Abstract: A large number of accurate and reliable settlement data were obtained via on-site long-term monitoring test. The basic settlement law of pile foundation and characteristics of settlement curve were studied. Single forecast model was used to fit the monitoring data. The inadequacy that the evaluation of reasonable prediction model was limited to the correlation coefficient index in current guidebook was pointed out. It was proposed that mean-square error, mean absolute percentage error and average absolute error were introduced to comprehensively examine, evaluate the fitting effect and the reference value corresponding to the evaluation index was recommended. Combination forecast model for high-speed railway bridge post-construction settlement prediction was proposed; the characteristics of existing combination prediction models were analyzed and compared; specific steps and basic principles of bridge pile foundation post-construction settlement forecast were brought forward; and corresponding computer program was developed to improve forecast accuracy and efficiency. It was found that, by engineering examples, the optimal combination forecast method based on least-squares criterion could be thought of as the favor model owing to effectively and comprehensively improving the prediction accuracy. The valuable supplement and reference were provided to confirm reasonable time to construct railway and calculate post-construction settlement.

Key words: high-speed railway, bridge pile foundation, on-site monitoring, post-construction settlement, combination forecast model