CN101230563B - Method for replacing bridge bearing without traffic interruption and special device thereof - Google Patents

Abstract

The invention discloses a method for a raising bridge without closing the traffic and a device which is specially used for the method. The device provided by the invention connects more than two self locking jacks in parallel by a dividing valve and the self locking jacks are supplied with oil by the same oil pump. The invention also provides the method adopting the device to raise the bridge. By applying the special device and the method which are provided by the invention, the operation technique is simple and the replacement of a support saddle can be realized under the condition without interrupting the traffic, so as to avoid the traffic crowd caused by closing the traffic, and alleviate the pressure of leading and distributary of the vehicles, thereby having obvious economic and social benefits.

Description

A kind of uninterrupted traffic is changed the method and the isolated plant thereof of bridge pad

Technical field

The present invention relates to a kind of uninterrupted traffic and change the method and the isolated plant thereof of bridge pad.

Background technology

In beam bridge, bearing is arranged between the superstructure and pier of bridge, its effect is that the various load counter-forces on the bridge span structure are delivered to pier, guarantees desired displacement of bridge span structure and rotation simultaneously, makes the actual loading situation of upper and lower part structure and theoretical graphic being consistent of calculating.

In many beam bridges at home, the phenomenon of bearing aged deterioration is comparatively general, and considerable bridge pad through after the use of regular period various diseases has taken place, as ageing of rubber, be full of cracks, external drum, come to nothing, steel plate exposes corrosion, support displacement transfinites etc.Particularly the bearing permanent deformation of Ramp bridge, curved bridge is serious, and the bearing failure phenomenon occurs repeatedly, and the reflection disease appears in bridge floor, pier stud, has influenced the normal use of bridge, has shortened the application life of bridge.Also have some to stride the less simply supported girder bridge in footpath bearing just is not set originally, under the load action of present large-tonnage, heavy traffic, it is severe more that the problem of bearing becomes.

Because the extensive use of neoprene bearing on bridge, recoverable amount increases year by year, and as time passes, a lot of diseases have in use also appearred in bearing.

The bent cap design of many early stage beam bridges is adopted mostly in the way of putting the local stiffener of support position, do not have outstanding bearing pad stone, or bearing pad stone is arranged but insufficient height, cause bent cap and beam body bottom spacing headroom minimum, can't put ordinary jack, more not have effective operating space.Therefore, the bearing replacement of this type of bridge has become suitable stubborn problem.And for the needs of the normal use, traffic safety and the communications and transportation that guarantee bridge, especially on speedway and urban express way, must not carry out totally-enclosed to traffic in the road construction, must guarantee The coast is clear, do not interrupting or shortening under the situation of the time that suspends traffic as far as possible the bearing that can not normally use is changed construction, this has just proposed new challenge to bridge pad replacing construction technology.

Traditional bearing replacement method is to set up support under bridge, or sets up bracing frame by pier, places jack thereon, then classification jacking synchronously.In order to guarantee balance, each jacking stroke is measured every grade of top lifting height of each beam by the dial gage that is arranged at the bottom of the beam generally in 3mm, difference occurs and adjusts at any time.Because the jack stroke is difficult for accurately control, support (or support) distortion etc., every grade of jacking need be adjusted repeatedly could balance, and every grade of jacking needs for a long time.In the jacking process, because jack stroke difference, cause each back rise difference, each depth of beam difference is equivalent to beam applied forces displacement, jack was born at the bottom of the weight of the beam that the jacking amount is little will be transferred to the big beam of jacking amount, if limiting case will appear in the jack leakage of oil, the weight of leakage of oil jack institute lifting beam will all be transferred to the jack that is positioned at the bottom of other beams and bear, and lateral ties have been born the transmission of power between beam.And lateral ties only consider to bear mobile load in the bridge design, and two beams support as it, horizontal span is less, and during asynchronous jacking, the beam both sides lateral ties that stroke is little are equivalent to be bearing on the adjacent beams at interval, and span has increased by one times, and the internal force of lateral ties certainly will heighten, this may cause destructions such as cracking considerably beyond its design bearing capacity.Because the uncertain factor in the bridge jacking process is more, for guaranteeing safety, close traffic piggybacking construction on highway during jacking.

Changing the whole bag of tricks of bridge pad, is to place jack bridge superstructure top (hanging) is risen on firm supporting mostly.Because the replacing method of bridge pad is subjected to the restriction of riverbed geology, the depth of water and various natural environments, bridge construction form and bridge pier form have nothing in common with each other, and use the form of bearing also inequality, thus method also varied, suit measures to local conditions.The common method of bearing replacement has:

1) sleeper is abound with the cribbing method

Sleeper is abound with cribbing method operating principle for sleeper to be set on the ground under the spanning, based on sleeper, be provided be abound with or the part timbering to the bridge beam body place, on support, settle the method for jack lifting beam body.This method construction period is long, and support and template consume steel, the wood amount is big, and the cost height is not suitable for the too high occasion of bridge pier, has the too soft occasion of water, ground to be restricted below spanning, and influences traffic under the bridge.

2) integral jacking method

The operating principle of integral jacking method is similar with the sleeper method, and supporting surface is newly-built jacking basis, bridge pier bottom.This method only is applicable to that non-navigable river, river discharge do the bridge that handle in the cofferdam than I.Foundation under the spanning is had relatively high expectations, need build the jacking basis, the duration is longer, for the hole stride down water, ground is soft or bridge pier is too high occasion is also inapplicable.

3) " saddle type support " method

Above the lift-up method of two kinds of forms all be to be brace foundation with ground, jacking behind the falsework is installed.Saddle type support is to adopt directly to set up support on bent cap, promptly does supporting with bent cap itself, is designed to " saddle type support " and places jack, goes up the method for lifting beam body at " saddle type support ".This method needs bent cap is carried out eccentric compression, flexural strength checking computations, and some bridge must leave the bearing platform type built-in fitting on pier, and the jack of beam both sides, Jacking point require symmetrical precision height, and wants the elevation of strict control beam in the jacking process.

4) steel shoulder pole girder method

The Support Position of steel shoulder pole girder method is on bridge floor, and bearing surface is the adjacent beam body of striding of lifting beam.Punching, tie up steel strip on lifting beam, settle girder steel, is brace foundation with the adjacent beam body of striding, and cooperates Lifting Equipment, lifting beam body.This method is bigger to the bridge floor local pressure, need check local pressure.

5) bridge floor steel nose girder method

The Support Position of bridge floor steel nose girder method is on bridge floor, and bearing surface is the adjacent beam body of striding of lifting beam.Colligation steel band on lifting beam is settled girder steel, is brace foundation with the adjacent beam body of striding, and cooperates Lifting Equipment, lifting beam body.This method girder steel limited length system, striding the footpath can not be excessive, requires to use than large-tonnage jack, bigger to the bridge floor local pressure, might damage the beam body, needs local pressure is checked.

6) " Very Low Clearance gasbag-type jack " replacing method

This method is satisfying the directly little requirement of top lifting and jacking gap on bent cap on the physical dimension, force analysis when jack-up is constructed also meets relevant requirements fully simultaneously, with regard to the rigidity and bridge abutment integral of bent cap, it is feasible replacing other supporting forms with it.The shortcoming of this method be (1) since during jacking contact area bigger, cause lifting surface area bigger, it is certain to be full of back air pressure, makes top lift less; (2) be subjected to the restriction of air bag plenum space, stroke is little.

Summary of the invention

The invention provides a kind of device of jacking bridge.

The device of jacking bridge provided by the invention comprises jack, oil pump and flow divider, is two above self-locking jack are passed through the flow divider parallel connection, unifies fuel feeding by oil pump.

The present invention also provides a kind of method of jacking bridge.

The method of jacking bridge provided by the present invention is to adopt said apparatus jacking bridge.

In jacking bridge process, the self-locking nut of described self-locking jack and the gap of oil cylinder are less than 1mm.

Described jacking can be adopted the classification jacking, every grade of jacking 3-10mm.

In jacking bridge process, the stroke of two above self-locking jack of described device is identical.

The stroke of described two above self-locking jack is identical can be realized as follows: supply identical pressure by flow divider to described two above self-locking jack by same oil pump.

The application of described device in changing bridge pad also belongs to protection scope of the present invention.

The application of described method in changing bridge pad also belongs to protection scope of the present invention.

The present invention uses on-site investigation according to bridge rubber bearing, analyzed the neoprene bearing source of damage, and simulation bridge jacking process, superstructure is set up spatial finite element model, analyzed the stressed of structure under the various rough sledding, determined the jack layout, type selecting, the jacking operating procedure, creatively synchronization of jacking up and self-locking jack are combined, a kind of method and isolated plant thereof of not close traffic jacking bridge are provided, and the public iron grade separation of good fortune speedway K104+159 in Beijing is used, obtain positive effect, realized the bearing replacement under the uninterrupted traffic situation.

Device construction provided by the invention is uncomplicated, and each element relativeness is clear and definite, and operating procedure is simple, can operate through certain training, and it is little to apply difficulty.Use apparatus and method of the present invention and change bearing, the vehicle that can avoid close traffic to bring blocks up, and alleviates vehicle and dredges, shunts the pressure that brings, and has tangible economic benefit and social benefit.

Following embodiment is convenient to understand better the present invention, but does not limit the present invention.

Description of drawings

Fig. 1 is operating mode I-1 end diaphragm place principal tensile stress distribution map.

Fig. 2 is near the stress envelope operating mode I-1 tensile stress extreme value place.

Fig. 3 is operating mode I-2 end diaphragm place principal tensile stress distribution map.

Fig. 4 is near the stress envelope operating mode I-2 tensile stress extreme value place.

Fig. 5 is operating mode I-3 end diaphragm place principal tensile stress distribution map.

Fig. 6 is near the stress envelope operating mode I-3 tensile stress extreme value place.

Fig. 7 is operating mode II-1 end diaphragm place principal tensile stress distribution map.

Fig. 8 is near the stress envelope operating mode II-1 tensile stress extreme value place.

Fig. 9 constitutes schematic diagram for jacking bridge beam body isolated plant.

Figure 10 is that (1 is fixed orifice to isobaric flow divider structure principle chart; 2,3 is oil outlet; 4 is valve body; α is the grease chamber).

Figure 11 is a T beam bridge jack arrangement diagram.

Figure 12 arranges schematic diagram for the vernier caliper measurement basic point.

Figure 13 arranges schematic diagram for dial gage.

Figure 14 is the public iron grade separation of a Beijing-Fuzhou expressway position of centre of gravity schematic diagram.

Figure 15 is an automobile-surpass 20 grades of vertical cloth to carry figure.

Figure 16 is that trailer-120 grade vertical cloth carries figure.

Figure 17 is the preliminary arrangement diagram of jack.

Figure 18 is the jack arrangement diagram.

Figure 19 is the steel plate of band stirrup.

Figure 20 adds pading plate for bent cap.

Figure 21 is the jack installation drawing.

The specific embodiment

The present invention is by simulation bridge jacking process, superstructure is set up spatial finite element model, analyze the stressed of structure under the various rough sledding, jack layout, type selecting, jacking operating procedure have been determined, creatively synchronization of jacking up and self-locking jack are combined, a kind of method and isolated plant thereof of not close traffic jacking bridge is provided.

The inventive method to set up process specific as follows:

One, the computational analysis of jack synchronization of jacking up

(1) layout of jack

1, the layout of jack needs the factor that emphasis is considered

1) desired design end reaction or claim top lift during the girder construction jacking;

2) locus on bridge pier structure form and the bridge pier and permission top lifting height;

3) span of girder construction, cross sectional shape, simply supported beam or continuous beam;

4) the concrete design strength grade of girder construction and bridge pier;

5) the maximum top lift of desired single jacking jack and jack height, outside dimension etc.;

6) to change model (fixed bearing or freely movable bearing) quantity, the position of neoprene bearing;

Do not allow when 7) changing bearing and suspend traffic.

2, jack arrangement principle

For jack center and the bridge superstructure center of making a concerted effort of making a concerted effort is overlapped, and superstructure is stressed less, jack should be arranged near the bearing, and suitably adjust its position, the as close as possible bearing of jack is installed, and avoided bearing replacement is impacted.Jack is subjected to the force direction out of plumb during jacking, may cause the superstructure horizontal-shift, also fragile jack, thereby jack is stressed should be vertically upward, level is answered in the jack bottom surface, and jack end face billet also should be parallel with the jack end face, and at beam (plate) bottom surface cushioning wedge-shaped steel plate to adapt to deck transverse slope, billet thickness is big as far as possible, reduces the space that occurs between steel plate.

Jack is arranged different with the bearing position, and the center to little with the support position deviation, therefore influences little at vertical bridge to the superstructure longitudinal stress but it is made a concerted effort.The jack direction across bridge is arranged with support position relatively large deviation, and lateral ties are stressed different with design during jacking.The internal force of lateral ties member (as T beam diaphragm) and near the local stress the jack supporting-point under dead load, the mobile load effect when analyzing jacking, when lateral ties internal force surpasses its ultimate bearing capacity, suitable mobile jack position or increase bearing area recomputate check, if internal force still has more greatly and transfinites after adjusting several times, can consider to increase jack quantity, reduce the bearing capacity of each supporting-point, the superstructure load is disperseed.When jack end face local stress transfinited, can adopt increased a pading plate number of plies, and jack load is distributed in a wider context, reduces local stress.If limited space system also can consider to increase jack quantity, the quantity that increases supporting-point reduces local stress.

3, jack quantity is determined

Arrange the number of the principle selection jack of a jack by every beam (plate), the counter-force that produces at the jack place according to superstructure dead load, mobile load is calculated and is selected suitable jack top lift then, if the space is restricted or for reducing the local stress of each supporting-point, can consider to increase the quantity of jack, but for for the purpose of the easy construction, still to use the jack minimum number to be advisable.

4, jack type selecting

Under the situation of close traffic not, adopt the jack parallel connection of same model, unify fuel feeding by same oil pump, realize synchronous classification jacking.Consider that impact, the jack oil sealing owing to vehicular load is aging in the jacking process, piston or cylinder body damage etc. are caused in the top partially; the situation that occurs the jack leakage of oil through regular meeting; the stressed disadvantageous situation of lateral ties still can appear in the superstructure of synchronization of jacking up at this moment; therefore adopt the mechanical self-latching type jack; the classification jacking; self-locking synchronously, stressed after the self-locking by the self-locking device instead of piston, thoroughly avoided the asynchronous damage that causes lateral ties of beam body.The top lift of jack need be considered superstructure dead load, mobile load and impact force thereof etc.

The superstructure dead load comprises deck paving, anticollision barrier, beam (plate), diaphragm etc., calculates its weight and position of centre of gravity according to the material type and the distribution situation of each member, determines jack quantity and layout thus.Because hydraulic oil pressure equates in the jack parallel connection, oil cylinder, even the lateral direction of car unbalance loading, by lateral ties between beam (plate), vehicular load and impact force thereof also are evenly distributed to each jack.

Because bridge is when concrete pouring, have phenomenons such as running mould, bloated mould, promptly there is super side in concrete, and the superstructure actual mass is generally greater than design dead load weight, therefore when calculating the superstructure dead load, generally multiply by 1.10 coefficient after calculating theoretical weight by drawing.Load-carrying vehicle ubiquity overload, these factors and vehicular impact power are difficult to accurate Calculation, multiply by 1.3 coefficient and consider as a whole on the basis of designing and calculating mobile load.

According to the maximum counter-force that superstructure dead load, mobile load produce on each jack, consider unfavorable factors such as overload of vehicle and jacking unbalance loading, multiply by 2 times safety factor by the maximum counter-force of calculating, determine the top lift of girder construction.

The maximum top lift of jack=1.10 * dead load/very heavy useful+1.3 * mobile load/very heavy serving as a fill-in

The maximum top lift of the specified top lift of jack=2 * jack

(2) bent cap, beam (plate) partial pressing are calculated

Check with reference to " highway reinforced concrete and prestressed concrete bridge are contained design specifications " (JTG D62-2004) 5.7.1 bar method.Local compression face size should satisfy formula:

γ ₀F _ld≤1.3η _sβf _cdA _ln

$\mathrm{\β}=\sqrt{\frac{A_b}{\mathrm{Al}}}$

In the formula: F _LdLocal pressure design load on the-local receiving area, i.e. jack top lift;

f _Cd-concrete axial compressive strength design load;

β-concrete partial pressing intensity improves coefficient;

A _bCalculating floor space during-local compression;

A _Ln, A _l-concrete local compression area, when local compression face has hole, A _LnBe the area behind the deduction hole, A _lFor not deducting the area of hole.Local compression area A on the bent cap _lFor the jack cylinder floor space counts the area that billet enlarges by 45 ° of rigidity angles; Local compression area on the beam (plate) counts the area that the billet gross thickness enlarges by 45 ° of rigidity angles for the jack piston area.

Above-mentioned bent cap, beam (plate) partial pressing calculate and show, when between beam (plate) and bent cap, putting into the jack synchronization of jacking up, by adding pading plate in jack end face, bottom surface, the contact area of jack bottom surface and bent cap, piston and beam (plate) is enlarged, bent cap, beam (plate) concrete partial pressing intensity are no more than its design strength, bent cap, beam (plate) concrete partial pressing safety during jacking.

(3) the lateral ties force analysis during beam (plate) jacking

Be example with the T beam bridge now, to bearing replacement, the stressed of diaphragm analyzed in the jack jacking process with ANSYS software.

1, bridge brief introduction

Freely-supported T beam bridge is striden 30 meters in footpath, 33.5 meters of bridge floor overall withs, and bridge divides 3 * 3.75 meters in each 3 track of uplink and downlink, and central authorities cut apart and are with 3.0 meters, 3.5 meters of both sides hardened verges, 2 * 0.5 meters of both sides anticollision barriers.7 T beams of bridge direction across bridge, 2.45 meters of case bays, T beam, diaphragm adopt 50 ^#(the tensile strength standard value is f to concrete _Tk=2.59Mpa), bent cap adopts 30 ^#Concrete.Design load vapour-20 grade, hang-100.

2, design condition

By each jack position difference, divide following various computing operating mode:

Operating mode I jack is arranged in T beam limit:

The I-1 dead load;

I-2 dead load+mobile load (not considering combination coefficient);

The I-3 dead load (is removed a jack.During the simulation bearing replacement, certain jack leakage of oil situation appears);

I-4 dead load+mobile load (removes a jack.If I-3 does not meet the demands, then do not carry out this condition calculating).

Operating mode II jack is arranged in the middle of the diaphragm:

The II-1 dead load;

II-2 dead load+mobile load (, then not carrying out this condition calculating) if II-1 does not meet the demands.

1) ANSYS model

T beam and diaphragm all use solid element (solid65) to simulate, and deck paving is not considered rigidity, only as load, consider by evenly distributed load.Full-bridge is totally 107018 nodes, 26880 unit.

2) result of calculation

Below do a summary with regard to each condition calculating result:

Operating mode I-1, end diaphragm place principal tensile stress distributes and sees Fig. 1, stress distribution is seen Fig. 2 near the tensile stress extreme value place, by calculating as can be known, only consider the dead load effect, during synchronization of jacking up, the principal tensile stress maximum value occurs on T beam and the diaphragm interface, maximum principal tensile stress is 2.33Mpa, less than concrete tensile strength standard value 2.59Mpa.

Operating mode I-2, end diaphragm place principal tensile stress distributes and sees Fig. 3, and stress distribution is seen Fig. 4 near the tensile stress extreme value place, under the acting in conjunction of dead load and vehicle, during synchronization of jacking up, the principal tensile stress maximum value occurs on T beam and the diaphragm interface, and maximum principal tensile stress is 2.39Mpa, less than concrete design tensile strength 2.59Mpa, hence one can see that, when jack is arranged in T beam limit, carry out synchronization of jacking up under the situation of uninterrupted traffic, bearing replacement is safe.

Operating mode I-3, end diaphragm place principal tensile stress distributes and sees Fig. 5, stress distribution is seen Fig. 6 near the tensile stress extreme value place, under the dead load effect, during the construction of simulation bearing replacement, there is a jack leakage of oil to occur and cisco unity malfunction phenomenon (removing a jack), the principal tensile stress maximum value occurs on T beam and the diaphragm interface, maximum principal tensile stress is 4.51Mpa, greater than concrete design tensile strength 2.59Mpa, thereby will cause that cracking appears in the stress raiser concrete, influences structure and construction safety this moment.

For analyzing the different positions of jack to the stressed influence of diaphragm, now get ultimate limit state, jack is supported on the diaphragm centre position.Operating mode II-1, end diaphragm place principal tensile stress distributes and sees Fig. 7, stress distribution is seen Fig. 8 near the tensile stress extreme value place, under the dead load effect, jack is arranged in the diaphragm centre position, the principal tensile stress maximum value occurs on T beam and the diaphragm interface, and maximum principal tensile stress is 3.19Mpa, greater than concrete design tensile strength 2.59Mpa.And the above tensile stress of 3Mpa has also appearred in T web in a big way, and Large Area Cracking will appear in concrete this moment, influence structure and construction safety.

3) conclusion

By the computational analysis of above each operating mode, it is as follows to reach a conclusion:

1. jack should be arranged near the T web, as far as possible near bearing, change the bearing construction but can not influence, and the jack center should be consistent with the diaphragm center line.

2. by calculating as can be known, the vertical internal force of superstructure and beam (plate) are bearing on the bearing basic identically during synchronization of jacking up, and lateral ties internal force is no more than the member ultimate strength, but the asynchronous meeting of jacking causes that the internal force of lateral ties is above its ultimate strength.Therefore close traffic does not carry out the bearing replacement construction and can realize, but should carry out sufficient preparation before the construction, should strict be undertaken by construction requirement and operating sequence in the construction, guarantees that the beam body is synchronous, integral jacking.

3. self-locking jacking synchronously is the unique conditional that guarantees structural safety, should detect each beam (plate) top lifting height at any time, deviation occurs and in time adjusts, and guarantees that each beam (plate) is synchronous.

4. consider that impact, the jack oil sealing owing to vehicular load is aging in the jacking process, the effect of factors such as piston or cylinder body damage is caused on the top partially, the phenomenon of leakage of oil may take place in jack, at this moment superstructure jacking is asynchronous, can occur that lateral ties are stressed to be surpassed permissible value and influence structure and construction safety, therefore adopt the mechanical self-latching type jack, synchronization of jacking up, classification self-locking, stressed after the self-locking by the self-locking device instead of piston, thoroughly avoided the asynchronous damage that causes lateral ties of beam body.

When 5. vehicle unbalance-loading was arranged, because each jack parallel connection, pressure was identical in its oil cylinder, by the transmission of lateral ties between beam (plate), guarantees that still each jack top lift is identical.

Two, the foundation of the synchronous self-locking raising method of uninterrupted traffic

(1) synchronization of jacking up principle

1, equipment constitutes schematic diagram

The formation schematic diagram of jacking bridge isolated plant is seen Fig. 9.

Oil pump is connected on the flow divider by an oil pipe, and jack is unified fuel feeding by same oil pump, after oil pump is opened, by flow divider with hydraulic oil distribution to each jack.The effect of isobaric flow divider no matter be magnitude of load, is supplied identical pressure (isobaric shunting) by same oil pump to a plurality of jack in the hydraulic system, keeps synchronously with the stroke of realizing a plurality of jack.

The hydraulic oil pressure that isobaric flow divider is assigned to every jack equates, because each jack piston area is identical, thereby the jack top lift is identical.Flow divider valve opening degree is identical in the jacking process, and this moment, the loss of each jack oil circuit was equal substantially, has guaranteed equating of each oil circuit flow, has promptly guaranteed the unanimity of jack stroke.When oil circuit loses (varying in size as each valve opening of flow divider) when variant, the little jack stroke of oil circuit loss can increase, bigger top lift will be born, pressure will be than the pressure height of other jack cylinders in the oil cylinder, because of each jack cylinder parallel connection, hydraulic oil just initiatively flows to other jack cylinders, makes the pressure of jack cylinder recover identical, has so just guaranteed the synchronism of jacking.

2, the operating principle of isobaric flow divider

Figure 10 is isobaric flow divider structure principle chart.If the imported hydraulic oil pressure is p ₁, flow is q ₁, enter behind the valve by fixed orifice 1, enter a of grease chamber, lead to two jack through oil- out 2 and 3 then.If the load of two jack is equal, then the outlet pressure p of diffluence pass ₂=p ₃, because the size of two branch flow passages is symmetrical fully in the valve, so output flow is also symmetrical, q ₂=q ₃=q ₁/ 2, and p ₂=p ₃When oil circuit loses when variant, oil pressure is asymmetric and p occurs ₂≠ p ₃, and establish p ₂＞p ₃The time, because the drag overall on two branch flow passages is identical, must make q ₂＞q ₃, and then (p ₁-p ₂)＞p ₃, the jack that connected of oil circuit 2 will be born bigger load this moment, the pressure height of the jack that its internal pressure will be connected than oil circuit 3, and because of two jack parallel connections, hydraulic oil just initiatively flows to the jack that oil circuit 3 is connected, i.e. q ₂Reduce q ₃Increase, up to q ₂=q ₃, p ₂=p ₃Till, the pressure of promptly transporting to two jack equates, realizes synchronously.

3, self-locking jack operating principle

Jack is the crane gear of a kind of lifting highly little (less than 1m).It has two kinds of mechanical type and fluid pressure types.Mechanic jacks has rack-and-pinion and spiral two kinds again, because lifting capacity is little, the operation effort generally only is used for flight-line maintenance work.And the hydraulic jack compact conformation, stable working is so use extensively.Hydraulic jack be exactly utilized hydraulic drive based on the most basic principle-pascal's principle, liquid pressure everywhere is consistent, in the system of the balance that is communicated with liquid, applied pressure is smaller above the smaller piston, and applied pressure is also bigger on the big piston, can keep the static of liquid like this.So by the transmission of liquid, can obtain the different pressure on the different ends, so just can reach the purpose of a conversion.

The jack hydraulic transmission is to utilize the working media of the hydraulic oil of pressure as transferring power arranged.Oil pump output hydraulic oil converts mechanical energy the pressure energy of fluid to, and pressure oil enters jack cylinder through piping and distributing valve, promotes piston and lifts weight, is that the pressure with fluid can convert mechanical energy again to.The speed of piston lifting depends on and flows into what of oily volume in the jack cylinder in the unit interval.This shows that the jack hydraulic transmission is the transfer process of a different-energy.

For preventing that reasons such as jack leakage of oil, oil cylinder crack, oil pipe explosion from causing that jack piston descends suddenly, on piston, add self-locking nut, constantly screw self-locking nut in the jacking process, when above situation occurring, the power that acts on the piston is transferred on the jack cylinder body by self-locking nut, be unlikely to because fortuitous event damages beam (plate) or causes the damage of lateral ties.

4, oil pump operating principle

Oil pump directly drives the pump shaft rotation by motor, and under the effect of pitch, plunger pumps along the plunger interplanting, and hydraulic oil sucks through inlet valve, discharges from draining valve, enters system oil-way.Low-lift pump is a gear pump, behind starter motor, is that the low-lift pump fuel feeding is arranged earlier, when the pressure of fuel feeding does not reach the needed pressure of jacking tonnage, will start high-pressure pump and carry out fuel feeding, to reach required pressure.Oil pump is totally two flowlines, the flowline of a low-lift pump, and the flowline of a high-pressure pump, for preventing that impurity causes damage to inside pipe wall after entering oil pipe when pressure is big, each oil-in place all is provided with oil cleaner screen.Oil pump has an oil return pipe, is provided with a reversal valve, a pressure meter at oil return pipe and two flowline junctions, by reversal valve oil mass is set, by the pressure meter controlled pressure.

(2) synchronization of jacking up method

1, support is set up

Scaffold adopts the qualified steel pipe meet national respective standard standard, and steel tube surface should be straight smooth, the crack that do not have, scab, layering, dislocation, hard curved, burr, impression and the dark road of drawing, forbid punching on the steel pipe, should scribble rustproof paint.

The fastener material should meet existing national standard " steel tube scaffold clasp " regulation (GB15831), and the use of forbidding of crack, distortion is arranged, and the bolt that stripped thread occurs must be changed, and should do antirust processing.

(1) sets up principle

Vertical rod: in length and breadth to vertical pole ' s span ≯ 2m, step pitch ≯ 1.8m, ground should flatten compacting, and underground 30～50cm is imbedded in vertical rod, in the time of can not burying ground, answers bolster wood under the vertical rod and adds the bar of sweeping the floor.

Cross bar: in length and breadth to girt step pitch ≯ 1.8m, operation layer cross bar spacing ≯ 40cm.

Bridging: should establish the angle of embrace diagonal brace for four jiaos, bridging is established on four limits, and the centre is longitudinally established bridging one every four row's vertical rods, and diagonal brace and bridging all should from bottom to top be provided with continuously.

Scaffold floor is laid: the frame height in 4m, scaffold floor gap ≯ 20cm, frame is tall and big in 4m, scaffold floor must completely be spread.Scaffold floor can be used material such as steel, wood, bamboo, and every quality should not be greater than 30kg.The stamped steel scaffold floor is that a kind of scaffold floor of using always generally forms with the steel plate compacting of thick 2mm, length 2～4m, and width 250mm, should there be non-skid feature on the surface.China fir plate or pine that the wood scaffold floor can adopt thickness to be not less than 50mm are made, length 3～4m, and width 200～250mm, zinc-coated wire hoop twice all should be established in two ends, destroy to prevent wooden scaffold floor end.The bamboo scaffold floor is then used mao bamboon or bamboo and is made bamboo string sheet plate and bamboo basketry plate.

(2) set up order

Put the bar of sweeping the floor-establish vertical rod by root, immediately with little cross bar of leger-second step in the bar fastening of sweeping the floor-the lay first step little cross bar-second step-add interim hound (upper end and the leger fastening of second step, dismountable behind installing twice wall connecting rod)-third and fourth goes on foot leger and little cross bar-wall connecting rod-connect vertical rod-add word support-shop, location scaffold floor.Little cross bar near vertical rod can be anchored in the vertical rod.

2, jack is arranged

(1) jack is installed

Calculate the weight and the position of centre of gravity of bridge superstructure before the jacking earlier, determine the jack quantity and the tonnage that need.For the sake of security, adopt nominal output greater than the jack that calculates 2 times of counter-forces in the construction.

For jack center and the bridge superstructure center of making a concerted effort of making a concerted effort is overlapped, superstructure is stressed again little, should install by as close as possible bearing when placing jack, but will avoid bearing replacement is impacted.Vertically upward stressed when making jacking, the jack bottom surface must level.If it is imappropriate that jack end face steel plate is placed, also can change by force direction, should guarantee that steel plate is parallel with the jack end face, and the steel plate of cushioning on the jack and rubber tile are closely contacted with diaphragm.Reduce the space that occurs between steel plate, in order to avoid changed by force direction.T beam bridge jack is arranged and is seen Figure 11.

(2) the bent cap end face is handled

Cause reasons such as the local out-of-flatness of bent cap end face owing to building waste residual on the bent cap or construction are not meticulous, the jack bottom surface can produce inclination angle or the part phenomenon of coming to nothing, can make the bent cap local stress excessive during jacking, cause the bent cap concrete to damage because of local stress is excessive, also can cause the jack top partially, the damage jack is so the bent cap leveling is an indispensable operation in the bearing replacement construction.Remove the building waste on the bent cap,, carve preliminary chipping with steel for the local inclination angle of bent cap, not floating concrete, exposed steel bar etc., or cut with after the angle grinding machine cutting, again with the levelling of polishing of angle grinding machine, by spirit level inspection planeness, should continue polishing as injustice, until smooth.

Though bent cap end face concrete through the leveling, rough surface, also there is small hole groove in the part, directly the placement jack can occur pushing up partially, the local compressive stress of concrete is excessive etc., therefore after the leveling of bent cap end face, steel plate of cushioning is evenly distributed on the bent cap jack counter-force.

(3) handle beam (plate) bottom surface

For making things convenient for draining, bridge floor is provided with horizontal wall inscription, the early stage bridge of building is adjusted by the triangle bed course of deck paving, the bridge of building is generally adjusted by the bearing absolute altitude in the recent period,, just there is certain horizontal wall inscription in beam (plate) end, and template deformation, alignment error etc. also make beam (plate) bottom surface out-of-flatness during prefabricated or cast-in-place beam (plate).Because the gap is little between beam (plate) bottom surface and bent cap; upwards cut (or the polishing of angle grinding machine) leveling work difficulty; and steel bar stress layout in superstructure beam (plate) bottom surface is closeer, topping is thinner; cut and to damage steel bar stress; generally only cut (or polishing) concrete that surface local protrudes, use the wedge-shaped steel plate leveling then.

The jack piston area is less, the compressive stress of its end face is identical with in-oil cylinder oil pressure, press the jack that the specified top lift of jack is selected greater than 2 times of principles of superstructure weight, when considering other unfavorable factor, its oil pressure also reaches 30～40MPa, be that the piston-top surface average compressive stress is 30～40MPa, high like this action of compressive stress will make beam (plate) damage because of partial pressing is too high in beam (plate) bottom surface.Therefore should pass through the cushioning multilayer steel plates, increase effective pressure area and disperse local compressive stress, reduce lifting beam (plate) bottom surface compressive stress.

(4) jack is installed

After the levelling of bent cap end face, the steel plate that cushioning 20mm is thick, a limit of steel plate is parallel with bearing pad stone, and near the pinner edge, places jack then, and the jack oil nozzle should be convenient to be connected with flow divider towards span centre.

Because range estimation is difficult to the steel plate centre of form is overlapped with the jack piston centre of form, on steel plate, weld the stirrup of an internal diameter in advance than the big 1～3mm of jack piston diameter, the stirrup center of circle overlaps with the steel plate centre of form, jack piston is ejected about 10mm, its end face adds the steel plate of rim strip stirrup, just guaranteed that steel plate overlaps with the jack piston centre of form, has avoided the steel plate off normal.

Because beam (plate) bottom surface concrete out-of-flatness, when steel plate directly contacted with its bottom surface, because of the contact leakiness, the compressive stress that the contact position produces may exceed the local resistance to compression bearing capacity of concrete, causes beam (plate) bottom surface concrete destruction; Stressed evenly for the contact surface that makes steel plate and beam (plate) bottom surface, be encased inside the rubber tile of thickness 10mm in steel plate and beam (plate) junction, make steel plate contact closely knit with beam (plate).

There is horizontal wall inscription beam (plate) bottom surface, cushioning plain plate only, to there be a wedge gap at steel plate and beam (plate) bottom surface, after the jack carrying, steel plate and beam (plate) are closely connected, just have wedge gap between steel plate and jack piston end face, top partially appears, cause jack to damage, so under rubber tile, be encased inside a bottom surface level, end face and the identical wedge-shaped steel plate of beam (plate) end horizontal wall inscription.

Continue cushioning 20mm steel plate then under wedge-shaped steel plate, in the time can not being encased inside the 20mm steel plate again, measure the gap between steel plate, the steel plate of choosing and gap same thickness is with beating, make contact between steel plate closely knit.Adjustment at last adds pading plate aligns with jack piston end face steel plate, makes all steel plate centres of form on a plumb line, overlaps with the jack piston centre of form.

(5) processing that is connected between superstructure and bent cap

Because construction deviation or mistake, may there be unnecessary the connection between beam (plate) and bent cap, race mould, spillage as cast abutment parados are connected as a single entity abutment and beam (plate); Block cast error causes beam (plate) and block closely connected; The slab bridge crab-bolt is an one etc. with hinge seam concrete casting.The existence that these do not have and connect, the one, the top lift when having increased jack-up, the 2nd, damaged member during jacking strong excessively also can cause jack overload, structural failure when being connected jacking, jeopardizes bridge security, answers scrutiny before jacking, removes these connections.

3, measuring apparatus is arranged

(1) measurement of top lifting height

Because construction error, every beam (plate) is different with the gap between bent cap, the steel plate number of plies difference that the jack end face is encased inside; Institute's pading plate is by manually-operated, and the slit is not of uniform size between steel plate; Steel plate not exclusively smooth (as warpage etc.) also makes slit difference between steel plate, these slits when the jack jacking by compacted, under the identical situation of jack top lift, the jack stroke can be variant, with the top lifting height of jack piston stretch value as each sheet beam (plate), there is initial measured error, can not guarantee that each sheet beam (plate) is synchronous, the absolute value added in gap is only the height of the real jacking of beam (plate) between beam (plate) and bent cap, therefore should measure the absolute value added in every beam (plate) and bent cap gap, as the top lifting height of this film beam (plate),, carry out Synchronization Control with the top lifting height comparison of other beam (plate).

(2) dial gage is arranged

The top lifting height of every beam (plate) can be measured with long gauge length slide measure or long range dial gage, when using vernier caliper measurement, earlier one fixed point is set in bent cap side suitable location, hang vertical line and determine the projected position of this point in beam (plate) bottom surface or side, fixing behind the mark, see Figure 12, the increase of this two fixed points spacing is exactly the top lifting height of this film beam (plate).When measuring with dial gage, every beam (plate) bottom surface or near the diaphragm bottom surface dial gage is installed, dial gage is fixed on the bent cap end face, its measuring stick is vertical with beam (plate) bottom surface, see Figure 13, the variation of every beam (plate) dial gage reading is exactly the top lifting height of this film beam (plate).

(3) oil pressure gauge is arranged

Jack top lift available pressure sensor or oil pressure gauge show, because of pressure sensor takies the jacking space, need join rereading equipment, reasons such as complicated operation, and the easy oil pressure gauge of general employing carries out top lift control in the construction.

Jack top lift and oil pressure are proportional, have recorded oil pressure, just can converse the top lift of jack.Oil pump arrives each jack by flow divider with hydraulic oil distribution, and because of in parallel between each jack, tubing length equates, the resistance of ducting of hydraulic oil is basic identical, the oil pressure that is assigned to each jack cylinder is also closely equal, is easy and simple to handle therefore, can only establish an oil meter at oil pump and measure oil pressure.

4, change the selection of time

Bearing is the important component that connects bridge top and the bottom structure, bearing and giving pier the superstructure Load Transfer, and the function of damping, vibration isolation, adaptive temperature distortion.Tetrafluoro slide plate bearing adapts to the temperature deformation of superstructure by the slip between superstructure and bearing, and neoprene bearing adapts to the temperature deformation of superstructure by the shear strain of bearing, and its deflection temperature difference of temperature when temperature was installed with beam (plate) at that time is directly proportional.Temperature when neoprene bearing is installed should so that bearing produces minimum shear strain, reduce the stressed of bearing near average temperature of the whole year, improves its durability.Some bridge is owing to reason such as trying to meet the deadline for the project, and bearing is installed near average temperature of the whole year, has produced bigger distortion, should eliminate during replacing.Therefore bearing replacement is implemented near preferably being selected in average temperature of the whole year, but because the duration restriction, and the replacing time can not be entirely at spring and autumn, can be selected in nighttime temperature during hot weather construction and change when low, and is at noon optional or change when afternoon, temperature was higher during winter construction.

Because close traffic is changed bearing, the gravity of vehicle, impact will make the instantaneous increase of oil pressure, and the jack-up system job stability is had certain influence.This highway section vehicle flowrate of reply is observed before going into operation, and selects vehicle flowrate less, and especially the period that the heavy-duty freight car flow is little is carried out the jacking operation, reduces the influence of vehicle to jack-up system.Should take into full account temperature and vehicle flowrate size, select suitable time to change bearing.

5, examination top

After the jack installation, jack, flow divider, oil pump are connected with high-pressure oil pipe, flow divider to the tubing length of each jack will equate.Try the top before the formal jacking earlier, check whether the synchronization of jacking up system works is normal, whether the jack center of making a concerted effort overlaps with the superstructure center of gravity, and whether the top and the bottom structure exists undissolved connection etc.The examination heights of roofs breaks away from bearing control with all beams (plate).Examination top step is as follows:

(1) open oil pump to the jack fuel feeding, after jack pair beam (plate) applied power, oil pressure began to raise, and the oil pressure gauge reading increases gradually, and slow down fuel supply flow rate this moment, and the oil pressure gauge reading is steadily increased.When the jack top of oil pressure correspondence power reach the superstructure calculated weight 70% the time, voltage stabilizing 3 minutes, observe synchronization of jacking up system, beam (plate), bent cap have no abnormal (as jack leakage of oil, oil pipe snap joint leakage of oil, pressure fuel pump deficiency, flow divider open not enough, concrete cracking is broken, top is inclined to one side, steel plate misplaces or the like), whether measurement has beam (plate) by jack-up etc.Occur unusually as synchronous jack-up system, beam (plate), bent cap, the oil return post processing by jack-up, illustrate that the jack center of making a concerted effort does not overlap with the superstructure center of gravity if any beam (plate), should adjust the jack position, pressurizes once more.

(2) oil pressure is added to corresponding jack top lift and reaches 90% of superstructure calculated weight, voltage stabilizing 3 minutes, observing synchronization of jacking up system, beam (plate), bent cap once more has no abnormally, measures whether beam (plate) is arranged by jack-up, if any unusually, repeating step after the oil return (1), (2).

(3) oil pressure is slowly added, observing synchronization of jacking up system, beam (plate), bent cap has no abnormally, has when unusual, handles back repeating step (1), (2).Whether measure beam (plate) simultaneously by jack-up, and examine part beam (plate) and whether break away from bearing, when the whole disengaging synchronously of beam (plate) bearing occurring, close oil pump, voltage stabilizing 5 minutes, observing synchronization of jacking up system, beam (plate), bent cap has no abnormally, has and repeats above step when unusual, examination is pushed up successfully when no abnormal, prepares formal jacking after the oil return and changes bearing.When part beam (plate) disengaging bearing occurring, the jack position is adjusted in oil return, repeats above step and breaks away from bearing synchronously up to beam (plate).

(4) if the jack top lift of oil pressure correspondence reaches 100% of superstructure calculated weight, beam (plate) does not all break away from bearing, and voltage stabilizing was observed in 3 minutes, as no abnormal, continues slowly pressurization, and operate (3) set by step.

(5) if the jack top lift of oil pressure correspondence reaches 105% of superstructure calculated weight, the voltage stabilizing 3 minutes back rest (plate) does not all break away from bearing.Reason is checked in oil return, if there is contact in the top and the bottom structure, should remove; If the super side of superstructure concrete should estimate the superstructure actual weight, by actual weight control top lift.Repeating step (1)～(4) once more after the issue handling.

6, bearing is changed in jacking

(1) synchronization of jacking up

After finish on the examination top, select the time that temperature is suitable, vehicle flowrate is little to carry out jacking, change bearing.Open oil pump to the jack fuel feeding, when treating the oil pressure of beam (plate) jack-up when oil pressure pushes up near examination, slowly fuel feeding, pressurization, while rotary self-locking nut, in whole jacking process, remain gap between nut and jack cylinder in 1mm, occur in order to the synchronization of jacking up system that self-locking device replaces jack piston stressed when unusual.

The jacking classification is carried out, every grade of 3～10mm, first every grade of 3mm of jacking, obtain experience after, can strengthen every grade of top lifting height gradually.During every grade of jacking, every beam (plate) is joined two operating personnel, one people is responsible for the rotary self-locking nut, one people is responsible for measuring top lifting height, when the top lifting height of a slice beam (plate) reached height at the corresponding levels, the top lifting height of every beam (plate) was measured in voltage stabilizing 3 minutes, if synchronous or every beam (plate) accumulative total at different levels maximum deviation during less than 1mm, can continue the next stage jacking.If every beam (plate) top lifting height deviation greater than 1mm, answers voltage stabilizing to check reason, common reason has:

1. the asynchronous rise of beam (plate) a side height occurs, a side is low, but each sheet beam (plate) top lifting height is proportional, and this is not overlapped with superstructure gravity center of gravity and caused by the jack center of gravity of making a concerted effort, and answers oil return to readjust examination top, jack position.

2. the asynchronous rise of beam (plate), certain sheet beam (plate) is bigger than other beam (plate) top lifting height, this is that the lateral ties damage causes between beam (plate), check lateral ties after answering oil return, power according to actual lateral ties, again estimate the top lift that every beam (plate) needs, and calculate the jack position, again the examination top with this.

3. workman's operate miss, in time do not find jack top partially, leakage of oil or the like, in time self-locking releasing and flow divider is connected near the standby jack of the installation damage jack, after flow divider is connected, with other jack synchronization of jacking up to damaging jack when loosening, all normal jack of self-locking are changed the damage jack, after new jack is installed in jack position under changing, repeat above step, change standby jack, continue the next stage jacking.In the jacking process, also will arrange the special messenger that beam (plate), bent cap, pier stud etc. are observed, observation has or not ANOMALOUS VARIATIONS, guarantees that crack, skew do not appear in construction safety and top and the bottom structure.Other anomaly occurs, should stop jacking immediately, ascertain the reason, to guarantee construction safety.

(2) change bearing

After former bearing taken out, whether scrutiny bearing pad stone end face had situations such as concrete breakage, honeycomb, hole, for the bearing that comes to nothing, pading plate on pinner, and with the epoxy mortar levelling to corresponding height, bearing can both be evenly stressed when guaranteeing to fall beam.To neoprene bearing, the japanning that should eliminate rust of the pre-embedded steel slab of its end face beam (plate); To tetrafluoro slide plate bearing, the corrosion resistant plate on the pre-embedded steel slab surface of its end face beam (plate) and bearing tetrafluoro slide plate end face should brushing silicone grease oil, and should replenishing of disappearance corrosion resistant plate accurately put into bearing then.

7, the top is unloaded in oil return

Inspection lay new bearing errorless after, beam body balance classification oil return when guaranteeing the beam beam (plate) that falls, synchronization of jacking up 0.5～the 1mm of elder generation is loosening to self-locking nut, revolves withdrawing nut then, and nut and oil cylinder gap remain in Luo Liang (plate) process and be not more than 1mm and be advisable.The height of the every grade of beam that falls (plate) is identical with every grade of top lifting height, is generally 3～10mm, and every grade of 3mm when changing bearing for the first time can strengthen after experience is arranged gradually.

Beam (plate) is fallen bearing, and after jack did not stress, it was loosening to jack end face steel plate to continue oil return, unload oil pipe after, block-by-block takes off jack end face steel plate, removal jack.When bent cap flattens, the bent cap end face was cut the situation of exposing reinforcing bar deeply, the cleaning concrete surface, be coated with corrosion inhibitor to exposed steel bar after, cut face with the third newborn mortar repairing.

Experimental technique among the following embodiment if no special instructions, is conventional method.

Embodiment 1, the not application of close traffic jacking bridge, replacing bearing

Present embodiment is connected in parallel on the same model jack on the isobaric flow divider, by same oil pump feed, has realized that each jack top lift is identical.Self-locking nut rotates with piston stroke when jacking or the beam that falls (plate), guaranteed under various rough sledding jack synchronously, self-locking jack-up system safety, reliable synchronously.Concrete example is as follows:

One, bridge overview

Section K104+159 public iron grade separation in Beijing-Fuzhou expressway Jinan is positioned at Beijing-Fuzhou expressway highway Jinan section, the center pile No. is K104+159, strides the footpath and is arranged as 6 * 30+6 * 30+5 * 30+40+6 * 30+7 * 30+7 * 30m, and superstructure is a prestressed concrete freely-supported T beam, substructure is the pillar pier, pile foundation.33.5 meters of bridge floor overall withs, two high six-lanes, 3 * 3.75 meters in every 3 track, central authorities cut apart and are with 3.0 meters, 3.5 meters of both sides hardened verges, 2 * 0.5 meters of both sides anticollision barriers.15.75 meters of single width bridge overall withs, direction across bridge have 7 T beams, 2.45 meters of case bays, and T beam, diaphragm adopt the 50# concrete (the tensile strength standard value are f _Tk=2.59MPa), bent cap adopts the 30# concrete.Full-bridge is divided into 6, and bridge floor is continuous in the connection.Design load: automobile-surpass 20 grades, hang-120.

According to check finding that the pier structure does not have obvious disease, the superstructure disease is concrete spalling, infiltration, the laminated rubber bearing ubiquity is aging, cracking, bulge, come to nothing, shear strain is big even cut off, most of Dun Ding has building waste.

If bearing is all changed, workload is big, and is long in time limit, and the expense height considers that bearing exists micro-cracks not influence normal use in a short time, changes after can using a period of time, to reduce construction costs, therefore only the bearing that serious plant disease occurs changed.

Two, superstructure is from re-computation

According to design drawing, single span single width superstructure and bridge deck material usage see Table 1.

Table 1 single span single width bridge superstructure, bridge deck material usage sheet

Title	Unit	Side bar				Central sill				Wet seam	Inboard anticollision barrier	Outside anticollision barrier
													The beam rib	Carriageway plate	Diaphragm	Sealing off and covering anchorage	The beam rib	Carriageway plate	Diaphragm	Sealing off and covering anchorage
		Bituminous concrete	m 3		8.4				29.4
Concrete	m 3									25.955	22.045	2.9	0.905	64.89	47.91	14.51	2.27	24.06	9.0	12.3

The steel concrete ratio refetches 25KN/m ³, the bituminous concrete ratio refetches 23KN/m ³, calculate single width according to table 1 and partly step up each member of portion's structure and bridge deck deadweight and position of centre of gravity (Figure 14), see Table 2, wherein G ₁Be interior side rail weight and position of centre of gravity, G ₂Be outer side rail weight and position of centre of gravity, G ₃Be deck paving weight and position of centre of gravity, G ₄Be inboard side bar weight and position of centre of gravity, G ₅Be outside side bar weight and position of centre of gravity, G ₆Weight and position of centre of gravity for diaphragm, 5 central sills, wet seam.

Table 2 single width is partly striden bridge superstructure, bridge deck weight table

Sequence number	The member title	Single-piece weight (KN)	Partly stride quantity	Partly stride weight (KN)	To bridge distance between center line (m)
						1	Inboard side bar	611.3	1/2	305.7	1.775
2	Outside side bar	611.3	1/2	305.7	16.475
						3	Diaphragm	435.3	1/2 strides	217.6	9.125
4	Central sill	575.4	5/2	1438.4
					5	Wet seam	100.3	6/2 strides	300.9
6	Deck paving	869.4	1/2 strides	434.7						9.375
					7	Inboard anticollision barrier	225.0	1/2 strides	112.5		1.0
8	Outside anticollision barrier	307.5	1/2 strides	153.8						17.5
					Add up to				3269.3		9.272

Superstructure and bridge deck from the doubling force center to the bridge distance between center line:

L＝[305.7×1.775+305.7×16.475+(217.6+1438.4+300.9)×9.125+434.7×9.375+112.5×1.0+153.8×17.5]÷3269.3＝9.272m

Three, mobile load calculates

The bridge design load is 20 grades in automobile-surpass, hangs-120, carries by the maximum vertically cloth of its support reaction, calculates the jack top lift.

1,20 grades of mobile loads of automobile-surpass calculate

The automobile that makes fulcrum produce maximum counter-force is arranged and is seen Figure 15, according to bridge deck width, laterally can arrange 3 trains, by ∑ M _B=0 draws:

F _Q＝3×(140×30+140×28.6+120×21.6+120×20.2+30×17.2+130×7.2+70×2.2)÷29＝1533.72KN。

2, trailer-120 mobile load calculates

The trailer that makes fulcrum produce maximum counter-force is arranged and is seen Figure 16, only considers that a trailer is current, by ∑ M _B=0 draws:

F _G＝(300×30+300×28.8+300×24.8+300×22.6)÷29＝1098.62KN。

Automobile-surpass 20 grades of end reactions greater than trailer-120 end reaction is got 20 grades in automobile-surpass for calculating the control mobile load.

Four, jack is arranged and type selecting

1, jack is arranged

According to the jack arrangement principle, because of the outer side rail of T beam superstructure is heavier than interior side rail, jack answers the biased outward guardrail to arrange, adjusts superstructure dead load center of gravity and jack the overlapping of center of gravity of making a concerted effort.7 T beams are arranged 7 jack at least, overlap for making jack center and the T beam superstructure center of making a concerted effort of making a concerted effort, and superstructure are stressed less, and jack is arranged near the bearing, and suitably adjusts its position, avoids bearing replacement is impacted.

The preliminary layout of jack seen Figure 17, and its center of gravity to distance of bridge center line of making a concerted effort is

L _D1＝(2.295+3.705+6.155+9.645+12.095+14.545+15.955)÷7＝9.199m。

The superstructure center of gravity is 9.272m to the bridge distance between center line, do not overlap with the jack center of gravity, adjust the jack position, because of outer side rail heavier, should with jack laterally the guardrail direction move, side bar jack position is motionless, through tentative calculation, only jack D, E, the F of mobile central sill, adjusted value 0.17m, this moment the jack top lift distance of center of making a concerted effort to the bridge center line:

L _D2＝(2.295+3.705+6.155+9.815+12.265+14.715+15.955)÷7＝9.272m。

The jack of finally taking is arranged and is seen Figure 18.

2, jack type selecting

According to the superstructure dead load, the mobile load that calculate, consider unfavorable factors such as overload and jacking unbalance loading, required jack top lift is:

Jack top lift=(1.10 * dead load+1.3 * mobile load)/very heavy serving as a fill-in

＝(1.10×3269.3+1.3×1533.72)÷7＝798.58KN

The maximum top lift of jack specified tonnage=2 * jack=2 * 798.58=1597.2KN

Select the jack of CLP-1602 model, supporting capacity is 160 tons, and stroke is 45mm, and oil mass is 1040cm ³, this height is 148mm, weight is 44kg.Available from U.S. enerpac grace Parker company, article No. is EN-P1601.

Five, jacking is prepared

1, support is set up

This bridge substructure is a twin shaft pier, and bridge pier is higher, need set up operating platform, carries out the ground leveling earlier, guarantees the stability of scaffold.Direction across bridge is put 4 bars of sweeping the floor, and 2 near pier stud, all the other 2 root distance pier stud 1.0m, and the bar of sweeping the floor connects with word deduction and joint staggers; Vertical rod arranges that by spacing 1.5m underground 50cm is imbedded in vertical rod, with the bar fastening of sweeping the floor.Spacing 1.6m of per step of cross bar, direction across bridge connects with word deduction, and joint staggers, and is connected with cross buckle with vertical rod.Progressively connect height then, the pier both sides respectively add diagonal brace two roads during to the 5th step.Take to when the 1.8m of T soffit, lay scaffolding board as working platform, platform outside scaffold is increased a step again as platform railing.

2, the bent cap end face is handled

Shrinkage joint, bridge floor be residual a large amount of building wastes on bent cap in construction or when maintenance continuously, remove the building waste on the bent cap.On bent cap, emit the jack position, irregular bent cap end face is carved the preliminary chipping of cutter with steel, again with the levelling of polishing of angle grinding machine, until qualified with spirit level inspection planeness.

3, handle the diaphragm bottom surface

This bridge is the quadrature bridge, and the diaphragm bottom surface horizontal wall inscription of design is 2%, but because diaphragm distortion, construction deviation etc., diaphragm bottom surface horizontal wall inscription alters a great deal, by the bottom surface chipping constructional difficulties that makes progress, and the easy damaged reinforcing bar.To smooth bottom surface, adopt the wedge-shaped steel plate leveling, to irregular bottom surface, cut off the concrete surface local crowning with the angle grinding machine after, still adopt the wedge-shaped steel plate leveling.Wedge-shaped steel plate is that the steel plate with 300 * 20 * 300mm is processed into thick 20mm on one side, and another side is thick to be respectively 4,6,8,10,12,14,16, the multiple model steel plate of 18mm, selects suitable types according to diaphragm bottom surface slope change during construction.

4, billet is selected

Jack bottom surface diameter 213mm is when acting directly on the bent cap, according to " highway reinforced concrete and prestressed concrete bridge are contained design JTG D62-2004 ", 30# concrete f _Cd=12.88MPa, η _s=1.0; Check in the important coefficient γ of bridge construction according to " highway bridge and culvert design general specification JTG D60-2004 " ₀=1.1.

$\mathrm{\&beta;}=\sqrt{\frac{\mathrm{\&pi;}{\left(3a\right)}^2/4}{\mathrm{\&pi;}{a}^2/4}}=3,A_l=\frac{\mathrm{\&pi;}{a}^2}{4}=356.1{\mathrm{<figure-callout\; id="2"\; label="cm"\; filenames="S2008100579413E00061.png,S2008100579413E00081.png"\; state="\{\{state\}\}">cm</figure-callout>}}^2$

Its partial pressing's intensity of bent cap concrete is:

$F_{\mathrm{ld}}\&le;\frac{1.3{\mathrm{\&eta;}}_s{\mathrm{\&beta;f}}_{\mathrm{cd}}{A}_{\ln }}{{\mathrm{\&gamma;}}_0}=\frac{1.3\&times;1.0\&times;3\&times;12.88\&times;{10}^3\&times;356.1\&times;{10}^{-4}}{1.1\&times;}=1626.15\mathrm{KN}>798.58\mathrm{KN}$

Be that the jack top lift is less than the pressure design value 16261.47KN on the concrete local compression area, pading plate not, it is local concavo-convex and easy to operate to consider that concrete exists, and the billet size is than jack slightly larger in diameter, and the steel plate of selecting 300 * 20 * 300mm for use is as backing plate.

Diaphragm adopts 50# concrete f _Cd=21.64MPa, thickness 16cm, jack piston diameter 120mm when acting directly on the diaphragm bottom surface, is a rectangle with the equivalence of jack piston top surface area.

The equivalence length of side is $a=\sqrt{\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="S2008100579413E00061.png,S2008100579413E00081.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}{4}}=\sqrt{\frac{3.14\&times;{120}^2}{4}}=107\mathrm{mm};$

A _l＝10.7×10.7＝114.49cm ²

A _b＝16×10.7×3＝513.6cm ²

$\mathrm{\&beta;}=\sqrt{\frac{A_b}{A_l}}=\sqrt{\frac{513.6}{114.49}}=2.12$

$F_{\mathrm{ld}}\&le;\frac{1.3{\mathrm{\&eta;}}_s{\mathrm{\&beta;f}}_{\mathrm{cd}}{A}_{\ln }}{{\mathrm{\&gamma;}}_0}=\frac{1.3\&times;1.0\&times;2.12\&times;21.64\&times;{10}^3\&times;114.49\&times;{10}^{-4}}{1.1}=620.74\mathrm{KN}<798.58\mathrm{KN}$

Be the jack top lift greater than the pressure design value on the concrete local compression area, should add billet, increase the concrete local compression area of diaphragm.During cushioning 20mm steel plate, the local compression area is pressed 45 and is enlarged in billet.

The equivalence length of side is a=107+20 * 2=147mm

A _l＝14.7×14.7＝216.09cm ²

A _b＝16×14.7×3＝705.6cm ²

$\mathrm{\&beta;}=\sqrt{\frac{A_b}{A_l}}=\sqrt{\frac{705.6}{216.09}}=1.81$

$F_{\mathrm{ld}}\&le;\frac{1.3{\mathrm{\&eta;}}_s{\mathrm{\&beta;f}}_{\mathrm{cd}}{A}_{\ln }}{{\mathrm{\&gamma;}}_0}=\frac{1.3\&times;1.0\&times;1.81\&times;21.64\&times;{10}^3\&times;216.09\&times;{10}^{-4}}{1.1}=1000.28\mathrm{KN}>798.58\mathrm{KN}$

This moment, diaphragm concrete local bearing strength met the demands, and promptly the billet length of side should be greater than 147mm, and billet thickness should be considered jack size and easy to operate greater than 20mm, and the billet size is identical with jack bottom surface backing plate, selects 300 * 300mm for use.

5, jack is installed

After the levelling of bent cap end face, the steel plate that cushioning 20mm is thick, a limit of steel plate should be parallel with bearing pad stone, places jack then, and the jack oil nozzle should be convenient to be connected with flow divider towards span centre, and jack, flow divider, oil pump are connected with high-pressure oil pipe.

Owing in construction, be difficult to backing plate and jack piston center-aligned are made the stirrup of an internal diameter than the big 2～5mm of jack piston diameter in advance, be welded on one heart on the billet, see Figure 19.Jack ejects 10～15mm in advance, with being with the steel plate of stirrup to be enclosed within on the piston, successively upwards adds pading plate, sees Figure 20.When steel plate and gap, diaphragm bottom surface during less than 100mm, fill in thick rubber tile of 10mm and wedge-shaped steel plate earlier in the diaphragm bottom surface, again that gap filling between wedge-shaped steel plate and billet is closely knit, adjust each piece billet position, make it all to align with each limit of steel plate of band stirrup.Figure 21 is seen in operating process, among Figure 21, and 1) for placing jack; 2) for the jack oil pipe is installed; 3) eject 1～1.5cm for jack; 4) for adding the steel plate of rim strip stirrup; 5) cushioning sheet rubber, wedge-shaped steel plate; 6) tight for the billet filling.

Six, change bearing

1, examination top

Try the top before the formal jacking earlier, check whether the synchronization of jacking up system works is normal, whether the jack center of making a concerted effort overlaps with the superstructure center of gravity, and whether the top and the bottom structure exists undissolved connection etc.

Examination top finds that ubiquity superstructure center of gravity is cut apart band than the center of gravity deflection central authorities of calculating, may be the communication cable support with about width of cloth bridging connect or deck paving thickness difference causes.Because uninterrupted traffic is changed bearing, it is continuous not remove bridge floor during jacking, and actual top lift is more bigger than calculated value.Because the superstructure center of gravity and the actual center gravity that calculate have difference, need to adjust the jack position in the construction, but generally can realize by the secondary adjustment.

2, synchronization of jacking up

Observe by the traffic volume, only morning, vehicle flowrate was less in this highway section, and construction is again in summer, selected morning 4～6 to carry out jacking, changed bearing.During the beginning jacking, every grade of jacking 3mm observes after the voltage stabilizing, and each sheet T beam stroke is basic identical, does not need independent adjustment, strengthens every grade of top lifting height subsequently gradually to 10mm.

Be of the influence of check mobile load to top lift, with the jack self-locking nut gap 1mm that outwards winding, observe vehicle by the time oil pressure gauge change, dilly by the time, the oil pressure gauge reading is constant substantially; When heavy vehicle passed through, the maximum 2MPa that increases of oil pressure gauge reading illustrated that mobile load is less to the jacking influence.

In the jacking process, T beam, bent cap, pier stud observed result are shown that each member of bridge is working properly, diseases such as crack, skew do not occur, this operating procedure is safe and reliable.

3, change bearing

When beginning to test, changing bearing needs jacking 50mm, and along with skilled operation, top lifting height 30mm just can change bearing smoothly.After former bearing taken out, whether scrutiny bearing pad stone end face had situations such as concrete breakage, honeycomb, hole, for the bearing that comes to nothing, pading plate on pinner, and with the epoxy mortar levelling to corresponding height, bearing can both be evenly stressed when guaranteeing to fall beam.To neoprene bearing, the japanning that should eliminate rust of the pre-embedded steel slab of its end face beam (plate); To tetrafluoro slide plate bearing, the corrosion resistant plate on the pre-embedded steel slab surface of its end face beam (plate) and bearing tetrafluoro slide plate end face should brushing silicone grease oil, should the replenishing of disappearance corrosion resistant plate.

4, the top is unloaded in oil return

New bearing lay errorless after, first synchronization of jacking up 0.5～1mm is loosening to self-locking nut, revolves withdrawing nut then, the height 3mm of every grade of whereabouts of T beam observes after the voltage stabilizing during beginning, and each sheet T beam stroke is basic identical, do not need independent adjustment, strengthen every grade of top lifting height subsequently gradually to 10mm.

Claims (3)

1. the method for a jacking bridge is to adopt the device of jacking bridge to carry out; The device of described jacking bridge comprises jack, oil pump and flow divider; Described jack is more than two, by described flow divider parallel connection, unifies fuel feeding by described oil pump; Described jack is the self-locking jack, and their stroke is identical; In jacking bridge process, the self-locking nut of described self-locking jack and the gap of oil cylinder are less than 1mm; Classification jacking, every grade of jacking 3-10mm are adopted in described jacking.

2. the method for claim 1, it is characterized in that: the stroke of realizing described two above self-locking jack as follows is identical: by same oil pump by flow divider to described two identical pressure of above self-locking jack supply.

3. claim 1 or the 2 described methods application in changing bridge pad.

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