EP0567507B1

EP0567507B1 - A method and a construction system for establishing light bridges and for demounting thereof

Info

Publication number: EP0567507B1
Application number: EP92902877A
Authority: EP
Inventors: Frede Andresen Petersen
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-01-14
Filing date: 1992-01-14
Publication date: 1997-12-10
Anticipated expiration: 2012-01-14
Also published as: AU1170592A; DE69223503T2; GR3026300T3; WO1992012295A1; DK0567507T3; DE69223503D1; EP0567507A1; ES2112899T3; DK6391D0

Abstract

For the working down of light poles, e.g. for light bridges, use is made of tubular poles (2), which are mounted by the flush-down method, whereby, however, use is not made of auxiliary flushing spears, but of the single tubular poles (2) as a self-contained permanent flushing spear. Correspondingly the poles are easy to take up, by introduction of compressed air therein. The mounting work is facilitated to the degree that light bridges can now be erected by a single operator, making use of an additionally disclosed method.

Description

The present invention relates to a method of establishing light bridges or similar structures that are carried by poles mounted in the sea bottom.
The erection of light bridges is an age-old craft, based on the ramming down of poles and in a variety of manners using these poles as carriers for longitudinal side members which, in turn, act as carriers for some upper step surface elements such as cross boards. Normally, the pole ramming work and some other mounting work is effected from the sea side, purely manually or with the aid of a sea carried ramming and working platform, when the work is done by professionals.
The invention is especially linked with the professional trade of establishing the light bridges, using suitable auxiliaries, so it is relevant to consider the more recent development in this field.
A major contribution over the past several years has been to avoid the ramming down of the poles and instead using an easier and quicker flushing down technique, whereby a flushing spear is used for easing the pole down into the ground, pressurised water being sent out through the lower end of the spear. The spear, which is usable for flushing down both pipe poles and wooden poles, is moved into the ground together with the pole, only with the spear point located slightly beneath the lower end of the pole, such that the material underneath the pole end is currently flushed away so as to condition a particularly easy and rapid working down of the pole.
In connection with the present invention it has been recognised that this type of mounting can be effected in a still simpler manner, namely in making use of the pipe poles themselves as permanent or remaining flushing spears. The pressure of the current of flushing water is not required to be particularly high, so it is very easy to arrange for the coupling on and off of a pump hose at the top of the single pipe poles. When the delivery of the flushing water takes place through the lower pole end the placing of the 'spear end' will automatically be correct, and the flushing down of the pole, therefore, can easily be effected by a single operator, even without the operator being particularly skilled.
Correspondingly, it is a very advantageous possibility that the poles may be taken up by utilising their upper connector ends for connection with a hose supplied with compressed air or pressurised water, as it is then possible to take up the otherwise rigidly mounted poles with a minimum of labour and equipment, such that the bridge may be taken in for the winter and re-established by spring in a rather easy manner.
Based on this integrated flushing technique the invention provides for a new and advantageous bridge mounting method as specified in claim 1, enabling a single operator to build out the bridge with the use of suitably prepared poles and bridge elements and without any assistance from the sea side. A simple crane structure is used for successively supporting each new bridge element at its mounting place, whereby the operator uses this element as a working platform for flushing down the proper poles therefor. An inverted method can be used for the dismounting of the bridge, with the crane supporting each outermost bridge element while the poles thereof are pressed up as described above.
Correspondingly, the invention comprises a relevant construction system as specified in claim 6.
It should be mentioned that there have been prior proposals as to the said "integrated flush-down" principle, e.g. as disclosed in GB-A-398 354. However, in the known proposals the elements to be flushed down are complicated structures for special purposes and certainly not comparable to simple, tubular carrier poles, and none of these known proposals have any relevant bearing on the erection of light bridges with mutually separated, simple lightweight poles.
In the following the invention is described in more detail with reference to the drawing, in which:

Fig. 1 is a schematic view illustrating the working down of pipe poles by flushing,
Fig. 2a)-e) are lateral views of different designs of the lower end of the poles, and
Figs. 3-6 illustrate the successive erection of a bridge with the use of an auxiliary crane.

Fig. 1 illustrates a sea bottom, in which a tubular pole 2 is flushed down by means of an upper connection hose 4 to a water pump (not shown), which may well be a centrifugal pump, as the required pressure is not particularly high. After the flushing down the bottom material will pack around the pole, which will then be able to stand in a stable manner when the depth of the flushing down is reasonably large; with the use of pipes of a diameter of 5-7.5 cm (2-3 inches) the depth should of course be somewhat larger than in case of thick wooden poles, typically of the magnitude 1-3 m. However, as mentioned below, the use of foot plates on the poles for contacting the sea bottom will greatly stabilise the poles and ensure a high carrying capacity.
In fig. 2 is shown such a pipe pole 2, the upper end of which is connected with the hose 4 by means of a suitable connector 6. At its lower end the pipe 2 is terminated by simple cutting, which will provide for a sufficient flushing effect for poles that should only be driven down to a depth of some 1.5 m, of course depending on the type of the bottom material. For larger depths it is recommendable to utilise a stronger flushing effect, which will not necessarily require a stronger pump, as it is obtainable merely by using a narrower nozzle opening 8 on the pipe pole 2, as shown in Fig. 2b. This opening may even be supplemented by an annular row of outwardly and downwardly directed nozzle openings 10 as shown in Fig. 2c; it has been found that poles with such a design are suitable for driving down to the depth range of 1.5 - 2.5 m.
With the use of the downwardly directed nozzle openings the phenomenon will occur that the pipe, upon a certain intrusion into the ground, starts to carry out vertical beat movements, which will promote the driving down. When large mounting depths are required, e.g. more than 2.5 m, pipe poles can be used, which, as shown in Figs. 2d and 2e, have a lower funnel shaped end member 12 that is vertically reciprocal on an axial guiding rod 14 relatively to the lower rigid end of the pole; hereby the said beat movements will occur in a more firm manner between the pipe pole 2 and the funnel member 12, this resulting in a still harder beat effect that is advantageous when the pole is driven down to a depth larger than e.g. 2.5 m.
Fig. 3 illustrates an initial building out of a bridge, by which it has been possible from the shore side to flush down the first set of pipe poles 2 for receiving a first, preferably prefabricated bridge element 16, which is fastenable to the upstanding poles by the use of any suitable type of fastening fittings. As indicated, the pole 2 may carry a horizontal bottom support plate 18 that will determine the intrusion depth and stabilise the pole against tilting and thus reduce the need of a deep intrusion of the pole in the ground.
Thereafter, as shown in Fig. 4, a crane 20 is mounted on the fixed bridge element 16, the crane having a jig 22 that is usable for carrying a further bridge element 16', which, as shown in Fig. 5, will be outwardly displaced into a suspended position adjacent the end of the bridge, in which position this element is used as a working platform for the flushing down of an additional pair of pipe poles 24 by means of a water pump 26 sucking water from the lake or sea water. Once these further poles are mounted the bridge element 16' is secured thereto, still from above and by the labour of but a single operator, and thereafter the bridge can be built further out with the use of more bridge elements as shown in Fig. 6. is
For a taking in of the bridge an inverted procedure is followed, now using the water pump or an air compressor, which is connected to the first of the outermost poles, the crane hereby being mounted on the second outermost bridge element and being brought into carrier connection with the outermost bridge element, whereafter the poles are drawn or blown up after being released from the bridge element. The outermost bridge element may then be brought in together with the poles, and then the crane is displaced one element inwardly for dismounting of the next bridge element.
Generally, instead of a single pipe pole of any suitable material, it will be possible to use more, closely juxtaposed poles for concurrent flushing down. It may even be possible to co-flush-down a solid pole, for which the associated flushing pole or poles will act as flush down spears. These 'permanent spears' will be of importance not only for the strength of the pole, but also because the solid pole portions will be quite easy to co-dismount by the said pressing up of the poles. This aspect has the further perspective that it is possible to use solid poles or for that sake thick tubular poles which can be flushed down with the use of one or more flushing pipes or even hoses. Hereby even rather thick poles can be handled, when they are provided with a relatively thin flushing conduit ending at the bottom area of the pole.
It has been mentioned that preferably light constructions and poles are involved, but the invention is not restricted to any special dimensions to the extent it will be applicable in an advantageous manner in some relevant situation.

Claims

A method of establishing light bridges, platforms and similar structures of the pole carried type, comprising selecting or providing tubular pole pieces (2) of required lengths, mounting the poles in the sea bottom using the flushing down principle and mounting bridge elements (16') in connection with the poles, characterized by the following steps:
- establishing an initial, first bridge section (16) projecting across the sea line,

- securing to the outer end of this bridge section (16) a crane structure (20,22) projecting both inwardly and outwardly of the outer end of the bridge section,

- transporting to said crane structure a second bridge section (16') and connecting it to hoist means of the crane structure (20,22),

- hoisting the second bridge section (16') and displacing it, suspended in the crane structure (20,22), to a position just outside the free end of the first bridge section (16),

- using the thus displaced bridge section (16') as a working platform for flushing down the proper poles (2) of that bridge section,

- hereby using the poles themselves for effecting their own flushing down by forcing flushing water through central or exterior channel means of the poles,

- securing the same bridge section (16') to the flushed down poles (2), and

- moving the crane structure (20,22) to the outer end of that bridge section (16') for a renewed mounting operation, if applicable.
A method according to claim 1, wherein the inner end of the new bridge section (16') is secured to the outer end of the first section (16) and new poles (2) are mounted only as a pair of poles adjacent the outer end of the new bridge section (16').
A method according to claim 1, wherein the poles are simple pipe pieces (2) cut in lengths corresponding to individual requirements as given by the depth of water at the relevant mounting place.
A method according to claim 1 or 3, wherein the pole pieces (2) are individually length adapted according to the desired intrusion depth in the sea bottom and the depth of water at the relevant mounting place and provided with a transverse sea bottom engagement plate (18) in the relevant position on the single pole piece (2).
A method corresponding to claim 1, but carried out in an inverted manner for a taking in of the bridge, now successively taking up the outermost poles (2) by using their flushing channels as downlets for compressed air or for a water flow.
A construction system for establishing light bridges by the method claimed in claim 1, comprising in combination:
- a number of bridge elements (16,16') to be joined end to end,

- a number of carrier poles (2) having central or external channel means for conducting flushing water therethrough from top to bottom of the pole,

- a water pump (26) operable to be connected with the top of said poles (2) for pumping flushing water to a bottom outlet thereof, and

- a crane structure (20,22) mountable in connection with the outer end of an outermost bridge element (16) so as to be able to receive a new bridge element (16') and carry this element outwardly to a position in front of the formerly outermost bridge element (16), with a carrier capacity sufficient to make the new bridge element (16') usable as a working platform for flushing down the relevant poles (2) to thereafter be connected with that element (16').
A system according to claim 6, in which the poles (2) are preadapted with relevant length portions above and beneath the sea bottom, respectively, and are provided with transverse foot plate means (18) located in respective positions corresponding to a measured or expected depth position of the sea bottom.