The Comparison And Analysis Of Monitoring And Prediction Of High Fill Subgrade Settlement After Construction

China has a vast territory,so the problems encountered in the construction of highway varies a lot.But the high embankment settlement is one of the common problems in subgrade engineering,which is not only related with the roadbed compaction degree and original subgrade slope,but also be related with the geological conditions and the nature of the filler,design specifications,construction equipment,etc.The main forms of deformation and failure of the high fill subgrade are listed as follows: the uneven settlement of the roadbed(the overall settlement of the embankment and the destruction of the local structure layer),the cracking of the road surface,and the collapse of the slope and so on.In view of this,for preventing the failure caused by settlement of high fill embankment effectively,it is necessary to research the high embankment projects in Gansu Province and settlement characteristics,to carry out the high fill subgrade settlement monitoring,and to do numerical analysis about the influential factors of embankment settlement.Based on domestic and international research,by means of single point settlement gauge and FLAC3 D finite element software,detailed study of treatment methods,the settlement prediction model,and settlement factors of soft soil foundation in high embankment engineering of subgrade settlement was fulfilled.The specific works and results are listed as follows:1.This paper started from the theoretical perspective,analysis of loss of deformation mechanism of failure analysis of soft soil subgrade,and introduces the present commonly used for soft soil subgrade treatment method;secondly the composition of soil ingredients into consideration,analysis of soft soil compression and lateral deformation,then analyze the main deformation characteristics;finally,according to the characteristics of soft the soil in the area of engineering,using engineering method analysis of soft soil treatment and the corresponding method and principle.2.Settlement monitoring points and settlement magnetic rings are placed in the high fill subgrade,which means the single point settlement sensors are buried in road shoulders and passing lane.Single point settlement gauges have been used for in-situ fill subgrade settlement monitoring for one year for each measuring point.Based on the data measured in site,through learning and exploring the mechanism of subgrade settlement,the settlement deformation law of fill is analyzed.3.According to the measured settlement monitoring data,the Origin software(Origin8.5)was used to fit the settlement of the High Fill Subgrade after construction.Thus,the four settlement prediction models were established.Comparing the measured value and the predicted value,the prediction accuracy of each prediction model(correlation coefficient R2)is calculated and compared.A new combination model is proposed from the results: Exponent-Hyperbola Model.On the basis of the least square method,the weight coefficient of the model is determined by the program Matlab2012 B.4.Based on field settlement monitoring,combining with the finite difference software FLAC3 D,the influences of different filling height,different slope and different fillers on the settlement of high fill subgrade are analyzed.Based on the simulation rule and the software Origin(Origin8.5),the expression of subgrade slope and horizontal displacement and the total settlement of subgrade are fitted,which can provide some guidance for the construction of high fill engineering.5.Based on the foundation settlement problem of numerical analysis of high embankment and the high fill embankment settlement monitoring data from the fourth section of Lan-Yong first class highway,the results show that the morphologies of two curves are same,and the actual subgrade construction process can be clearly reflected.So the ultimate settlement of high embankment can be accurately predicted and guidance for practical engineering is provided.