Research On Rationality Of Prediction Method For Srttlement Of Engineered Structures Under Certain High-Speed Railway Tracks And The Two Control Indicators

One of the most important problems for construction of high-speed railway is reasonable prediction together with control of post-construction settlement. At present, most of researches at home and abroad of curve fitting method are based on the analysis of large deformation data, engineered structures under railway tracks of the high-speed railway have the characteristic of small deformation data with big fluctuation,while the study related to the reasonable curve fitting method wich have that characteristic is quite limited. Therefore, it’s necessary to do a comparative study of the existing curve fitting methods and determine a reasonable curve fitting method suitable for the property of high-speed railway settlement. And based on the further study of correlation coefficient of curve fitting method and the limit of the ratio of current settlement to predicted settlement, the limit of the index for assessment of China’s high-speed railway settlement is determined.The main contents and corresponding results of this paper are as follows:By summarizing and analyzing the existing test data of the first section of engineered structures under railway tracks of the high-speed railway(DIK5+280～DK238+470), it can be concluded that the characteristic of settlement deformation of roadbed segment and bridge section are small deformation and large fluctuation, respectively,the most of the settlement less than15mm, the fluctuations divided the settlement is greater than about0.54.Through fitting pre-test data and predicting post-settlement, different methods including Hyperbolic method, Exponent method, Asaoka method and Gray system method are studied. The advantages and disadvantages of these methods are summarized. It is shown that Hyperbolic method and Exponent method are suitable for predicting high-speed railway settlement because they have small predicting error.Depending on the predicted final settlement, the predicting error size under different correlation coefficient and settlement ratio of Hyperbolic method and Exponent method is studied. Based on the study of roadbed segment and bridge sections respectively, according to the predicted final settlement of0-5mm,5~10mm,10~20mm and larger than20mm, the correspondence correlation coefficient of0.85~0.92and settlement ratio of0.6~0.75are proposed.Based on about200test data of engineered structures under railway tracks in Beijing-Shanghai railway, the curve fitting method suitable for this section and correlation coefficient and limit of settlement ratio are proposed in this paper. The results of this paper can be served as guideline and reference for settlement predicting of Beijing-Shanghai High-speed railway and corresponding engineered structures under railway tracks, also can perfect the limits of the current relevant regulations of assessment methods.