METHOD FOR PRODUCING A FOUNDATION ELEMENT IN THE GROUND AND FOUNDATION ELEMENT

Abstract

The invention relates to a method for producing a foundation element in the ground, in which a hole is produced in the ground and a hardenable mass is introduced into the hole, which hardens to form the foundation element. According to the invention provision is made in that an insert body is inserted approximately centrally into the hole, the insert body being spaced apart from a circumferential wall of the hole, wherein a ring-shaped intermediate space is formed between the circumferential wall of the hole and the insert body, and in that a hardenable mass is introduced into the ring-shaped intermediate space, which hardens to form a ring-shaped foundation element.

Description

The invention relates to a method for producing a foundation element in the ground, in which a hole is produced in the ground and a hardenable mass is introduced into the hole, which hardens to form the foundation element, in accordance with the preamble of claim 1.

Furthermore, the invention relates to a foundation element in accordance with the preamble of claim 11.

It has been long known that foundation elements are produced in the ground especially for transferring greater structure loads into deeper layers of ground. To this end, a hole is produced in the ground by removing ground material or by displacing ground material. The hole thus produced is filled with a hardenable mass that can harden to form the foundation element. In doing so, the transfer of structural loads takes place for the most part via skin friction between the outer circumferential side of the hardened foundation element and the surrounding borehole wall and, to a small extent, via the horizontal contact surface of the pile at the borehole bottom. To increase the load-bearing capacity of such a foundation element it is known to design this with a corresponding axial length in order to achieve a desired skin friction.

Furthermore, it is known that in addition to the actual load-bearing function of a foundation element this is also employed for geothermal purposes. In this case, a piping system serving geothermal purposes can be inserted into the not yet hardened mass which is filled into the hole in the ground.

The invention is based on the object to provide a method and a foundation element, with which a useful purpose of a foundation element can be significantly widened in a particularly efficient way.

In accordance with the invention the object is achieved by a method having the features of claim 1 and by a foundation element having the features of claim 11. Preferred embodiments of the invention are stated in the respective dependent claims.

The method according to the invention is characterized in that an insert body is inserted approximately centrally into the hole, the insert body being spaced apart from a circumferential wall of the hole, wherein a ring-shaped intermediate space is formed between the circumferential wall of the hole and the insert body, and in that the hardenable mass is introduced into the ring-shaped intermediate space, which hardens to form a ring-shaped foundation element.

A basic idea of the invention can be seen in the fact that a foundation element in the ground is no longer of solid construction over the entire foundation cross-section but designed as a ring-shaped foundation element. This is achieved in that a preferably releasable insert body is provided approximately centrally, wherein the hardenable mass is preferably introduced exclusively into the ring-shaped intermediate space between a wall of the hole in the ground and the outer side of the insert body towards the foundation element and hardens therein.

Though, it is a finding of the invention that a ring-shaped design has no significant influence on a load-bearing function of the foundation element because, as with a solid body foundation element, the same skin friction continues to be present on the outer circumferential side which is of particular relevance for the load-bearing capacity. It is only in the region of the contact surface that the ring shape can result in a certain reduction of the contact surface. By providing a central non-load-bearing region on the contact surface of the foundation element the load-bearing capacity is therefore only lowered to a marginal extent, yet at the same time the required hardenable mass is reduced considerably. This is cost-saving.

Moreover, a space inside the ring-shaped foundation element can be used in a variety of ways, for instance for geothermal purposes, for measurement purposes or for numerous other functions.

A preferred embodiment of the invention resides in the fact that the insert body is of tubular design. The insert body can substantially only serve for the support and design of the inner ring contour of the ring-shaped foundation element. The insert body can remain in the foundation element or be released therefrom. The insert body can consist of a metal, especially steel, or a plastic material of lower load-bearing capacity.

According to a further development of the invention, on intended recovery of the insert body it is advantageous that the insert body is surrounded on its outer side by a sheathing element and that after hardening of the mass to the ring-shaped foundation element the insert body is withdrawn from the foundation element, wherein the sheathing element remains on the ring-shaped foundation element. Thereby the sheathing element can be a thin tube or preferably a film, a fabric or another type of dimensionally instable planar formation. The sheathing element is fixed as a lost element on the outer side of the insert body. The sheathing element can remain on the hardened foundation element while the insert body can be easily withdrawn from the sheathing element and be reused. This also results in a further saving of material and costs.

To increase the load-bearing capacity of the ring-shaped foundation element consisting of the hardenable mass it is expedient according to a method variant of the invention that prior to the hardening of the mass one or several reinforcement elements can be inserted into the ring-shaped intermediate space. The reinforcement elements can in particular be bars, girders or cages of steel.

According to a further development of the invention it is advantageous that the ring-shaped foundation element is designed to absorb a desired foundation load, in particular a cross-sectional surface of the ring-shaped foundation element can be designed such that the necessary axial forces can be absorbed and transferred via the outer circumferential surface. In addition, the foundation element can be designed with a base plate so that contact forces can also be transmitted directly via this base plate of the foundation element that is otherwise designed with a cavity.

Basically, the insert body can be designed in one piece. Especially for greater depths and thus for foundation elements of greater length it may be expedient in accordance with a further development that the insert body is constructed of ring-shaped segments. The ring-shaped segments can be connected axially to each other so that a longer insert body is formed. The insert body can have the same diameter over its length or show a certain conicity, with the diameter enlarging in the upward direction. This facilitates withdrawal of the insert body from the foundation element.

According to an advantageous embodiment of the invention provision is made in that a central cavity is surrounded by the ring-shaped foundation element. The central cavity can be used for various purposes, for example for the insertion of a heat exchanger element for geothermal purposes. In this case, heat can be extracted from the ground by means of a heat pump and used for heating purposes, in particular in the structure which is erected on the foundation element. Alternatively, for cooling purposes heat can also be dissipated into the ground, whereby, for example, a climatization and cooling can be realized in the structure. However, the cavity can also be deployed for metrological purposes as well as for inspection.

According to a further development of the invention it is especially advantageous that during the production of the hole ground material is removed and conveyed as excavated material out of the hole and that at least a part of the excavated material is returned into the central cavity of the ring-shaped foundation element. This is advantageous in two respects: On the one hand, excavated material can thus be returned into the ground so that the excavated material does not have to be transported away from the construction site and deposited. As a result, transportation and landfill costs can be saved. On the other hand, the foundation element is additionally reinforced by the filled-up central cavity so that the strength of the foundation element and therefore also its load-bearing capacity are enhanced.

Basically, the hole for forming the foundation element can be produced in any chosen way. According to an embodiment variant of the invention it is especially advantageous that the hole is produced through drilling with a circular cross-section or through cutting with an angular cross-section. In the case of drilling, both material-removing drilling and displacement drilling can be employed. In displacement drilling the ground material from the region of the hole is displaced into the surrounding ground by means of a displacement drill.

An angular cross-section can in particular be achieved by a diaphragm wall cutter, with which a diaphragm wall segment having a preferably rectangular cross section is produced.

Within the meaning of the invention a foundation element in the ground is to be understood in a broad sense, in which case not only can this be used for absorbing structural loads but also for forming a cut-off wall by adjoining foundation elements for example.

Another preferred method variant of the invention resides in the fact that the ground material is mixed with a concrete mass. In this way, so-called ground mortar can be produced which can be introduced into the ground as the hardenable mass in order to form the ring-shaped foundation element. However, the ring-shaped foundation element can also be produced from a concrete mass or a ground mortar of higher strength, while a ground mortar of lower strength is introduced into the central cavity. In this way, a saving in excavated material can be realized whilst still ensuring relatively high strength and load-bearing capacity of the foundation element.

The invention further comprises a foundation element which is characterized in that this is produced in a ring-shaped manner from a hardenable mass in the ground. Hence, the foundation element is not over the entire cross-section of the foundation element but only in a ring-shaped region produced of the hardenable mass. The foundation element is in particular produced using the previously described method according to the invention. The advantages set out beforehand can be achieved by way of the foundation element according to the invention.

According to a further development of the invention it is especially advantageous that a central cavity is designed in the ring-shaped foundation element. This can be used to accommodate different functional components, such as heat exchanger elements or measuring instruments.

According to a further embodiment variant of the invention it is especially advantageous that the central cavity in the ring-shaped foundation element is filled with a non-hardenable material, in particular removed ground material. As a result, transportation and landfill costs can be saved.

The invention is described further by way of a preferred, exemplary embodiment illustrated schematically in the accompanying drawings, wherein show:

FIG. 1 a cross-sectional view during the production of a foundation element according to the invention with inserted insert body; and

FIG. 2 a cross-sectional view of the foundation element of FIG. 1 after removal of the insert body.

To produce a foundation element 10 according to the invention in a ground 5 a hole 7 is initially introduced into the ground 5. The production of the hole 7 can take place in a conventional way e.g. through drilling or cutting. The drilling concerned can be cased or uncased drilling.

Before introduction of a hardenable mass into the hole 7 an insert body 20 is inserted into a central region of the hole 7. The insert body 20 can be inserted as early as during the sinking of the hole 7 or only on completion of the hole 7. In the illustrated embodiment the insert body 20 is constructed of three ring-shaped segments 22 in total which are axially connected to each other.

The insert body 20 is inserted approximately centrally into the hole 7 such that a defined distance is formed between an outer side of the insert body 20 and a circumferential wall 8 of the hole 7. In this way, an intermediate space is created which is filled with a hardenable mass to form the ring-shaped foundation element 10.

In the illustrated embodiment the insert body 20 is placed onto a bottom 14 of the hole 7. On its outer side the insert body 20 has a sheathing body 24 that can be a film or a fabric for example. The sheathing body 24 can be a lost element which mainly serves to prevent direct adhesion of the hardenable mass to the insert body 20. The sheathing body 24 can be open or closed at its lower end.

After hardening of the hardenable mass to form the ring-shaped foundation element 10 the insert body 20 is pulled upwards out of the hole 7 so that a central cavity 12 is formed in the ring-shaped foundation element 10, as illustrated graphically in FIG. 2. The sheathing body 24 remains on the inner side of the ring-shaped foundation element 10 and can, for example, serve to additionally seal the central cavity 12 with respect to the ring-shaped foundation element 10.

According to an embodiment of the invention a material of the ground that arises as excavation material 30 during the production of the hole 7 can be introduced into the central cavity 12. This reduces the amount of excavated material 30 that has to be transported away from the construction site and deposited. At the same time, in the illustrated embodiment the excavated material 30 serves for the stabilization and inner support of the ring-shaped foundation element 10. The ability of the latter to transfer structural loads into the ground 5 is accomplished to a decisive degree through the skin friction of the outer side of the foundation element 10 with the circumferential wall 8 of the hole 7.

Claims

1.-13. (canceled)

14. The method for producing a foundation element in the ground, in which

a hole is produced in the ground and

a hardenable mass is introduced into the hole, which hardens to the foundation element,

wherein an insert body is inserted approximately centrally into the hole, the insert body being spaced apart from a circumferential wall of the hole, wherein a ring-shaped intermediate space is formed between the circumferential wall of the hole and the insert body, and

wherein the hardenable mass is introduced into the ring-shaped intermediate space, which hardens to form a ring-shaped foundation element,

wherein

the insert body is surrounded on its outer side by a sheathing element and

after hardening of the mass to the ring-shaped foundation element the insert body is withdrawn from the foundation element, wherein the sheathing element remains on the ring-shaped foundation element.

15. A method according to claim 14,

wherein

the insert body is of tubular design.

16. A method according to claim 14,

wherein

prior to the hardening of the mass one or several reinforcement elements are inserted into the ring-shaped intermediate space.

17. A method according to claim 14,

wherein

the ring-shaped foundation element is designed to absorb a desired foundation load.

18. A method according to claim 14,

wherein

the insert body is constructed of ring-shaped segments.

19. A method according to claim 14,

wherein

a central cavity is surrounded by the ring-shaped foundation element.

20. A method according to claim 19,

wherein

during the production of the hole ground material is removed and conveyed as excavated material out of the hole and

at least a part of the excavated material is returned into the central cavity of the ring-shaped foundation element.

21. A method according to claim 14,

wherein

the hole is produced through drilling with a circular cross-section or through cutting with an angular cross-section.

22. A method according to claim 20,

wherein

the ground material is mixed with a concrete mass.

23. The foundation element produced pursuant to a method according to claim 14,

wherein the foundation element is produced in a ring-shaped manner from a hardenable mass in the ground,

wherein

the sheathing element remains on the ring-shaped foundation element.

24. A foundation element according to claim 23,

wherein

a central cavity is designed in the ring-shaped foundation element.

25. A foundation element according to claim 24,

wherein

the central cavity in the ring-shaped foundation element is filled with a non-hardenable material, in particular removed ground material.