中國臨海公路路基沉降模型預測與分析(1)

1、山東交通學院英文科技資料翻譯Topic：Analysis and model prediction of subgrade settlement for Linhai highway in China題目：中國臨海公路路基沉降模型預測與分析 院 部：交通土建工程學 專 業(yè)： 土木工程 班 級： 土升141 學 號： 140714150 姓 名： 李玉萍 指導教師： 左珅 Analysis and model prediction of subgrade settlement for Linhai highway in ChinaGao Lei, Zhou Qiu-yue, Yu Xiang-j

2、uan, Chen Zhi-hui,School of Civil Engineering and Transportation, Hohai University, Nanjing,210098, ChinaABSTRACTLinhai highway is the fundamental and support key project of national coastal development strategy implemented by Jiangsu Province, China, which is also the largest highway in the highway

3、 construction history of Jiangsu. In order to ensure the safety and stability of the road, the rules of subgrade settlement in Linhai highway is studied. The subgrade settlement observation work is made based on the section of Sheyang in Linhai highway. By analysis of the observed data, the roadbeds

4、ettlement canbe divided into four stages:occurrence,development,stability and limitation with time Hyperbolic.model, exponential curve model, Logistic model and Gompertz model are applied to predictthe settlement of three typical sections in Sheyang project. The differences betweenthe measured value

5、s and the four different prediction modelsvalue are analyzed. Gompertz settlement predictions model is useful for the settlement prediction of Sheyang project.KEYWORDS: subgrade settlement; settlement prediction; hyperbolic model; exponential curve model; Logistic model; Gompertz modelINTRODUCTIONTh

6、e soft soil has the characteristics of high compressibility, high water content, low strength and poor permeability, so when the road is constructed on the coastal soft soil areas, it will produce greater subgrade settlement easily. That will lead to subgrade failure, pavement cracking, bridge bump

7、and other phenomena, which affects the flatness of the road, driving speed and road safety. In order ot ensurethe security and stabilityof soft soil subgrade, subgradesettlement observations should be carried out, the studies of softsoil subgrade settlement deformation rule will be pay more attentio

8、n, the subgradesettlement calculation and prediction methods will be perfect, the reliability and prediction accuracy of settlement calculation will be improved, the use of roads function and service will life enhance, reduce maintenance cost, produce good economic and social benefits.Linhai highway

9、 construction in Jiangsu Province is the largest longest,mileage and the most technologically sophisticated road, close to the beach,from north to south, through Lianyungang, Yancheng and Nantong three cities of the coastal Jiangsu. It serves a population of 15 million with a total length of 526 km

10、and a total investment of 3 billion US dollars. It has a very important significance that its construction drives industrial development in the coastal areas, urban construction, feature configuration, and the concentration of population, and promotes coastal development and large open. The subgrade

11、 construction and operation period of settlement deformation is crucial for guiding the project construction highway construction, the scientific computing and predict of subgrade settlement deformation is a very important to study the subgrade settlement issue. In order deformation ofLinhai highway

12、, guiding construction and controlling post-construction settlement more effectively, Sheyang segment of Linhai highway is used for example in this paper. The subgrade is located at Sheyang land-sea interaction and sediment accumulation soft soil area. Aiming at the actual situation of this project

13、that Sheyang subgrade passes through the complex geological conditions of the soft soil area, the subgrade settlement observation and predictions carried out based on the actual situation of this project that Sheyang subgrade passes through the complex geological conditions of the soft soil area.OBS

14、ERVATION OF SUBGRADE SETTLEMENTThree typical section K096+450, K118+350, K136+817 in Sheyang segment of Linhai Highway for example are used in this paper. The curves of measured subgrade settlement are shown in Figure 1(a)、(b)、(c).Figure 1: Measured settlement of three sectionsFigure 1 shows that, i

15、n the early development ofsubgrade settlement theload increases, subgrade settlement increases almost linearly At Full load,variations of the subgrade cumulative settlement become smoother overtime,and the settlement tends to stability. Finallythe cumulativesettlement of three sections K096+450、K118

16、+350、K136+817 tendto 103mm、105mm、95mm respectively. In the initial stage of loading,monthly settlement rate is higher. The first month after loading,the settlement of section K096+450、K118+350、K136+817are 13mm、8mm、12mm respectively. With the loading time increasing, the monthly settlement rate decre

17、ases wavily. Two months later at full load, monthly settlement rate of three sections is controlled within 2mm, and the subgrade becomes stabile. The K096 +450 for example, the development of subgrade settlement process can be approximated divided into four stages: occurrence, development, stability

18、 and limitation. Among them, occurrence is the initial loading stage, at this time the soil is still in the elastic stage, so that its too late to exclude the porewater. The load makes the soil instantaneous shear deformation occurring, and as the load increases the settlement increases almost linea

19、rly; development stage: with the embankment height increasing, that is increasing load and the time of growth, subgrade soil pore water gradually drained, excess pore water pressure gradually dissipated, the soil is compacted to produce compression deformation, and gradually goes into plastic state.

20、 With the continuous development of the plastic zone, the settling velocity of the subgrade is also accelerating; stability stage: when filling height does not change, that is the load no longer increasing, the pore water pressureis dissipated completely, then the consolidation process has not been

21、fully completed, and the soil skeleton viscous creep begins to appear. Over time subgrade settlement will continue to increase, but the settlement rate is gradually reduced; Limitation stage: with the decreasing speed, ultimately subgrade settlement value becomes stable.PREDICTION METHODS OF SUBGRAD

22、ESETTLEMENTNow, the subgrade settlement prediction methods can be divided into three categories: (1) theory method based on Terzaghi consolidation; (2) combined with soil constitutive model, using numerical analysis method based on Biot consolidation theory; (3) extrapolating sedimentation and time

23、to develop relations according to the measured settlement monitoring data, which is curve fitting method based on the empirical formula 8. Because the complexity of the subgrade settlement affecting factors and difficulty of the constitutive model parameter selection with other issues, the settlemen

24、t calculation value based on the theory of consolidation and the measured value are often quite different. Therefore, how to derive the late settlement law of soft soil subgrade from the early settlement data is very important for engineering applications value 9. In order to learn the variation of

25、the Linhai highway subgrade settlement, curve fitting model prediction method isused to study subgrade settlement. The subgrade settlement of curve fitting predicting method usually assumes that subgrade settlement can meet certain mathematical model and use monitoring data to determine the unknown

26、parameters in the model to predict the future settlement and final settlement. There are two main type of mathematical models, first is the mathematical models of predicting the whole process: the growth curve model,which are Logistic Curves, Gompertz curve and Weibull curvegenerally; second is math

27、ematical models of predicting settlement after that is represented by hyperbolic model, exponential model. Because curve fitting method is simple,so it has been widely used in practice, with which the short-term settlement prediction method can often be satisfied with the result. Its shortcomings ar

28、e: site selection have greater randomness, as we select different points in S-t curve to try, there are certain differences between the final prediction results, which means relatively large affects by human factors.Hyperbolic methodNow hyperbolic method is more commonly used for prediction in found

29、ation settlement, which the subgrade settlement and time is approximately hyperbolic relationship. It is entirely based on experience curve fitting. yBfitting curve of settlement and time, some moment settlement or final settlement of subgrade is derived. The general formula is:St= S0+(t-t0)/p+q(t-t

30、0)In the formula: t0 represents the inflection point time of settlement curve; S0 corresponds settlement at to; St corresponds settlement at some point; p、q are undetermined parameters.Exponential curve methodExponential curve method is based on the disposable loading Terzaghi one-dimensional consol

31、idation theory of penetration, assumingsoil average degree of consolidation Ut as exponential function of time t. According tothe relationships of degree of consolidation and settlement, it shows that:St=-exp(-t) In the formula:St corresponds settlement at time t; is the final settlement; 、are undet

32、ermined parameters.Logistic curve methodLogistic model curve is also called poisson curve or reasoning curve. In the prediction of time series, it is expressed as:Slt=a1+bexp(-ct)-1Slt=abcexp(-ct)(1+bexp(-ct)-2Slt=abc2exp(-ct)1+bexp(-ct)-3bexp(-ct)-1In the formula: Slt is the subgrade settlement at

33、time t;a、b、c are undetermined parameters and they are plus, where a is the final settlement.Logisticl model reflects the immediate settlement; the limit of subsidence occurred: when t, Slt=a(1+b)；Slt>0，that is to say the settlement increases monotonically; By the second derivative formula availab

34、le, there is a point of inflection, the settlement curve presents 'S' type, the ratio of inflection point of settlement and final settlement is 0.37 invariantly.Gompertz curve methodThe expression of Gompertz model curve in time series prediction and its derivative expression are respectivel

35、y:Sgt=kexp-mexp(-nt)Sgt=kmnexp-mexp(-nt)-ntSgt=km2nexp-mexp(-nt)-ntmexp(-nt)-1In the formula:Sgt is the subgrade settlement at time t; km、n are undetermined parameters and they are plus, where k is the final settlement.According to the features of their models, it shows that Gompertz model character

36、istics are similar to Logisticl model, but theratio of inflection point of settlementand final settlement is 0.5.ANALYSIS OF SUBSIDENCE PREDICTION METHODCurve fittingThe parameters and correlation coefficients which invert hyperbolic model、Exponential curve model、Logistic model、Gompertz model based

37、on the site monitoring data are shown in table 1.Table 1 Parameters and correlation coefficients the methods of curve fittingAfter analyzing Table 1, it shows that the section K096+450, K118+350, K136+817 are applied the four different ways of hyperbolic model, exponential curve model, Logistic mode

38、l, Gompertz model to predict settlement and the effects are better, because correlation coefficients are all above 0.96.Results of prediction method When the exponential model and hyperbolic model is used, the actually working conditions are usually simplified into a disposable loading, then we usua

39、lly choose constant load on start time as settlement calculation 0 time t0. The starting point of the fitted curve in the stable period is selected, it will have better fitting with actual settlement curve, so that the resulting error will be smaller. Worthy of note, while applying the exponential m

40、odel and hyperbolic model ,we cant take advantage of settlement sample observed in construction period, but can only use the sample after settlement curve inflection point that are effective. More settlement monitoring data can result to a better settlement after prediction. Engineering examples pro

41、ve that predicted subgrade final settlement which uses hyperbolic method is generally larger than the actual value. Logistic and Gompertz curve method in the whole process can predict the load time from the start, but they require settling observed sample with adequate construction or before inflect

42、ion points, otherwise it would be difficult to get better results.The predictions and measured values of the three sections K096+450, K118+350, K136+817 obtained by hyperbolic model, exponential curve model, Logistic model, Gompertz model are shown in Table 2,3,4 respectively. Table 2: Comparison be

43、tween measured and predicted settlement values atK096+450Table 3: Comparison between measured and predicted settlement values atK118+35中國臨海公路路基沉降模型預測與分析高蕾,周秋悅,于湘娟,陳志輝, 中國，南京, 河海大學, 土木工程與交通運輸學院，210098。摘 要臨海高速公路是江蘇省實施國家沿海發(fā)展戰(zhàn)略的基礎和支撐，也是江蘇公路建設史上最大的一級公路。為了保證公路的安全穩(wěn)定，對臨海高速公路路基沉降規(guī)律進行了研究。臨海公路射陽段路基沉降觀測工作。通過對觀測

44、數(shù)據(jù)的分析，路基沉降可分為四個階段：發(fā)生、發(fā)展，隨著時間的推移，雙曲線模型和時效穩(wěn)定性、指數(shù)曲線模型，Logistic模型和Gompertz模型應用于預測射陽項目的三個典型斷面的沉降。測量值和四個不同的預測模型值之間的差異進行了分析。Gompertz沉降預測模型對射陽工程的沉降預測。 。關鍵詞:路基沉降,沉降預測;雙曲模型;指數(shù)曲線模型;物流模式;龔帕茲模型介 紹土具有高壓縮性、高含水量、低的特點 ，強度和滲透性差，所以當?shù)缆繁粯嬙煸谘睾＼浲恋貐^(qū)，它會產生更大的路基沉降容易。這將導致路基破壞，路面裂縫、橋梁橋頭等現(xiàn)象，影響路面平整度，行車速度和道路安全。為了確保安全和軟土路基的穩(wěn)定性，路基沉降

45、觀測應開展研究軟土路基沉降變形規(guī)律將被更多關注，路基沉降計算及預測方法進行了完善，可靠性和沉降計算預測精度得到提高，道路的功能和使用壽命使用將大大提高，降低了維修成本，產生良好的經濟效益和社會效益。臨海省江蘇公路建設規(guī)模最大、里程最長、最長、最先進的公路，靠近海灘，從北到南，通過連云港、鹽城和南通三城市江蘇沿海。它是一個人口1500萬，總長度526公里，總投資30億美元。它具有非常重要的意義，它的建設帶動產業(yè)發(fā)展在沿海地區(qū)，城市建設，特征配置，和濃度人口，促進沿海發(fā)展和大開放。路基施工沉降變形手術期是指導工程建設的關鍵公路建設，科學計算和路基沉降預測變形是一個非常重要的問題。為了研究路基沉降臨

46、海公路變形，指導施工和施工控制更有效的解決，臨海公路射陽段為例在這紙。路基位于射陽市陸海相互作用和泥沙淤積軟土區(qū)。針對射陽路基工程的實際情況通過軟土地區(qū)的復雜地質條件，路基沉降根據(jù)本項目的實際情況，進行了觀測和預測射陽路基經過軟土地區(qū)的復雜地質條件。路基沉降觀測三個典型斷面k096 + 450，K136 K118350、817在臨海射陽段本文采用高速路。實測路基沉降曲線 圖1（1），（1），（2）。圖1顯示，在路基沉降發(fā)展的早期，這種負荷的增加，路基沉降的增加幾乎林早在滿負荷，路基的累積沉降變化變得平滑，隨著時間的推移，和沉降趨于穩(wěn)定。最后三部分k096 + 450、K136、K1183508

47、17的累積沉降往往比較、105mm、95mm分別。在加載初始階段，月沉降率較高。加載后的第一個月，第k096 +、K136 450、K118350817的沉降、13mm、8mm 12mm。隨著加載時間的增加，每月結算率減小波浪。兩個月后，在滿負荷時，三個月結算率控制在2mm，與路基變得穩(wěn)定k096 + 450為例，對路基沉降的發(fā)展過程可近似分為四個階段：發(fā)生、發(fā)展、穩(wěn)定和限制。其中，發(fā)生初始加載階段，此時土壤仍處于彈性階段，因此排除孔隙水太晚了。荷載使土體瞬時剪切變形發(fā)生，隨著荷載的增加，沉降量幾乎呈線性增加；發(fā)展階段：隨著路堤高度的增加，荷載和生長時間增加，路基土體孔隙水逐漸排水，超孔隙水壓

48、力逐漸消散，土體產生壓縮變形，逐漸進入塑性狀態(tài)。與塑性區(qū)的不斷發(fā)展，對路基的沉降速度也在加快；穩(wěn)定期：當填土高度不發(fā)生變化，即載荷不再增加，孔隙水壓力消散完全，然后整理過程還沒有完全完成，和土骨架的粘性蠕變開始出現(xiàn)。隨著時間的推移，路基沉降量將繼續(xù)增加，但沉降速率逐漸減?。粫r效階段：隨著速度的減小，路基沉降值趨于穩(wěn)定。路基沉降預測方法研究現(xiàn)在，路基沉降預測方法可以分為三類：（1）基于太沙基固結理論方法；（2）結合土的本構模型，采用基于Biot固結理論的數(shù)值分析方法；（3）將沉淀時間根據(jù)實測沉降監(jiān)測數(shù)據(jù)的發(fā)展關系，這是基于在經驗公式 8 曲線擬合方法。由于路基沉降的復雜性、影響因素和本構模型參數(shù)選擇難度等問題，基于固結理論的沉降計算值與實測值往往是比較不同的。因此，如何從早期的沉降數(shù)據(jù)中推導出軟土路基的后期沉降規(guī)律，對工程應用價值的研究具有重要意義。為了了解臨海公路路基沉降的變化，曲線擬合模型的預測方法用于研究路基沉降。曲線擬合法的路基沉降預測方法通常假定路基沉降可以滿足一定的