Construction method for overhead jacking of multi-track existing railway of frame bridge

Abstract

Disclosed is a construction method for overhead jacking of a multi-track existing railway of a frame bridge. By means of construction modes of transition overhead construction-dewatering construction-formal overhead and two-end opposite jacking and middle cast-in-place, the risk caused by the groundwater level to a dig-hole pile is directly avoided. The overall construction scheme for the overpass pipe section follows the principle of segmented construction and line production, a jacking part of the overpass is firstly constructed, and after the jacking part is in place, a middle frame is cast in place, which guarantees not only the railway operation but also the construction period quality, and thus good economic benefits and construction guidance significance are achieved.

What is claimed is: 
     
         1 . A construction method for overhead jacking of a multi-track existing railway of a frame bridge, comprising the specific steps as follows:
 one, excavating working foundation on both sides of the multi-track existing railway;   two, prefabricating jacking pipe sections in the working foundation pits;   three, performing transition overhead;   four, dewatering by a broached groove;   five, performing hole digging construction for a formal overhead pile;   six, after the step five is completed, jacking, by a jack, the prefabricated jacking pipe sections into an overhead system from both sides of the multi-track existing railway in a direction perpendicular to the existing railway;   seven, performing overhead conversion in a mode of pile breaking while jacking, after the jacking pipe sections on both sides of the multi-track existing railway are jacked in place, replacing an overhead pile with the jacking pipe sections to serve as a supporting structure, and forming a construction space of a middle cast-in-place pipe section by erecting a horizontal lifting beam; and then casting a pipe section in place between the jacking pipe sections; and   eight, after the pipe section is cast in place, regarding that the construction of the frame bridge underpass multi-track existing railway is completed, dismounting overhead equipment to recover the normal operation of the railway.   
     
     
         2 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 1 , wherein in the step one and step two, a side wall of the working foundation pit is provided with formwork concrete. 
     
     
         3 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 1 , wherein the specific method of transition overhead in the step three is as follows: digging a pile hole below the existing railway according to the load design, with a hole digging depth above groundwater level; then casting a temporary overhead pile, and erecting an upper overhead component by taking the pile top of the temporary overhead pile as a fulcrum. 
     
     
         4 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 3 , wherein the upper overhead component comprises longitudinal beams and steel sleepers. 
     
     
         5 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 1 , wherein the specific method in the step four is as follows: after the transition overhead in the step three is completed, constructing working grooves below the existing railway and between the temporary overhead piles in each row, constructing foundation pit fender piles and dewatering wells by using working faces in the working grooves, and then performing dewatering to enable the ground water level to reach the designed water level. 
     
     
         6 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 5 , wherein in the step four, the dewatering wells are distributed at both sides of the multi-track existing railway and in the working grooves; the dewatering wells are mechanically constructed. 
     
     
         7 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 1 , wherein the specific method in the step five is as follows: digging a pile hole, underneath the temporary overhead pile, below the existing railway according to the load design, with a hole digging depth below the groundwater level, and then casting the formal overhead pile, and arranging a horizontal lifting beam in a penetrating manner with the pile top of the formal overhead pile as a fulcrum so as to form an overhead system. 
     
     
         8 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 7 , wherein the formal overhead pile is constructed by a manual hole digging method. 
     
     
         9 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 1 , wherein in the step seven, the jacking pipe section and the cast-in-place pipe section each comprise a pipe section roof, a pipe section baseplate, pipe section side walls and a pipe section middle partition wall; the pipe section roof is in contact with an upper load, the pipe section baseplate is in contact with the ground, the pipe section side walls and the pipe section middle partition wall are connected to the pipe section roof and the pipe section baseplate, and the pipe section middle partition wall is located between the pipe section side walls and is parallel to the pipe section side walls. 
     
     
         10 . The construction method for overhead jacking of multi-track existing railway of a frame bridge according to  claim 9 , wherein one side of the pipe section baseplate of the jacking pipe section is provided with a triangular correction block, such that the jacking pipe section and the existing railway are constructed in a skew jacking manner.