Research On Erection Control Factors Of Main Cable System Of 2000 Meter Suspension Bridge

Nowadays,China’s sea crossing projects are booming,and the suspension bridge with the strongest crossing capacity has become the first choice.After the completion of the Akashi Strait Bridge in Japan in 1998,it has occupied the largest span in the world for more than 20 years.At present,there are four suspension bridges with a span of more than 2000 m under planning and construction at home and abroad,and the span of suspension bridges in the world has entered the ranks of 2000 m.For suspension bridge,cable system is its lifeline,and its erection control is the top priority of suspension bridge construction.The increase of suspension bridge span is bound to lead to a significant increase in the diameter of the main cable strand,and the erection accuracy of the main cable is more difficult to ensure due to the influence of the manufacturing accuracy of the cable strand and the on-site environmental conditions.Therefore,focusing on the suspension bridge with a span of more than 2000 m,starting from the processing and manufacturing accuracy and erection method of largediameter main cable strand,this paper makes a series of research on the erection control of the main cable system of conventional super long-span double main cable suspension bridge.Moreover,in order to avoid the problems of manufacturing,transportation and erection of large-diameter main cables of super long-span suspension bridges,this paper also puts forward an alternative new four main cable system scheme,and studies the unique transverse statically indeterminate system of this scheme.The main contents of this paper are as follows:Firstly,by studying a large number of completed suspension bridge data,various factors affecting the fabrication accuracy of cable strands are analyzed,and the corresponding control methods are put forward.In order to improve the manufacturing accuracy of cable strand above the standard requirements,a new ultra-high precision cable strand manufacturing technology is further proposed.Based on the new cable strand manufacturing technology,the marking method erection technology of the reference cable strand is proposed,which realizes the marking alignment erection method that the reference cable strand is not affected by wind and temperature,improves the erection accuracy of the cable strand,simplifies the construction method,and saves manpower and equipment investment.Secondly,the main influencing parameters of super large diameter main cable are studied,and the corresponding detection requirements of each parameter are put forward.The anti sliding stability of super large diameter main cable strand,the torsion of empty main cable and the later adjustment of main cable shape are studied,and the corresponding control technology is put forward.Finally,aiming at the new four main cable structure,a control scheme for the transverse spacing of single side double cables in the cable strand erection stage is proposed to prevent the main cable collision accident.The influencing factors of sling force,including unstressed length error of main cable,elastic modulus error and unstressed length error of sling,are analyzed and studied,and the index formula of sling manufacturing error is put forward.The influence of unsynchronized jacking of main cable saddle of four cable suspension bridge on sling force and bridge tower in construction stage is studied.The research results of this part can provide a certain technical reference for the construction control of the main cable system of super long-span four cable suspension bridge in the future.