Static structures (e.g. – buildings) – Specified terranean relationship
Reexamination Certificate
2001-03-26
2004-01-06
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Specified terranean relationship
C052S334000, C052S600000, C052S169130, C405S036000, C405S050000
Reexamination Certificate
active
06672015
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to improvements in a ground, and possibly thereover, especially a weak ground such as a clay.
BACKGROUND OF THE INVENTION
Various types of foundations are already known for erecting facilities, buildings, and supermarkets or for obtaining an embankment for a highway, for example.
It is especially known to dispose piles in the ground above which the building is erected. However, it is traditionally required to dispose a network of structural inclusions (beams, piles, etc.) made of a traditional reinforced concrete for supporting the floor of the building, or the road. If the piles are disposed in a mechanically weak ground, the strength induced by the building is typically essentially transmitted by the piles to a harder portion of the ground. Thus, substantially no charge of the building is transmitted to the weak ground.
It is to be noted that, in the present description, a ground is considered as weak if its modulus of elasticity (E), also called Young's modulus, is less than about 8 to 9 MPa. A series of so-called ballasted columns is sometimes used in such a situation. Typically, such ballasted columns are wells dug into the ground and having a diameter between about 0.5 m and 1.20 m. The wells are filled with stones or a mixture of sand and gravel having dimensions typically comprised between 10 mm and 60 mm.
If the ground is too weak (e.g. the modulus of elasticity of the ground is less than about 5 MPa), such columns often break off, if a quite high building is erected thereon. Embedding rigid inclusions within the ground is another solution. Such rigid inclusions are piles having a small diameter. The distance between two piles is typically between about 1.50 m and 2.50 m. The piles are either micropiles including a metallic tube, or full piles made of a traditional concrete. But the stiffness is then typically too high to share the loads between the soil and the inclusions.
The equivalent stiffness of a network comprising such rigid inclusions is very high. Then, more than 95% of the charge is transmitted to the piles, and only 5% is transmitted to the weak ground.
DESCRIPTION OF THE RELATED ART
A ground displacement auger head adapted for making inclusions in a ground is known from WO-A-95/12050 in which the auger head comprises a tip, a displacement body having at least over a lower portion a core diameter increasing in a direction away from said tip, and at least one screw flange extending at least over said lower portion of the displacement body, the auger head being characterised in that the screw flange has a pitch which increases at least over said lower portion of the displacement body in the direction away from the tip.
In WO-A-95/12050, a main object is to present an auger head by which the ground can be displaced more efficiently, requiring less energy during screwing in, and which allows also to screw through more resistive, in particular more sandy, layers of ground.
Another drill is described in EP-B-228 138 in which the object is to avoid that a high resistance be encountered during screwing into the ground. To that end, the tubular screw drill described in EP-B-228 138 comprises a screw fin (also called screw flange) and is characterised in that said screw fin extends between an end of the drill and a displacer which consists successively of a first closed spiral part having the same screw direction as the fin, and a second closed spiral part having the opposite screw direction.
In the present invention, it is considered that the drills of the prior art, and especially the above-mentioned drills, have drawbacks including a too high resistance still encountered during forcing the drill in the ground.
SUMMARY OF THE INVENTION
So, an object of the invention relates to a system having an improved efficiency for reinforcing a ground on which is disposed a loading structure, such as a building.
A further object is to dispose in the ground inclusions having a modulus of elasticity (E) substantially equal to the modulus of elasticity of the so-called ballasted columns, but which do not weak off so often.
Another object of the invention is to offer an improved concrete material having a modulus of elasticity (E) less than a traditional hard concrete, so that a structure made of such an improved concrete does not systematically concentrate all the strengths in the inclusions.
A further object relates to an improved drill adapted for digging an annular hole in a ground, and for providing said hole with a concrete or a structural material.
Another object refers to an improved ground displacement auger head adapted for drilling a hole in a structure.
The first object of the invention is achieved through a device for reinforcing a ground on which is disposed a loading structure, such as a building, the device comprising:
a series of structural inclusions disposed essentially vertically within the ground and adapted to mechanically reinforce said ground, the series of inclusions having an external diameter (D) comprised between substantially 0.1 m and 0.8 m (preferably 0.2 m and 0.6 m), and two adjacent inclusions being separated in the ground by a distance (A) such as 2D ≦A ≦10 D, said series of inclusions being made of a material having a Young's modulus (long term) comprised between 500 and 10,000 MPa, and preferably between 1,000 and 10,000 MPa,
a load transmitting layer interposed between the ground and the loading structure disposed thereon, for transmitting and distributing the load from the loading structure to both the ground and the series of inclusions, the load transmitting layer having:
a Young's modulus less than the Young's modulus of the series of inclusions (viz. of every inclusion of said series),
a first nominal height between two adjacent inclusions of said series of inclusions, and
a second height less than the first nominal height at locations situated just above the series of inclusions, where the load transmitting layer is plastically compressed by the series of inclusions which partially penetrate within said load transmitting layer.
In the instant description and claims, it is considered that:
D is indifferently either an external diameter of one inclusion of the series of inclusions, or the external diameter of the cylinder having the same volume as one inclusion of said series,
A is indifferently either the horizontal distance between two adjacent inclusions of the series, or the length of one side of a square equivalent to said distance between two adjacent inclusions in the ground,
10 bars=1 MPa
all the values in the present text are given to within 10%,
“Modulus” are long term modulus (a few days or weeks, at least) as opposed to immediate modulus calculated immediately after the load has been applied to the corresponding structure,
a (structural) inclusion is an essentially vertical, elongated structure adapted to mechanically reinforce a ground, especially a weak ground. An inclusion can be made of different types of materials, such as aggregates of stones, mortar, specific concrete (especially concrete having a low modulus of elasticity, as above-mentioned). The inclusions can be annular tubes or parallelepiped piles. Their section can be rounded or parallelepiped. If the (external) section is rounded, it is considered that the corresponding inclusions have an (external) diameter. The inclusions can be either hollow (such as annular piles) or full of material.
According to another feature of the invention, the device for reinforcing the ground comprises:
a series of structural inclusions disposed within the ground and adapted to mechanically reinforce said ground,
a load transmitting layer interposed between the ground and the loading structure disposed thereon, for transmitting and distributing the load from the loading structure to both the ground and the series of inclusions, the load transmitting layer having a Young's modulus less than the Young's modulus of the series of inclusions, wherein:
(E
i
) being the Young's modulus of (one of)
Friedman Carl D.
Menard Soltraitement
Nguyen Chi Q.
Rothwell Figg Ernst & Manbeck
LandOfFree
Concrete pile made of such a concrete and method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Concrete pile made of such a concrete and method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Concrete pile made of such a concrete and method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3263056