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EP 1 961 867 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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03.07.2013 Bulletin 2013/27 |
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Date of filing: 20.02.2008 |
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International Patent Classification (IPC):
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A method of building a monolithic underground concrete structure
Verfahren zum Formen einer monolithischen Untergrundbetonstruktur
Procédé de construction de structure souterraine monolithique en béton
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Designated Contracting States: |
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CH DE GB IT LI |
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Priority: |
22.02.2007 IT TO20070127
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Date of publication of application: |
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27.08.2008 Bulletin 2008/35 |
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Proprietor: Trevi S.p.A. |
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I-47023 Cesena (Forli) (IT) |
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Inventors: |
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- ZILLER, Marco
20133 Milano (IT)
- TREVISANI, Stefano
47020 Roncofreddo(Forli) (IT)
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Representative: Fioravanti, Corrado et al |
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Jacobacci & Partners S.p.A.
Corso Emilia 8 10152 Torino 10152 Torino (IT) |
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References cited: :
EP-A1- 1 045 073 GB-A- 2 301 134
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DE-A1- 19 953 819 NL-C2- 1 027 252
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] The present invention relates to a method of constructing a monolithic underground
artificial conglomerate structure for the purposes of consolidation and/or waterproofing.
[0002] In order to consolidate volumes of soil having a clearly defined geometry, methods
known as "jet grouting" are used to form columnar artificial conglomerate structures,
spaced apart from each other, around the portion of soil to be excavated. These methods
are based on the mixing of particles of the soil itself with binders, usually cement
mixtures, which are injected at high pressure through small radial nozzles formed
in the proximity of the lower end of a tubular shaft which is rotated and raised towards
the surface. The jets of binder disgregate and are mixed with the surrounding soil,
thus creating a column of conglomerate which, when hardened, consolidates the soil.
The disgregating efficiency of the jet can be increased by the addition of injected
water and/or pressurized air.
[0003] The object of the present invention is to propose a method of constructing monolithic
artificial conglomerate structures which extend continuously in the soil. In particular,
the aim is to form a stable waterproof structure, regardless of any non-uniformity
of the soil and the inevitable deviations from the vertical of the columnar formations
created by jet grouting.
[0004] This and other objects and advantages are achieved, according to the invention, by
a method as defined in Claim 1. Other important characteristics of the method according
to the invention are defined in the dependent claims.
[0005] Two preferred, but non-limiting, embodiments of the invention will now be described;
reference will be made to the attached drawings, in which:
Figure 1 is a schematic cross section showing a group or cell of columnar blocks which,
together with other similar contiguous groups, forms a monolithic artificial conglomerate
structure;
Figure 2 is a view similar to Figure 1, showing a possible condition which may develop
during the application of the method according to the invention;
Figure 3 is a schematic cross section of a cell of columnar blocks according to an
embodiment of the method which is an alternative to that shown in Figure 1;
Figure 4 is a schematic view in vertical section of part of the cell of Figure 3;
Figure 5 is a schematic view in elevation of three contiguous cells of the type shown
in Figure 3;
Figure 6 is a schematic plan view of part of a structure formed by cells of the type
shown in Figures 3-5;
Figure 7 is a schematic view, similar to that of Figure 5, of a preferred embodiment
of the method with cap formations joined together to form a continuous slab which
is superimposed on the previously formed columnar blocks; and
Figure 8 is a schematic plan view of part of a structure according to the embodiment
of Figure 7.
[0006] With reference to Figure 1 initially, the construction of a monolithic underground
artificial conglomerate structure according to the invention is carried out in a sequence
of steps in which ordered groups of columnar blocks of consolidated soil, closely
and rigidly interconnected and called "closed cells" in this text, are constructed.
One of these cells is shown in Figure 1. The columnar blocks P, S, and T which make
up the cell are formed by jet grouting methods.
[0007] The equipment and methods for jet grouting are well known in the field of soil mechanics,
and therefore they will not be described or illustrated in detail in this document.
The shape, dimensions and function of the underground structure can vary according
to requirements, and are not to be interpreted as limiting the scope of the patent
in any way. For example, the invention can be used for constructing a substantially
tubular shell of consolidated and waterproofed soil which is to be constructed around
a portion of soil in which a tunnel is to be excavated.
[0008] Using jet grouting equipment (not shown) placed on a working surface above a portion
of soil in which the structure is to be constructed, a first set of artificial conglomerate
blocks P is formed, these blocks being positioned in a predetermined reticular geometrical
layout. These blocks, referred to hereafter as primary columns, are vertical columnar
elements whose height depends on the vertical thickness of the structure to be constructed.
The primary columns P are parallel to each other and spaced apart from each other.
In the example of embodiment shown in the drawings, the cells have a reticular layout
with a triangular or hexagonal (honeycomb) mesh, in which the central axes of the
primary columns P are positioned at the vertices of an equilateral triangle or at
the non-consecutive vertices of a regular hexagon.
[0009] After the primary columns have reached a predetermined degree of setting or hardening,
a jet grouting method is used to form a second set of columnar blocks or parallel
secondary columns S of artificial conglomerate. Each secondary column S is interposed
between, and securely joins, two primary columns P formed previously, causing the
combined primary and secondary columns of each cell to form a closed ring structure.
In the illustrated example, the secondary columns have their respective axes positioned
on the vertices of the hexagon alternating with the vertices on which the axes of
the primary columns are located.
[0010] After the secondary columns have reached a certain degree of hardening, a tertiary
column T is formed, again by jet grouting, in the central space formed between the
primary and secondary columns of each cell.
[0011] Because of the hardening of the primary columns, which theoretically have a circular
cross section, the secondary columns have a cross section with concave lobes along
their surfaces adjoining the primary columns. The tertiary columns have a cross section
of multiple-lobed shape with concave lobes along their surfaces adjoining the primary
and secondary columns. In the preferred embodiment of the invention, all the columns
of each type (primary, secondary, tertiary) are formed with a constant jet grouting
treatment intensity for each metre of column, for example with a jet having a flow
rate of 300-320 1/min. at a pressure of 400-420 bars. The different shapes of the
primary, secondary and tertiary columns correspond to different cross-sectional areas,
this area in the secondary columns being about 60% of that of the primary columns,
while in the tertiary columns it is about 30% of the area of the primary columns.
Consequently, the specific energy per cubic metre of consolidated soil for the secondary
columns is 160% of that of the primary columns, while it is 300% for the tertiary
columns, assuming that the same jet grouting parameters are maintained for each linear
metre of column.
[0012] The tertiary columns are formed in the spaces enclosed by the primary and secondary
columns, and are therefore protected from any negative external effects such as movements
of the water-table and the presence of soils with increasing permeability which could
lead to losses of cement mixture from the outside of the cell.
[0013] Clearly, the primary and secondary columns of each cell are also primary and secondary
columns of contiguous cells. The formation of the tertiary columns improves the overall
strength by compensating for any deviations from the parallel arrangement of the previously
formed columns. The tertiary columns closely bind all the surrounding columns, by
which they are also protected, and therefore the cement mixture which is injected,
or "jetted", scarifies and penetrates the surfaces of the primary and secondary columns
facing the centre of the cell.
[0014] In some cases, the formation of the tertiary column remedies any untreated areas.
As shown by way of example in Figure 2, an area Z of soil which has not been treated
during the formation of the secondary column S because of a body A (for example a
rock or a tree trunk) is subsequently reached by the cement mixture when the tertiary
column T is formed. Even in soils with very high local horizontal permeability, the
formation of the tertiary column takes place in the centre of a "well" formed by the
primary and secondary columns of the cell, which confine the jetting mixture without
making it flow out. This confining or sealing effect is multiplied as the operation
proceeds.
[0015] Furthermore, the mutual "grooving" of the columns opposes their separation when the
finished structure is stressed by a load, for example when part of the soil at one
side of the structure is excavated.
[0016] Depending on the extension of the artificial conglomerate structure, the operating
requirements and the soil conditions, the structure is completed by forming more or
less numerous groups of cells simultaneously or in succession, until the whole area
specified by the design is covered, thus providing a continuous monolithic structure.
If required by the geometrical conditions, the closed cells can be formed with some
columns vertical and some inclined, or with all the columns inclined.
[0017] With reference now to Figures 3-5, in a preferred embodiment of the method according
to the invention it is possible to reinforce the joining of the component columns
of the structure and to make the structure more waterproof and monolithic by forming
caps C of substantially disc-like shape. These caps are widened upper and/or lower
extensions of the tertiary columns T, and extend transversely so as to cover, at least
partially, the ends of the primary and secondary columns which surround the tertiary
columns concerned.
[0018] The caps C are formed by increasing one or more of the jetting parameters for the
tertiary columns when the jetting nozzle has risen above the tops of the primary and
secondary columns. The larger diameter of the cap can be obtained, for example, by
increasing the pressure or the flow rate of the mixture, or by retarding the rising
movement of the hollow shaft (not shown) which carries the cement mixture injection
nozzles. If required by the soil condition or by the requirements of the construction,
the caps C can be formed at both the bottoms and the tops of the primary and secondary
columns, in other words at both ends of the structure. Alternatively, the caps can
be formed on only one end of the structure, for example over the tops of the columns.
[0019] The diameter of the caps depends on the intensity of the jetting. As shown in Figure
6, the diameter can be specified in such a way that the caps of the contiguous closed
cells are tangential to each other. Thus the vertical contact surfaces between the
columns P, S and T are sealed by the caps of the tertiary columns and cannot form
preferential paths for the flow of water through the structure.
[0020] The best results are obtained if the caps C, as shown in Figures 7 and 8, are extended
in such a way that they are joined securely to each other, penetrating into each other
and forming a continuous monolithic layer or slab of conglomerate which covers the
underlying structure comprising the primary and secondary columns. The superimposed
layer formed by the caps C seals off all possible paths for the infiltration of water
and also greatly reinforces the overall rigidity of the structure. Experimental trials
conducted by the applicant have demonstrated that a continuous layer formed by inter-penetrating
caps gives excellent results when the soil below the conglomerate structure is excavated;
the cap layer minimizes the deformation of the structure and the yielding due to the
weight of the soil bearing on its top, and is of fundamental importance in ensuring
that the joints between the columns do not open except to a negligible extent, and
that any significant infiltration of water through the structure therefore continues
to be impeded.
1. A method of constructing a monolithic underground artificial conglomerate structure,
comprising the steps of:
a) forming, by jet grouting methods, a first plurality of parallel primary columns
(P) which are spaced apart from each other and are positioned with a spacing between
them according to a predetermined reticular layout;
b) forming, by jet grouting methods, a second plurality of secondary columnar blocks
(S), each of which is interposed between and securely joins two consecutive primary
blocks (P), thus providing at least one closed ring structure composed of a sequence
of primary blocks alternating with secondary blocks which surround at least one central
portion of soil;
c) forming in the said central portion(s), by jet grouting methods, a corresponding
tertiary column (T) which securely joins the surrounding primary (P) and secondary
(S) blocks.
2. A method according to Claim 1, wherein the columnar blocks (P) are positioned in a
reticular layout with a triangular or hexagonal mesh.
3. A method according to Claim 1, wherein step b) is carried out after the columnar blocks
formed in step a) have reached a predetermined degree of setting or hardening.
4. A method according to Claim 1 or 3, wherein step c) is carried out after the columnar
blocks formed in step b) have reached a predetermined degree of setting or hardening.
5. A method according to Claim 1, wherein the columnar blocks (P, S, T) are formed with
a constant jet grouting intensity along their length.
6. A method according to Claim 5, wherein the secondary columnar blocks (S) have a cross
section whose area is about 60% of that of the primary columnar blocks (P).
7. A method according to Claim 5 or 6, wherein the tertiary columnar blocks (T) have
a cross section whose area is about 30% of that of the primary columnar blocks (P).
8. A method according to Claim 1, wherein step c) includes the step of
forming, at one end at least of a tertiary columnar block (T), a widened extension
(C) which extends transversely so as to cover, at least partially, the ends of the
primary (P) and secondary (S) columnar blocks which surround the tertiary columnar
block.
9. A method according to Claim 8, wherein step c) includes the step of
forming, at each end of a tertiary columnar block (T), a corresponding widened extension
(C) which extends transversely so as to cover, at least partially, the ends of the
primary (P) and secondary (S) columnar blocks which surround this tertiary columnar
block.
10. A method according to Claim 8 or 9, wherein the widened extension (C) of a given tertiary
columnar block (T) has a transverse dimension such that it is tangential to a similar
widened extension (C) of another tertiary columnar block positioned close to the said
given tertiary block.
11. A method according to Claim 8 or 9, wherein the widened extension (C) of a given tertiary
columnar block (T) has a transverse dimension such that it is securely joined to similar
widened extensions (C) of other neighbouring tertiary columnar blocks, so as to form
a continuous monolithic layer or slab of conglomerate which covers the structure lying
above and/or below, comprising the primary (P) and secondary (S) columnar blocks.
12. A method according to any one of Claims 8 to 11, wherein the widened extensions (C)
are formed by increasing the pressure or the flow rate of the cement mixture used
to form the tertiary columnar blocks beyond the upper and/or lower ends of these blocks.
13. A method according to any one of Claims 8 to 12, wherein the widened extensions (C)
are formed by retarding the vertical movement of cement mixture injection means with
respect to the vertical speed at which the said injection means move to form the tertiary
columnar blocks.
1. Verfahren zum Aufbauen einer künstlichen monolithischen Untergrundkonglomeratstruktur,
das die folgenden Schritte umfasst:
a) Ausbilden einer ersten Vielzahl von parallelen primären Säulen (P), die voneinander
beabstandet sind und gemäß einem vorgegebenen netzartigen Layout bzw. einer Anordnung
mit einem Abstand untereinander positioniert sind, durch Strahlgieß- bzw. -einspritzverfahren;
b) Ausbilden einer zweiten Vielzahl von sekundären Säulenblöcken (S), von denen jeder
zwischen zwei aufeinander folgenden primären Blöcken (P) eingefügt ist und sie fest
verbindet, durch Strahlgießverfahren, womit wenigstens eine geschlossene Ringstruktur
bereitgestellt wird, die aus einer Abfolge von primären Blöcken, die sich mit sekundären
Blöcken abwechselt, besteht, welche wenigstens einen zentralen Landabschnitt umgeben;
c) Ausbilden einer entsprechenden tertiären Säule (T), welche die umgebenden primären
(P) und sekundären (S) Blöcke fest verbindet, durch Strahlgießverfahren in dem/den
zentralen Abschnitt/en.
2. Verfahren nach Anspruch 1, wobei die Säulenblöcke (P) in einem netzartigen Layout
mit einem dreieckigen oder sechseckigen Gitter positioniert sind.
3. Verfahren nach Anspruch 1, wobei der Schritt b) ausgeführt wird, nachdem die in Schritt
a) ausgebildeten Säulenblöcke einen vorgegebenen Festwerdungs- oder Härtungsgrad erreicht
haben.
4. Verfahren nach Anspruch 1 oder 3, wobei der Schritt c) ausgeführt wird, nachdem die
in Schritt b) ausgebildeten Säulenblöcke einen vorgegebenen Festwerdungs- oder Härtungsgrad
erreicht haben.
5. Verfahren nach Anspruch 1, wobei die Säulenblöcke (P, S, T) entlang ihrer Länge mit
einer konstanten Strahlgießintensität ausgebildet werden.
6. Verfahren nach Anspruch 5, wobei die sekundären Säulenblöcke (S) einen Querschnitt
haben, dessen Fläche etwa 60% der der primären Säulenblöcke (P) ist.
7. Verfahren nach Anspruch 5 oder 6, wobei die tertiären Säulenblöcke (T) einen Querschnitt
haben, dessen Fläche etwa 30% der der primären Säulenblöcke (P) ist.
8. Verfahren nach Anspruch 1, wobei der Schritt c) den folgenden Schritt umfasst:
Ausbilden einer verbreiterten Erweiterung (C), die sich quer erstreckt, an einem Ende
wenigstens eines tertiären Säulenblocks (T), um die Enden der primären (P) und sekundären
(S) Säulenblöcke, welche den tertiären Säulenblock umgeben, wenigstens teilweise zu
bedecken.
9. Verfahren nach Anspruch 8, wobei der Schritt c) den folgenden Schritt umfasst:
Ausbilden einer entsprechenden verbreiterten Erweiterung (C), die sich quer erstreckt,
an jedem Ende eines tertiären Säulenblocks (T), um die Enden der primären (P) und
sekundären (S) Säulenblöcke, welche den tertiären Säulenblock umgeben, wenigstens
teilweise zu bedecken.
10. Verfahren nach Anspruch 8 oder 9, wobei die verbreiterte Erweiterung (C) eines gegebenen
tertiären Säulenblocks (T) eine Querabmessung hat, so dass sie tangential zu einer
ähnlichen verbreiterten Erweiterung (C) eines anderen tertiären Säulenblocks ist,
der nahe an dem gegebenen tertiären Säulenblock positioniert ist.
11. Verfahren nach Anspruch 8 oder 9, wobei die verbreiterte Erweiterung (C) eines gegebenen
tertiären Säulenblocks (T) eine Querabmessung hat, so dass sie fest mit ähnlichen
verbreiterten Erweiterungen (C) anderer benachbarter tertiärer Säulenblöcke verbunden
ist, um eine zusammenhängende monolithische Schicht oder Platte aus Konglomerat zu
bilden, die die darüber und/oder darunter liegende Schicht bedeckt, welche die primären
(P) und sekundären (S) Säulenblöcke umfasst.
12. Verfahren nach einem der Ansprüche 8 bis 11, wobei die verbreiterten Erweiterungen
(C) ausgebildet werden, indem der Druck oder der Durchsatz der Zement- bzw. Betonmischung,
die verwendet wird, um die tertiären Säulenblöcke über die oberen und/oder unteren
Enden dieser Blöcke auszubilden, vergrößert wird.
13. Verfahren nach einem der Ansprüche 8 bis 12, wobei die verbreiterten Erweiterungen
(C) ausgebildet werden, indem die vertikale Bewegung der Betonmischungseinspritzmittel
in Bezug auf die vertikale Geschwindigkeit, mit welcher die Einspritzmittel sich bewegen,
um die tertiären Säulenblöcke auszubilden, verzögert wird.
1. Procédé de construction d'une structure sous-terraine monolithique en conglomérat
artificiel, comprenant les étapes suivantes :
a) former, par des procédés d'injection, une première pluralité de colonnes principales
parallèles (P) qui sont espacées les unes des autres et qui sont positionnée avec
un espacement entre elles selon une disposition réticulaire prédéterminée ;
b) former, par des procédés d'injection, une deuxième pluralité de blocs columnaires
secondaires (S), chacun d'entre eux étant intercalé entre et reliant de façon solide
deux blocs principaux consécutifs (P), fournissant ainsi au moins une structure d'anneau
fermé composée d'une suite de blocs principaux alternant avec des blocs secondaires
qui entourent au moins une partie centrale de terrain ;
c) former dans ladite ou lesdites partie(s) centrale(s), par des procédés d'injection,
une colonne tertiaire correspondante (T) qui relie de façon solide les blocs principaux
(P) et secondaires (S) environnants.
2. Procédé selon la revendication 1, dans lequel les blocs columnaires (P) sont positionnés
selon une disposition réticulaire avec un maillage triangulaire ou hexagonal.
3. Procédé selon la revendication 1, dans lequel l'étape b) est exécutée après que les
blocs columnaires formés à l'étape a) ont atteint un degré de prise ou durcissement
prédéterminé.
4. Procédé selon la revendication 1 ou 3, dans lequel l'étape c) est exécutée après que
les blocs columnaires formés à l'étape b) ont atteint un degré de prise ou durcissement
prédéterminé.
5. Procédé selon la revendication 1, dans lequel les blocs columnaires (P, S, T) sont
formés avec une intensité d'injection constante sur toute leur longueur.
6. Procédé selon la revendication 5, dans lequel les blocs columnaires secondaires (S)
ont une section transversale dont l'aire vaut environ 60 % de celle des blocs columnaires
principaux (P).
7. Procédé selon la revendication 5 ou 6, dans lequel les blocs columnaires tertiaires
(T) ont une section transversale dont l'aire vaut environ 30 % de celle des blocs
columnaires principaux (P).
8. Procédé selon la revendication 1, dans lequel l'étape c) comprend l'étape consistant
à former, à une extrémité au moins d'un bloc columnaire tertiaire (T), une extension
élargie (C) qui s'étend transversalement afin de couvrir, au moins partiellement,
les extrémités des blocs columnaires principaux (P) et secondaires (S) qui entourent
le bloc columnaire tertiaire.
9. Procédé selon la revendication 8, dans lequel l'étape c) comprend l'étape consistant
à former, à chaque extrémité d'un bloc columnaire tertiaire (T), une extension élargie
correspondante (C) qui s'étend transversalement afin de couvrir, au moins partiellement,
les extrémités des blocs columnaires principaux (P) et secondaires (S) qui entourent
ce bloc columnaire tertiaire.
10. Procédé selon la revendication 8 ou 9, dans lequel l'extension élargie (C) d'un bloc
columnaire tertiaire donné (T) a une dimension transversale telle qu'elle est tangentielle
à une extension élargie similaire (C) d'un autre bloc columnaire tertiaire positionné
près dudit bloc tertiaire donné.
11. Procédé selon la revendication 8 ou 9, dans lequel l'extension élargie (C) d'un bloc
columnaire tertiaire donné (T) a une dimension transversale telle qu'elle est liée
de façon solide aux extensions élargies similaires (C) d'autres blocs columnaires
tertiaires voisins, afin de former une couche ou dalle monolithique continue de conglomérat
qui couvre la structure se trouvant au-dessus et/ou en dessous, comprenant les blocs
columnaires principaux (P) et secondaires (S).
12. Procédé selon l'une quelconque des revendications 8 à 11, dans lequel les extensions
élargies (C) sont formées en augmentant la pression ou le débit du mélange de ciment
utilisé pour former les blocs columnaires tertiaires au-delà des extrémités supérieures
et/ou inférieures de ces blocs.
13. Procédé selon l'une quelconque des revendications 8 à 12, dans lequel les extensions
élargies (C) sont formées en retardant le mouvement vertical du moyen d'injection
de mélange de ciment par rapport à la vitesse verticale à laquelle ledit moyen d'injection
se déplace pour former les blocs columnaires tertiaires.