Research On Key Technologies For Construction Of Chengdu Metro Steel Spring Floating Slab Track

Metro transportation is large,fast,safe and reliable,and has become the first choice for public transportation in megacities.Chengdu will form a metro transportation network with a total length of more than 700 kilometers by the end of 2024.When the subway passes through residential and commercial areas,noise will affect people’s lives.When passing through a precision manufacturing enterprise,vibration will affect product accuracy.It is necessary to adopt technical measures to reduce vibration and noise.The steel spring floating slab track is a new type of track structure with good vibration and noise reduction effects,and construction is the key to ensuring its vibration and noise reduction effect.Therefore,it is very important to carry out research on the construction technology of the steel spring floating slab track significance.This paper focuses on the steel spring floating slab track of a certain line of Chengdu Metro.Based on the systematic summary of its vibration and noise reduction mechanism,the main characteristics of the steel spring floating slab track on this line are analyzed in detail,and the track construction sequence is optimized.The key construction technology and quality control of the slab track were studied,and the finite element theory was used to simulate and analyze the construction techniques of rail row lifting,rail row adjustment bracket setting,floating plate shear hinged shear installation and floating plate jacking.And optimization research,the following conclusions were obtained:(1)Reasonable arrangement of the construction sequence of each sub-project is the key to ensuring construction quality and improving construction efficiency,and should be carefully arranged when designing the construction group.The CPⅢ control network is the basis for ensuring the accuracy of the entire track construction.When laying,it is necessary to ensure that the point settings are firm and stable,and the accuracy fully meets the design requirements.(2)The construction of the base should clear the debris generated by the tunnel construction to ensure the base is firm and reliable during operation.The installation of formwork is the key technology of base construction.Its quality directly affects the final forming accuracy of the base.If it fails to meet the requirements,it will lead to the failure of subsequent construction.(3)The rail row adjustment bracket is both a support structure and an adjustment mechanism.During installation,it should be ensured that the lower support is stable and the adjustment of the screw in each direction is convenient.The installation position of the shear hinge should be strictly controlled,otherwise it will cause excessive stress.The key to the installation of floating slab template is to ensure the accuracy of the target and the accuracy of various embedded parts.Otherwise,the construction error of the floating slab is too large,and the track cannot be fine-tuned.(4)The lifting of the floating plate is a key process in construction.When jacking is used,it should be lifted symmetrically from left to right,and then lifted in sequence from front to back.Strictly control a certain lifting height to make the floating plate and the steel spring evenly stressed.In order to prevent the construction from causing cracking of the floating plate and damage to the steel spring.(5)The fine adjustment of the track is the difficulty of the entire construction,including the gauge,level,direction,height,irregularity,bottom slope of the track,geometric radius and super-height changes on the curve.These parameters will affect each other during adjustment.The three parameters of gauge,height,and direction are mainly used,and others are supplemented to improve the efficiency of fine adjustment.(6)Construction simulation and optimization analysis show that: the best spacing between the lifting points is 13 m when the rail row is hoisted;the best spacing between the rail row adjustment brackets is 4-6m;the force of the shear hinge increases with the increase of the base error,it is recommended The base error during construction is controlled within 3mm to ensure that the shear hinge is not overloaded;the lifting sequence and height have a significant impact on the stress of the floating slab.To facilitate fine adjustment of the track,it is recommended to use the vertical lifting operation method during construction.And limit the height of one-time jacking to no more than 10 mm.