中国临海公路路基沉降模型预测与分析(1)

1、山东交通学院英文科技资料翻译Topic：Analysis and model prediction of subgrade settlement for Linhai highway in China题目：中国临海公路路基沉降模型预测与分析 院 部：交通土建工程学 专 业： 土木工程 班 级： 土升141 学 号： 140714150 姓 名： 李玉萍 指导教师： 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中国临海公路路基沉降模型预测与分析高蕾,周秋悦,于湘娟,陈志辉, 中国，南京, 河海大学, 土木工程与交通运输学院，210098。摘 要临海高速公路是江苏省实施国家沿海发展战略的基础和支撑，也是江苏公路建设史上最大的一级公路。为了保证公路的安全稳定，对临海高速公路路基沉降规律进行了研究。临海公路射阳段路基沉降观测工作。通过对观测

44、数据的分析，路基沉降可分为四个阶段：发生、发展，随着时间的推移，双曲线模型和时效稳定性、指数曲线模型，Logistic模型和Gompertz模型应用于预测射阳项目的三个典型断面的沉降。测量值和四个不同的预测模型值之间的差异进行了分析。Gompertz沉降预测模型对射阳工程的沉降预测。 。关键词:路基沉降,沉降预测;双曲模型;指数曲线模型;物流模式;龚帕兹模型介 绍土具有高压缩性、高含水量、低的特点 ，强度和渗透性差，所以当道路被构造在沿海软土地区，它会产生更大的路基沉降容易。这将导致路基破坏，路面裂缝、桥梁桥头等现象，影响路面平整度，行车速度和道路安全。为了确保安全和软土路基的稳定性，路基沉降

45、观测应开展研究软土路基沉降变形规律将被更多关注，路基沉降计算及预测方法进行了完善，可靠性和沉降计算预测精度得到提高，道路的功能和使用寿命使用将大大提高，降低了维修成本，产生良好的经济效益和社会效益。临海省江苏公路建设规模最大、里程最长、最长、最先进的公路，靠近海滩，从北到南，通过连云港、盐城和南通三城市江苏沿海。它是一个人口1500万，总长度526公里，总投资30亿美元。它具有非常重要的意义，它的建设带动产业发展在沿海地区，城市建设，特征配置，和浓度人口，促进沿海发展和大开放。路基施工沉降变形手术期是指导工程建设的关键公路建设，科学计算和路基沉降预测变形是一个非常重要的问题。为了研究路基沉降临

46、海公路变形，指导施工和施工控制更有效的解决，临海公路射阳段为例在这纸。路基位于射阳市陆海相互作用和泥沙淤积软土区。针对射阳路基工程的实际情况通过软土地区的复杂地质条件，路基沉降根据本项目的实际情况，进行了观测和预测射阳路基经过软土地区的复杂地质条件。路基沉降观测三个典型断面k096 + 450，K136 K118350、817在临海射阳段本文采用高速路。实测路基沉降曲线 图1（1），（1），（2）。图1显示，在路基沉降发展的早期，这种负荷的增加，路基沉降的增加几乎林早在满负荷，路基的累积沉降变化变得平滑，随着时间的推移，和沉降趋于稳定。最后三部分k096 + 450、K136、K1183508

47、17的累积沉降往往比较、105mm、95mm分别。在加载初始阶段，月沉降率较高。加载后的第一个月，第k096 +、K136 450、K118350817的沉降、13mm、8mm 12mm。随着加载时间的增加，每月结算率减小波浪。两个月后，在满负荷时，三个月结算率控制在2mm，与路基变得稳定k096 + 450为例，对路基沉降的发展过程可近似分为四个阶段：发生、发展、稳定和限制。其中，发生初始加载阶段，此时土壤仍处于弹性阶段，因此排除孔隙水太晚了。荷载使土体瞬时剪切变形发生，随着荷载的增加，沉降量几乎呈线性增加；发展阶段：随着路堤高度的增加，荷载和生长时间增加，路基土体孔隙水逐渐排水，超孔隙水压

48、力逐渐消散，土体产生压缩变形，逐渐进入塑性状态。与塑性区的不断发展，对路基的沉降速度也在加快；稳定期：当填土高度不发生变化，即载荷不再增加，孔隙水压力消散完全，然后整理过程还没有完全完成，和土骨架的粘性蠕变开始出现。随着时间的推移，路基沉降量将继续增加，但沉降速率逐渐减小；时效阶段：随着速度的减小，路基沉降值趋于稳定。路基沉降预测方法研究现在，路基沉降预测方法可以分为三类：（1）基于太沙基固结理论方法；（2）结合土的本构模型，采用基于Biot固结理论的数值分析方法；（3）将沉淀时间根据实测沉降监测数据的发展关系，这是基于在经验公式 8 曲线拟合方法。由于路基沉降的复杂性、影响因素和本构模型参数选择难度等问题，基于固结理论的沉降计算值与实测值往往是比较不同的。因此，如何从早期的沉降数据中推导出软土路基的后期沉降规律，对工程应用价值的研究具有重要意义。为了了解临海公路路基沉降的变化，曲线拟合模型的预测方法用于研究路基沉降。曲线拟合法的路基沉降预测方法通常假定路基沉降可以满足一定的