The Construction Technology And Management Of The Box Beam Fabrication And Erection In Qinshen Special Passenger Line

Qinshen special passenger line (from Qinhuangdao island of Hebei province to Shenyang the capital city of Liaoning province) is the first railway line with design operation speed over 160 km/h. The project is technological information reservation for the coming high speed railway line drive in China. A great amount of post tensioned pre-stressing concrete single box beam for double track (as called the Box Beam hereinafter) has been used on the line. It is of infeasibility in adoption of the traditional practice of pre-fabrication in precast factory and erection of the Box Beam with the track laying machine for that this type of beam is characterized by new structure,complicated workmanship,large volume and difficulty in transportation. Therefore,the key and hardest problem to tackle is that what processing should be adopted to precast the Box Beam on site and that what kind of machinery should be used to transport and erect the Box Beam. This paper,taking the construction practice into consideration of prefabrication and erection of the Box Beam carried out by the Sixth Company Limited of Fifth China Railway Group on the Qinshen Line,gives a comprehensive exploration in the construction technology and management of the Box Beam fabrication and erection.Fabrication of the Box Beam is divided into such parts as reinforcement,formwork,concreting,prestressing,moving and storing of beam,pipe grouting under pressure,end sealing of the beam,water-proof layer on the bridge surface system,protective coating etc. The paper makes description of effective box beam construction technology and workmanship which can be adopted in other projects,such technologies as:manufacturing and fixing of reinforcement,steel reinforcement fixing baseplate,web plate and top plate respectively and lifting the steel skeleton into form,requirements of design and manufacturing and way of utilization for dismantling-erection type formwork and hydraulic formwork,optimization of concrete ratio,concrete pouring process of two ends of beam in priority over the middle,in sequence of first baseplate followed by web plate and top plate at last,concrete pouring in inclined section and in horizontal layer,concrete vibration mainly byexternal vibrator in assistance with internal vibrator,methods and regulation for steam curing of concrete,dual controls over stress and strain to ensure quality of prestressing workmanship,construction method of effective beam moving by heavy-weight special moving facility,some regulations and key notes about construction of grouting under pressure,beam ends sealing,water-proof layer on the bridge surface system,protective coating. In addition,the Box Beam static loading test,which is one of the effective means of inspecting quality of box beam,is also described in the paper for the purpose of reference.This paper also makes brief description of the technical specifications,mechanical structure,major features of the Italian beam transporting and erecting machine with type of NICOLA YJ-550,which was introduced firstly in China and chosen carefully in combination with the site conditions. The future beam erection and relevant design and construction can find the reference from description of this paper in terms of erection process for box beam,working efficiency of the Italian beam transporting and erecting machine with type of NICOLA YJ-550,issues and revelations concerning about box beam erection,special beam erection method to avoid three legs supporting.Furthermore,the construction management of the fabrication and erection of the Box Beam is in complexity for the new workmanship,various procedures,and very special site conditions which should be taken into account so as to achieve the construction objectives in terms of safety,quality,progress respectively. With the various external affections,the working period was extremely tight for fabrication and erection of the Box Beam by the Sixth Company Limited of Fifth China Railway Group on the Qinshen special passenger line,consequently,progress management bec...