Four settlements occurred in the transitional period.There is a 0.5m to 5m thick sandy loess distributed on the surface of the foundation subsidence section.Each section is uneven in thickness and has non-self-weight collapsibility or collapsibility.The foundation treatment measures include heavy hammer compaction and impact grinding.Pressure based.The drainage measures in each settlement section are: drainage ditches on the high side of the roadbed,and natural protection roads on both sides;the annual average rainfall above100 mm above the Junmachang-Mangle area exceeds 450mm;the basement loess layer of the settlement section is detected.The moisture content was between 15% and 28%.Therefore,due to increased rainfall and poor drainage,the bearing capacity of the sandy loess layer is reduced due to the accumulation of subsurface water,and the increase in compression is the main reason for the subsidence of the subgrade.According to the analysis of the actual and subgrade settlement of the Lanzhou-Xinjiang high-speed railway from the horse farm to the folk music,the grouting reinforcement of the lower part of the roadbed and the basement,the addition of protection and the reinforcement of the drainage plan shall be adopted to treat subsidence and sinking diseases;the specific measures shall be adopted for the lower part of the roadbed and the base.Slurry reinforcement,additional retaining walls and closed surface back pressure protection pathways,additional drainage ditch and seepage blind ditch.After the remediation work was completed,roadbed deformation detection was performed through a combination of dynamic and static inspections.The results showed that the high-and low-wavelength waveforms of the dynamic inspections had high overall coincidence and good waveforms;the dynamic inspection peaks changed little and remained stable overall;the static leveling measurements included individual section deformations.The overall roadbed of the volatility tends to be stable,and settlement settlement has a good effect.Numerical simulation analysis shows that under normal circumstances,the subgrade settlement is not large enough to meet the post-construction settlement control requirements for high-speed railway subgrade;however,if rain and water infiltrate the road bed subgrade and sandy loess foundation,the strength and rigidity will be reduced.As a result,the subgrade settlement increases;when the base thickness of sandy loess increases,the subgrade settlement increases;the subgrade settlement increases significantly under rainwater infiltration;the grouting reinforcement increases the strength and stiffness of the subgrade soil and decreases The subgrade settlement can play a good role in controlling the subgrade settlement and disease,so it can be used to improve the settlement of high-speed railway roadbed.Combined with the analysis of the causes of the deformation of the foundation of Lanzhou-Xinjiang high-speed railway and the experience of settlement adjustment,the treatment of the loess foundation should be strengthened when constructing the high-speed railway embankment in the cold regions of the west,and measures such as heavy hammer compaction and impact roller compaction should not be adopted;And compaction;do a good job in subgrade protection and subgrade waterproof and drainage,and strengthen the elimination of surface water and groundwater affecting the stability of subgrade.