Technical Field
[0001] The present disclosure relates to an underwater concrete structure capable of preventing
subsidence in seabed soft ground and a construction method therefor and, particularly,
to an underwater concrete structure and a construction method thereof, in which concrete
columns are capable of supporting the lower end of a main concrete structure to prevent
the main concrete structure from subsiding in seabed soft ground.
Background Art
[0002] An underwater structure, such as berthing facilities for ports, coastal wave-dissipating
structures, and breakwaters, are installed underwater for various purposes. As used
above and below, the term "underwater structure" refers to an underwater structure
installed with a lower part thereof submerged in water, and an upper part thereof
may protrude above the water surface or be located below the water surface.
[0003] A widely known construction technique in the construction of an underwater structure
is the construction method of a large caisson. The large caisson construction method
has the advantage of allowing a very large caisson to withstand large waves, but requires
manufacturing the very large caisson on land, transporting it to an installation site,
and then installing it underwater, so the large caisson construction method requires
very high transportation and construction costs and has many restrictions.
[0004] In order to solve the problems of this type of large caisson construction method,
a method of forming an underwater structure by stacking small concrete blocks in several
layers according to the water depth is known.
[0006] Meanwhile, soft ground is widely distributed on the seabed, and when an underwater
concrete structure is directly installed on the soft ground, the underwater concrete
structure subsides, thereby threatening structural stability thereof.
[0007] Therefore, the construction of an underwater concrete structure installed on soft
ground is required to be preceded by creating a foundation ground suitable for the
installation of the underwater concrete structure through various soft ground improvement
methods (a replacement riprap method and a deep mixing treatment method, etc.).
[0008] However, it is difficult to create an appropriate foundation ground in a case in
which the depth of the seabed is very deep or a soft ground layer is very thick.
[0009] When the water depth is very deep or the soft ground layer is very thick, it is very
difficult for soft ground improvement equipment located on the water surface to pass
through the soft ground and reach bedrock, and it is also difficult to accurately
inject materials for improving the soft ground.
[0010] For example, in the case of the southern coast of South Korea, the water depth is
30 to 50m, and the thickness of the soft ground is also about 30 to 50m, so in this
case, the soft ground improvement equipment is required to be at least 60 to 100m
long to reach the bedrock.
Disclosure
Technical Problem
[0011] The present disclosure has been made to solve the problems in the prior art as described
above, and is intended to propose an underwater concrete structure and a construction
method therefor, in which a soft ground concrete column part, which is a portion of
a concrete column, is capable of supporting the lower end of a main concrete structure
to prevent the main concrete structure from subsiding in seabed soft ground.
Technical Solution
[0012] In order to accomplish the above objectives, the present invention provides a construction
method for an underwater concrete structure for preventing subsidence at seabed soft
ground, the construction method including: installing a main concrete structure having
a plurality of vertical penetration holes extending vertically on an upper part of
seabed soft ground which is on a top of seabed rock; forming a ground perforated part
in the seabed soft ground and the seabed rock by perforating the seabed soft ground
and the seabed rock located under each of the vertical penetration holes through the
vertical penetration hole after the installing of the main concrete structure; and
forming a concrete column along the vertical penetration hole and the ground perforated
part by inserting a concrete column formation part, which comprises a concrete reinforcing
member extending vertically, a waterproof membrane covering lower and side portions
of the concrete reinforcing member, and fresh concrete injected into the waterproof
membrane, into the vertical penetration hole and the ground perforated part after
the forming of the ground perforated part, wherein the concrete column is divided
into a penetration hole concrete column part located in the vertical penetration hole,
a soft ground concrete column part located in the seabed soft ground, and a rock concrete
column part located in the seabed rock, wherein the soft ground concrete column part
is formed to support a lower end of the main concrete structure by having a diameter
larger than a diameter of the penetration hole concrete column part.
[0013] In the above, a waterproof membrane protective cover with a shape of a tube or a
basket may be provided on an outer side of the waterproof membrane, with an upper
end of the waterproof membrane protective cover positioned on a vertical middle of
the waterproof membrane.
[0014] In the above, the waterproof membrane protective cover may be formed as a mesh and
be coupled to the outer side of the waterproof membrane via a skirt member.
[0015] In the above, in the forming of the ground perforated part, a protection pipe extending
vertically may be inserted through the vertical penetration hole, and the inserted
protection pipe may be positioned across the vertical penetration hole and the ground
perforated part; and in the forming of the concrete column, the waterproof membrane
may be inserted into the vertical penetration hole and the ground perforated part
along an interior of the protection pipe, and the protection pipe may be removed after
the waterproof membrane is inserted.
[0016] In another idea of the present disclosure, an underwater concrete structure for preventing
subsidence at seabed soft ground includes: a main concrete structure which is installed
on an upper part of seabed soft ground which is on a top of seabed rock and is spaced
apart upward from the seabed rock and has a plurality of vertical penetration holes
extending vertically; and a plurality of concrete columns formed continuously along
the vertical penetration holes and the seabed soft ground and the seabed rock located
under the vertical penetration holes, wherein each of the concrete columns is divided
into a penetration hole concrete column part located in each of the vertical penetration
holes, a soft ground concrete column part located in the seabed soft ground, and a
rock concrete column part located in the seabed rock, and the soft ground concrete
column part supports a lower end of the main concrete structure by having a diameter
larger than a diameter of the penetration hole concrete column part to prevent subsidence
of the main concrete structure.
[0017] In the above, the concrete column may include a concrete reinforcing member formed
vertically and arranged across the vertical penetration hole, the seabed soft ground,
and the seabed rock, a waterproof membrane covering lower and side portions of the
concrete reinforcing member, concrete poured and cured inside the waterproof membrane,
and a waterproof membrane protective cover with a shape of a tube or a basket located
on an outer side of the waterproof membrane and having an upper end positioned on
a vertical middle of the waterproof membrane to protect the waterproof membrane located
in the seabed soft ground.
[0018] In the above, the waterproof membrane protective cover may be formed as a mesh and
be coupled to the outer side of the waterproof membrane via a skirt member.
Advantageous Effects
[0019] As described above, according to the present disclosure, the soft ground concrete
column part, which is a portion of the concrete column, is capable of supporting the
lower end of the main concrete structure to prevent the main concrete structure from
subsiding in the seabed soft ground.
[0020] Furthermore, according to the present disclosure, the work of forming the soft ground
concrete column part is very simple compared to a conventional soft ground improvement
method, so it is possible to reduce an overall construction cost.
Description of Drawings
[0021]
FIG. 1 is a perspective view of a concrete block used in a construction method for
an underwater concrete structure for preventing subsidence at seabed soft ground according
to a first embodiment of the present disclosure,
FIG. 2 is a plan view of a main concrete structure formed on the top of the seabed
by installing the concrete blocks of FIG. 1,
FIG. 3 is a cross-sectional conceptual drawing of FIG. 2,
FIG. 4 is a drawing of a ground perforated part formed after forming the main concrete
structure of FIG. 3,
FIGS. 5 to 8 are drawings illustrating the process of forming a concrete column in
sequence after forming the ground perforated part of FIG. 4,
FIG. 9 is a front view of a waterproof membrane to which a waterproof membrane protective
cover of FIG. 5 is attached,
FIG. 10 is an exploded cross-sectional view of FIG. 9,
FIG. 11 is a perspective view of a concrete block used in a construction method for
an underwater concrete structure for preventing subsidence at seabed soft ground according
to a second embodiment of the present disclosure,
FIG. 12 is a cross-sectional view of a main concrete structure formed by the concrete
blocks of FIG. 11,
FIG. 13 is a cross-sectional view of a ground perforated part and a concrete column
formed after the state of FIG. 12, and
FIG. 14 is a cross-sectional view of a cap concrete formed after the state of FIG.
13.
Best Mode
[0022] Hereinafter, embodiments of the present disclosure will be described in detail with
reference to the accompanying drawings so that those skilled in the art to which the
present disclosure belongs can easily embody the present disclosure. However, the
present disclosure may be embodied in various different forms and is not limited to
the embodiments described herein. In addition, in the drawings, parts irrelevant to
the description of the present disclosure are omitted in order to clearly describe
the present disclosure, and similar reference numerals are assigned to similar parts
throughout the specification.
[0023] Throughout the specification, when a part "includes" a certain component, it means
that other components may be further included without being excluded unless specifically
stated to the contrary.
[0024] First, a construction method for an underwater concrete structure for preventing
subsidence at seabed soft ground according to a first embodiment of the present disclosure
will be described.
[0025] FIG. 1 is a perspective view of a concrete block used in a construction method for
an underwater concrete structure for preventing subsidence at seabed soft ground according
to a first embodiment of the present disclosure, FIG. 2 is a plan view of a main concrete
structure formed on the top of the seabed by installing the concrete blocks of FIG.
1, FIG. 3 is a cross-sectional conceptual drawing of FIG. 2, FIG. 4 is a drawing of
a ground perforated part formed after forming the main concrete structure of FIG.
3, FIGS. 5 to 8 are drawings illustrating the process of forming a concrete column
in sequence after forming the ground perforated part of FIG. 4, FIG. 9 is a front
view of a waterproof membrane to which a waterproof membrane protective cover of FIG.
5 is attached, and FIG. 10 is an exploded cross-sectional view of FIG. 9.
Manufacturing a concrete block
[0026] As in FIG. 1, a concrete block 20 is manufactured.
[0027] The concrete block 20 may be formed to have various shapes, but preferably includes
at least two block penetration holes 21 extending vertically formed therein.
[0028] Each of the block penetration holes 21 extends vertically with a first diameter.
[0029] Depending on an embodiment, the concrete block 20 may have a space formed for filling
the inside thereof, or a space for other purposes or a shape for other purposes.
Forming a main concrete structure
[0030] FIG. 2 is a plan view of a main concrete structure 100, and FIG. 3 is a cross-sectional
view of the main concrete structure 100.
[0031] A plurality of concrete blocks 20 manufactured in the manufacturing of the concrete
block is installed on the upper part of seabed soft ground 12 which is on the top
of seabed rock 11 as in FIG. 3, and as in FIG. 2, the plurality of concrete blocks
20 is installed horizontally and continuously to form the main concrete structure
100.
[0032] That is, in this embodiment, the main concrete structure 100 has a plurality of concrete
blocks 20 arranged horizontally and continuously.
[0033] According to an embodiment, the main concrete structure 100 may be composed of one
concrete block 20.
[0034] As illustrated in FIG. 3, the main concrete structure 100 is installed spaced apart
upward from the seabed rock 11.
[0035] The block penetration holes 21 of the concrete blocks 20 constituting the main concrete
structure 100 form vertical penetration holes 101 extending vertically with lower
end parts thereof blocked by the seabed soft ground 12 and upper end parts thereof
open.
[0036] That is, in this embodiment, the concrete blocks are manufactured in large sizes
and installed in only one level vertically, and each of the block penetration holes
21 of each of the concrete blocks 20 functions as each of the vertical penetration
holes 101 of the main concrete structure 100.
[0037] Accordingly, the vertical penetration hole 101 is in the form of extending vertically
with the first diameter.
Forming a ground perforated part
[0038] After the forming of the main concrete structure, as illustrated in FIG. 4, the seabed
soft ground 12 and the seabed rock 11 located under the vertical penetration hole
101 are perforated through the vertical penetration hole 101 and thus a ground perforated
part 102, which is a space continuous to the vertical penetration hole 101, is formed
in the seabed soft ground 12 and the seabed rock 11.
[0039] In this embodiment, when the ground perforated part 102 is formed by perforating
the seabed soft ground 12 and the seabed rock 11 located under the vertical penetration
hole 101, a protection pipe 30 extending vertically is vertically inserted into the
seabed soft ground 12 and the seabed rock 11 through the vertical penetration hole
101.
[0040] The protection pipe 30 inserted in this manner is positioned across the vertical
penetration hole 101 and the ground perforated part 102, and the ground perforated
part 102 is formed inside the protection pipe 30.
[0041] In this case, the protection pipe 30 prevents the surrounding seabed soft ground
12 from collapsing into the ground perforated part 102 or prevents various types of
foreign substances from being introduced into the ground perforated part 102 during
or after the perforating operation.
[0042] In addition, the protection pipe 30 serves to protect the waterproof membrane 112
when a waterproof membrane 112 to be described later is inserted into the protection
pipe 30.
Forming a concrete column
[0043] After the forming of the ground perforated part, a concrete column 110 is formed
along the vertical penetration hole 101 and the ground perforated part 102.
[0044] The forming of the concrete column in this embodiment is performed step by step as
illustrated in FIGS. 5 to 8.
[0045] A concrete column formation part, which includes a concrete reinforcing member 111
extending vertically, the waterproof membrane 112 covering lower and side portions
of the concrete reinforcing member 111, fresh concrete 113 injected into the waterproof
membrane 112, and a waterproof membrane protective cover 114 coupled to the outer
side of the waterproof membrane 112, is inserted into the vertical penetration hole
101 and the ground perforated part 102 so as to form the concrete column 110 along
the vertical penetration hole 101 and the ground perforated part 102.
[0046] First, as illustrated in FIGS. 5 and 6, the concrete reinforcing member 111, such
as a reinforcing bar assembly extending vertically, is inserted into the vertical
penetration hole 101 and the ground perforated part 102.
[0047] In this embodiment, since the protection pipe 30 is already positioned in the vertical
penetration hole 101 and the ground perforated part 102, the concrete reinforcing
member 111 is inserted into the protection pipe 30.
[0048] In this case, while the lower and side portions of the concrete reinforcing member
111 is covered by the waterproof membrane 112, the concrete reinforcing member 111
is inserted into the vertical penetration hole 101 and the ground perforated part
102.
[0049] Meanwhile, the waterproof membrane protective cover 114 is provided on the outer
side of the waterproof membrane 112 via a skirt member 115.
[0050] The waterproof membrane protective cover 114 is in the form of a tube or basket (the
form of a basket in the present embodiment) with an upper end thereof positioned on
the vertical middle of the waterproof membrane 112, and a lower end portion of the
waterproof membrane 112 (specifically, a portion to be positioned in the seabed soft
ground) is positioned inside the waterproof membrane protective cover 114.
[0051] The waterproof membrane protective cover 114 may be a mesh which is woven from wire
or carbon fiber and formed into the shape of a tube or a basket.
[0052] Here, the tube shape is a cylindrical shape with the top and bottom open, and the
basket shape is a cylindrical shape with the top open and the bottom closed.
[0053] The skirt member 115 is provided between the waterproof membrane protective cover
114 and the waterproof membrane 112.
[0054] The upper end of the skirt member 115 is joined to the vertical middle of the outer
side of the waterproof membrane 112, and the upper end of the waterproof membrane
protective cover 114 is coupled to the lower end of the skirt member 115 by means
of stitching or the like.
[0055] Accordingly, after the concrete reinforcing member 111 covered by the waterproof
membrane 112 is inserted into the protection pipe 30, the concrete 113 is poured inside
the waterproof membrane 112 to form the concrete column 110 as illustrated in FIGS.
7 and 8.
[0056] FIG. 7 is a drawing showing a state in which the protection pipe 30 is slightly raised
while some of the fresh concrete 113 is poured inside the waterproof membrane 112.
[0057] That is, in FIG. 7, the protection pipe 30 is raised so that the lower end of the
protection pipe 30 is just outside the ground perforated part 102, and the fresh concrete
113 required for the ground perforated part 102 is poured inside the waterproof membrane
112.
[0058] In this case, the waterproof membrane 112 located in the seabed soft ground 12 has
a diameter increased by the pressure of the fresh concrete 113.
[0059] In FIG. 7, extent to which the diameter of the waterproof membrane 112 located in
the seabed soft ground 12 increases is greatly exaggerated, and in reality, as the
fresh concrete 113 is gradually injected into the waterproof membrane 112, the pressure
of the fresh concrete 113 located in the seabed soft ground 12 gradually increases.
As the pressure gradually increases, the diameter of the waterproof membrane 112 located
in the seabed soft ground 12 gradually increases, and this increase of the diameter
of the waterproof membrane 112 continues until the fresh concrete 113 is fully injected
into the waterproof membrane 112, as illustrated in FIG. 8.
[0060] The waterproof membrane 112 is required to have a structure that allows for the diameter
increase structurally (e.g., a structure that unfolds from a folded state) or through
a material (e.g., a stretchable elastic material) in consideration of the increase
of a diameter.
[0061] In addition, the waterproof membrane protective cover 114 prevents the waterproof
membrane 112 from being damaged due to excessive diameter increase by allowing the
waterproof membrane 112 to expand in diameter only within a certain limit.
[0062] In addition, the waterproof membrane protective cover 114 is made as mesh and prevents
air or water from remaining between the waterproof membrane protective cover 114 and
the waterproof membrane 112.
[0063] In this manner, the protection pipe 30 is gradually raised while the fresh concrete
113 is gradually poured inside the waterproof membrane 112, and finally, as illustrated
in FIG. 8, the protection pipe 30 is completely removed, and the pouring of the fresh
concrete 113 throughout the vertical penetration hole 101 and the ground perforated
part 102 is completed.
[0064] That is, the protection pipe 30 is removed before the fresh concrete 113 that has
been poured is hardened.
[0065] When the fresh concrete 113 is poured into the waterproof membrane 112 in this way,
the waterproof membrane 112 is brought into close contact with the seabed rock 11
and the concrete block 20 (or the main concrete structure 100) by the pressure of
the fresh concrete 113, and has a diameter increased significantly in the seabed soft
ground 12 increases, and then goes through a curing process to be the concrete column
110.
[0066] In this way, the concrete column 110 is formed in the main concrete structure 100,
thereby completing an underwater concrete structure 200.
[0067] That is, the concrete column 110 includes a penetration hole concrete column part
110a located in the vertical penetration hole 101 and extending vertically with the
first diameter, a soft ground concrete column part 110b located in the seabed soft
ground 12 and extending vertically with a second diameter, and a rock concrete column
part 110c located in the seabed rock 11 and extending vertically with a third diameter.
[0068] In addition, since the soft ground concrete column part 110b has a diameter larger
than the diameter of the penetration hole concrete column part 110a, the soft ground
concrete column part 110b supports the lower end of the main concrete structure 100,
thereby preventing the main concrete structure 100 from subsiding.
[0069] That is, according to the present disclosure, the main concrete structure 100 may
be prevented from subsiding without performing separate soft ground improvement work
on the seabed soft ground 12.
[0070] Hereinafter, a second embodiment of the present disclosure will be described.
[0071] FIG. 11 is a perspective view of a concrete block used in a construction method for
an underwater concrete structure for preventing subsidence at seabed soft ground according
to a second embodiment of the present disclosure, FIG. 12 is a cross-sectional view
of a main concrete structure formed by the concrete blocks of FIG. 11, FIG. 13 is
a cross-sectional view of a ground perforated part and a concrete column formed after
the state of FIG. 12, and FIG. 14 is a cross-sectional view of a cap concrete formed
after the state of FIG. 13.
[0072] Below, only differences from the first embodiment are mainly explained, and the descriptions
of parts that are the same as the first embodiment are omitted.
Manufacturing a concrete block
[0073] In this embodiment, the concrete block 20 as illustrated in FIG. 11 is manufactured.
[0074] The concrete block 20 of the present embodiment has a plurality of block penetration
holes 21 formed therein, and each of the block penetration holes 21 has the shape
of a corrugated pipe extending vertically as illustrated in FIG. 12.
Forming a main concrete structure
[0075] The concrete blocks 20 are stacked vertically to form the main concrete structure
100 as illustrated in FIG. 12. The concrete blocks 20 are stacked in 7 layers.
[0076] Compared to the first embodiment, in the second embodiment, water depth is greater,
and the layer of the seabed soft ground 12 is thicker.
[0077] In this case, since the block penetration hole 21 of the concrete block 20 has the
shape of a corrugated pipe that extends vertically, the vertical penetration hole
101 of the main concrete structure 100 also has the shape of a corrugated pipe that
extends vertically.
[0078] The vertical penetration hole 101 in the form of a corrugated pipe enhances bonding
strength with the concrete column 110.
[0079] As described above, the main concrete structure 100 may be formed by stacking a plurality
of concrete blocks 20 vertically.
Forming a ground perforated part and forming a concrete column
[0080] After the state of FIG. 12, the ground perforated part is formed through the vertical
penetration hole 101 of the main concrete structure 100, and the concrete column 110
is formed along the vertical penetration hole 101 and the ground perforated part to
obtain a state as in FIG. 13.
[0081] This step is substantially the same as the first embodiment, so a detailed description
thereof is omitted.
Forming cap concrete
[0082] After the state of FIG. 13, a cap concrete 120 is formed on the top of the main concrete
structure 100.
[0083] The reinforcing bar assembly of the cap concrete 120 is connected to the concrete
reinforcing member 111 of the concrete column 110.
[0084] The foregoing description of the present disclosure is for illustrative purposes
only, and those skilled in the art to which the present disclosure pertains will understand
that the present disclosure may be easily modified into another specific form without
changing its technical idea or essential features. Therefore, the embodiments described
above should be understood in all respects as illustrative and not restrictive. For
example, any component described as a single component may be implemented in a divided
form, and similarly, components described as separate may be implemented in a combined
form.
[0085] The scope of the present disclosure is indicated by the claims described below rather
than the detailed description above, and the meaning and scope of the patent claims
and all changes or modified forms derived from the equivalent concept thereof should
be construed as being included in the scope of the present disclosure.
Industrial Applicability
[0086] The present disclosure may be used as an underwater concrete structure installed
underwater for various purposes, such as berthing facilities for ports, coastal wave-dissipating
structures, and breakwaters.
1. A construction method for an underwater concrete structure for preventing subsidence
at seabed soft ground, the construction method comprising:
installing a main concrete structure having a plurality of vertical penetration holes
extending vertically on an upper part of seabed soft ground which is on a top of seabed
rock;
forming a ground perforated part in the seabed soft ground and the seabed rock by
perforating the seabed soft ground and the seabed rock located under each of the vertical
penetration holes through the vertical penetration hole after the installing of the
main concrete structure; and
forming a concrete column along the vertical penetration hole and the ground perforated
part by inserting a concrete column formation part, which comprises a concrete reinforcing
member extending vertically, a waterproof membrane covering lower and side portions
of the concrete reinforcing member, and fresh concrete injected into the waterproof
membrane, into the vertical penetration hole and the ground perforated part after
the forming of the ground perforated part, wherein the concrete column is divided
into a penetration hole concrete column part located in the vertical penetration hole,
a soft ground concrete column part located in the seabed soft ground, and a rock concrete
column part located in the seabed rock, wherein the soft ground concrete column part
is formed to support a lower end of the main concrete structure by having a diameter
larger than a diameter of the penetration hole concrete column part.
2. The construction method of claim 1, wherein a waterproof membrane protective cover
with a shape of a tube or a basket is provided on an outer side of the waterproof
membrane, with an upper end of the waterproof membrane protective cover positioned
on a vertical middle of the waterproof membrane.
3. The construction method of claim 2, wherein the waterproof membrane protective cover
is formed as a mesh and is coupled to the outer side of the waterproof membrane via
a skirt member.
4. The construction method of claim 1, wherein in the forming of the ground perforated
part, a protection pipe extending vertically is inserted through the vertical penetration
hole, and the inserted protection pipe is positioned across the vertical penetration
hole and the ground perforated part; and
in the forming of the concrete column, the waterproof membrane is inserted into the
vertical penetration hole and the ground perforated part along an interior of the
protection pipe, and the protection pipe is removed after the waterproof membrane
is inserted.
5. An underwater concrete structure for preventing subsidence at seabed soft ground,
the underwater concrete structure comprising:
a main concrete structure installed on an upper part of seabed soft ground on a top
of seabed rock, wherein the main concrete structure is spaced apart upward from the
seabed rock and has a plurality of vertical penetration holes extending vertically;
and
a plurality of concrete columns formed continuously along the vertical penetration
holes and the seabed soft ground and the seabed rock located under the vertical penetration
holes,
wherein each of the concrete columns is divided into a penetration hole concrete column
part located in each of the vertical penetration holes, a soft ground concrete column
part located in the seabed soft ground, and a rock concrete column part located in
the seabed rock, and
the soft ground concrete column part supports a lower end of the main concrete structure
by having a diameter larger than a diameter of the penetration hole concrete column
part to prevent subsidence of the main concrete structure.
6. The underwater concrete structure of claim 5, wherein the concrete column comprises
a concrete reinforcing member formed vertically and arranged across the vertical penetration
hole, the seabed soft ground and the seabed rock, a waterproof membrane covering lower
and side portions of the concrete reinforcing member, concrete poured and cured inside
the waterproof membrane, and a waterproof membrane protective cover with a shape of
a tube or a basket located on an outer side of the waterproof membrane and having
an upper end positioned on a vertical middle of the waterproof membrane to protect
the waterproof membrane located in the seabed soft ground.
7. The underwater concrete structure of claim 6, wherein the waterproof membrane protective
cover is formed as a mesh and is coupled to the outer side of the waterproof membrane
via a skirt member.