In the construction of the large section box-type ventilation duct of metro with two storeys and double spans,there are many construction features involving large-span excavation,such as complex temporary support system,complicated force transfer for secondary structure and so on.

The water injection and gas discharge device is added,the flexible pressure testing sub is used and the high and low pressure water conversion valve body is improved.

Study on influence of system conversion of construction to deformation of PC continuous beam bridge;

The article introduces the technical flow of the structural system conversion of Fenghua Bridge on Haihe River and the stress deformation control in the course of its implementation,and the preparation and selection of the hanger rod stretching technology.

As the huge potential energy will release after the system conversion and relieving the temporary constraint,the slipping of main girder of unidirectional sloping cable-stayed bridge with floating system will appears,the construction and the whole bridge stability will be influenced.

This paper analyzes the constructing technique of prestressing concrete continual T-beam bridge precisely and discusses the prefabrication, tense, problems and solution of T-beams, selection of temporary stand as well as its system transformation.

In balanced cantilever erection of bridge beam,the technology of bearing system transformation is really ripe,while assembling continuous curved beam by bridge fabrication machine is a totally new method.

In this paper,the construction methods for the system transformation of the suspension bridge are described.