EP0580098A1 - Method and device for pile foundation - Google Patents

Abstract

The invention is shown essentially in Figure 1. It relates to a method and a device for lifting a structure by means of a multiplicity of jacked piles (1). In this arrangement, each of the jacked piles consists of segments (2, 3). A sufficiently large working pit is created under the foundation of the structure to be lifted for each of the jacked piles so that an initial segment of the respective jacked pile (1) and a jack (12) can be placed therein. The jack (12) is arranged between the foundation and the initial segment (2) of the jacked pile (1). The initial segment (2) is forced into the subsoil by the pressure exerted by the jack (2). Any number of following segments (3) which can be put onto the initial segment (2) are forced into the subsoil one after the other in the same manner as the initial segment (2) until the initial segment (2) has reached a load-bearing layer in the subsoil, specifically designed pile segments (2, 3) being used which in their interior have recesses of different size and number. <IMAGE>

Description

The invention relates to a method according to claim 1 and an apparatus for performing the method according to claim 13.

Pile foundations are required in a wide variety of construction areas.

On the one hand in new buildings if the building ground does not have the required strength and on the other hand in the renovation of existing buildings that have moved (lowered, raised and / or twisted) due to a weakness of the subsoil.

The use of driven piles has been known for thousands of years. For example, the historic pile dwellings are built on ram piles. There is a certain limitation from the length of the driven piles, which affects the maximum possible depth of the pile foundation.

Another disadvantage of the pile-driving technique is that this method is always associated with a vibration of the ground and thus also surrounding buildings. The vibrations can cause damage to the buildings in question, so the use of ram piles for the subsequent pile foundation of buildings that are sensitive to vibrations is ruled out.

Also known are bored piles, the use of which means that the piles are not rammed. With this method, the cutting head of a pipe cuts into the ground. The pipe has a dual function. On the one hand, it serves to cut into the ground, on the other hand it acts like a formwork or a well wall in relation to the surrounding ground, ie the surrounding ground is physically completely separated from the ground inside the pipe. The inside of the pipe can now be dredged with suitable excavators, so-called fall excavators. In the resulting cavity is then a in the usual way Reinforced steel reinforcement and the entire cavity filled with concrete.

A bored pile is therefore comparable to a column with formwork (= pipe) located in the ground. The combined drilling and excavation equipment used for this purpose is usually several tons heavy and must be very high in order to have a suitable fall height for the fall excavator.

For these reasons, the use of such devices in tight spaces is just as impossible as the simultaneous use of several corresponding devices close to each other. If, according to this method, several piles are to be arranged one inside the other in order, for example, to achieve a wall defect, several holes are drilled side by side in such a way that the adjacent hole is only drilled when the concrete pile is in the previous hole.

Another disadvantage of bored piles is that, unlike rammed piles, which compact the surrounding ground in the area of the piles, bored piles have a relatively small effect on the physics of the surrounding soil and the existing layers are penetrated without any significant change. This puncture can lead to various consequences. If, for example, a deeper water-bearing earth layer with a higher pressure is separated by a barrier layer from a higher water-bearing or non-water-bearing earth layer with lower pressure ratios, the drilling process along the cutting tube can cause water to rise from the lower water-bearing layer due to the higher pressure and the change earth physics there.

Contaminated water flows near the surface can be mixed with deeper lying drinking water flows in an undesired manner etc.

With peat layers, air may get to the peat at the interface, which may lead to a long-term change in the consistency of the subsoil (e.g. decomposition of the peat by penetrating bacteria).

A significant disadvantage of both the bored pile foundation and the driven pile foundation results from the space required by the drill or ram to insert the piles, making it impossible to insert several adjacent piles at the same time.

Another disadvantage of both the pile pile foundation and the bored piles is that in both methods the piles cannot be installed vertically below the supporting walls of existing buildings.

From DE-OS 37 39 917 a method and a device for carrying out the method is known, in which piles can be inserted below load-bearing walls. For this purpose, a sufficiently large working pit is created under the foundation at several points of the building to be aligned in order to be able to incorporate press pile segments and hydraulic presses. As a result of the lifting pressure on the foundation of the building to be lifted, the press pile segments penetrate into the ground, whereupon the next press pile segment is placed on the previously pressed press pile segment.

With a soft consistency of the subsurface and at the same time a large foundation depth is necessary, many segments must be placed on top of each other. Because of the low lateral clamping forces due to the soft surface, there is a risk that the foundation pile created according to the known method will buckle laterally. To avoid this, the press pile should have the properties of a solid column.

In the prior art, the segments are not connected to one another with tensile strength. A statically calculable column cannot be realized in this way. This is particularly disadvantageous if the load-bearing layer is far below the level of the building foundation and / or if the subsoil settles due to the lowering of the groundwater level.

The maximum press-in depth is also limited in the prior art due to the skin friction on the press pile which occurs with increasing press-in depth.

The invention has for its object to provide a method and create an apparatus for performing the method, whereby the disadvantages of the prior art are avoided.

This object is achieved according to the invention by a method according to the characterizing part of claim 1 and by a device according to the characterizing part of claim 13.

The invention adopts the knowledge that a large number of pressed pile segments must be arranged one above the other on soft ground and that these must be connected to one another in a tensile manner by appropriate measures in order to create a statically calculable column on which the building ultimately stands.

Another consideration that led to the creation of the invention is based on the fact that with increasing press-in depth, the skin friction on the outer surfaces of the already pressed-in segments becomes so great that a large part of the press-pressure is thereby absorbed and the seat pressure of the lowermost segment is too low to make it go deeper. It is therefore provided that one or more further segments with a smaller cross section are telescopically pressed out of the lowest segment.

Developments and particularly advantageous embodiments of the invention are the subject of the dependent claims.

A possible exemplary embodiment of the invention is explained in more detail below with reference to the drawing.

Figur 1

in Teils gebrochener Darstellung den Einsatz der Erfindung an einem Gebäude

Figur 2

einen Längsschnitt durch das Anfangssegment des Presspfahles und ein darauf aufgesetztes Folgesegment.

Figur 3

einen Querschnitt durch das Anfangssegment gemäß Figur 2 entlang der Schnittlinie II-II

Figur 4

einen Querschnitt durch das Fundament eines Hauses, dessen ursprüngliches Fundament durch ein Hilfsfundament verstärkt wurde

Figur 5

in schematischer Darstellung die Lage einer Vielzahl von Presspfählen unter einem Gebäude.

Show it:

Figure 1

partly broken representation of the use of the invention on a building

Figure 2

a longitudinal section through the initial segment of the press pile and a subsequent segment placed thereon.

Figure 3

a cross section through the starting segment of Figure 2 along the section line II-II

Figure 4

a cross section through the foundation of a house, the original foundation of which was reinforced by an auxiliary foundation

Figure 5

the location of a plurality of press piles under a building in a schematic representation.

FIG. 1 shows a partially sectioned illustration of a press pile 1 and a press 12, as well as parts of the building to be lifted and the subsurface. Below a load-bearing outer wall, only as much space had to be created as the press 12 and a press pile segment 2 or 3 require in space. The reaction force to apply the pressure is applied by the weight of the building. It is imperative that the reaction force from the weight of the building must be greater than that from the resistance of the ground at the time the pile is founded Reactive power, otherwise the building would be lifted at this point.

In order to avoid an unintentional lifting of the building when inserting the press piles 1, it is provided according to the invention to press these in segments one after the other when founding several press piles 1 lying next to one another, which ensures that the initial segments of all press piles are at approximately the same depth at all times during the insertion establish (Is explained in more detail in Figure 5).

The reaction force for the introduction of a single (or fewer) press piles 1 (piles) can be applied by the building. If, after completion of the foundation of all press piles 1, a lifting element is pressurized on each press pile 1, the entire building rises. In this way, the same hydraulic elements can advantageously be used first for the introduction of the press piles 1 and then for the lifting of the building.

From a certain press-in depth, the resistance to further press-in also increases due to the skin friction on the outside of the press pile 1. Pressing in further under certain circumstances would require such high forces that the load on the foundation site serving as an abutment for the press 12 would become so great that damage to the building would have to be feared. Nevertheless, the starting segment of the press pile 1 is not yet on a load-bearing layer.

From a certain depth of foundation, which depends in each case on the nature of the subsoil and the load-bearing capacity of the building to be lifted, the press pile 1 as a whole is therefore not further pressed in according to the invention, but inner segments with a smaller cross section described in more detail in FIG .

Depending on the requirement, several inner segments with different diameters can also be arranged one inside the other, the smaller inner segment being pressed further when the pressure to be pressed in has reached a predetermined limit.

In this way, it is possible to press deeply into the load-bearing layers, and due to the skin friction on the segments 2, 3 with a large diameter, some of the foundation loads are already absorbed.

In the case of large foundation depths, the various inner segments, each with a smaller inner diameter, can be extended telescopically, the next smaller inner segments each being extended further when the peak pressure or the jacket friction has exceeded a predetermined value.

The uppermost inner segments can be very thin-walled and made of steel, for example.

2 shows a press pile 1, which is composed of an initial segment 2 and any number of subsequent segments 3. In segments 2, 3 there are several axially extending recesses. A large recess 4 runs directly centrally, several smaller reinforcement recesses 5 are arranged concentrically around the central axis of the segment.

In contrast to the continuous reinforcement recesses in the following segments 3, the reinforcement recesses in the starting segment 2 are designed as blind holes. An inner segment 6 is located within the recess 4.

The underside of the press pile 1 is thus closed, and separating layers in the subsurface can be punctured, without the risk that the earth's physics of the individual layers are changed by compensating processes, for example water movements.

A reinforcing steel 7 inserted into a reinforcement recess 5 is drawn as an example for all other reinforcement recesses 5.

In order to enable a continuous insertion of the reinforcement steels 7, the reinforcement recesses 5 must be aligned over the entire length of the column 1, which is known to consist of a large number of subsequent segments 3. The alignment can take place, for example, by visual inspection when the next following segment 5 is placed on it, or it can be forcibly carried out by coding on the top and bottom sides of the press pile segments 2, 3. Such coding can be implemented, for example, in the form of grooves and corresponding projections. For the sake of clarity, the projections and grooves are not shown in this illustration.

The individual press pile segments 2, 3 each have a helical reinforcement 8 made of steel. Due to the combination of spiral reinforcement 8, the reinforcing steel 7 passing through and the reinforcement recesses 5 poured with concrete, the press piles 1 according to the invention receive a non-positive connection and the predictable statics of a column.

As can be seen, the inner segment 6 can be pressed telescopically out of the press pile 1. Because the inner segment 6 has a significantly smaller cross-section, the inner segment 6 can achieve a significantly higher surface pressure due to the building weight acting on the press pile 1. For this purpose, a press is used which only presses on the inner segment 6. This is particularly advantageous if, for example, the entire press pile 1 has penetrated the poorly load-bearing layers of the subsurface and stands on a load-bearing gravel layer. then the pressure on the inner segment 6 can "extend" it telescopically from the press pile 1 and thus bring about an improved anchoring of the press pile 1, which stands on the gravel layer, in this gravel layer.

FIG. 3 shows a section along the section line II-II from FIG. 1, the position of the centrally running recess and the concentrically arranged reinforcement recesses can be clearly seen.

An embodiment for an application in which the original foundation has to be reinforced is shown in FIG. For this purpose, reinforcement is carried out by an auxiliary foundation 9 attached below the foundation. For this purpose, the soil beneath the foundations is removed at certain points near the load-bearing wall under which a press pile 1 will later be placed, inside or outside the building, and continuously or relatively continuously by an armored or non-armored person Concrete to be replaced. There is also the option of fastening the subsurface using concrete injections. A plurality of tension struts 10 are anchored in the auxiliary foundation 9 thus created. The free ends of the tension struts 10 protruding from the auxiliary foundation 9 are connected to a stable supporting frame 11. The press 12 is supported on this support frame 11. When the pile is founded, the entire weight of the building is placed on this second foundation, so that a stable abutment is available. The building stands with its foundation on this second foundation, so to speak, and is moved with this second foundation in the subsequent lifting process, i. H. usually lifted.

A schematic representation of a possible arrangement of a plurality of press piles 1/1 .. 1/16 under the outer walls of a building is shown in FIG. A partial amount of the press piles is pressurized to insert the press piles. In order not to bring about a local elevation of the building when the press piles are inserted the first, third, fifth, etc. press pile 1/1, 1/3, 1/5, ... brought down together. In a second step, the second, fourth, sixth, etc. press piles 1/2, 1/4, 1/6, ... are inserted. Of course, any other distribution is also conceivable, only the principle is to be explained here, namely, when inserting the press piles, alternately loading only a subset of all press piles used later for lifting.

The method according to the invention further provides not to first bring one or more press piles all the way down to the load-bearing layer, but rather to insert all press piles approximately equally deep in the individual phases. For this purpose, the first segments of the first press pile group are pressed in, then the initial segments of the second press pile group are pressed in. The individual indentation steps are very small. They are preferably in the range of a few millimeters.

In the next step, the second segments of the first press pile group are pressed in, then the second segments of the second press pile group.

The pressing in of the pile segments 2, 3 is carried out under computer control by a control unit 13, the pressing speed being kept constant for each pressing pile and the pressing pressure being stored as a function of the pressing depth.

When the next following segment is put on, the respective press pile is relieved. The elastic part of the settlement is determined from the relief movement. The smaller this elastic part is, the closer the starting segment of the press pile 1 is to a load-bearing layer.

Thus, the specific load-bearing behavior is measured for each individual press pile 1 and is available for later proof of stability.

By pressing them together in small, simultaneous press-in steps it is achieved according to the invention that the starting segments of all press piles 1/1 to 1/16 are located approximately on the same level in the subsurface. This has the advantage over successive, complete insertion of the individual piles down to the foundation level that an undesired change in the subsurface, caused by the complete introduction of the previous press pile 1, does not occur here. Such an undesirable change would be, for example, a compensation of different pore water pressures in the different foundation depths.

According to the invention, in a first step all press piles (1/1 to 1/16) can be pressed in simultaneously, and in a second step when pressing in the press piles (1/1 to 1/16) alternately a first subset of press piles ( 1/1, 1/3, 1/5, ..) and a second subset (1/2, 1/4, .1 / 6, ..) or vice versa. This enables an optimal adaptation to the local soil conditions.

In a further development of the invention, the forces opposing the individual press piles are also checked when they are pressed in. If the press-in force is not the same, readjustment is carried out via the press-in path, so that a force transmission is evenly distributed over all press piles.

Accordingly, in the method according to the invention, the following case cannot occur that, for example, in the case of an inclined sand / rock transition, part of the press piles is based on the rock, but the other part is still completely in the sand.

Claims (17)

Method for lifting a building using a plurality of press piles, wherein - each of the press piles consists of segments, a sufficiently large working pit is created below the foundation of the structure to be lifted for each of the press piles, so that an initial segment of the respective press pile and a press can be introduced therein, - the press is placed between the foundation and the initial segment of the press pile, the initial segment is pressed into the ground by the pressure exerted by the press, any number of subsequent segments that can be placed on the starting segment are pressed one after the other in the same way as the starting segment, characterized in that - Specially designed pile segments (2, 3) are used, each of which has recesses (4, 5) of different sizes and numbers in their interior. Method according to claim 1,
characterized in that
the individual segments (2, 3) are placed one above the other so that the recesses (4, 5) are each aligned. A method according to claim 1 or claim 2,
characterized in that
the individual segments (2, 3) are made of reinforced concrete and have a helical reinforcement (8) made of steel near the recesses (5) lying within them. A method according to claim 1 or claim 2,
characterized in that
the individual segments (2,3) are made of steel. Method according to one of the preceding claims, characterized in that - A steel rod (7) running over the entire press pile or part of its length is inserted into the aligned recesses (5) of the individual segments provided for receiving steel reinforcements, - The recesses (5) are filled with a potting material - After the potting material has hardened, the individual segments (2, 3) of the press pile (1) produce a monolithic, firmly connected, statically calculable column. Method according to one or more of the preceding claims 1 to 5,
characterized in that - The individual segments each have a central recess (4) in which there are in turn inner segments (6) and - The inner segments (6) are pressed in independently of the segments (2,3). Method according to one or more of the preceding claims 1 to 6,
characterized in that
the inner segments (6) are pressed further after the potting material introduced into the recesses (5) has hardened. Method according to one or more of the preceding claims 1 to 7, characterized in that - an additional auxiliary foundation (9) is created under the foundation of the building to be lifted, - A support structure (10, 11) is anchored in the auxiliary foundation (9), which forms the counter bearing for the press (12). Method according to one or more of the preceding claims 1 to 8, characterized in that - when pressing in the press piles (1/1 to 1/16) alternately a first subset of press piles (1/1, 1/3, 1/5, ..) and a second subset (1/2, 1/4, .1 / 6, ..) is pressed in. Method according to one or more of the preceding claims 1 to 8, characterized in that - all press piles (1/1 to 1/16) are pressed in simultaneously. The method of claim 9 or 10
characterized in that - in a 1st step all press piles (1/1 to 1/16) are pressed in at the same time, and / or - That in a second step, when pressing in the press piles (1/1 to 1/16), alternately a first subset of press piles (1/1, 1/3, 1/5, ..) and a second subset (1 / 2, 1/4, .1 / 6, ..) is pressed in. Method according to one or more of the preceding claims 1 to 11,
characterized in that - The press-in speed is kept constant for each press pile and the press-in pressure is saved depending on the press-in depth. Method according to one or more of the preceding claims 1 to 12,
characterized in that - the opposing force measured by the individual press piles during the pressing in and - The press-in distance is regulated depending on the counterforce. Method according to one of the preceding claims, characterized in that - When a predetermined counterforce is reached, only the inner segments (6) are pressed in further. Device for carrying out the method according to claim 1, consisting of a press and a plurality of stackable pile segments
characterized in that
the segments (2, 3) have aligned recesses (4, 5) in the course of the individual segments. Device according to claim 15,
characterized in that
inner segments (6) are arranged in each of the segments (2, 3) and can be pressed in independently of the segments (2, 3). Device according to claim 15 and / or 16
characterized in that - An auxiliary foundation (9) and an attached supporting structure can be attached to the building to be lifted and the supporting structure (10, 11) forms the abutment for the press (12).

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