EP0495061B1 - Method for building an underground construction, particularly a vehicle park, while leaving in place obstacles such as trees - Google Patents

Abstract

A method is provided for building an underground construction, particularly a vehicle park, while leaving in place obstacles which are at least partially buried around the edge of the construction, e.g. trees. Before digging is begun, a curtain of elongate retaining elements for the obstacles is constructed from the surface, said elements being driven into the ground substantially around the edge of the construction, so as to be inclined outwards underneath said obstacles (6).

Description

The present invention relates to a method of constructing a buried structure, in particular a parking lot, preserving obstacles at least partially buried in the periphery of the structure, such as trees.

The current useful width of an underground car park is approximately 15 meters. A central aisle of 5 meters provides access to two lateral rows of opposite parking spaces of 5 meters each.

The construction of the upper slab and / or that of the pedestals of the structure generally requires that the underground space located above it be free or temporarily freed during the work period, unless these are carried out using old traditional mining techniques, which are not very mechanized and therefore expensive.

Likewise, it is necessary for drilling or handling equipment that the air space situated above the structure to be constructed be clear of any obstacle for reasons of safety and convenience.

When an underground structure such as a parking lot must be laid out under the public thoroughfare, it often happens that the distance between the two rows of trees bordering this thoroughfare is precisely around 15 meters. It therefore follows that the roots of these trees occupy the underground space located at the level of the pedestals of the structure and that the overhead volumes occupied by their antlers are intercepted by drilling and handling equipment.

FIG. 1 represents a buried parking lot 1 with its slab 2 and its pedestals 3, buried under a public road 4 bordered by buildings 5, a row of trees 6 being planted between each edge of track 4 and the building adjacent 5. There are shown in hatches the locations which must be freed for the realization of the buried structure 1.

Among these locations are in particular the trees 6 whose roots 7 occupy substantially a buried half-sphere and the branches an aerial part which can be assimilated to a sphere or to a cylinder.

The construction of the structure 1 consequently requires that the trees bordering the public road be sacrificed.

The document EP-A-0 188 282 describes a method for making a mass of land constructible by producing around it an elastic waterproof envelope, waterproof and airtight. This method does not allow a search to be carried out below this sealing wall by supporting obstacles which are located above the latter.

Document DE-A-1 801 892 describes a method for stiffening a structure in the ground which consists in joining piles by horizontal injection lines intersecting said piles, but this document does not provide for carrying out excavations below obstacles supported by curtains of supporting elements.

The present invention aims to overcome this drawback.

To this end, the invention relates to a method of constructing a buried structure, in particular a parking lot, preserving obstacles at least partially buried on the periphery or above the structure such as trees , characterized by the fact that, before the digging of the structure, a curtain of elongated elements for supporting obstacles is produced, said elements being driven into the ground substantially at the periphery of the latter towards the outside of this last and under said obstacles, since the excavation is carried out partially below the curtain of support elements.

According to a first embodiment, the support is produced from the surface in an inclined plane with respect to the vertical, thus allowing the construction of underground parks or other buried structures without uprooting the trees or intercepting their roots or damaging their antlers.

The support elements are preferably spaced transversely, the cohesion of the ground preventing it from flowing between the support elements.

If this cohesion is insufficient, the ground can be treated, for example by the methods described in documents FR-A-2 528 441, FR-A-2 583 441 or FR-A- 2 585 698, these methods not endangering the survival of the trees.

In this embodiment of the invention, it is advantageous to make substantially vertical piles between the obstacles, for example in the form of sections of molded walls substantially perpendicular to the periphery of the structure, to fix support beams substantially horizontal on said piles, and to bear on said beams the upper ends of the supporting elements.

In a second embodiment of the invention, an excavation is carried out at the periphery of the obstacles to be supported and the support beams are engaged from this excavation under the obstacles to be supported.

In this case, the support beams can be inclined or even substantially horizontal. They can rest on load-bearing elements which are used to hold the walls of the excavation.

• la figure 1 est une coupe illustrant le problème posé,
• la figure 2 est une vue en demi-coupe transversale d'un premier mode de réalisation de l'invention,
• la figure 3 est une demi-vue de dessus, correspondant à la figure 2,
• la figure 4 est une vue en coupe transversale de l'ouvrage terminé,
• et la figure 5 est une vue en coupe transversale d'un second mode de réalisation de l'invention.

Two specific embodiments of the invention will now be described, by way of nonlimiting examples, with reference to the appended drawing in which:

• FIG. 1 is a section illustrating the problem posed,
• FIG. 2 is a view in half cross-section of a first embodiment of the invention,
• FIG. 3 is a half view from above, corresponding to FIG. 2,
• FIG. 4 is a cross-sectional view of the finished structure,
• and Figure 5 is a cross-sectional view of a second embodiment of the invention.

If we refer to Figures 2 and 3 which show the same public road 4 lined with trees 6 as in Figure 1, we see how according to the first embodiment we realize between the trees 6 piles or vertical bars 8 according to the well-known technique of diaphragm walls.

These bars 8 are produced between the trees 6 so as not to damage them and not to intercept their roots.

Of course, these bars 8 which are intended to constitute vertical support elements could be replaced, for example by permanent or temporary bored piles.

Horizontal support beams are then fixed to the bars 8 by any suitable means, for example by embedding or using metal inserts. These horizontal beams are for example produced in the form of concrete beams 9 as shown in FIG. 2, or in the form of metal beams 9 ′ as shown in FIG. 3.

The oblique support elements are then placed in the ground, for example at an angle of 45 °, which in the present case are constituted by metal tubes 10. In an urban environment, the insertion of the tubes 10 is preferably carried out by drilling to avoid any impact or vibration on the environment.

We see in Figure 2 how the tubes 10 are driven perpendicular to the periphery of the structure, being inclined downward towards the outside thereof, and how their upper end is supported on the horizontal beams 9.

The length of the tubes 10 is such that they cannot damage the foundations of the waterfront buildings 5.

The tubes 10 are also inserted in such a way that they do not risk intercepting the hemisphere 7 of the roots of the trees 6.

It is understood that, during the subsequent digging of the structure, the ground located above the tubes 10 is supported by the latter which are on the one hand embedded in the ground at their lower end and on the other hand resting on the beams 9 at their upper part.

We can then pour the upper slab 2 of the structure, this slab possibly including the horizontal beams 9 and 9 ′, then make the underground structure by any known means safe from this slab as shown in Figure 4 , the earth and tree support 6 being produced by the tubes 10 which constitute the support elements.

FIG. 5 shows a second embodiment of the invention, in which the support elements 10 are arranged in a substantially horizontal manner below the obstacles which are located above the structure to be constructed.

In this second embodiment, first of all vertical walls are molded into the ground 11, 12 and 13, by usual techniques. These walls are made along lines which do not include obstacles on the ground surface.

It can be seen in FIG. 5 that the part of the structure which is situated to the left of the wall 12 comprises obstacles schematically represented such as trees or pipes which must be preserved, while the part situated to the right of the wall 12 does not have one.

As shown in FIG. 5, in this part on the right, the tiles 14 and 15 which delimit the volume 16 have been produced.

For this realization, we first excavated the land located above the location of the slab 14, which made it possible, then we excavated the volume 16, which allowed the realization of slab 15, as a result of which, the volume located above slab 14 was backfilled, which freed up the ground which is above slab 14.

At this stage of the work, the supporting elements 10 are put in place which can be constituted by tubes or beams that one engages in substantially horizontal cavities, which are produced below the obstacles.

The left end of the retaining elements is embedded in the wall 13 and in the ground which is located to the left of the latter, while the right end of the elements 10 is supported by the wall 12 which constitutes the support element vertical.

A beam 9 is advantageously produced, arranged perpendicular to the plane of FIG. 5, which joins the ends of the supporting elements 10 and which stiffens the upper part of the wall 12.

The ground being thus maintained above the supporting elements 10, it is possible to excavate the volume 17 which is situated below this part of the ground, which then makes it possible to produce the slab 18 which is situated immediately below the supporting elements 10 and which is supported by the walls 12 and 13.

We can then pour the left part of the slab 15 and after successive excavations, the floors of the lower floors.

We see that according to this second embodiment of the invention, the excavation of a first level next to the obstacles which must be supported, makes it possible to place the support elements in a horizontal or substantially horizontal position, below the said obstacles, which, in certain cases, makes it possible to significantly increase the useful volume below said obstacles.

It is thus understood that the method according to the invention allows almost complete release of the footprint of the structure, with the exception of the access hoppers to the site.

Various variants and modifications can of course be made to the above description without departing from the scope or the spirit of the invention.

It is understood in particular that the invention makes it possible to save obstacles such as trees which are situated both at the periphery and at the center of the right-of-way of the underground structure to be constructed.

Claims (9)

1. Method for carrying out digging with a view to constructing buried works, in particular a car park, while protecting the obstacles which are at least partially buried at the periphery or above the works such as trees, characterised by the fact that a sheet of elongate elements (10) for shoring the obstacles is built, prior to the actual digging, the said elements (10) being placed in the ground substantially at the periphery of the works towards the outside of the latter and below the said obstacles (6,7), and then the digging is done partly below the sheet of shoring elements.
2. Method according to Claim 1, characterised by the fact that the said shoring elements (10) are spaced apart transversely.
3. Method according to either of Claims 1 and 2, characterised by the fact that the ground is treated, at the location of the sheet of shoring elements (10), by injecting a product which increases its cohesion.
4. Method according to any one of Claims 1 to 3, characterised by the fact that substantially vertical piles (8) are built between the obstacles, that substantially horizontal support beams (9, 9′) are fixed onto the said piles, and that the ends of the shoring elements (10) which point towards the inside of the works are supported onto the said beams.
5. Method according to Claim 4, characterised by the fact that the piles (8) are built in the form of sections of cast walls substantially perpendicular to the periphery of the works.
6. Method according to any one of the preceding claims characterised by the fact that the shoring elements (10) are installed so as to be sloping, for example, at 45° from the surface of the site at a point located outside the obstacles (6, 7) to be safeguarded.
7. Method according to any one of Claims 1 to 5, characterised by the fact that the shoring elements (10) are installed in a substantially horizontal position from an excavation (16) carried out outside the obstacles (6, 7) to be safeguarded.
8. Buried works, the digging for which has been done by means of the method according to any one of Claims 1 to 7, characterised by the fact that they comprise a sheet of shoring elements (10) which are located below the obstacles (6, 7) to be safeguarded.
9. Buried works according to Claim 8, characterised by the fact that the shoring elements (10) are supported by vertical columns (8) joined at their upper parts by a horizontal beam (9).

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