Simply-supported slab bridge jack-up method and height-adjustable combined cushion structure applied therein

Abstract

The invention discloses a simply-supported slab bridge jack-up method and a height-adjustable combined cushion structure applied therein. The simply-supported bridge jack-up method includes: firstly, setting up distributive girders under a girder, arranging jacks and putting up temporary supports, and then entirely synchronously jacking up a simply-supported slab to the height 1-3mm higher than design elevation; preliminarily supporting the bridge by the aid of the height-adjustable combined cushion structure and supports prior to performing zero-clearance girder falling to the designed elevation, and then demounting the jacks and the temporary supports. The height-adjustable combined cushion structure comprises a precast portion composed of precast supports and a height-adjustment combined mechanism capable of adjusting the height of the precast supports and a cast-in-situ portion coating a height-adjustable mechanism and part of the precast supports. The simply-supported slab bridge jack-up method and the height-adjustable combined cushion structure applied therein have the advantages of high applicability, controllable security, high construction precision, high operability, high economical efficiency, good application prospect and the like, thereby being capable of being used in support replacement projects of expressways and the bridges of urban roads and especially applicable to jack-up engineering when jack-up height of a sole-across simply-supported girder (slab) is larger than the stroke of one jack.

Description

technical field [0001] The invention belongs to the technical field of bridge engineering, in particular to a method for the top height of simply supported slab bridges and a height-adjustable combined pad stone structure applied in the method. Background technique [0002] In the past ten years, many expressways and urban road networks need to be rebuilt and expanded because they cannot meet the growing traffic requirements. Many simply supported slab bridges are required to undergo appropriate jacking reconstruction to ensure smooth connection of the road network and improve driving comfort. and bridge safety to further improve the service level of the road network. The commonly used jacking method is: the jack is directly placed on the cover beam or cap beam of the pier, and N or 2N (N is the number of pieces of the same span girder) symmetrically arranged side by side at each slab girder, by a pump Station control, using multi-point synchronous jacking method to jack up...

AI Technical Summary

Problems solved by technology

[0005] 2. The distance between the simply supported slab bridge and the top surface of the cap beam or cap beam is generally within 6 cm. When the jack is directly placed on the cap beam or cap beam of the abutment, only an ultra-thin jack with a small stroke can be used for jacking up (using stroke Most of them are within 5 cm), for large-height jacking and replacement of supports, multiple jacking and beam dropping are required, which greatly reduces the synchronization of jacking and increases the possibility of hinge cracking

[0006] 3. Generally, the jacking height of simply supported slab bridges for reconstruction and expansion is within 20 centimeters, and there are small and large height jacking constructions at the same time. The construction space within 20 centimeters is too small to conveniently and accurately stake out at the bottom of the beam and installation and construction; for large-height jacking of simply supported slab bridges, it is necessary to reset the support pad stone at the original support position, and then place a new rubber support on the new pad stone. There is basically no concrete pouring within 20 cm. Feeding space

[0007] 4. For simply supported slab bridges, generally the single slab girder is provided with four supports and four plinth stones, resulting in more convex and concave structures on the cap girder or cap girder. If the jacking is carried out on the cap beam or cap beam, the placement of the jack is very limited, which usually leads to construction space difficulties

[0008] 5. For the large-height jacking of simply supported slab bridges, due to the small construction space, it is impossible to strengthen the connection between the old and new pad stones by planting reinforcement at the original pad stone position, especially for the case of replacing the support when the jacking exceeds 20 cm. The reliable connection between the pad stone and the original cap beam and the top surface of the cap beam is more important

For simple-supported slab bridges with small spans, due to the relatively light weight of single-slab girders (less than 20 tons), this is not only technically unsuitable, but also very poor in economy. Then, how to reduce the number of jacks and reduce construction costs has become a problem. first economic problem

[0010] 7. It takes at least ten days of construction time for the simply supported slab bridge to be lifted in place until the girder falls. During this process, the multi-point jacking equipment and other temporary support pads must be kept in a static working state, which requires a lot of temporary Shift fee for backing plate and jacking equipment

Since the simply supported slab bridge is lifted into place, the jacking equipment cannot be dismantled, which greatly increases the construction cost

How to reduce the working time of the static force of the jack and reduce the construction cost has become the second economic problem

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