【摘要】 沉井基础广泛应用于各类大型构筑物建设中，其下沉倾斜程度是下沉姿态最重要的指标之一，准确预测下沉倾斜程度有利于确保沉井安全平稳下沉以及预防潜在施工风险。基于bagging和boosting两种集成学习机制，分别采用随机森林算法和XGBoost框架建立沉井下沉倾斜程度预测模型，利用沉井底部结构应力监测数据，预测下沉过程中沉井基础顺桥向高差与横桥向高差。依托常泰长江大桥主塔超大型沉井基础下沉工程，验证本文提出预测模型的可靠性。之后，将本文预测模型与其他单一机器学习算法模型进行对比，并分析模型重要参数对预测精度的影响。结果表明：本文预测模型可以准确预测沉井下沉过程中的顺桥向高差和横桥向高差，能够合理确定沉井下沉倾斜程度；本文模型的预测精度高于其他单一机器学习模型，模型运行速度快、实用性强，且模型预测精度随基学习器个数和最大树深度的增大而提高。研究成果实现沉井下沉倾斜程度实时预测，可为类似的大型沉井下沉监控提供重要参考。更多还原

【Abstract】 Open caisson foundations are widely used in the construction of various large structures,and the inclination of an open caisson is one of the most important indexes of its sinking attitude. Accurate prediction of the inclination is conducive to ensuring the sinking safety and steady of the open caisson and preventing potential construction risks. Based on two ensemble learning techniques,bagging and boosting,the random forest algorithm and XGBoost framework are applied for the inclination prediction modeling. The monitoring data of the structural stress at the bottom of the open caisson are used to predict the longitudinal height difference and transverse height difference. The reliability of the prediction model was verified by applying it to the super-sized open caisson foundation of the main bridge pylon in the Changtai Yangtze River Bridge Project,and the proposed model was compared with the prediction models applying other single machine learning algorithms. Then,the important parameters of the ensemble learning model were analyzed to study their influence on prediction accuracy. The results show that the prediction model in this paper can accurately predict the longitudinal height difference and transverse height difference and reasonably determine the inclination of the open caisson foundation. With fast operating speed and strong practicability,the proposed model has higher prediction accuracy than other single machine learning models. In addition,the prediction accuracy increases with the number of base learners and the maximum tree depth.The research results achieve the real-time prediction of the inclination of the open caisson foundation during the sinking process,which can provide an important reference for the monitoring of similar foundations.更多还原