CN102605718A

CN102605718A - Prefabrication and construction method of box girder in-situ pedestal

Info

Publication number: CN102605718A
Application number: CN2012101059747A
Authority: CN
Inventors: 张志军; 李建军; 梁胜国; 李周伟; 于剑舟; 吕亚杰; 祁玺剑
Original assignee: China Railway 12th Bureau Group Co Ltd; Third Engineering Co Ltd of China Railway 12th Bureau Group Co Ltd
Current assignee: China Railway 12th Bureau Group Co Ltd; Third Engineering Co Ltd of China Railway 12th Bureau Group Co Ltd
Priority date: 2012-04-12
Filing date: 2012-04-12
Publication date: 2012-07-25

Abstract

The invention particularly relates to a prefabrication and construction method of a box girder in-situ pedestal, which solves the problems that cast-in-place box girders are high in cost and slow in progress and engineering construction is affected. The prefabrication and construction method includes: a, surveying lofting, performing replacement and layered compaction, and backfilling and tampering the area around an abutment; b, erecting a formwork to concrete a concrete pedestal serving as a bottom form, reserving pull bar holes on the top of the pedestal, and casting a concrete foundation around the pedestal; c, tying tie bars to fasten the bottoms of the lateral forms, using support bars to adjust the top elevation of the lateral forms, using a cup-lock scaffold to reinforce the lateral forms, and placing adjustable jacks and square timber on the top of the scaffold; d, pre-stressing the lateral forms to eliminate non-elastic deformation of a foundation and the scaffold, and correcting elevation of the foundation and the lateral forms again according to pre-stressing results; and e, sequentially installing bottom web reinforcement, inner membrane forms, top plate reinforcement and embedded parts, and pouring body concrete of the box girder. By the method, the stress effect of the forms can be improved greatly, and the prefabrication and construction method has the advantages of simple structure, reasonable design, simplicity in operation and effectiveness in use.

Description

Case beam original position pedestal precast construction method

Technical field

The present invention relates to the box girder construction method, be specially a kind of case beam original position pedestal precast construction method.

Background technology

Cast-in-place beam is one of important way of crossing in existing road, water channel, has characteristics such as widely applicable, that construction technology is easily understood, and can significantly reduce case beam cost of transportation.The existing cast-in-place method construction cost of case beam is higher, and need set up a bowl buckle scaffold in a large number, and progress is slower, needs a large amount of plant equipment to cooperate simultaneously, and via hole also needs big quantity space and influences the difficult problem of all the other engineering constructions of tunnel.

Summary of the invention

The present invention provides a kind of case beam original position pedestal precast construction method in order to solve the problem that the case beam adopts cast-in-place method to have that cost is high, progress slow and influences engineering construction.

The present invention adopts following technical scheme to realize: case beam original position pedestal precast construction method; Adopt following steps: a, measure setting-out; Confirm box girder body position and ground process range and height, change fill out, layered rolling, and to backfilling compaction around the pier; B, formwork erection concreting pedestal be as bed die, and under the pedestal end face, reserve tie rod hole, concreting basis around the pedestal; C, cross pull bar in pedestal to drawing fixedly the side form bottom, the strut that is connected between side form and the concrete foundation is regulated side form top absolute altitude, and through the bowl fastening type scaffold side form is reinforced, and the scaffold top is provided with the adjustable jacking and the lumps of wood; D, carry out the side form precompressed, eliminate the nonelastic deformation of ground and scaffold, again ground and side form are carried out the absolute altitude correction according to the precompressed result; E, successively end web reinforcement, inner membrance template, top board reinforcing bar and built-in fitting are installed after, build box girder body concrete.

This box girder construction is directly prefabricated on the adjacent bridge pier; The concrete pedestal with box girder body weight evenly distributed load in ground, efficiently solve the support cast-in-place method need set up in a large number the bowl fastening type scaffold cause progress slow, need that a large amount of plant equipment cooperate, via hole needs big quantity space and influence the problem of constructing tunnel.

The present invention replaces bed die through pedestal is set in case beam original position; Improve the stressed effect of template greatly, significantly reduced the quantity of setting up of bowl buckle scaffold, saved the expense of mobile formwork assembling; And the template of this method and bracing reinforcement material can repeatedly have enough to meet the need; Economic benefit is particularly outstanding, has advantage simple in structure, reasonable in design, easy and simple to handle, that result of use is good, is applied to cast-in-place beam construction use under cast-in-place beam construction of squat pier bridge location or the complex environment.

Description of drawings

Fig. 1 is a structural representation of the present invention.

Among the figure: 1-pedestal, 2-tie rod hole, 3-concrete foundation, 4-strut, 5-scaffold.

The specific embodiment

Case beam original position pedestal precast construction method adopts following steps: a, measures setting-out, confirms box girder body position and ground process range and height, change fill out, layered rolling, and to backfilling compaction around the pier; B, formwork erection concreting pedestal 1 be as bed die, and under pedestal 1 end face, reserve tie rod hole 2, concreting basis 3 around the pedestal 1; C, cross pull bar in pedestal 1 to drawing fixedly the side form bottom, the strut 4 that is connected between side form and the concrete foundation 3 is regulated side form top absolute altitude, and reinforces through 5 pairs of side forms of bowl fastening type scaffold, and scaffold 5 tops are provided with the adjustable jacking and the lumps of wood; D, carry out the side form precompressed, eliminate the nonelastic deformation of ground and scaffold 5, again ground and side form are carried out the absolute altitude correction according to the precompressed result; E, successively end web reinforcement, inner membrance template, top board reinforcing bar and built-in fitting are installed after, build box girder body concrete.

In the practical implementation process, change to fill out to adopt and contain the stone amount and change at the sand gravel more than 60% and fill out, after the mechanical equating; And single slope drainage slope and charge for remittance well are set, every layer of loose laying depth is no more than 30cm, carries out layered rolling; Adopt the 37 lime earth backfill around the pier, battering ram is tamped.

Pedestal 1 height 25 ㎝; The pedestal template adopts that [25 channel-section steels, pedestal 1 end face absolute altitude are absolute altitude at the bottom of the beam that is provided with after the camber, and formwork erection must carry out accurate levelling to it; Error must not be greater than 2 ㎜; Return 5 ㎝ places under pedestal 1 end face and reserve the tie rod hole 2 that crosses pedestal, tie rod hole 2 is centered close to by vertical 20 ㎝ places, form joint both sides between side form, and tie rod hole 2 adopts the pvc pipe of Ф 40 ㎜ pre-buried in pedestal 1; Ф 10 steel mesh reinforcements that 40 ㎝ * 40 ㎝ are installed are built the C20 concrete in pedestal, end face is repeatedly received flat the processing, and health in time; Concrete foundation adopts the C20 concrete, and thickness is 10 ㎝, and the end face absolute altitude is control to be lower than pedestal end face 25 ㎝.

Earlier the end side form is positioned, all the other side forms are installed successively again, make that side form bottom pull bar preformed hole is corresponding with 2 positions, pedestal 1 draw-in bar hole and pull bar in time is installed; Pull bar adopts the special fining twisted steel of Ф 32 ㎜; The high-strength nut socket of Ф 32 ㎜ is adopted in pull bar two ends and junction, side form bottom, and the outside strut 4 of side form is anchored in the concrete foundation of the outside through expansion bolt, and side form top absolute altitude can be regulated through strut 4; Scaffold 5 material specifications: vertical, cross bar length is 0.6m; Vertical rod length is 0.6m, 0.3m, and jacking adopts adjustable holder support, and jacking is laid vertical lumps of wood.

Side form precompressed and adjustment; Safety for the check side form; Grasp its distortion after stressed, eliminate the nonelastic deformation of ground nonelastic deformation and scaffold 5, the employing sand pocket loads precompressed to side form; Prefabricating load is pressed box girder body Approximate Equivalent load and is arranged, the precompressed maximum load is got 120% box girder body and added the internal mold deadweight from heavy load; Simulating beam body casting sequence divides level Four symmetry to load during precompressed, during loading according to first web, the order symmetry of base plate, back frange plate loads again.Through precompressed, draw nonelastic deformation value and elastic deformation value; The camber sum of calculating according to the distortion of the amount of deflection of case beam and scaffold 5, as the peak of camber, what be arranged on the case beam strides the footpath mid point; The camber of other each points is peak with the mid point, is the rack elasticity deflection with the both ends of case beam, distributes by second-degree parabola; Again adjust according to the ground and the side form absolute altitude of absolute altitude at the bottom of the case beam that calculates after precompressed.

Claims

1. case beam original position pedestal precast construction method is characterized in that: adopt following steps: a, measure setting-out, confirm box girder body position and ground process range and height, change fill out, layered rolling, and to backfilling compaction around the pier; B, formwork erection concreting pedestal (1) be as bed die, and under pedestal (1) end face, reserve tie rod hole (2), and pedestal (1) is concreting basis (3) on every side; C, cross pull bar in pedestal (1) to drawing fixedly the side form bottom; The strut (4) that is connected between side form and the concrete foundation (3) is regulated side form top absolute altitude; And through bowl fastening type scaffold (5) side form is reinforced, scaffold (5) top is provided with the adjustable jacking and the lumps of wood; D, carry out the side form precompressed, eliminate the nonelastic deformation of ground and scaffold (5), again ground and side form are carried out the absolute altitude correction according to the precompressed result; E, successively end web reinforcement, inner membrance template, top board reinforcing bar and built-in fitting are installed after, build box girder body concrete.