EP0423029B1 - Device and method for lifting and moving objects - Google Patents

Abstract

The device for lifting and moving objects (14) comprises means (19) for lifting the objects resting on stationary supports (12, 13) and means (21) for moving these objects in order to displace them in a translational direction relative to the said supports (12, 13), the said means interacting with a sliding surface (S) located in the vicinity of the supports. The surface (S) forms, with the contact surface between the object (14) to be moved and the supports (12, 13), a dihedron whose edge faces away from the direction (D) in which it is desired to move the object (14), the said means (19, 21) being adapted for raising and for simultaneously being able to push the objects in order to hold them during their movement at a predetermined distance above the supports (12, 13). Use, in particular, for pushing deck elements of a bridge over the piers thereof. <IMAGE>

Description

The present invention relates to a device for lifting and moving objects.

The invention relates in particular to a device for building a bridge according to the method known as "pushed bridges", in which the objects to be lifted and to be moved are elements of the deck of said bridge.

Figures 1 to 6 attached illustrate the conventional method of construction by pushing bridges.

In these figures, the reference 1 designates piles of bridges which are pre-installed.

In a first step, a first concrete deck element 2 is poured in front of the concrete abutment 3 which must connect the bridge to the ground 4 (see Figure 1).

In a second step, the element 2 is pushed above the abutment 3 by a force F₁ (See Figure 2).

In a third step, a second element 5 is cast behind the first element 2 (see FIG. 3).

In a fourth step, the two elements 2 and 5 are pushed together towards the stacks 1 by a force F₂ (FIG. 4).

A third element 6 is then poured (see FIG. 5) and the three elements 2, 5 and 6 are pushed together on the piles 1 (FIG. 6).

• 1) des patins de glissement, qu'on place sur les piles et parfois même sur des palées intermédiaires provisoires ;
• 2) des dispositifs capables de produire et de transmettre des efforts d'axe sensiblement parallèle à l'axe de l'ouvrage, ci-après nommés "efforts de poussage".

This known technique partially eliminates the cost of scaffolding but requires the use of two means which are not incorporated into the final structure:

• 1) sliding pads, which are placed on the piles and sometimes even on temporary intermediate bearings;
• 2) devices capable of producing and transmitting forces of axis substantially parallel to the axis of the structure, hereinafter called "pushing forces".

These forces are directly proportional to the weight of the pushed deck and to a factor which is the sum of two terms: the friction generated by the sliding devices and the longitudinal slope of the deck.

The weight of a pushed deck can reach 30,000 tonnes in the final phase (approximate maximum value achieved to date). The coefficient of friction commonly varies between 1% and 5% in the case of a sliding surface made of PTFE (polytetrafluoroethylene). Longitudinal slopes can reach 3.5% in the case of works for TGV (high speed trains) and they can be higher than this value for road works. It can therefore be seen that the pushing forces can reach values greater than 30,000 × (0.035 + 0.05), or 2,550 tonnes.

• 1) le tablier glisse sur tous ses appuis. L'effort de poussage est appliqué directement à l'arrière du tronçon ou élément qui vient d'être réalisé, à l'aide par exemple d'un vérin ;
• 2) le tablier glisse sur tous ses appuis mais l'"effort de poussage" est remplacé par un "effort de tirage". Cet effort est appliqué soit à l'arrière du tronçon, soit en des positions intermédiaires. L'effort de tirage est exercé par des câbles, eux-mêmes tendus par des vérins ;
• 3) le tablier glisse encore sur tous ses appuis mais certains (un pour des tabliers légers, deux ou trois si nécessaire) sont privilégiés en ce sens qu'ils sont équipés de dispositifs qui permettent de soulever le tablier puis de le faire glisser. C'est sur les dispositifs de soulèvement que sont appliqués une partie des efforts de poussage (qui sont transmis au tablier par frottement).

These two means (sliding and pushing) can be dissociated or associated according to the techniques used. These techniques can be classified into 3 main families:

• 1) the apron slides on all its supports. The pushing force is applied directly to the rear of the section or element which has just been produced, using for example a jack;
• 2) the apron slides on all its supports but the "pushing force" is replaced by a "pulling force". This force is applied either at the rear of the section, or in intermediate positions. The pulling force is exerted by cables, themselves stretched by jacks;
• 3) the apron still slides on all its supports but some (one for light aprons, two or three if necessary) are preferred in the sense that they are equipped with devices that allow the apron to be lifted and then slid. It is on the lifting devices that part of the pushing forces are applied (which are transmitted to the deck by friction).

It is to this latter technique that the invention relates, in particular.

In the known technique, the bearing surface of the device on the stack is either horizontal or parallel to the deck.

The Applicant has found that this conventional technique is not satisfactory. Indeed, during the implementation of this technique, the entrepreneur is in no way in control of the intensity of the necessary pushing forces, as indicated by the numerical values cited above.

The conventional technique also has the defect of not ensuring the safety of the apron if the movement of the latter escapes the control of the operator, in the event for example of failure of the lifting and displacement means used.

The known technique of moving a bridge by pushing is illustrated for example by French patent application 2,616,459.

Furthermore, German patent application 1 905 997 describes a device (according to the preamble of claim 1) for moving heavy loads on a horizontal surface by means of a lifting cylinder and a pushing cylinder.

The object of the present invention is to remedy the drawbacks of known devices.

The invention thus relates to a device for lifting and moving objects, comprising means for lifting objects resting on one or more temporary fixed supports and means for moving these objects to make them undergo translation relative to this or these supports, said means cooperating with a sliding surface located near said temporary support (s).

According to the invention, this device is characterized in that said surface forms with the contact surface between the object to be moved and the support (s), a dihedral whose edge is directed opposite to the direction in which wishes to move the object, said surface being on a downward slope relative to the direction of movement of the object, said means being adapted to simultaneously lift and push the objects in order to maintain them during their movement at a predetermined distance from the - above the support (s).

Thus, when the objects have to be moved along an upward slope, the means for moving these objects raise them and move over a surface forming a downward slope.

The value of the slope along which the means of lifting objects move can be decided by the company. The more this slope is downward relative to the surface of displacement of the objects, the more the effort of pushing or displacement of the objects is reduced.

Furthermore, in the event of uncontrolled sliding of the objects, since the displacement means move along an opposite slope, the objects deposit themselves on their supports, so that their sliding will be automatically stopped.

Furthermore, since the lifting and moving means are actuated simultaneously, despite the above-mentioned dihedral, the displaced objects can be kept at a predetermined distance above the support (s).

When the device according to the invention is applied to the construction of a bridge, the objects to be lifted and moved are elements of the deck of said bridge, the supports being arranged on piers of this bridge intended to support the deck elements.

According to a preferred version of the invention, said means for lifting and moving the deck elements, comprise a lower plate fixed on a surface formed on a bridge pier, an upper plate slidably mounted on the fixed lower plate, a first jack fixed perpendicular to the movable upper plate and whose movable head is adapted to come into contact with the deck element resting on one or more supports to lift it, at least one second jack having one of its fixed ends and its another end secured to the movable plate to move the latter relative to the fixed plate.

• a) on commande le déplacement du premier vérin pour soulever un élément de tablier, et
• b) on commande le déplacement du second vérin pour faire coulisser la plaque mobile par rapport à la plaque fixe,
• c) on commande le retrait du premier vérin, puis celui du second vérin et on répète les opérations précitées dans l'ordre a), b) et c) jusqu'à la position finale désirée de l'élément de tablier.

According to another aspect of the invention, the method for implementing the device according to the invention for lifting and moving deck elements of a bridge on the pre-installed piles thereof comprises the following steps:

• a) the movement of the first cylinder is controlled to lift an apron element, and
• b) the movement of the second cylinder is controlled to slide the movable plate relative to the fixed plate,
• c) the withdrawal of the first cylinder is controlled, then that of the second cylinder and the aforementioned operations are repeated in order a), b) and c) until the desired final position of the deck element.

Other features and advantages of the invention will become apparent in the description below.

• les figures 1 à 6 illustrent schématiquement le procédé classique de construction d'un pont au moyen d'éléments de tablier poussés ;
• la figure 7 est une vue en élévation d'un dispositif selon l'invention, placé sur une pile de pont et destiné à soulever et déplacer un tablier de pont ;
• la figure 8A est une demi-vue de dessus du dispositif, le vérin de poussage étant rentré ;
• la figure 8B est une demi-vue analogue à la figure 8A, le vérin de poussage étant en position étirée ou sortie,
• les figures 9 à 13 montrent en élévation schématique le dispositif selon l'invention dans ses différentes positions de fonctionnement.

In the appended drawings, given by way of nonlimiting examples:

• Figures 1 to 6 schematically illustrate the conventional method of building a bridge by means of pushed deck elements;
• Figure 7 is an elevational view of a device according to the invention, placed on a bridge pier and intended to lift and move a bridge deck;
• Figure 8A is a half top view of the device, the push cylinder being retracted;
• FIG. 8B is a half-view similar to FIG. 8A, the pushing cylinder being in the stretched or extended position,
• Figures 9 to 13 show in schematic elevation the device according to the invention in its different operating positions.

The device designated by the reference 10 in Figure 7 is placed in a cavity 11 formed at the top of certain piers 1 of the bridge to be built. Certain batteries 1 thus receive such a device 10.

The upper part of the stack 1 comprises in the example shown, two supports 12, 13 on which the deck member 14 which is to be moved rests.

In the example shown, we want to move the deck element 14 in the direction D which is parallel to the surface along which the element 14 rests on the supports 12, 13.

This bearing surface is here located on a rising slope.

According to the present invention, the surface S along which the device 10 is capable of moving, forms with the contact surface S₁, S₂ between the apron element 14 to be moved and the supports 12, 13 a dihedral whose edge (not visible in FIG. 7) is directed opposite the direction D in which it is desired to move the element 14.

In the example of FIG. 7, this surface S is on a downward slope relative to the direction of displacement D of element 14, so that it is inverse to the slope on which element 14 must move.

The device 10 shown in Figures 7, 8A and 8B comprises a lower plate 15 fixed by a layer of mortar 17 on the inclined bottom 16 of the cavity 11 between two supports 12, 13. On this fixed plate 15 is mounted so sliding top plate 18.

A first cylinder 19 is fixed perpendicularly to the movable upper plate 18 and whose movable head 20 is adapted to come into contact with the deck element 14 resting on the two supports 12, 13 to lift it. Stops 29 are provided on the movable plate 18 to prevent any sliding of the jack 19.

Other jacks 21, 22 extend between the two supports 12, 13.

One 21a, 22a of the ends of the jacks 21, 22 is fixed to the fixed plate 15 and the other ends 21b, 22b are integral with the movable plate 18.

The jacks 21, 22 are thus designed to move the movable plate 18 relative to the fixed plate 15, along the surface S, between the two positions shown in Figures 8A and 8B.

To facilitate sliding, a layer 23 of material with a low coefficient of friction such as PTFE is interposed between the two plates 15 and 18.

It can also be seen in FIG. 7 that the head 20 of the first jack 10 has a striated surface 24 parallel to the contact surface S₁, S₂ between the deck member 14 and the two supports 12, 13. These ridges 24 allow d '' avoid any risk of sliding of the apron element 14.

This striated surface can be replaced by a layer of neoprene or other anti-slip surface.

It can also be seen in FIGS. 9 to 13 that the device 10 includes manometers 25, 26 for controlling the operating pressure of each of the jacks, as well as sensors 27, 28 for measuring the displacements of the bulkhead element 14 , order the jacks 19, 21 and to perfectly control their vertical and longitudinal movements.

We will now detail the operation of the device according to the invention and at the same time the method for its implementation.

In the position shown in FIG. 9, the device 10 is at rest, the jacks 19 and 21 are all retracted, the pressure gauges 25, 26 display zero pressure, and the apron element 14 rests on the supports 12, 13: it cannot therefore move in one direction or the other.

In a first step (see FIG. 10), the operation of the lifting cylinder 19 is controlled until it develops approximately 90% of the force necessary to lift the deck element 14.

Immediately after (see FIG. 11), the operation of the push cylinder 21 is controlled until it develops sufficient force (see position 1 of the pressure gauge 26) to prevent the recoil of the bulkhead element 14.

Alternatively, the hydraulic circuit of the push cylinder 21 could include a non-return valve.

In a subsequent step (see FIG. 12), the lifting cylinder 19 is mounted under pressure until it develops the necessary force (see position 100% of the pressure gauge 25), to lift the bulkhead element 14.

The stroke of the lifting cylinder 19 is stopped as soon as the bulkhead element 14 has risen a few millimeters above the supports (12, 13).

In the following phase, the pushing cylinder 21 is mounted in pressure until developing the force necessary for pushing (see FIG. 13; position 2 of the pressure gauge 26).

As soon as the bulkhead element 14 begins to advance in the direction D, due to the downward slope of the sliding surface S, the lifting cylinder 19 is actuated to hold the bulkhead element a few millimeters above the supports 12, 13. In practice, a sensor 27 (see FIG. 9) determines the position in altitude of the element 14 and thus controls the power supply to the jack 19.

The push cylinder 21 can thus move the apron element 14 along its maximum stroke, for example equal to 30 cm.

In the next step, the pressure in the lifting cylinder 19 has dropped to 90% of its maximum value. The apron element 14 then rests again on the supports 12, 13.

The pressure in the pushing cylinder 21 is then reduced to 0. The same is done for the lifting cylinder 19. The strokes of the two cylinders 19 and 21 are also reduced to 0.

The device 10 has thus returned to its initial position shown in FIG. 9. It is then ready for a new lifting and pushing cycle.

The main advantages of the device according to the invention are as follows:

1) Reduction of the pushing force:

The fact that the value of the slope on which the sliding surface S is located is decided by the company makes it possible to reduce the pushing effort by a chosen value: it will therefore no longer depend solely on the characteristics of the structure and coefficients of friction which result from the technique.

For example, if the company chooses a down slope equal to -10%, the resulting reduction will be 1,700 × (0.035 + 0.10) = about 230 tonnes per equipped support if the weight of a span is equal to 1,700 tonnes and if the slope of the deck is equal to + 3.5%.

The pushing force being reduced, it may be possible to reduce the number of supports to be fitted with the device.

2) Safety in case of uncontrolled sliding:

The device according to the invention can be equipped with two control members:
- a vertical steering device which will avoid bending the deck excessively at any time, keeping it at the chosen altitude. If the apron advances too quickly in the direction of pushing, it will deposit itself on its rest supports. If the apron begins to "move back" it will be raised by the wedge effect and the piloting of the lifting cylinder will cause a reduction in its pressure which will maintain it at the desired level and will avoid bending the apron by uneven support. In addition, a safety device will instantly deactivate the lifting cylinder (the deck will fall back onto its rest supports) if the support drop becomes too large (we could, for example, limit it to 1 cm, which would induce a reaction additional of the order of 100 tonnes, which corresponds to an overpressure of 100/1 700 = 5.9% in the example taken above).

The fact that the lifting cylinder must be pressurized during the sliding phases ensures conversely that the safety of the deck is ensured as soon as the pressure falls below the lifting pressure.
- a longitudinal control member which can also instantly deactivate the lifting cylinder (for example by preventing the movable plate from moving back 1 cm if the lifting cylinder is loaded).

We see that we will have a double intrinsic safety in uncontrolled recoil. Finally, we can add a mechanical stop which will limit the movement of the movable plate and consequently of the deck.

Of course, the invention is not limited to the embodiment which has just been described, and many modifications can be made to it without departing from the scope of the invention.

Thus, the device according to the invention can be used to lift and move objects other than bridge deck elements.

Furthermore, the movement of objects can be carried out horizontally or along a downward slope, the main thing being that the sliding surface of the lifting and pushing means takes place along a slope different from that of the objects to be moved.

In addition, in certain applications, it may be envisaged to use the difference in slope to slow down the downward movement of the objects to be moved.

In addition, the invention can also be applied to the pushing of bridges made of steel deck elements or other material.

Claims (8)

1. A device for lifting and moving objects (14) and comprising means (19) for lifting the objects on one or more temporary fixed supports (12, 13) and means (21) for moving the objects in translation with respect to the support or supports (12, 13), the lifting means (19), under the action of the moving means (20), being adapted to slide on a sliding surface (S) disposed near the temporary support or supports, characterised in that the surface (S) co-operates with the surface of contact (S₁, S₂) between the object (14) to be moved and the support or supports (12, 13) to form a dihedron (S₁, S₂, S) the edge of which extends opposite the direction (D) along which the object (14) is to be moved, the surface (S) being on a slope which descends relative to the direction of motion (D) of the object (14), and the means (19, 21) being adapted to lift and simultaneously push the objects in order to hold them during motion thereof at a predetermined distance above the support or supports (12, 13).
2. A device according to claim 1, for constructing a bridge, characterised in that the objects to be lifted and moved are the components of a bridge floor (14), the temporary supports (12, 13) being formed on bridge piers (1) for supporting the components of the floor (14).
3. A device according to claim 2, characterised in that the means for lifting and moving the floor components comprise a bottom plate (15) secured to a surface (16) formed on a pier (1), a top plate (18) slidably mounted on the fixed bottom plate (15), a first jack (19) secured at right angles to the movable top plate (18) and having a movable head (20) adapted to come into contact with the floor component (14) resting on one or more supports (12, 13) in order to raise it, and at least one second jack (21) having one end fixed and its other end secured to the movable plate (18) in order to move it with respect to the fixed plate (15).
4. A device according to claim 3, characterised in that a layer (23) of material having a low coefficient of friction is interposed between the two plates (15, 18).
5. A device according to claim 3 or 4, characterised in that it comprises means (25, 26) for monitoring the operating pressure of each of the two jacks (19, 21) and pick-ups (27, 28) for measuring the movements of the floor component (14) and operating the jacks (19, 21).
6. A method of operative the device according to claim 3 or 4 for raising and moving the floor components of a bridge (14) on pre-installed piers (1) thereof, characterised in that it comprises the following stages:

   a) the first jack (19) is actuated so as to raise a floor component (14),

   b) the second jack (21) is actuated so as to slide the movable plate (18) with respect to the fixed plate (15), and

   c) the first jack (19) and then the second jack (21) are retracted and the aforementioned operations are repeated in the order a), b) and c) until the floor component (15) reaches the desired final position.
7. A method according to claim 6, characterised in that in a first step, the first jack (19) is pressurised up to a certain pressure insufficient to raise the floor component (15), then the second jack (21) is pressurised up to a certain pressure insufficient to move the movable plate (18) bearing the first jack, then the pressure of the first jack (19) is increased to raise the floor component (14) and then the pressure of the second jack (21) is increased to move the floor component (14).
8. A method according to claim 7, characterised in that when the floor component (14) is moved, the first jack (19) is actuated so as to hold the floor component (14) at a certain predetermined distance above the supports (12, 13).

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