FR2694030A1 - Device and method for making a foundation on vertical piles at sea, including the foundation of a bridge pile. - Google Patents

Abstract

The invention relates to the realization of a foundation on vertical piles at sea. A freestanding ballastable caisson (1) surmounted by a foundation primer (2) and equipped with vertical tubular liners (3) along which the caisson can be made. slide. This assembly is moved to its final location at sea and a sliding of the casing is suitably controlled first upwards above sea level and then downwards below the zone exposed to shocks. The invention applies in particular to the production of a bridge pier.

Description

The invention relates to a device and a method for carrying out a

  foundation on vertical piles at sea and it applies

  in particular to a foundation of a pile of a bridge.

  To make such a foundation, it is known to manufacture a ballastable caisson, to bring this caisson in-situ by floating or by means of a barge, and to make the piles from the caisson,

last being immersed.

  This technique has a certain number of disadvantages, and in particular the fact that it involves provisionally fixing on the box a metal riser surrounding the entire work area for the realization of all the piles, the cost of this extension being such that the caisson can be immersed only at shallow depth, in an area where the caisson as well as the metal riser are thus exposed to shocks and lateral thrusts (boats, ice, currents) In addition, the caisson being submerged at low depth, the piles are necessarily of great length, this

which increases their cost.

  The present invention aims to avoid these disadvantages and to

  in addition, provide specific advantages.

  It is achieved according to the present invention by means of a device consisting essentially of a prefabricated assembly comprising a ballastable and freestanding box, surmounted by a foundation primer and equipped with a plurality of vertical tubular shirts along which the box can move up or down under the action of appropriate control means, and tubular, waterproof and removable collapses able to be arranged individually on and in extension of the shirts to constitute

  access to the shirts and the inside of the box.

  This device makes it possible to implement a method in which, according to the invention: the prefabricated assembly is moved to its final location at sea; we order a descent of the shirts to the ground level, the

box remaining floating.

  if necessary, the casing is raised by sliding on the jackets to a sufficient level that the lower surface of the casing is above the waves, at the expense of the lateral forces due to the current and to the swell; the shirts are used as cofferdams to make piles fixed in the ground; the tubular tubular extensions are placed on the box in extension of the shirts to form subsequent accesses to the interior of the box and to the shirts; the box is lowered along the shirts until it is submerged below the area exposed to the shocks of the boats, to the thrust of ice and other possible lateral efforts, but the foundation rumbling remaining submerged; the shirts are pumped, the part of the shirts inside the metal extensions is cut off, and the shirts and the caisson are filled with reinforced concrete; and we disassemble the extensions; we use the emergent foundation primer of the caisson as support

to continue the foundation.

  An example of implementation of such a method will be described below with reference to the schematic figures of the accompanying drawing which illustrate the method and a device for its implementation: Figure 1 is an elevation of the box during transport; Figure 2 is an elevation of the box after sliding of the box up on the tubular shirts; Figure 3 is an elevation of the box during the realization of the piles; Figure 4 is an elevation of the submerged vessel; Figure 5 is an elevation of the box of Figure 4 equipped with metal extensions; FIG. 6 is an elevation of the box of FIG.

  concrete filling and removal of metal extensions.

  The method of the invention, with reference to FIGS. 1 to 6, comprises the steps of: prefabricating a concrete base 1 in the form of a ballastable and self-supporting box, surmounted by a foundation primer 2, for example a bait of a bole , this pre-manufacturing being carried out in a dry dock or on a launching ramp, and installing on the box vertical tubular shirts 3 ("casing") and the system that will allow the box to go up or down along these shirts, for example under the action of jacks or winches, as a self-elevating platform This system itself known

  not shown in the figures.

  float (Fig. 1) the box thus equipped to its final location; slide the shirts 3 to the contact of the shirts with the seabed, the floating remaining box is moored to anchors (not shown), then slide the box 1 up to a sufficient level above from the sea so that the box is above the waves and is no longer subject to lateral forces due to current and waves (fig 2); use the shirts 3 as cofferdams to make piles 4 in the ground of the seabed (fig 3); lower the box along the shirts until it is submerged below the area exposed to the shocks of the boats, the thrust of the ice and other possible lateral forces, the barrel primer 2 remaining emerged (fig 4 ) It is generally considered that immersion at a depth of about ten meters is sufficient; set up on the box around each liner a metal riser 5 at a height sufficient to exceed the upper level of the sea (Fig. 2 or 3) when the box is immersed These extensions could be installed in a previous step, for example when the box was above the water (fig 3), or they are installed by divers, the box being already immersed (flg 4 or 5); pump the shirts and fill the shirts and caisson with reinforced concrete; cut off the part of the shirts that is inside the

  metal folders 5 and disassemble the extensions (flg 6).

  We thus set up the foundation primer 2 on which

  we continue the foundation in a way that is well known.

  The advantages of such a method include the following: the box is a freestanding work platform that is out of the water during the casting of the piles, which allows to achieve this casting in excellent conditions; the immersion depth of the box is easily adjustable to the desired level; the tubular jackets may have any cross section: round, square, rectangular, triangular, trapezoidal, etc., which makes it possible to produce the piles with variable sections as a function of the force curves and the stability conditions.

Claims (2)

  1 Device for making a foundation on vertical piles at sea, in particular the foundation of a bridge stack, which comprises a ballastable box able to be moved to its final location at sea and to be immersed, characterized in that the box (1) is provided with a foundation primer (2) and a plurality of vertical tubular sleeves (3) along which the box can move up or down under the action of appropriate control means, and in that the device comprises tubular (5), watertight and dismountable extensions that can be arranged individually on and in extension of the folders for   provide access to the folders and the interior of the box.   2 Method for making a foundation on vertical piles at sea, in particular the foundation of a bridge stack, in which: it prefabricates an assembly comprising a self-stable ballastable caisson (1) surmounted by a foundation primer (2) and the team a plurality of vertical tubular jackets (3) arranged at the right of passages which pass vertically through the box and means for controlling on demand a relative vertical displacement of the box and the tubular jackets; this set is moved to its final location at sea; it controls a descent of the shirts (3) to the ground level, the box remaining (1) floating, moored to anchors; if necessary, the casing (1) is raised by sliding on the jackets to a sufficient level that the lower surface of the casing is above the waves, away from the lateral forces due to the current and the swell; the shirts are used as cofferdams for making piles (4) fixed in the ground; sealing tubular extensions (5) are placed on the box in extension of the shirts (3) to constitute subsequent accesses to the interior of the box and to the shirts; the box (1) is lowered along the shirts (3) until it is submerged below the area exposed to the shocks of the boats, to the thrust of the ice and any other lateral forces, but bait foundation remaining emerged; the water of the shirts is pumped, the part of the shirts is cut off inside the metal extensions, and the shirts and the caisson are filled with reinforced concrete; we remove the extensions; we use foundation bundle emerging from the caisson as support to continue the foundation.