The Study On Remediation Measures And Treatment Effect Of A Section Of Lanzhou-Xinjiang High Speed Railway Subgrade Settlementic

The Lanzhou-Xinjiang high-speed railway passes through areas such as the northwest loess region,alpine regions,Gobi and windy sand regions.The proportion of this line base is relatively large,and the design structure of the roadbed is diverse.There are many types of roadbed base soil including loess,expansive soil,red clay,mudstone,Gobi soil,etc,they have special engineering properties.Under some harsh natural conditions and under the action of vehicle loads,the roadbed will be deformed and deteriorated,which will adversely affect the smoothness of the track structure.This article relies on the settlement of the subgrade of the K2090+450~K2090+750 subgrade of the Lanzhou-Xinjiang high-speed railway,and analyzes the causes of the settlement from field survey data and monitoring data.The detailed introduction of the roadbed remediation measures and the effects of the remediation are carried out.Analytical research,finally using the finite element software PLAXIS to compare the vertical displacement and stress magnitude of different parts of the roadbed under different working conditions,put forward remediation proposals for the situation of the subgrade,and the research results have certain reference for similar projects.(1)Through on-site investigation and monitoring data analysis,it was found that the settlement of the subgrade was mainly due to the presence of sandy loess on the base of the roadbed.The sandy loess is a kind of foundation soil that is not easily compacted in the dry state and is easily compressed and deformed in contact with water.The micro-topography of the subgrade changes,causing the original surface runoff to change.After submerged in the rain,the subgrade fills and the subgrade soils are reduced in wetting and softening strength,causing subsidence of the subgrade.(2)According to the analysis of settlement and settlement of the roadbed in this section,a single slurry of sulphoaluminate cement injected into the lower part of the roadbed and the basement is used for reinforcement treatment;the grouting reinforcement of the site where the settlement occurs is performed by using the sleeve valve pipe grouting construction technology and grouting.During the process,level gauges were used to closely monitor the elevation changes of the grouting section.(3)After grouting reinforcement and remediation,subsidence deformation monitoring was performed on the subgrade,and a combination of dynamic monitoring and static monitoring was used.The analysis of the data measured by the monitoring results shows that the remediation effect is good.(4)Numerical calculation shows that under normal conditions,the subgrade settlement is not large enough to meet the post-construction settlement control requirements for high-speed railway subgrade.At the same time,the stress at each point in the subgrade bed is not large,and no excessive stress appears.If there is rain and other infiltrate,the strength of the subgrade filling body and the sandy loess base will be reduced,and the subgrade settlement will increase significantly with the subgrade bed surface stress;when the thickness of the sandy loess base increases,the subgrade subsidence and surface stress on the bed will also increase accordingly.The grouting reinforcement improves the strength and rigidity of the foundation soil,reduces the settlement of the roadbed and the surface stress of the subgrade bed,and can play a good role in controlling the roadbed diseases.Therefore,it can be used in the settlement of high-speed railway roadbed.(5)Combined with the remediation of subsidence and settlement of high-speed railway subgrade,it is concluded that under similar engineering conditions,the construction of new lines should be strengthened and the choice of subgrade filling should be strengthened;and the subgrade foundation due to the effect of water should be prevented.Settlement diseases should be based on the principle of adapting to local conditions and adopting scientific,reasonable,and perfect subgrade drainage and drainage measures according to the actual conditions of the actual worksite.After the subsidence and damage of the high-speed railway subgrade,grouting reinforcement measures can be taken to rectify the disease.