Soft Soil Embankment Consolidation Settlement Characteristics Of Jiangmifeng-Huangsongdian First-class Highway

Abstract: This dissertation analyzes the soft soil groundsedimentation in k121+750 mileage in Jiang-Huang first-classhighway segment. The research involves field geological surveyand sampling, indoor soil test analyses , test data collation,parametric confirmation of sedimentation distortion,consolidationsettlement computational analysis and special engineering treatmentmeasure. The article analyzed and summarized the k121+750mileage in Jiang-Huang highway segment soft soil ground--turf soiland silt soil engineering geology properties, and sedimentationdeformation characteristics. Special engineering treatmentmeasure's improving effect for such kind of soft ground wasdiscussed, in the hope of provide suggestions to engineeringconstruction. First, regional as well as route engineering geological conditionwere depicted. This segment is a transitional region lies in Jilinprovince middle plain area eastward mountainous area. It belongs toCathaysian second order uplift belt. The magnitude of topologyfluctuation is increasing gradually, most the lithology which the routego through are YanShan Group, HuaLiXi period granite. The routepasses through regions mainly for drag turf soil, silt soil, low liquidlimit clay, without landslide, collapse, debris flow and some othernatural hazards. The climate the route passes through mostly is eastnortheast upland wetness monsoon climate, dry and windy in spring,torrid and rainy in summer, cool and temperature change great inautumn, lengthy while frigidity in winter, annual temperature isaround 5 degrees, annual precipitation about 600-800mm, focusedMostly on July to AugustSecond,engineering geology characteristic soil test analyses wascarried out aiming at k121+750 segment soft ground strata, includingphysical, mechanics, chemistry, water-physical property test andchronological age and architectural feature analyses etc, Naturaldensity of turf soil is relatively small, ranged from1.07g/cm3~1.14g/cm3 ,while that for the silt soil is around1.85g/cm3 ,the water content of turf is above 200%, that for the silt isabout 35%. The particle unit weight of the turf, which is between1.65-1.75, is smaller than that of the general soft soil because of theuncompleted decomposed plant fiber, which for the silt is about 2.37.The coefficient of compressibility for turf soil is over 2MPa-1, initialvoid ratio is over 3, 5-6 times that of silt soil, the cohesive of turf issmaller than that of silt, while the inner friction angle is going theother way around, according to compression test and shear test.Both the ignition loss and organic content are over 50% for turf soil,the Ph index indicate its weak acidic formation environment, the 14Cindex tells its 2000-3000 age from now. The ignition loss and organiccontent for silt soil are less than 10%, and formed 10,000 years ago.The coefficient of permeability indicates the irregular distribution ofthe plant fiber, and anisotropy. In this paper, it is simplified intodifference in horizontal and vertical directions;conclusion was thatthe coefficient of the permeability decline with the seepage pressure.The representative element of the turf soil is framed by uncompleteddecomposed plant fiber and filling inside the humus and mineralcolloid. The connectivity between the void is well developed. There isan increasing trendy in natural density and particle unit weight, whilea decline trendy in water content, organic content, ignition loss, voidratio, and PH index when the soil becomes from turf to silt along withdepth.The paper introduced briefly both home and abroad researchsituation for soft soil embankment sedimentation recently. Hereby thepaper presented its own research techniques and fundamentalassumptions. Combining engineering practice the paper analyzedthe action the stack trapezoidal load bearing counter-press berms onthe field stress distribution, discussions mainly aiming at fivegeometrical property points. The stress declines gradually for point O,and increase from 0 to the maximum in the sandy layer and thendecreases for D. The stress displayed its peak in the axial line anddecline in the bilateral direction in a certain horizontal line. The articleadopts stress control condition Δp / p0≤ 0.2 and deformationcontrol condition Δ S n / ∑ Δ Si≤0.025 giving out compact layerthickness of 30 meter and 10 mete respectively, according topredecessors' engineering experience (Zhang ChengHou , DaiJiQun,etc),as well as comprehensively consideration strataconfiguration characteristic, taken compact layers thickness in 10meter.In the precondition of the above-mentioned theories andfundamental assumptions, the article analyzes the highway softground natural consolidation settling characteristics of the studysection, soft soil layer in loading early days sedimentation rateaggrandize swiftly, although its thickness only occupies compactlayer's thickness 24%,less than 1/3 of the compact layer thickness,its displacement, 42.167cm, accounts for 90% of the total settlementwhich is 44.113cm. It tells that soft soil layer sedimentation is ofimportance. Road embankment soft soil layer immediatesettlement,9.69cm, of each characteristic point occupy totalsettlement,42.17cm, 20 % approximately, secondary consolidatesettlement occupy less than 10%approximately ,the rest 70% mainlyfor consolidation settlement.The paper analyzed treated embankment sedimentation in wellchannel by adopting finite element method;embankment settlementcharacteristics in each filling level were studied. In untreated area thesettlement is higher than that of well channel treated area. A "V"shape settlement curve occurs in each representative element, whichis quite clear near the symmetrical axial of the road embankment, thedifference mitigated with the shape of the embankment. There is aslightly up-swell out the scope of the load action area.The article brings up representative volume body penetrationmodel with which consider this kind of well channel treatmentmeasure sedimentation, transformation characteristic analyze bytime approximately as plastic drain board, mainly based on the samepervious course in these two models. Judging from the consolidationangle , treated soft soil ground's consolidation rate increasesignificantly, nearly 1 year needed for consolidated completely for theuntreated 2.4 meters soft ground, while with engineering treatment, itneeds 3 months for basically completely consolidation, the main pointis in well channel which filled water permeability materials for softground supplying favorable pervious course. Simultaneouslymountain skin stones and underlay sands also play a vital acting.Some conclusions and suggests were arrived at, the aim is atoffering supervise and use for subsequent engineering, also offeringseveral contents for future study, in regard to particularity soft groundtreatment design, as well as different kinds of theory in particularityengineering condition adjustment.