Study On Super High Span Gantry Construction Safety Under The Restrictive Environment

With the rapid development of national urban construction,the traffic volume keeps increasing,and the bridge reconstruction projects in important urban nodes are increasing constantly.Especially in some cities in southwest China,the bridge height is large,the site is small,the project is affected by the site and other environment,the conventional construction method cannot be implemented.For such high piers and large-span Bridges affected by geographical environment,time limit and other factors,adopting the scheme of super-high and large-span gantry frame can effectively save cost,shorten the construction period and effectively reduce the influence of bad environment on construction,compared with other types of hoisting methods.At present,although the use of gantries in our country is becoming more and more widespread,there are still many problems that seriously hinder their own development,such as the imperfect design methods,low levels of professional collaboration,the development of new materials that can ￠ t keep up with requirements,and some construction safety issues,which are all the difficulties to be studied in the domestic super-high span gantries development process.During the gantry installation process,the pit treatment,foundation excavation,soil and stone excavation,the short-term effects of natural soil or local natural climate on soil quality,and the effects of wind load on the safe construction of super-high span heavy-duty concrete support system and gantry lifting equipment are all important factors that affect the installation and construction safety of the gantries.Based on the summary of the types and characteristics of gantries,this paper systematically analyzed the installation and construction safety of super-high span gantries in constrained environments.Then the finite element numerical simulation method was used to systematically analyze the overall stability of the gantry structure and the local stability of the steel tubes of the columns,the overall deformation analysis of the structure under unfavorable load position,and the bearing capacity,anti-slip and stability of the gantry column foundation.Through the establishment of the gray correlation security evaluation system,the security of the lifting process of the super-high span gantry was analyzed and demonstrated,and the gray correlation-based super-high span gantry security evaluation level was proposed to further analyze and verify the security evaluation effect of the super-high span gantry.Finally,based on the engineering application,the construction procedures and construction attentions of lifting,moving and installation of small box girder using super-high span gantry were elaborated,and the construction safety was further increased by monitoring the super-high span gantry during the construction process to ensure the successful progress of construction.Reasonable application of the super-high span gantry to the bridge project lifting construction,not only can quickly and effectively solve the installation and splicing oflarge-span bridges,the use of this equipment can also correspondingly shorten the construction period,reduce costs,and the adverse effects of external conditions,and can be used continuously to ensure the successful progress of the project.In this paper,super-high span gantry small box girder bridge technology is applied to similar installation height more than 60 m,span of more than 30 m high pier and large-span bridge engineering construction process,can copy can promote experience for similar engineering projects,the important node of city region with type high piers large-span bridge construction has important reference meaning and are of great promotion value.