FIELD OF THE INVENTION
[0001] The present invention relates to a method as defined in the preamble of claim 1.
Further, the invention relates to a system as defined in claim 12.
BACKGROUND OF THE INVENTION
[0002] Vehicles travelling on roadways induce ground vibration that is transmitted via the
soil into buildings close to the roadways, causing various damages and reducing the
quality of life. This is a serious problem especially on roadways with heavy traffic
volumes. In the long run, the vibration may also cause structural damages to the buildings.
As used herein, the term "roadway" refers both to railways with train traffic and
to highways with wheeled vehicles. In the case of railway traffic, in order to avoid
extreme vibration levels, sometimes the maximum train speeds must be limited in such
areas where the ground vibration causes problems. The problem has been understood
to be so serious that new international standards are under preparation work in the
European Community for stating limits to acceptable vibration levels. This is an important
element leading towards environmentally friendly ground transport especially in the
neighbourhood of highly populated urban towns. On the other hand, demands to increase
the performance of ground transportation are forcing the expedition and railway companies
to use heavy wagons with increasing speeds. It has been observed that higher speeds
lead to higher structural and ground responses especially in the case of soft soil
(Bahrekazemi, M & Bodare, A. Reduction of Train-induced Ground vibrations by Lime-Cement
Columns, Seventh International Workshop on Railway Noise, Solving Urban Rail Noise
and Vibration Problems, Portland, Maine USA, October 24-27, 2001). Because this development
is in conflict with both building protection and environmental requirements one has
started to examine technical solutions to reduce ground vibration close to roadways.
[0003] In the state of the art, one has introduced and used between the vibration source
and object:
- stiff ground vibration isolator barriers (use of a concrete structure has been disclosed
in publications [Ahmad, S. and Al-Hussaini, T.M. Simplified Design for Vibration Screening
by Open and In-filled Trenches, Journal of Geotechnical Engineering (1991) 117(1)
pp. 67-88]),
- soft ground vibration isolator barriers (the use of an air cushion has been disclosed
in publication [Al-Hussaini, T.M. and Ahmad, S. Design of Wave Barriers for Prediction
of Horizontal Ground Vibration, Journal of Geotechnical Engineering (1991) 117(4),
pp. 616-636]), and
- medium hard barrier walls [Bahrekazemi, M & Bodare, A. Reduction of Train-induced
Ground vibrations by Lime-Cement Columns, Seventh International Workshop on Railway
Noise, Solving Urban Rail Noise and Vibration Problems, Portland, Maine USA, October
24-27, 2001].
[0004] Field tests have shown that said methods and structures are relatively effective
in their primary function and, therefore, it has opened the discussion on how these
structural elements could be installed in a cost-effective way.
[0005] Prior-art structures are also known from patent publications PL 168171, JP11280099,
US 2004091316, EP 0 913 527 A1, US 5,173,012 and JP 04-312607, in which the vibration-damping
walls are vertical. Due to the verticality of the insulator wall, no doubt the ground
vibration can be reduced to some extent, but not sufficiently. Furthermore, known
installation methods are expensive and structures very complicated.
OBJECTIVE OF THE INVENTION
[0006] The objective of the invention is to eliminate the drawbacks referred to above.
[0007] One specific objective of the invention is to disclose an advantageous and fast installation
method and system which require very little labour and damp the ground vibration transmitted
into an object to be protected more efficiently than before.
SUMMARY OF THE INVENTION
[0008] The method of the invention is characterized by what has been presented in claim
1. Further, the system of the invention is characterized by what has been presented
in claim 12.
[0009] According to the invention, in the method, an isolator wall is placed to an inclined
angle so that the isolator wall is slanting downward at said angle and away from the
roadway to direct the vibration obliquely downward, the insulator wall thus both damping
and directing the vibration into the direction determined by the insulator wall.
[0010] Similarly, according to the invention, in the system, the insulator wall is with
respect to the vertical direction at an inclined angle so that the insulator wall
is slanting downward at said angle and away from the roadway to direct the vibration
obliquely downward, the insulator wall thus both damping and directing the vibration
into the direction determined by the insulator wall.
[0011] The invention has the advantage that thanks to it an object such as a building can
be protected against traffic-induced vibration more efficiently than before because
besides being damped, the vibration is directed downward.
[0012] In one embodiment of the method, the insulator wall is installed with respect to
the horizontal direction to an angle of about 10° ≤ α ≤ 60°, preferably about 45°.
[0013] In one embodiment of the method, the depth of the insulator wall below ground level
is adjusted to be about 5 m. The depth is adjusted according to the soil type into
which the insulator wall is to be installed.
[0014] In one embodiment of the method, a noise barrier is attached to the insulator wall
to damp the noise transmitted from the roadway via the air, the insulator wall thus
acting as a foundation for the noise barrier.
[0015] In one embodiment of the method, a number of wall elements are installed into the
ground and attached to one another side by side in line to form a uniform insulator
wall.
[0016] In one embodiment of the method, the wall elements are driven one by one into the
ground at the aforesaid angle.
[0017] In one embodiment of the method, soil material is removed from above the wall elements
that were driven into the ground to expose the side surface; a soft insulator layer
such as an air cushion, a layer of cellular plastic, of light gravel or the like is
placed against the side surface in engagement therewith; and the excavation is filled
to cover the formed insulator wall formed together by the wall elements and the insulator
layer. In one alternative embodiment of the method, the wall elements are not driven
into the ground, instead an excavation groove is formed in the ground having a peripheral
wall disposed at the aforesaid angle and facing the roadway; the insulator wall is
placed on top of the peripheral wall; the insulator layer is placed on top of the
wall elements; and the excavation groove is filled.
[0018] In one embodiment of the method, rails of a railway serve as the roadway, whereby
a) a railway wagon is arranged which serves as an intermediate storage for the wall
elements and/or the insulator layer material in the work site;
b) a working machine is arranged which is equipped with an articulated boom arm having
a quick clamping device at the end thereof for removable fastening of a tool, which
working machine is arranged to be movable under the control of the rails;
c) a gripping and jolting apparatus and a bucket are arranged to act as the tools
for the working machine;
d) the railway wagon and the working machine are transferred to the work site;
e) the gripping and jolting apparatus is attached to the quick clamping device of
the articulated boom arm;
f) the gripping and jolting apparatus is used to grasp the wall element;
g) a number of wall elements are driven side by side one after the other into the
ground at the aforesaid angle,
h) soil material is removed from above the wall elements that were driven into the
ground;
i) a soft insulator layer such as an air cushion, a layer of light gravel or the like
is placed against the side surface of the wall elements; and
j) the insulator wall formed by the wall elements driven into the ground and the insulator
layer is covered with soil material.
[0019] In one embodiment of the method, after step j), the wall elements are removed from
inside the ground, and just one insulator layer is left inside the ground, acting
as the insulator wall alone.
[0020] In one embodiment of the method, after step j), a noise barrier is attached to the
wall elements.
[0021] In one embodiment of the system, the insulator wall is with respect to the horizontal
direction at an angle of about 10° ≤ α ≤ 60°, preferably about 45°.
[0022] In one embodiment of the system, the depth of the insulator wall below ground level
is about 5 m.
[0023] In one embodiment of the system, a noise barrier is attached to the insulator wall
to damp the noise transmitted from the roadway via the air, the insulator wall thus
acting as a foundation for the noise barrier.
[0024] In one embodiment of the system, the insulator wall includes a number of wall elements
that have been attached to one another side by side in line to form a uniform insulator
wall.
[0025] In one embodiment of the system, the wall element is a profile sheet element having
connecting members in the edges thereof to consecutively attach similar profile sheet
elements to one another.
[0026] In one embodiment of the system, the wall element is a so-called sheet pile profile
element.
[0027] In one embodiment of the system, the wall element is a box consisting of a profile
sheet element and of a sheet attached to the open flank of the profile sheet element.
The profile sheet element can be e.g. a sheet pile profile element, and the sheet
can be e.g. a steel sheet. A supporting plate such as a steel sheet can be further
placed between the profile sheet element and the sheet attached to its open flank.
The sheet can be fastened to the open flank of the profile sheet element, for example,
by welding. In the same manner, the supporting plate can also be welded to the box
formed by the profile sheet element and the sheet. The box can be filled with concrete,
soil material and/or any other suitable medium.
[0028] In one embodiment of the system, the wall element refers to a predefined number of
tubes that have been attached to one another by means of connecting members as a series
of no less than two interlocked tubes. The tubes can be e.g. steel tubes. To form
the wall element, two separate tubes can be e.g. welded together, and thereafter a
predetermined number of parts formed by two tubes can be connected to one another
by means of connecting members such as flat iron bars. In one embodiment of the system,
the tubes can be filled with concrete, soil material and/or any other suitable medium.
[0029] In one embodiment of the system, the bottom end of the wall element can be provided
with a tip part which facilitates installing of the wall elements into the ground.
[0030] In one embodiment of the system, the insulator wall comprises steel, concrete and/or
plastic.
[0031] In one embodiment of the system, the insulator wall includes an insulator layer of
substantially soft material that is arranged against that side surface of the wall
elements which is facing the building to be protected.
[0032] In one embodiment of the system, the insulator layer is an air cushion, a layer of
cellular plastic and/or of light gravel.
[0033] The system can be utilised in protecting buildings situated close to a railway or
highway against ground vibration.
LIST OF FIGURES
[0034] In the following section, the invention will be described in detail with reference
to the accompanying drawing, in which
Fig. 1 is a schematic partially sectioned view illustrating one embodiment of the
system according to the invention;
Fig. 2 is a schematic partially sectioned view illustrating another embodiment of
the system according to the invention;
Fig. 3 shows a working machine to be used in one embodiment of the method according
to the invention; and
Fig. 4 shows a combination of a working machine and a railway wagon to be used in
one embodiment of the method according to the invention;
Figs. 5 - 9 illustrate different steps of one embodiment of the method according to
the invention;
Figs. 10 - 13 shows four different insulator wall structures;
Fig. 14 illustrates directing the vibration into the direction determined by the insulator
wall;
Fig. 15 is a schematic sectional view showing the sheet pile profile elements to be
used in one embodiment of the system according to the invention when attached to form
a wall structure;
Fig. 15a is a schematic sectional view showing the wall elements to be used in another
embodiment of the system according to the invention when attached to form a wall structure;
Fig. 15b schematically shows the wall structure of Fig. 15a as seen from the side;
Fig. 15 c further shows a wall element according to one embodiment of the invention;
and
Figs. 16 and 17 schematically show one preferred gripping and jolting apparatus and
a sheet pile profile element in its grasp.
DETAILED DESCRIPTION OF THE INVENTION
[0035] Fig. 1 shows a system using which a building to be protected 1 has been protected
against vibration induced by train traffic and transmitted from a railway track 2
via the ground. The system may as well be used on highways to protect buildings nearby
against ground vibration induced by heavy traffic.
[0036] The system as shown in Fig. 1 comprises an insulator wall 3, which has been buried
into the ground at a distance from the roadway substantially in parallel with respect
to the roadway between the roadway and the object being protected to damp vibration.
The insulator wall 3 is with respect to the horizontal direction at an inclined angle
α so that the insulator wall is slanting downward at the aforesaid angle α and away
from the roadway 1. In that case, as shown in Fig. 14, the ground vibration is directed
obliquely downward deep into the ground, where it is damped and not transmitted into
the building 1. Thus, the insulator wall 3 both damps and directs the vibration into
the direction determined by the insulator wall. The insulator wall is with respect
to the horizontal direction at an angle α, which is 10° ≤ α ≤ 60°, preferably about
45°, as shown in Fig. 1. The depth L of the insulator wall 3 below ground level is
about 5 m. The depth is adjusted according to the soil type. Preferably, the insulator
wall 3 can consist of a wall formed from solid, stiff materials such as steel or concrete,
of artificial gravel layers and of air cushion walls.
[0037] Fig. 2 shows a preferred embodiment of the system of Fig. 1, in which an underground
insulator wall 3 has been provided with an aboveground noise barrier 4 to damp the
noise transmitted from the roadway 1 via the air. In that case, the underground insulator
wall 3 acts as a founding for the noise barrier 4, and no separate founding for the
noise barrier is needed. The noise barrier 4 can be of any suitable prior-art type.
[0038] Preferably, the insulator wall 3 includes a wall structure consisting of a number
of wall elements 5, which have been attached to one another in line side by side to
form a uniform insulator wall. Fig. 15 shows a portion of the wall in which the wall
elements 5 are profile sheet elements, that is sheet pile profiles. The edges of the
elements 5 are provided with connecting members 16 for connecting similar profile
sheet elements 5 successively to one another. The connecting members 16 form together
a tongue-and-groove joint. Fig. 15a shows a portion of the wall in which the wall
elements 5 are boxes, filled e.g. with concrete 23, formed from profile sheet elements,
that is so-called sheet pile profile elements, and from sheets 20 attached to the
open flanks of the profile sheet elements. Fig. 15a further shows a supporting plate
21 attached to the middle portion of the box. Fig. 15b shows the aforesaid portion
of the wall as seen from the side. Fig. 15b further shows the tip part 22 disposed
at the lower end of the wall element 5. Fig. 15c shows an example of a part of the
wall element, formed from a predetermined number of tubes 24, which have been connected
to one another by means of connecting members 25 as a series of no less than two interlocked
tubes. In one embodiment of the invention, the tubes 24 can be so-called RHS tubes
(e.g. 100x200x6). As the connecting members 25, e.g. PL flat iron bars (e.g. 100x8)
can be used. The tubes can be filled e.g. with concrete 23 or with any other suitable
medium.
[0039] Fig. 10 shows an embodiment in which the insulator wall 3 consists of just a wall
formed from sheet pile profiles 5.
[0040] Fig. 11 shows an embodiment in which the insulator wall 3 consists of a wall formed
from sheet pile profiles 5 and from an insulator layer 7, disposed against that side
surface 6 of the wall which is facing the building to be protected, which insulator
layer is herein, for example, a layer of light gravel (artificial gravel).
[0041] Fig. 12 shows an embodiment in which the insulator wall 3 consists of a wall formed
from sheet pile profiles 5 and from an insulator layer 7, disposed against that side
surface 6 of the wall which is facing the building to be protected, which insulator
layer is herein an air cushion.
[0042] Fig. 13 shows an embodiment in which the insulator wall 3 consists of a sheer insulator
layer 7, which is herein an air cushion.
[0043] The wall that is formed from sheet pile profiles to be driven into the ground can
be used mainly in soft soil.
[0044] Figs. 3 - 9 illustrate a method by which the insulator wall 3 is installed into the
ground.
[0045] Fig. 3 shows a working machine 11, which is an excavator equipped with an articulated
boom arm 12 having a standard quick clamping device 13 at the end thereof for removable
fastening of a tool 14, 15, which working machine is equipped with railway wheels
17 as it is designed to be movable under the control of railway rails 2. Preferably,
the railway track 2 is used as a mechanical guide element in order to keep the distance
between the insulator wall 3 and the railway substantially constant. As the tools
of the working machine 11 act a gripping and jolting apparatus 14 (see Figs. 3, 5,
9, 16) and a bucket 15 (see Figs. 6, 7 and 8), which one uses in the quick clamping
device 13 by turns according to each work phase.
[0046] The gripping and jolting apparatus 14 to be used in the method is preferably the
device schematically shown in Figs. 16 and 17 engaging with the sheet pile profile
5 from the side and provided with a jolting tool 18 and a gripper 19 as a single small-sized
complex that flexibly performs all the necessary material handling, manipulation,
adjusting, automatic steering and piling operations. This kind of excavator accessory
is sold under the trade name Movax (manufacturer Unisto Oy, Finland.
[0047] Fig. 4 shows another preferred complex to be used in a railway embodiment, in which
a railway wagon 10 acts as an intermediate storage of the wall elements 5 and/or the
insulator layer material 7 (not shown in the figure) in the work site. The working
machine 11 can also be connected to the railway wagon 10. Also herein the working
machine 11 is an excavator which is equipped with an articulated boom arm 12 having
at the end thereof a quick clamping device 13 for removable fastening of the tool
14, 15. Also in this embodiment, the railway track 2 is used as a mechanical guide
element in order to keep the distance between the insulator wall 3 and the railway
substantially constant. As the tools of the working machine 11 act a gripping and
jolting apparatus 14 and a bucket 15, which one uses in the quick clamping device
13 by turns according to each work phase. When the one is not used, the other can
be kept in the railway wagon 10, enabling one to carry the necessary tools at all
times as the work proceeds.
[0048] With the aforementioned arrangements, the method can be made fast, enabling one to
avoid long traffic breaks. Furthermore, the method requires very little labour because
the installation work can be performed by a single person, who operates an installation
device 13 and a bucket 14 installed into the excavator 11.
[0049] Fig. 4 shows a phase in which the railway wagon 10 and the working machine 11 have
been transferred to the working site and the gripping and jolting apparatus 14 has
been attached to the quick clamping device of the articulated boom arm, and in which
the gripping and jolting apparatus 14 is used to grasp the wall element 5 with a side
grip.
[0050] In Fig. 5, the wall element 5 has been conveyed to a desired place and to a suitable
angle position α, and is being driven into the ground. Once one element 5 has been
driven into the ground, the wagon 10 or the excavator 11 is driven along the railway
track about the width of the element 5, and the next wall element 5 is driven next
to the previous one and so that the connecting members 16 are connected to one another
as shown in Fig. 15. The aforementioned steps are repeated until there are in the
ground wall elements 5 driven side by side one after the other and having a common
width corresponding to the width of the air cushion 7 to be used as the insulator
layer.
[0051] Fig. 6 shows a situation in which the articulated boom arm 12 has a bucket 15 attached
to the end thereof to the quick clamping device 13. Soil material is removed from
above the wall elements 5 that were driven into the ground to show their side surface
6. The removed soil material is used for filling the adjacent dig place.
[0052] In Fig. 7, by using the articulated boom of the excavator 11 as the hoisting device,
a soft insulator layer 7 such as an air cushion or the like is placed against the
inclined side surface 6 of the wall formed by the wall elements 5.
[0053] In Fig. 8, the insulator wall 3 formed by the wall elements and insulator layer 7
is covered with soil material.
[0054] In Fig. 9, the bucket 15 has been replaced with the gripping and jolting apparatus
14. If the sheet pile wall is a temporary one and is only used as an installation
aid of the insulator layer 7, then the wall elements 5 can be removed from inside
the ground, leaving just the insulator layer 7 therein, arriving at the result as
shown in Fig. 13. Alternatively, when using a sheet pile wall to be permanently left
inside the ground, one arrives at the result shown 11 or 12.
[0055] The method can propagate as some kind of a window which propagates along the railway
track according to the aforementioned steps. One can flexibly proceed with the method
as long as the terrain and the soil material are suitable for driving wall elements
into the ground.
[0056] The invention is not limited merely to the embodiment examples referred to above;
instead many variations are possible within the scope of the inventive idea defined
by the claims.
1. A method for protecting an object to be protected (1), such as a building, from vibration
induced by traffic and transmitted from a roadway (2) via the ground, in which method
an insulator wall (3), which is substantially parallel with respect to the roadway,
is driven into the ground at a distance from the roadway between it and the object
to be protected to damp vibration, characterised in that the insulator wall (3) is installed so as to be at an inclined angle α so that the
insulator wall is slanting downward at the aforesaid angle α and away from the roadway
(2) to direct the vibration obliquely downward, the insulator wall both damping and
directing the vibration into the direction determined by the insulator wall.
2. The method as defined in claim 1, characterised in that the insulator wall (3) is installed with respect to the horizontal direction so as
to be at an angle (α), which is 10° ≤ α ≤ 60', preferably about 45'.
3. The method as defined in claim 1 or 2, characterised in that the depth (L) of the insulator wall (3) below ground level is adjusted to be about
5 m.
4. The method as defined in any one of claims 1 - 3, characterised in that a noise barrier (4) is attached to the insulator wall (3) to damp the noise transmitted
from the roadway (1) via the air, the insulator wall (2) thus acting as a foundation
for the noise barrier (4).
5. The method as defined in any one of claims 1 - 4, characterised in that a number of wall elements (5) are driven into the ground and attached to one another
side by side in line to form a uniform insulator wall (3).
6. The method as defined in claim 4, characterised in that the wall elements (5) are driven one by one into the ground at the aforesaid angle
(α).
7. The method as defined in claim 6, characterised in that soil material is removed from above the wall elements (5) that were driven into ground
to expose the side surface (6); a soft insulator layer (7), for example an air cushion,
a layer of cellular plastic, of light gravel or the like, is placed against the side
surface in engagement therewith; and the excavation is filled to cover the formed
insulator wall (3) formed together by the wall elements (5) and the insulator layer
(7).
8. The method as defined in any one of claims 1 - 6, characterised in that an excavation groove (8) is formed in the ground having a peripheral wall (9) disposed
at the aforesaid angle (α) and facing the roadway (1); the insulator wall (3) is placed
on top of the peripheral wall; the insulator layer (7) is placed on top of the wall
elements (5); and the excavation groove is filled.
9. The method as defined in any one of claims 5 - 7,
characterised in that the rails of a railway serve as the roadway, and that
a) a railway wagon (10) is arranged acting as an intermediate storage of the wall
elements (5) and/or the insulator layer material in the work site,
b) a working machine (11) is arranged which is equipped with an articulated boom arm
(12) having at the end thereof a quick clamping device (13) for removable fastening
of a tool (14, 15), which working machine is arranged to be movable under the control
of the railway rails,
c) a gripping and jolting apparatus (14) and a bucket (15) are arranged to act as
the tools for the working machine (11);
d) the railway wagon (10) and the working machine (11) are transferred to the work
site;
e) the gripping and jolting apparatus (14) is attached to the quick clamping device
of the articulated boom arm;
f) the gripping and jolting apparatus (14) is used to grasp the wall element (5);
g) a number of wall elements (5) are driven side by side one after the other into
the ground at the aforesaid angle (α);
h) soil material is removed from above the wall elements (5) that were driven into
the ground;
i) a soft insulator layer (7) such as an air cushion, a layer of light gravel or the
like is placed against the side surface (6) of the wall elements; and
j) the insulator wall (3) formed by the wall elements (5) driven into the ground and
the insulator layer (7) is filled with soil material.
10. The method as defined in claim 9, characterised in that after step j) the wall elements are removed from inside the ground, and just the
insulator layer (7), acting as the insulator wall (3) alone, is left inside the ground.
11. The method as defined in claim 9, characterised in that after step j) a noise barrier (4) is attached to the wall elements (5).
12. A system for protecting an object to be protected (1), such as a building, from vibration
induced by traffic and transmitted from a roadway (2) via the ground, which system
includes an insulator wall (3), which is driven into the ground at a distance from
the roadway substantially in parallel with respect to the roadway between the roadway
and the object to be protected to damp vibration, characterised in that the insulator wall (3) is with respect to the vertical direction at an inclined angle
α so that the insulator wall is slanting downward at the aforesaid angle α and away
from the roadway (1) to direct the vibration obliquely downward, the insulator wall
(3) both damping and directing the vibration into the direction determined by the
insulator wall.
13. The system as defined in claim 12, characterised in that the insulator wall (3) is with respect to the horizontal direction at an angle (α),
which is 10° ≤ α ≤ 60°, preferably about 45°.
14. The system as defined in claim 12 or 13, characterised in that the depth (L) of the insulator wall (3) below ground level is about 5 m.
15. The system as defined in any one of claims 12 - 14,characterised in that a noise barrier (4) is attached to the insulator wall (3) to damp the noise transmitted
from the roadway (1) via the air, the insulator wall (3) thus acting as a foundation
for the noise barrier (4).
16. The system as defined in claim 12 - 14, characterised in that the insulator wall (3) includes a number of wall elements (5) that have been attached
to one another side by side in line to form a uniform insulator wall.
17. The system as defined in claim 16, characterised in that the wall element (5) is a profile sheet element having at the edges thereof connecting
members (16) for connecting similar profile sheet elements consecutively to one another.
18. The system as defined in claim 16, characterised in that the wall element (5) is a so-called sheet pile profile element.
19. The system as defined in claim 16, characterised in that the wall element (5) is a box formed from a profile sheet element and a sheet (20)
attached to the open flank of the profile sheet element.
20. The system as defined in claim 16, characterised in that the wall element (5) refers to a predetermined number of tubes (24) that have been
attached to one another by means of connecting members (25) as a series of no less
than two interlocked tubes.
21. The system as defined in claim 19 or 20, characterised in that the box/tubes have been filled with concrete, soil material and/or some other medium.
22. The system as defined in any one of claims 16 - 21, characterised in that the wall element (5) has at the lower end thereof a tip part (22).
23. The system as defined in any one of claims 12 - 22, characterised in that the insulator wall (3) includes steel, concrete and/or plastic.
24. The system as defined in any one of claims 12 - 23, characterised in that the insulator wall (3) includes an insulator layer (7) of substantially soft material,
arranged against that side surface (6) of the wall elements (5) which is facing the
building to be protected.
25. The system as defined in claim 18, characterised in that the insulator layer (7) is an air cushion, a layer of cellular plastic and/or of
light gravel.
26. The use of a system as defined in any one of claims 12 - 25 for protecting buildings
close to railways and highways against ground vibration.