Test Study On The Laws Of Post-construction Settlement Of Loess-filled High Embankment

With the rapid development of economy, the need of high grade highwayand other infrastructure construction increase, more and more highways need toconstruct in mountain area. In the northwest of China, because of the restrictionand influence of natural conditions and geographical distribution, the emergenceof a large number of loess-filled high embankment for highway constructionin mountain area. For the high filled embankment, the domestic and foreignresearch mainly focuses on theoretical research, numerical simulation,inversion，etc; For the filler Loess， researches customarily focused on thelaboratory soil test and simulation test. These methods have many limitations inpractical engineering application.In this paper, in-situ subsidence monitoring was made on the basis of aloess filled high embankment project at Taihang Road Engineering Yan Jiafengsections in Taiyuan city east central of Shanxi rovince,laboratory test of loesswas combined with as well. Then the paper carried out the following research:1During a long-term in situ monitoring of actual project for one year, some conclusions were obtained:(1) the settlement of fillers is the main body oftotal; settlement after construction of embankment was mainly formed withunfinished consolidation settlement and creep, the settlement was influenced bythe vehicle load and frost heaving and thaw settlement of seasonal frozen soil.(2) each layer of the embankment subsided with time to present the stagegrowth, and tended to be stable after240days. In late-stage settlementobservation, the same section subsides differently, the west side subsides mostand then the middle and then the east side.(3) the filling height is one of theimportant factors that influencing the high embankment settlement afterconstruction, the smaller filling height is, the smaller total settlement is, and thesmaller the proportion of the foundation in the total settlement is; there is linearcorrelation between filling height and the average settlement rate.(4) the terrainis another important factor for embankment settlement after construction, thesettlement after constrction of filling located in the groove place is less than it inthe gentle terrain.2Regression analysis and curve fitting were made for high filledembankment data, based on the measured data of high filled settlement. Thensome conclusions was known that:there is a logarithm relationship with the timeand settlement of embankment after construction, the formula couldbe“.”. Long-term settlement after-construction can be predictedwith that formula,and “μ”was associated with the properties of fillers and theway they filled,“μ” can value0.15%in this type of project. 3The method of artificial excavation was used in the high filled sectionsto take the filling loess and undisturbed loess as two types of soil samples. Thetwo types of loess were used to make soil test respectively in laboratory. Someconclusions were drawn that:(1) the compactness and density of loess wasincreased after dynamic compaction,and the mechanical properties of the soilwas improved.(2) the compression coefficientof undisturbed loess is greaterthan the filling loess, and the compressibility of loess decreased significantlyafter backfill compaction.(3)the compaction of soil samples have beenimproved to a certain extent after compaction, the proposed was made that themoisture content of filler would be better control in12%~14%whenconstruction.