CN-122013672-A - Method for erecting in-situ precast beam

CN122013672ACN 122013672 ACN122013672 ACN 122013672ACN-122013672-A

Abstract

The invention discloses an in-situ precast beam erection method which comprises seven steps of slope excavation and protection, lower structure construction, section steel pedestal construction, beam sheet in-situ prefabrication, maintenance and tensioning, transverse movement and beam falling and subsequent construction, wherein a precast beam is a T beam which is adaptive to a travelling crane overpass, in-situ prefabrication at a bridge site is realized without in-situ prefabrication and beam conveying processes, three differential transverse movement beam falling schemes are designed, the section steel pedestal adopts a modularized detachable structure and can be reused, and a leveling cushion layer is arranged on the contact surface of the precast beam and a permanent support. The invention greatly reduces the construction safety risk, has simple and convenient process, short construction period, saves construction cost, has strong construction flexibility and adaptability, high erection precision and good structural stability, is suitable for T beam erection projects with limited various places, and is particularly suitable for the engineering of the overpass crossing a newly built main line expressway and positioned in a remote excavation section.

Inventors

RAN YI
LI TINGTING
YANG BO
WU DONG
JIN JUNQI
WANG SUO
ZHANG YOUZHI
Kuang Ze
BAI JIANXIONG
SHEN GUILIN

Assignees

贵州路桥集团有限公司

Dates

Publication Date: 20260512
Application Date: 20260323

Claims (10)

1. The method for erecting the in-situ precast beam is characterized by comprising the following steps of: A. The slope excavation and protection, namely, the slope excavation bottom line is lofted out by using a measuring instrument, the slope is excavated to be below 50cm of the beam bottom, and the slope protection construction is synchronously completed; B. constructing a lower structure, namely sequentially constructing lower components of the bridge such as pile foundations, bridge abutment, permanent supports and the like after accurate measurement and lofting; C. The construction of the section steel pedestal, namely, detecting the bearing capacity of the foundation after excavating earthwork below 50cm of the beam bottom, and replacing the foundation when the requirement is not met, and then constructing 2 precast beam section steel pedestals on two sides of the bridge abutment, wherein the height of the section steel pedestals is 10cm higher than that of permanent supports on two sides of the bridge abutment; D. prefabricating beam sheets in situ, namely finishing prefabricating procedures of steel bar binding, template mounting, concrete pouring and the like of the prefabricated beam on a steel section pedestal which is qualified in acceptance; E. curing and tensioning, namely curing the precast beam for seven days, and completing prestress tensioning operation according to design requirements after curing; F. The transverse moving and beam falling are that after the precast beam is lifted by the lifting device, the tensioned precast beam is transversely moved to a designed installation position by utilizing the transverse moving device below the lifting device, and then the precast beam is lowered to the top of the permanent support by the lifting device; G. and (3) carrying out subsequent construction, namely after all the precast beam pieces are installed, carrying out bridge deck system and auxiliary engineering construction, dismantling the profile steel pedestal, excavating the main line roadbed to the designed elevation, and prohibiting the up-down cross operation in the whole construction process.
2. The method for erecting an in-situ precast beam according to claim 1, wherein in the step A, one of anchor spraying, grout stone and section steel support is adopted for slope protection, and geological conditions of a silty clay, sandstone and mudstone interbedded at bridge positions are adapted.
3. The method for erecting an in-situ precast beam according to claim 1, wherein in the step C, the section steel pedestal is formed by splicing H-shaped steel, I-shaped steel or box-shaped steel, and after the construction of the section steel pedestal is completed, the section steel pedestal is subjected to bearing capacity acceptance, and after the acceptance is qualified, the beam sheet prefabrication operation can be carried out.
4. The method for erecting an in-situ precast beam according to claim 1, wherein the traversing device in the step F has the functions of traversing, limiting and accurately positioning, and can prevent the precast beam from traversing excessively, and a supporting structure for preventing a beam piece from overturning is arranged in the traversing process of the precast beam, and the supporting structure is a steel pipe bracket or a section steel bracket.
5. The method of erecting an in-situ precast beam according to claim 1, wherein the step F is to install traversing devices integrating lifting functions on two sides of the permanent support, and traversing and beam dropping of the precast beam are completed directly through the traversing devices.
6. The method for erecting the in-situ precast beam according to claim 1, wherein in the step F, a transverse track is arranged below the profile steel pedestal and anchored on a foundation, hydraulic jacks are arranged on two sides of the track to provide transverse movement power, the precast beam is transversely moved and then falls to temporary supports of sand barrels on two sides of the permanent support, and the beam falling is completed through the temporary supports of the sand barrels.
7. The method for erecting an in-situ precast beam according to claim 1, wherein in the step F, a transverse track is arranged below a section steel pedestal and anchored on a foundation, hydraulic jacks are arranged on two sides of the track to provide transverse moving power, the jacks are additionally arranged at the crossing positions of the section steel pedestal and the precast beam to serve as special lifting devices, and the accurate beam falling of the precast beam is completed through the device.
8. The method for erecting an in-situ precast beam according to claim 1, wherein the precast beam is a T-beam and is adapted to an upper structure of a overpass, and the precast beam is precast and formed in situ at a bridge site without an off-site precast and beam transporting process.
9. The method for erecting an in-situ precast beam according to claim 8, wherein the precast beam is erected by matching with a section steel pedestal, a traversing device and a lifting device on a bridge site, the section steel pedestal is matched with the precast beam in size and load, and the section steel pedestal is of a modularized detachable structure and can be reused.
10. The method for erecting an in-situ precast beam according to claim 9, wherein a leveling cushion layer is arranged on a contact surface between a beam end of the precast beam and the permanent support, and is made of mortar or steel plates, so that flatness and stability of precast beam erection are guaranteed.

Description

Method for erecting in-situ precast beam Technical Field The invention belongs to the technical field of bridge construction, and particularly relates to an erection method of an in-situ precast beam. Background The T beam is used as a common form of a bridge upper structure, the main stream construction technology at the present stage is to perform centralized prefabrication in a professional prefabrication beam field, and the girder erection operation is completed through a bridge girder erection machine after Liang Chechang paths of transportation to a construction site. The technology is mature, has high standardization degree, is suitable for bridge engineering with wide field and convenient traffic, but has the limitation that is difficult to overcome in the construction of partial special bridge sites. The construction of the bridge crane is limited by multiple sites, namely, the space around the bridge site is narrow, the beam transporting vehicle cannot be parallel to the installation position of the precast beam, the running, steering and beam transporting operation of the beam transporting vehicle cannot be realized, the site is not satisfied with the assembly, debugging and operation space requirements of the bridge crane, the bridge erecting mode of the bridge crane is difficult to implement, and the T-beam span of the bridge crane is large and the dead weight is high. In the prior art, the improvement on the erection of the precast beams is mainly carried out around the structural optimization of the girder transporting vehicle and the bridge girder erection machine, and the construction scheme which is not designed and adapted for the special bridge site with limited places cannot solve the problem of the T-shaped girder erection of the overpass crossing the expressway in the remote excavation of the square section. Disclosure of Invention Aiming at the problems, the invention aims to provide an in-situ precast beam erection method for solving the technical problems that a traditional beam transporting and bridge erecting machine cannot be used for construction due to narrow site of a special bridge site and the risk of double-machine crane is high. The invention is realized by the following technical scheme: The method for erecting the in-situ precast beam comprises the following steps: A. The slope excavation and protection, namely, the slope excavation bottom line is lofted out by using a measuring instrument, the slope is excavated to be below 50cm of the beam bottom, and the slope protection construction is synchronously completed; B. constructing a lower structure, namely sequentially constructing lower components of the bridge such as pile foundations, bridge abutment, permanent supports and the like after accurate measurement and lofting; C. The construction of the section steel pedestal, namely, detecting the bearing capacity of the foundation after excavating earthwork below 50cm of the beam bottom, and replacing the foundation when the requirement is not met, and then constructing 2 precast beam section steel pedestals on two sides of the bridge abutment, wherein the height of the section steel pedestals is 10cm higher than that of permanent supports on two sides of the bridge abutment; D. prefabricating beam sheets in situ, namely finishing prefabricating procedures of steel bar binding, template mounting, concrete pouring and the like of the prefabricated beam on a steel section pedestal which is qualified in acceptance; E. curing and tensioning, namely curing the precast beam for seven days, and completing prestress tensioning operation according to design requirements after curing; F. The transverse moving and beam falling are that after the precast beam is lifted by the lifting device, the tensioned precast beam is transversely moved to a designed installation position by utilizing the transverse moving device below the lifting device, and then the precast beam is lowered to the top of the permanent support by the lifting device; G. and (3) carrying out subsequent construction, namely after all the precast beam pieces are installed, carrying out bridge deck system and auxiliary engineering construction, dismantling the profile steel pedestal, excavating the main line roadbed to the designed elevation, and prohibiting the up-down cross operation in the whole construction process. Further, in the step A, the slope protection adopts one of anchor spraying, slurry rubble or profile steel support, and the geological conditions of the silty clay, sandstone and mudstone interbedded at the bridge position are adapted. And C, splicing the section steel pedestal by adopting H-shaped steel, I-shaped steel or box-shaped steel, checking and accepting bearing capacity after the construction of the section steel pedestal is completed, and carrying out beam sheet prefabrication operation after the checking and accepting is qualified. Further, in the step F, the transverse moving device has th