MONITORING AND ASSESSMENT OF A FRAME TUNNEL BRIDGE DURING JACKING CONSTRUCTION STAGE

摘要

Jacking is the popular construction method of frame tunnel bridges. There are twoproblems should be solved in the jacking process. One is cracking caused by unbalancedjacking force between the both sides along the railway line,especially for slender frametunnel bridge. The other is cracking caused by different settlement,especially for bridge onsoft subsoil. In this paper the monitoring on a frame tunnel bridge (a structure located inTangshan city,Hebei province,China) is discussed. Before field monitoring a 3-D finiteelement model is created using MIDAS software and the mechanical behavior under differentload cases are analyzed. The critical points are identified and the concrete strain andtemperature at critical points are monitored during the jacking stage. The construction qualityof this tunnel bridge is guaranteed,and helpful advice is proposed for the design,constructionand prevention of cracks of the frame tunnel bridge.