WO2004081295A1

WO2004081295A1 - A support element, a support element positioning device, a method of positioning a support element and a fixed construction

Info

Publication number: WO2004081295A1
Application number: PCT/SE2004/000360
Authority: WO
Inventors: Roger Ericsson
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-03-11
Filing date: 2004-03-11
Publication date: 2004-09-23
Anticipated expiration: 2005-09-11

Abstract

The invention presents a pile guide (1), for positioning a pile (4) e.g. for a building, presenting at least one hollow interior space (3), and being arranged so that the inte-rior space (3) can communicate with the pile guide exterior surrounding (8) essen-tially along at least a substantial part of the pile guide (1). A method of positioning a pile (4) comprises the steps of: forcing a soil affecting device (1) into the ground to obtain an affected soil volume (11), removing the soil affecting device (1) from the affected soil volume (11), and positioning the pile in the affected soil volume (11). A load distributing layer (19), located between a load carrying structure and the piles (4), is adapted to carry loads in a horizontal direction, and at least one of the piles (4) is located in a position that is shifted horizontally in relation to vertically load transferring elements (14) of the structure.

Description

A SUPPORT ELEMENT, A SUPPORT ELEMENT POSITIONING

DEVICE, A METHOD OF POSITIONING A SUPPORT ELEMENT

AND A FIXED CONSTRUCTION.

TECHNICAL FIELD

The invention relates to supports for fixed constructions,, such as buildings. More particularly, the invention relates to a support element positioning device, for positioning a support element for a fixed construction such as a building, a method for positioning a support element, a support element, for a fixed construction such as a building, and a fixed construction, such as a building.

BACKGROUND

During cohesion piling, when the pile is driven into the ground, the soil softens and, as a result loses some of its strength. Therefore the pile is not able to transfer the ex- act amount of load which it is intended to immediately after it has been driven. By

"cohering" to the pile, the soil regains its strength, after the pile has been driven into the soil.

The methods for piling and the shape of the piles used have in principle remained un-changed for hundreds of years. Traditionally, in cohesion piling as well as in other types of piling, the piles are forced into the soil by means of a ram pounding the pile into the ground. In cohesion piling large forces are required to force the piles into the soil, since the contact between the soil and the pile provides a great resistance. To resist the large forces during the piling procedure, the piles have to be strong enough. More specifically, the piles need to have a sufficient flexural rigidity in all transverse directions. Therefore, the cross-section of the piles is usually square or circular. Piles used today are usually cast in standard concrete such as K30-K40 or K50-K60, and reinforced with steel, slacked or pre-tensioned, respectively. In cohesion piling, piles with square or circular cross-sections have a relatively low efficiency when supporting a structure, since the circumference of the cross-section in relation to the cross-sectional area is small, resulting in less surface area to provide the desired pile to soil friction. A pile with a cross-sectional shape being elongated, such as the pile described in US6382879B1, has more surface area in relation to cross-sectional area and therefore they are more efficient and as a result, shorter piles can be used. However, such a pile does not have enough flexural rigidity in all transverse directions to be positioned by traditional methods used in cohesion piling described above.

In traditional piling the piles have to be positioned in relation to the building to be supported so as to properly support the building structure. This means that each pile has to be positioned straight below a vertical load carrying element of the building. The vertical load carrying elements could be columns or structural walls in the building. In any type of piling, whether in cohesion piling, friction piling or end bearing piling, a problem arises when a pile, or piles, can not be positioned exactly under (a) vertical load carrying element(s). The reason could be that an obstacle, e.g. a rock, is present in the soil. The traditional way of solving this problem is to drive a plurality of piles adjacent to the originally intended position of the pile, and using transverse load carrying members on the top of the piles to distribute load from the structure transversely to the piles. This results in much more piles being used than the actual supporting task requires, which is material and labour consuming, and therefore costly. In other words, in cases where one pile is enough to support a specific load, additional piles are of superfluous.

SUMMARY OF THE INVENTION

An object of the invention is to decrease the forces exerted on a pile when positioning the latter in soil. Another object is to provide a support element for cohesion piling that support loads more effectively than traditional piles.

Yet another object is to reduce material and labour needed to carry out piling for a fixed structure.

The first object is reached with a support element positioning device, for positioning a support element for a fixed construction such as a building. The support element positioning device presents an extended shape and at least one hollow interior space, and it is arranged so that the interior space can communicate with the support element positioning device exterior surrounding essentially along at least a substantial part of the support element positioning device.

Suitably, the support element positioning device is used in cohesion piling. Since the interior can communicate with the surrounding along a substantial part of the support element positioning device, the support element positioning device can at the beginning of the support element positioning procedure be forced into the ground without the support element, whereby soil can enter the interior of the support element positioning device. This is advantageous compared to the soil remaining in the surrounding providing resistance due to the contact between the soil and the exterior of the object being forced into the ground. As a result of the invention, considerably less force is needed when positioning the piles. In cohesion piling the support element positioning device according to the invention can be positioned using a continuously applied force, by means of a traditional construction machine, the force being of much smaller magnitude than the pounding forces in traditional piling.

Also, using the support element positioning device of the invention, no special ramming equipment is needed for piling. Instead, more handy equipment such as excavators may be used. Preferably, the support element positioning device is pro- vided with connecting means that are compatible with a standard mounting equip- ment, e.g. for a ladle, on an excavator, so that a normal excavator can be used to force the support element positioning device into the ground.

Additionally, the geometry of the piles can be chosen without consideration for re- quirements of withstanding large forces during the pile positioning procedure.

Preferably, the support element positioning device has an elongated cross-sectional shape. Thereby, the interior space will be narrower than in the case of e.g. a square or circular cross-sectional shape of the support element positioning device. This makes the softening of the clay easier, which in turn results in even less force needed to drive the device into the soil. In other words, the device can perform a "cutting process" of the soil.

Also, since the forces in the pile positioning procedure are much lower than in tra- ditional piling, support elements, or piles, with elongated cross-sections can be used. By presenting an elongated cross-sectional shape, the ratio between the circumference and the cross-sectional area can be kept high, and therefore the friction forces per unit length of the support element can be increased. For most normal building construction applications, a suitable length of the inventive support element is at least 2 meters, preferably, 3-8 meters, and the aspect ratio of the cross-section could suitably be at least 1 :3. Thus, shorter piles can be used in cohesion piling than in the case of a square or circular cross-section pile, the piles nevertheless being long enough to reach levels at which the clay is of a quality such that it will support the piles.

Optionally, the support element positioning device could be provided in at least two sections, whereby an individual section can be mounted to a section already forced into the ground, so that deeper penetration of the soil can be carried out by successively adding sections of the device. Also, the support element could be sectioned in this manner. The first object is also reached with a method of positioning a support element, for a fixed construction such as a building, in the ground, the method comprising the steps of: forcing a soil affecting device into the ground to obtain an affected soil volume, removing the soil affecting device from the affected soil volume, and positioning the support element in the affected soil volume.

Preferably, the method is used in cohesion piling. It is particularly suited for piling in clay. Thereby, the affected soil volume is formed by clay that is disturbed so that it has obtained a loose consistence. In other words the initially hard clay is mixed and stirred by the soil affecting device so that it turns liquid or semi-liquid. Thereby, the support element can be positioned in the loose clay with considerably less force than in the case of the support element being positioned directly into the ground. In other words, the support element can be optimised solely for supporting a structure, and not for large forces inflicted during its positioning.

Preferably, the soil affecting device is forced into the ground so that the affected soil volume obtains a vertically extended shape with a delimitation substantially corresponding to the shape of the support element. Thereby, immediately after the posi- tioning of the support element, before the cohesion process is finalised, the support element will be held in place by solid soil surrounding the affected soil volume.

Preferably, the step of positioning the support element in the affected soil volume comprises, positioning the support element in an interaction position in relation to a support element positioning device, positioning the support element positioning device in the affected soil volume, with the support element in the interaction position, removing the support element positioning device from the affected soil volume, leaving the support device. Thereby, since the support element positioning device guides the support element, a high precision can be obtained when positioning the latter. Also, no special devices have to be formed on the support element itself in order to lower and position the latter in the soil. The support element positioning device could be identical to the soil affecting device, or a separate device. If they are identical, preferably the support element positioning device is at least partly removed from the affected soil volume before the support element is positioned in an interaction position in relation to a support element positioning device. Thereby, the support element can be partly inserted in the support element positioning device and supported by the latter in an up- right position, whereupon the latter is pulled further out of the ground for the support element to be gradually further inserted into the support element positioning device.

Preferably, the support element positioning device encloses at least partially the support element in the interaction position. Thereby, the support element positioning device will give lateral support to the support element.

Preferably, the support element is locked to the support element positioning device when the support element is in the interaction position, and the support element is unlocked from the support element positioning device when the support element is essentially at its intended final position in the ground. Thereby, relative movement between the support element positioning device and the support element is prevented during the positioning step, and it is assured that the support element follows the support element positioning device when the latter is forced into the ground.

The object of providing a support element for cohesion piling, that supports loads more effectively than traditional piles, is reached with a support element, for a fixed construction such as a building, having an extended shape and being adapted to transfer load to the soil by cohesion the support element presenting an elongated cross-sectional shape. Preferably, the support element comprises a high performance concrete. Thereby, the lack of flexural rigidity of the extended cross-section in relation to a square cross-section, can be compensated for. Preferably, the concrete is of the type de- scribed in PCT/SE2004/000148, incorporated herein by reference.

The third object is reached with a fixed construction, such as a building, comprising a plurality of support elements, each positioned essentially vertically and at least partly in the ground, a load carrying structure located above the support elements, the structure comprising vertically load transferring elements. The fixed construction comprises a load distributing layer, located between the structure and the support elements and adapted to carry loads in a horizontal direction, and in that at least one of the support elements is located in a position that is shifted horizontally in relation to the vertically load transferring elements.

Since the load distribution layer can transfer loads in a horizontal, or transverse direction, the positioning of the support elements, or piles; in relation to the vertically load transferring elements of the structure is not critical.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention will be described in detail with the aid of the drawings, in which

- fig. 1 shows a side view of a support element positioning device according to one embodiment of the invention,

- fig, 2 shows a side view of a detail of the support element positioning device is fig. 1,

- fig. 3 shows a cross-section oriented along the line III-III in fig. 2, with a support element in the support element positioning device, - fig. 4 shows another side view of a support element positioning device in fig 1, - fig. 5 shows cross-sections of support elements according to alternative embodiments of the invention,

- fig. 6-10 show side views of the support element positioning device in fig. 1, and a support element in different steps according to a preferred embodiment of a method of positioning a support element,

- fig. 11 shows a fixed construction according to known art,

- fig. 12 shows an exploded view of a fixed construction according to a preferred embodiment of the invention,

- fig. 13 shows the fixed construction in fig. 12 in an un-exploded perspective view, and

- fig. 14 and 15 shows perspective views of fixed constructions according to alternative embodiments of the invention.

DETAILED DESCRIPTION

Fig. 1 shows a support element positioning device 1, herein also referred to as a pile guide or a soil affecting device, for positioning a support element for a fixed construction such as a building, in a position in which it is forced into the ground 2, as indicated with the arrow A. The pile guide 1 has an extended shape and a hollow interior space 3, as can be seen in fig. 3, also depicting a support element 4, herein also referred to as a pile, in the pile guide 1. The pile 4 also has an extended shape and the pile guide 1 is adapted to, at least partially, enclose the pile 4.

Referring to fig. 2, the pile guide 1 comprises two U-profiles 5, preferably in steel and/or aluminium, interconnected by a framework 6, preferably made of steel bars. Thereby, gaps 7 between the framework members and the U-profiles 5 form apertures 7, by means of which the interior space 3 can communicate with the pile guide exterior surrounding 8 essentially along all of, or a substantial part of the pile guide 1. Alternatively, the pile guide can be of any other suitable form, for example a pipe with a circular cross-section, provided with large apertures along its length, for providing the communication between the interior space 3 and the exterior surrounding

The pile guide 1 is suitable to penetrate soil in the form of clay. Referring to fig. 2 and 4, at the bottom of the pile guide 1, soil penetration aiding elements 9, in the form of cutting profiles 9 are arranged for facilitating the procedure of forcing the pile guide 1 into the soil. The cutting profiles are arranged along the periphery of the pile guide 1, and delimiting a bottom aperture 10, through which soil can move during the soil penetration procedure. Alternatively, another type of soil penetration element could be used, for example horizontally oriented bars with or without sharp penetration edges.

Referring to fig. 1, according to a preferred method of positioning a support element, initially the pile guide 1 is forced into the soil without the pile 4 in it, whereby the soil or clay is disturbed, creating an affected soil volume 11, indicated with broken lines in fig. 7. As the pile guide 1 is forced further, soil can enter the interior of the pile guide through the gaps 7 and aperture 10. Thereby, instead of moving the soil, the soil is merely stirred so that the clay turns soft and subsequent positioning of the pile is facilitated.

As can be seen in fig. 3, the pile guide 1 as well as the pile 4 has an elongated cross- sectional shape. Fig. 5 shows alternative cross-sectional shapes of the support de- vice, i.e. an I-beam shape (fig. 5a) and an elliptic shape (fig. 5b). The I-beam shape further increases the ratio between the circumference and the cross-sectional area.

Referring to fig. 6, when the pile guide has been driven to the desired depth, the pile is positioned partly inserted from the top in the pile guide. Referring to fig. 7, there- after the pile guide is lifted out of the soil, so that the pile 4 is further enclosed, and whereby the pile 4 is positioned in an interaction position in relation to the pile guide 1. The pile and the pile guide are providing with interengagable locking means (not shown), and in the interaction position shown in fig. 7, the pile is locked to the pile guide by means of the locking means.

Referring to fig. 8, subsequently the pile guide 1 is moved into the affected soil volume 11 with the pile 4 locked to it. When the pile 4 is in the desired position in relation to the ground, the locking means are manoeuvred so as to unlock the pile 4 from the pile guide 1, and the pile guide is thereafter removed from the affected soil volume 11 (fig. 9), leaving the support device 4 in the affected soil volume 11 (fig. 10).

Alternatively, the support element positioning device 1, or soil affecting device 1, could be adapted solely to create a volume 11 of disturbed soil or clay. Thereby, af- ter use of the soil affecting device 1 to create an affected soil volume 11, the pile 4 could be positioned in the affected soil volume without any special device being forced into the ground together with the pile 4.

After positioning of piles, a structure can be built above them. Fig. 11 shows a con- struction according to known art, whereby a building structure 12 is raised on a base plate 13. Piles 4 are positioned beneath respective vertically load carrying elements 14 for reasons described above under the section "background". As also described above, where needed a plurality of piles 4 are positioned to support one single vertically load carrying element 14. For this reason reinforcement brackets 15 are posi- tioned at the bottom of the vertically load carrying elements 14, as well as possible additional reinforcement members 16.

Fig. 12 shows an exploded view of fixed construction, according to a preferred embodiment of the invention. The construction comprises a plurality of support ele- ments 4, or piles 4, each positioned essentially vertically and at least partly in the ground. A load carrying structure 12 is located above the piles 4, the structure comprising vertically load transferring elements 14 in the form of columns 14. Below the structure 12 and above the piles 4 are respective base plates 17, 18, separated by a load distributing layer 19. The load distributing layer 19 has enough internal fric- tion to be able to carry loads by distributing the forces in a horizontal direction. Therefore, the piles 4 can be shifted horizontally in relation to the vertically load transferring elements 14 of the structure 12. Pile heads 20 are positioned on top of the piles to facilitate the interaction between the piles and the lower base plate 18.

The load distribution layer 19 can be formed by frictional soil, broken stone, haydite or a similar material with a high internal friction. Due to the load distribution layer, the positioning of the piles 4 in relation to the vertically load transferring elements 14 of the structure 12 is not critical.

Fig. 13 shows the fixed construction of fig. 12 in a non-exploded view. Fig. 14 shows an alternative embodiment in which the upper base plate 17 is replaced with individual plates 21, each placed at the bottom of a respective vertically load carrying element 14. Fig. 15 shows another alternative, in which the vertically load carrying element are formed by load carrying walls 14, at which support plates 21 are provided along the lower edge of respective walls 14.

Claims

1. A support element positioning device (1), for positioning a support element (4) for a fixed construction such as a building, characterised in that it presents an extended shape and at least one hollow interior space (3), and in that it is arranged so that the interior space (3) can communicate with the support element positioning device exterior surrounding (8) essentially along at least a substantial part of the support element positioning device (1).

2. A support element positioning device (1) according to claim 1, having an elongated cross-sectional shape.

3. A support element positioning device (1) according to claims 1 or 2, comprising soil penetration aiding elements (9).

4. A method of positioning a support element (4), for a fixed construction such as a building, in the ground, characterised in that it comprises the steps of:

- forcing a soil affecting device (1) into the ground to obtain an affected soil volume (11), - removing the soil affecting device (1) from the affected soil volume (11), and

- positioning the support element in the affected soil volume (11),

5. A method according to claim 4, wherein the soil affecting device (4) is forced into the ground so that the affected soil volume (11) obtains a vertically extended shape with a delimitation substantially corresponding to the shape of the support element (4).

6. A method according to claim 4 or 5, wherein the step of positioning the support element in the affected soil volume comprises - positioning the support element (4) in an interaction position in relation to a support element positioning device (1),

- positioning the support element positioning device (1) in the affected soil volume, with the support element (4) in the interaction position, - removing the support element positioning device (1) from the affected soil volume, leaving the support device.

7. A method according to claim 6, further comprising the steps of locking the support element (4) to the support element positioning device (1) when the support element (4) is in the interaction position, and unlocking the support element (4) from the support element positioning device (1) when the support element (4) is essentially at its intended final position in the ground.

8. A support element (4), for a fixed construction such as a building, having an ex- tended shape and being adapted to transfer load to the soil by cohesion, characterised in that it presents an elongated cross-sectional shape.

9. The support element (4) according to claim 8, comprising a high performance concrete.

10. A fixed construction, such as a building, comprising a plurality of support elements (4), each positioned essentially vertically and at least partly in the ground, a load carrying structure located above the support elements (4), the structure comprising vertically load transferring elements (14), characterised in that it comprises a load distributing layer (19), located between the structure and the support elements (4) and adapted to carry loads in a horizontal direction, and in that at least one of the support elements (4) is located in a position that is shifted horizontally in relation to the vertically load transferring elements (14).