EP0910710B1

EP0910710B1 - Process for carrying out a sheet piling underneath an existing bearing wall or partition

Info

Publication number: EP0910710B1
Application number: EP98914718A
Authority: EP
Inventors: Etienne Heirwegh
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-04-15
Filing date: 1998-04-14
Publication date: 2001-07-11
Anticipated expiration: 2018-04-14
Also published as: BE1011109A3; DE69801084D1; WO1998046834A1; AU6912598A; DE69801084T2; EP0910710A1

Description

This invention relates to a process for carrying out a sheet piling underneath an existing bearing wall or partition, whereby a series of columns is formed in the ground, underneath the wall or partition to be supported, using a case-shaped element having three sides and one open side, which is directed towards the bearing wall or partition.

Such a process is described in the Belgian patent applications no. 09600552 (BE-A-1010365) and 09600963 (BE-A-1010752) to the applicant.

The process and device used therein according to these patent applications produce excellent results, when the sheet piling has to be carried out up to a depth of 4 to 5 metres. With larger depths, problems may arise, and it is therefore the aim of this invention to prescribe a process and a device allowing to carry out sheet pilings to a depth of 8 - 10 m, by application of an improved technique which is derived from the process and device described in the above said patent applications.

In order to make this possible according to the invention, work should proceed as follows:

a) ground is removed from within the case-shaped element, and simultaneously ground is removed over a surface corresponding to the sheet piling to be introduced, and this over a height which corresponds to a modular fraction of the height of the case-shaped element;

b) a U-shaped encasement part is introduced in the space created underneath the bearing wall or partition, with the open side towards the case-shaped element;

c) the operations a) to b) are repeated until the desired depth is reached, each of the U-shaped encasement parts piled on each other is temporarily secured to the vertical edges of two sides of said case-shaped element;

d) an enlarged foundation slab is laid on the ground, or squeezed through, underneath the bottom U-shaped encasement part;

e) lost encasement sheets are secured to the open front side of each of the U-shaped encasement parts, and the bolts between the U-shaped encasement parts and the case-shaped elements are removed;

f) concrete is poured in the encasement thus created.

According to a preferred embodiment of the invention, each of the columns is built up according to a sequence, in which a column with the same or similar dimensions is formed between two already finished columns, and for that purpose, the lost encasement sheets of the U-shaped encasement parts belonging to two neighbouring columns are used as lateral encasement parts, and at the back side of the column to be formed, vertical sheets with a width somewhat larger than the width of the column to be formed, and a height equal to that of the U-shaped encasement parts, are put up and manually slided with their outer edges behind the already formed U-shaped encasement part, upon which the created encasement space is finished in the same way as described in claim 1, with sheets which are secured with their edges to the neighbouring U-shaped encasement parts.

Other details and advantages of this invention will appear from the following description of a process for carrying out a sheet piling underneath an existing bearing wall or partition and the device used therein according to the invention. This description, given as an example, refers to the attached figures.

Figures 1-3 show three subsequent steps of the process according to the invention.

Figure 4 shows the final situation, after the positioning one on top of the other of five case-shaped elements.

Figure 5 schematically shows the positioning of a series of U-shaped encasement parts with respect to two case-shaped elements.

Figure 6 is a top view of a case-shaped element connected with a U-shaped encasement part in a particular embodiment, in which a platform is represented in dotted lines, from which the U-shaped encasement parts are mounted constructively underneath the foundation and to the cases.

Figure 7 schematically shows, also from a top view, two finished columns with an encasement under construction between those columns.

Figure 8 schematically shows, on another scale, two U-shaped parts according to a horizontal cross section.

Figures 9 and 10 relate to details of the process according to the invention.

This process, illustrated by the different figures, is derived from the technique described in the patent applications referred to in the preamble.

In the first phase of this technique, in front of the wall 1 with foundation footing 2 to be sheet piled, a case-shaped element 3 is put up. In principle, the first case-shaped element 3 is resting on the ground, although according to figure 1, this case-shaped element has already sunk, up to a certain depth into the excavated soil, and this to a depth allowing to dig up the ground underneath the foundation footing, from the case-shaped element. In practice, such an element is preferably 2.50 m long, having a width of 1.20 m and a height of almost 2 m. These dimensions are not binding, and are only given here as an example. As soon as the ground underneath the wall 1 is removed, a first U-shaped encasement part 4 is shoved into the created space. The encasement part 4 consists of two wings 4' and a wall 4" which extends between the wings 4'. In practice, this wall 4" may be considered as the back wall.

Figures 7 and 8 show more details of these U-shaped parts.

It should also be noted in this stage, that for the forming of a series of columns in order to form a sheet piling, work should proceed according to a predetermined scheme, in such a way that at a certain moment the sheet piling columns to be constructed are realised between two already finished columns.

The excavations, of which figure 1 shows the first step, are continued until the situations according to figures 2 and 3 are reached. Herein, the first case-shaped element 3 is sunk sufficiently deep, to allow to shove all U-shaped encasement parts 4, which together correspond to the height of the case-shaped element, into place.

The excavation is continued until the desired depth is reached. This situation is shown in figure 4, in which five case-shaped elements are piled onto each other, and an enlarged foundation slab 15 is put in. Depending on the arbitrary height of the U-shaped encasement parts, 18 up to for example 30 U-shaped encasement parts can be introduced.

All U-shaped encasement parts 4 are provided with flanges 5 transversely welded on, for the connection by bolts with flanges 6 belonging to the side sheets of each case-shaped element 3. By way of illustration, reference is made to figures 7 and 8, in which the side walls 7 and the back wall 7' of the case-shaped elements 3 are visible.

Then, in the reverse sense, from bottom to top, lost encasement sheets 10 are placed on the inside of the U-shaped encasement parts 4, against the flanges 5. These sheets have about the same height as the U-shaped encasement parts, and are for example kept in place by a small angle iron 12 (visible in figure 8). This is only required until the moment the concrete 22 is cast. At this moment, also the bolts between the

flanges

5 and 6 of the

elements

3 and 4 are removed.

In figure 7, three case-shaped elements are positioned at a distance from each other. The spaces 8 and 8' between two case-shaped elements 3 have about the width of these elements 3. The space 8 is already excavated, while the space 8' has yet to be excavated. The spaces 8 and 8' are only excavated when the neighbouring U-shaped encasement parts 4 of 3 have already been backfilled.

The space 8 was excavated by using as an encasement the side walls 7 of neighbouring case-shaped elements 3, already put into place, and their backfilled encasement 4. At the back, i.e. at the side opposite the wall 1, every time sheets 9 have been used, corresponding to the height of a case-shaped element, or a fraction thereof. These sheets 9 were slided manually or mechanically behind two neighbouring walls 7'.

Along the back side, the lost encasement sheets 17 are put into place, and this from top to bottom, while gradually digging deeper. The sheets 17 are secured, for example by tack-welding, to the back wall 4". As soon as the bottom is reached, the encasement sheets 10 are put into place from bottom to top, as described above.

During excavation of a shaft, short reinforcing bars 13 are shoved through holes 14 provided thereto in the side walls 4' of the U-shaped encasement part 4 (figures 5 and 8).

When the desired depth is reached, at the bottom of the excavated shaft, a foundation slab 15 is laid or pressed underneath the foundation to be formed. This slab 15 can be a steel plate or be made of concrete. A concrete slab may be provided with vertical short reinforcing rods 16 for anchoring the foundation slab 15 to the concrete mass of the sheet piling. With this, it should be noted that, apart from the short reinforcing bars 13 (figure 10), in order to form a monolithic structure, common reinforcing bars may be present in each column. Thereupon, starting with the bottom U-shaped encasement parts 4, sheets 17 are secured to both side edges of the wings 4', for example by spotwelding. These different sheets 17, one on top of the other, finish the complete encasement of a column on the inside. On the outside, in the same way as described with respect to a case-shaped element 3, sheets 10 are secured against the flanges 5. Concrete can now be poured from the top into this encasement.

After filling up the realised encasement, the concrete mass is vibrated. This causes the concrete mass to subside over a not insignificant depth. As described in the first said patent application, making use of a slantingly secured close-up sheet 18, concrete is further poured underneath the foundation footing 2 of the wall 1. Due to the height of this slanting close-up sheet 18 and to the weight of the concrete, the cavity formed during the vibrating of the concrete can be correctly filled up (figure 9).

During the excavation works, removable shoring beams 21 were placed between the walls 7 of the case-shaped elements 3 in order to ensure the stability of these elements (figures 5 and 6).

In the final phase, the platforms 19 are recovered. These necessary parts are used to enable the operations during the excavation and the putting into place of the encasement to be carried out. Their supports along the side walls 7 of the case-shaped elements are clearly indicated by reference 20 (figures 5 and 6).

The U-shaped encasement parts 4 can be manufactured from widely differing materials, such as steel or recycled synthetics.

Claims

Process for carrying out a sheet piling underneath an existing bearing wall or partition, whereby a series of columns is formed, in the ground, underneath the wall or partition (1) to be supported, using a case-shaped element with three sides and one open side which is directed towards the bearing wall or partition, characterised in that the process contains the following steps:

a) ground is removed from within the case-shaped element (3), and simultaneously ground is removed over a surface which corresponds to the sheet piling to be introduced, and this over a height which corresponds to a modular fraction of the height of the case-shaped element (3);

b) in the space created underneath the bearing wall or partition (1), a U-shaped encasement part (4) is introduced with the open side towards the case-shaped element (3);

c) the operations a) to b) are repeated until the desired depth is reached, each of the U-shaped encasement parts (4) piled on each other, is temporarily secured to the vertical edges of two sides of said case-shaped element (3);

d) an enlarged foundation slab (15) is laid on the ground, or squeezed through underneath the bottom U-shaped encasement part (4);

e) lost encasement sheets (10) are secured to the open front side of each of the U-shaped encasement parts (4), and the bolts (11) between the U-shaped encasement parts and the case-shaped elements are removed;

f) the concrete is poured in the encasement thus created.
Process according to claim 1, characterised in that each of the columns is built up according to a sequence, in which a column with the same or similar dimensions is formed between two alreay finished columns, and that for that purpose, the walls of the U-shaped encasement parts (4) serving as a lost encasement and belonging to two neighbouring columns, are used as lateral encasement parts, and that vertical sheets (17) with a width somewhat larger than the width of the column to be formed, and a height equal to that of the U-shaped encasement parts (4), are put up at the back side of the column to be formed, and are manually shoved with their outer edges behind the already formed U-shaped encasement part, upon which the created encasement space is finished in the same way as described in claim 1, with sheets (10) which are secured to the edges of the neighbouring U-shaped encasement parts.
Process according to any one of claims 1 and 2, characterised in that reinforcing bars (13) are put through the vertical side walls of aforesaid U-shaped encasement parts (4), before the concrete is poured, in order to create a monolithic structure.
Process according to any one of claims 1 - 3, characterised in that in aforesaid case-shaped elements (3), internal, transverse shoring beams (21) are put in, against the bending inwards of the walls of the case-shaped elements (3).
Process according to any one of claims 1 - 4, characterised in that aforesaid U-shaped encasement parts (4), which may be made from steel, concrete or plastic material, show a height of almost 0.30 m at a length of almost 1.20 m.
Process according to any of claims 4-5, characterised in that the opposing walls of said case-shaped elements (3) are provided with supports to receive the ends of shoring beams (21).
Process according to any one of claims 1 - 6, characterised in that the foundation slab is made of steel or prefabricated concrete, in order to form an enlarged foundation footing.