EP0679761B1

EP0679761B1 - Flat hoses for use in the compaction of soft ground and compaction method using the same

Info

Publication number: EP0679761B1
Application number: EP19950302811
Authority: EP
Inventors: Mamoru Takasaki; Seigi Yamase; Kuninori Aramaki; Toshitaka Ohtsuka
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 1994-04-26
Filing date: 1995-04-26
Publication date: 1999-06-16
Anticipated expiration: 2015-04-26
Also published as: EP0679761A1; DE69510268D1; DE69510268T2

Description

This invention relates to a flat hose for use in the compaction of soft ground by a water loading method and a compaction method using the same.
It is well-known that a loading method is used in the compaction, backfilling, or banking of soft ground. In this case, a load equal to or larger than a weight of a structural body is previously applied to a soft base ground prior to the application of the structural body to promote consolidation settlement of such a ground and increase the strength thereof until the quantity of the settlement or the strength level reaches a previously anticipated level. After the compaction of the soft ground, the load is removed and then the structural body is applied on the compacted ground. According to this method, the distance between mutual soil particles becomes smaller to increase the earth density and decrease the water permeability and hence increase the shearing resistance of the soil.
In general, embankment is used in the above loading method. However, an area to be effectively compacted with the embankment is about 1/4 of an area of the embankment, so that the use of the embankment is impossible when an area of soft ground to be compacted is less than 4 times an area of a structural body to be applied. Furthermore, earth for the embankment is obtained from a given place and carried to a working site and then removed from the working site after the completion of the compaction, so that a great number of working steps is required. Moreover, scattering of dust is caused during transportation of the earth or at a dry state of the embankment. That is, the use of the embankment has many problems in view of economical and environmental reasons.
Recently, there has been developed a water loading method wherein a plurality of hoses are arranged on soft ground side by side instead of the embankment and water is filled in these hoses. For example, JP-A-1-278613 proposes a preload member used for the improvement of soft ground through a preloading method and consisting of a rubber or synthetic resin tube provided at both ends with taps for supply and discharge of water. Furthermore, this prior art reference discloses that a plurality of preload members are arranged side by side on a fill material placed on soft ground and having a space substantially equal to an area of an institution to be applied and a plurality of the preload members are further placed on the tube row in the same direction or a direction perpendicular to the tube direction of this row and then water is filled in all of these preload members.
In the water loading method, only a space substantially equal to the size of the institution is required as an area of soft ground to be compacted, and also the operation of arranging and removing the preload members is easy, so that the problems caused in the use of the embankment can be solved.
However, the tube of the preload member used has an original shape corresponding to a cylindrical shape created by the filling of water, so that when water is discharged from the inside of the tube to deflate the tube, a curved swelling is formed in each side portion of the tube at the deflated state thereof without being flattened owing to the thickness of the tube as shown in Fig. 1 of the accompanying drawings. As a result, water still remains in the swelling, which obstructs the removal work of the preload member after the completion of the soft ground compaction. Furthermore, the swellings at both side portions of the tube at the deflated state are considerable, so that when the tube is wound around a reel or the like, the winding can not be efficiently and compactly conducted and also a large space is required for the transportation and storage of the wound tube.
It is, therefore, an object of the invention to provide a flat hose for use in the compaction of soft ground by a water loading method which is capable of completely discharging water from the inside of the hose at a deflated state and conducting compact winding and facilitating the transportation and storage of the hose.
According to a first aspect of the invention, there is provided a flat hose for use in the compaction of soft ground by a water loading method, comprising; a flexible plate body composed of a rubbery elastomeric material and provided in a deflated state with a hollow split portion at a predetermined position in a transverse direction and extending along a lengthwise direction thereof; said split portion terminating at each side end with a solid fin portion extending in the transverse direction; and said split portion in an inflated state defining an inflated chamber for housing water supplied to said split portion.
In a preferred embodiment of the invention, each of both end portions of the hose in the lengthwise direction thereof is sandwiched between a pair of keep members and a flanged connection pipe is watertightly inserted into the end portion between the keep members so as to communicate with the hollow split portion.
In another preferred embodiment of the invention, the flexible plate body is provided with a reinforcing layer around the hollow split portion.
In a further preferred embodiment of the invention, coupling holes are formed in the solid fin portion at given intervals in the lengthwise direction.
According to a second aspect of the invention, there is provided a method of compacting soft ground, which comprises arranging a plurality of flat hoses as defined above side by side on a fill material placed on soft ground in a volume corresponding to a given settlement volume of the soft ground,to form a first stage comprised of said flat hoses, piling a plurality of flat hoses on the first stage and arranging them side by side while shifting laterally from the first stage only by a given pitch to form a second stage comprised of said flat hoses, providing a third and a four on stage in the same way, and then successively supplying water into each of the flat hoses from the first stage to one fourth stage to inflate said hoses.
In a preferred embodiment of the invention, when the flat hoses are arranged side by side and piled one upon the other to form at least four stages of pyramid form, the flat hose in the second stage is shifted laterally by a half pitch from the flat hose in the first stage, and the flat hose in the third stage is shifted laterally by 1/4 pitch from the flat hose in the second stage, and the flat hose is shifted laterally by a half pitch from the flat hose in the fourth stage.
In another preferred embodiment of the invention, vibrations are f rcedly applied to water filled in the inflated hoses, more preferably by means of a vibrator or pump.
In the other preferred embodiment of the invention, the flat hoses arranged in at least a first stage are connected to each other; more preferably at least three flat hoses located at each outward end of the stage are connected to each other. Alternately, two flat hoses located at each outward end of each stage are connected to each other.
According to the invention, the hose itself is comprised of flat flexible plate body, so that when water is discharged from the hollow split portion of the plate body after use, the plate body is immediately returned to the original flat shape, whereby the discharge of water can be completely conducted. Furthermore, the hose can be efficiently and compactly wound around a reel or the like at the deflated state, which can facilitate the transportation and storage of the wound hose.
The invention will be further described with reference to the accompanying drawings, wherein:
Fig. 1 is a section view of a conventional cylindrical tube at a deflated state;
Fig. 2 is a partially perspective view of a first embodiment of a flat hose according to the invention;
Fig. 3 is a perspective view illustrating a state of arranging a plurality of flat hoses according to the invention side by side;
Fig. 4 is a partially perspective view illustrating a state of inflating flat hoses according to the invention by supply of water;
Fig. 5 is a partially perspective view of a second embodiment of a flat hose according to the invention;
Fig. 6 is a section view taken along a line VI-VI of Fig. 5;
Fig. 7 is a section view showing a modified embodiment of Fig. 6;
Fig. 8 is a partially perspective view of a third embodiment of a flat hose according to the invention;
Fig. 9 is a section view taken along a line IX-IX of Fig. 8;
Fig. 10 is a section view of a fourth embodiment of a flat hose according to the invention;
Fig. 11 is a diagrammatic view of a coupling metal member for connecting adjacent joint holes between adjoining solid fin portions to each other;
Fig. 12 is a schematic partial section view illustrating a state of piling flat hoses according to the invention one upon the other on a fill material placed on soft ground;
Fig. 13 is a diagrammatical view illustrating a state of inflating flat hoses at a first stage by the supply of water;
Fig. 14 is a diagrammatical view illustrating a state of inflating flat hoses at a second stage by the supply of water;
Fig. 15 is a diagrammatical view illustrating a state of inflating flat hoses at third and fourth stages by the supply of water;
Fig. 16 is a diagrammatic partial section view illustrating a water loading method with the flat hoses shown in Fig. 5;
Fig. 17 is a diagrammatic section view illustrating a state of arranging different flat hoses between a fill material and a lowest row comprised of flat hoses for preventing collapsing of inflated hoses from the outward end of the lowest row in the compaction of soft ground;
Fig. 18 is a diagrammatic section view illustrating a state of inflating different flat hoses shown in Fig. 17 by the supply of water for preventing collapsing of inflated hoses from the outward end of the lowest row when uneven settlement of soft ground is caused;
Fig. 19 is a diagrammatic partial section view illustrating another embodiment for preventing collapsing of inflated hoses from the outward end of the lowest row when uneven settlement of soft ground is caused;
Fig. 20 is a diagrammatic partial section view illustrating a further embodiment for preventing collapsing of inflated hoses from the outward end of the lowest row when uneven settlement of soft ground is caused;
Fig. 21 is a schematic front view illustrating a first embodiment of compacting soft ground through a water loading method using flat hoses according to the invention; and
Fig. 22 is a schematic front view illustrating a second embodiment of compacting soft ground through a water loading method using flat hoses according to the invention.
In Fig. 2 is a perspective view showing an end portion of a first embodiment of a flat hose according to the invention. A flat hose 1 comprises a flexible plate body 2 composed of a rubbery elastomeric material such as rubber, polyvinyl chloride or the like and provided in a deflated state with a hollow split portion 3 at a predetermined position in a transverse direction and extending along a lengthwise direction thereof. The hollow split portion 3 terminates at each side end with a solid fin portion extending in the transverse direction. Further, the hollow split portion 3 in an inflated state defines an inflated chamber for receiving and housing water supplied to the split portion 3.
In the flexible plate body 2 is embedded a flexible reinforcing layer 4 of a flat cylindrical shape surrounding the hollow split portion 3. The reinforcing layer 4 is comprised of a canvas or a bias cut weave fabric of a synthetic fiber such as polyamide fiber, polyester fiber, aramide fiber or the like.
When the flexible plate body 2 is inflated by supplying water into the hollow split portion 3, breakage which is particularly apt to be caused in both solid fin portions can be prevented by the reinforcing layer 4 surrounding the hollow split portion 3.
Moreover, fine undulations may be formed in the outer surface of the plate body 2 or an anti-slipping material such as ceramic particles or the like may be applied to the outer surface of the plate body for the prevention of slipping.
As shown in Fig. 2, each of both end portions of the plate body 2 in the lengthwise direction thereof is sandwiched between a pair of keep members 10 each having, for example, a semi-circular curved portion and a flanged connection pipe 11 is watertightly inserted into the end portion between the keep members 10 so as to communicate with the hollow split portion 3 and fixed at both sides thereof with the keep members 10 by bolts and nuts 12. In order to further ensure the watertightness, the flanged connection pipe 11 may be provided at its periphery with a flexible packing (not shown) which is symmetrical in configuration with respect to the center axis of the pipe and is gradually tapered from the up and down sides toward the left and right sides in a direction perpendicular to the center axis of the pipe.
Furthermore, bolt holes 11b are formed in a flange portion lla of the flanged connection pipe 11.
According to the invention, the flat hose 1 is used for the compaction of soft ground as shown in Fig. 3. That is, a plurality of the flat hoses 1 are arranged side by side on a fill material (not shown) placed on soft ground (not shown), wherein the flanged connection pipes 11 located at the adjacent end portions between the mutual flat hoses 1 are connected to a U-shaped joint pipe 13 having flange portions 13a at both ends thereof and the joint pipes 13 are zigzag arranged with respect to the lengthwise direction of the flat hose arrangement. In this case, each of the joint pipes 13 is secured to the flanged connection pipe 11 by interposing a seal member (not shown) between the flange portions lla and 13a and passing bolts 14 through bolt holes formed in the flange portions and fastening with nuts.
The flanged connection pipe 11 of an outermost flat hose 1 not connected to a joint pipe 13 is closed with a cover member 16, while the flanged connection pipe 11 of the other outermost flat hose 1 not connected to a joint pipe 13 is connected to a pipe 17 for the supply and discharge of water.
Once water is supplied into the hollow split portion 3 of the outermost flat hose 1 through the pipe 17, water penetrates into the hollow split portion 3 of the next flat hose 1 through the joint pipe 13 one after another to successively inflate the hollow split portions 3 of the flexible plate bodies 2. As shown in Fig. 4, the flexible plate body 2 is inflated into a substantially cylindrical form other than the end portions sandwiched between the keep members 10 and the solid fin portions by water filled in the hollow split portion 3.
In the compaction of soft ground, a plurality of the flat hoses 1 are arranged side by side on a space to be compacted corresponding only to an area of an institution. Moreover, these flat hoses 1 are piled one upon the other at multi stages in the form of a pyramid so as to provide water loading sufficient to compact the soft ground up to a given settlement volume when water is supplied to these flat hoses. After the completion of the soft ground compaction, water is discharged from the inside of each of the inflated hoses 1. Since the flat hose 1 has a flat shape by nature, the inflated hose 1 is substantially completely deflated to the original flat shape as shown in Fig. 2 during the discharge of water from the inside of the inflated split portion. As a result, the deflated flat hose can easily be removed from the compacted soft ground. In the removal operation, the deflated flat hose can be efficiently and compactly wound around a reel. Since the compactly wound flat hose does not occupy a great volume during transportation and storage, a great number of flat hoses 1 can be transported and stored at once.
When the flat hoses 1 are piled one upon another at the multi stages, the adjoining flat hoses 1 are connected to each other through the connection pipes 13 and the fine undulations formed on the outer surface of the flat hose 1, so that the multi-stage piled inflated hoses will not collapse unless the piling height is extreme.
In Fig. 5 is shown a second embodiment of a flat hose according to the invention, which is a modified embodiment of Fig. 2. That is, a flat hose 20 comprises a flexible plate body 21 composed of a rubbery elastomeric material such as rubber, polyvinyl chloride or the like and provided in a deflated state with a hollow split portion 3 at a predetermined position in a transverse direction and extending along a lengthwise direction thereof. The hollow split portion 3 terminates at each side end with a solid fin portion 22 extending in the transverse direction. Further, the hollow split portion 3 in an inflated state defines an inflated chamber for receiving and housing water supplied to the split portion 3.
In the flexible plate body 21 is embedded a flexible reinforcing layer 4 of a flat cylindrical shape surrounding the hollow split portion 3. The reinforcing layer 4 is comprised of a canvas or a bias cut weave fabric of a synthetic fiber.
As shown in Fig. 6, each of the solid fin portions 22 is reinforced with a pair of fiber reinforcing layers 24 embedded in the plate body 21 and provided with a plurality of joint holes 26 formed at a given pitch in the lengthwise direction of the plate body.
As shown in Fig. 7, a pair of fiber reinforcing layers 25 may be embedded in the plate body over substantially the full width thereof instead of the fiber reinforcing layer 24 in addition to the reinforcing layer 4.
In Fig. 8 is shown a third embodiment of a flat hose according to the invention, which is a modified embodiment of Fig. 5. A flat hose 30 has the same structure as the flat hose 20 except that a rubber cut-out portion 32 is formed in the solid fin portion 22 between the adjacent joint holes 26 for reducing the weight of the flat hose. As shown in Fig. 9, a ringshaped metal reinforcement 34 is embedded around the joint hole 26.
In Fig. 10 is shown a fourth embodiment of a flat hose according to the invention, which is a modified embodiment of Fig. 7. A flat hose 40 has the same structure as the flat hose of Fig. 7 except that an upper solid fin portion 42a and a lower solid fin portion 42b are formed on both sides of the plate body in the widthwise direction with respect to a center line of the plate body in the transverse direction as shown in Fig. 10. The upper solid fin portion 42a of one flat hose 42 is piled on the lower solid fin portion 42b of an adjacent flat hose 42.
As shown in Fig. 11, flat hoses 20 are connected to each other by fitting opposed hook portions 50a of a coupling metal member 50 into joint holes 26 of the adjoining flat hoses 20. Moreover, the connection between the adjoining flat hoses may be conducted by using a rope or the like instead of the coupling metal member 50.
The compaction of soft ground using the aforementioned flat hose according to the invention will be described in detail below.
As shown in Fig. 12, a plurality of flat hoses 1 each defining an inflated chamber of, for example, 1 m in diameter at an inflated state are arranged side by side and at the same time piled one upon the other in up to four stages in one form of a pyramid. Numeral 60 is a soft ground to be compacted, and numeral 62 a fill material placed on the soft ground 60 in a volume corresponding to a given settlement volume of the soft ground.
First, a plurality of flat hoses l_-1 are arranged on the fill material 62 side by side at a constant pitch (2.1 m) to form a first stage A comprised of the flat hoses l_-1. Then, a plurality of flat hoses l_-2 are piled on the first stage A and arranged side by side while being shifted laterally from the first stage A by a half pitch to form a second stage B comprised of the flat hoses l_-2. Next, a plurality of flat hoses l_-3 are piled on the second stage B and arranged side by side while being shifted laterally from the second stage B by 1/4 pitch to form a third stage C comprised of the flat hoses l-₃. Thereafter, a plurality of flat hoses l_-4 are piled on the third stage C and arranged side by side while being shifted laterally from the third stage C by a half pitch to form a fourth stage D comprised of the flat hoses l_-4.
As shown in Fig. 13, when the flat hoses l_-1 of the first stage A are inflated by the supply of water, each of the flat hoses l_-2 locates between the adjoining inflated hoses l_-1. Then, when the flat hoses l_-2 of the second stage B are inflated by the supply of water, each of the inflated hoses l_-2 locates between the adjoining inflated hoses l_-1 to form a first row H comprised of the inflated hoses l_-1 and l_-2 as shown in Fig. 14. Thereafter, when the flat hoses l_-3 and l_-4 of the third and fourth stages C and D are inflated by the supply of water, the inflated hoses l_-3 and l_-4 are alternately arranged side by side to form a second row I as shown in Fig. 15.
As previously mentioned, water may be supplied to the flat hoses l through flanged connection pipes 13 connecting the flat hoses to each other, or the supply of water may be conducted separately to each flat hose l.
In the arrangement of the flat hoses as shown in Fig. 12, the adjoining flat hoses l arranged side by side are connected to each other by using ropes, bands or the like. In this case, the length of the rope is preferably not less than a half of a circumference of the inflated hose. Alternatively, plural clamping bands (not shown) are secured at one end to the fill material at an interval of 5 m for clamping the inflated hoses to prevent collapsing of the inflated hoses from the upper stage.
In case of the flat hose 20 having a solid fin portion provided with the joint holes, as shown in Fig. 16, at least three flat hoses 20_-1, 20_-2, 20_-3 located at each outward end of each of first to third rows H, I, J are connected to each other by connecting the opposed joint holes between the adjoining flat hoses with coupling metal members. Moreover, all flat hoses of each row may be connected to each other with the coupling metal members, ropes, bands or the like, if necessary.
Even when the adjoining inflated hoses in each row are connected to each other as mentioned above, there is a risk of the inflated hoses collapsing due to uneven settlement of the soft ground. That is, if the soft ground is unevenly settled, the inflated hoses begin to fall down from the upper row of the piled flat hoses. Particularly, when falling down of the inflated hoses is caused at the outer end of a row in the pyramid-shaped piling, great damage may be caused not only to workers operating around the piled rows but also to monitoring and operating devices. Therefore, it is strongly demanded to prevent collapsing of the inflated hoses from the piled rows in the water loading method.
According to a preferred embodiment of the invention, when a plurality of flat hoses 20 are arranged on a fill material 62 placed on soft ground 60 side by side and piled one upon the other in pyramid form (two rows in the illustrated embodiment), a flat hose 70 having an inflating diameter larger than that of the flat hoses 20 is interposed between the outward end of the first row H and the fill material 62 as shown in Fig. 17. If the soft ground 60 is unevenly settled during the compaction of the soft ground after the inflation of the flat hoses 20 by the supply of water, water is supplied to the inside of the flat hose 70 as shown in Fig. 18, whereby the inflated hoses 20 ride on the inflated hose 70 to prevent collapsing of the inflated hoses 20 from the outward end of the first row H. Moreover, the flat hose 70 may previously be shaped to have substantially a triangular form in section at an inflated state.
Alternatively, a rigid plate 72 may be interposed between the inflated hoses 20 of the lowest row and the fill material 62 and a flat hose 70 is disposed between the rigid plate 72 and the fill material 62 as shown in Fig. 19. In this case, the rigid plate 72 is lifted upward by supplying water into the flat hose 70 to prevent collapsing of the inflated hoses 20 if uneven settlement of soft ground is caused. In this case, the flat hose 70 may integrally bonded to the rigid plate 72 by vulcanization.
As shown in Fig. 20, at least two flat hoses 74 having an inflating diameter larger than that of the flat hose 20 may be located at each outward end of the lowest row comprised of the flat hoses 20 and connected to each other. If abnormal or uneven settlement of the soft ground is caused, collapsing of the inflated hoses 20 located at the outward end of the upper row is prevented by the inflation of the flat hoses 74 by the supply of water.
In general, a construction period for the compaction of soft ground through the water loading method is required to be about 2-3 months. According to circumstances, it is demanded to shorten the construction period as far as possible. For this purpose, there may be adopted various means for forcedly vibrating water filled in the inflated hose such as vibrators, pumps and the like. When such a vibration generating device is used, vibration frequency can freely be changed in accordance with soft ground strata to be compacted, loading state and the like, but is desirably about 0.1-1 Hz.
As shown in Fig. 21, after the flat hoses l_-1, l_-2 and l_-3 are arranged side by side and piled one upon the other in three rows H, I and J in a pyramid form and then inflated by the supply of water, a vibration generating device 80 fixed onto the inflated hoses l_-3 of the upper third row J is actuated by applying voltage to directly transfer vibrations to the inflated hoses l_-3, whereby water filled in the inflated hose l_-3 is vibrated, which is transferred through the inflated hoses l_-2 and l_-1 and the fill material 62 to the soft ground 60 to promote the compaction of the soft ground 60. Moreover, the vibration generating device 80 may be disposed between the third row J and the second row I or between the second row I and the first row H, or may be arranged on an outer side face of each of the rows H, I and J.
As shown in Fig. 22, the compaction of soft ground may be promoted by actuating a pump 82 possessing a function of repeatedly feeding water under pressure, which is connected to several inflated hoses 1-3 of the upper third row J through respective connecting pipes 84, to vibrate water filled in these inflated hoses 1-3.
As mentioned above, according to the invention, the hose to be used is originally a flat plate body composed of a rubbery elastomer material having a hollow split portion therein, so that when the hose inflated by the supply of water is deflated by the discharge of water, the shape of the hose becomes flat and hence water can completely be discharged from the inside of the inflated hose. As a result, the deflated hose can be efficiently and compactly be wound around a reel or the like and also the transportation and storage of the wound hose become easy. Furthermore, a plurality of such flat hoses are arranged side by side on a fill material placed on a soft ground to be compacted connected to each other through a connecting pipe at the deflated state, so that the arrangement of the flat hoses in a multi-stage piling of pyramid form is easy and accurate. Moreover, a plurality of joint holes are suitably formed in each solid fin portion of the plate body at given intervals in the lengthwise direction thereof, so that when the solid fin portions of the adjoining plate bodies arranged side by side are connected to each other by connecting the joint holes with each other through coupling metal members or ropes, collapsing of the inflated hose from the outward end of each of the piled rows can be prevented.

Claims

A flat hose (1;20;30;40) for use in the compaction of soft ground by a water loading method, comprising: a flexible plate body (2;21) composed of a rubbery elastomeric material and provided in a deflated state with a hollow split portion (3) at a predetermined position in a transverse direction and extending along a lengthwise direction thereof; the split portion (3) terminating at each side end with a solid fin portion (22;42a,42b) extending in the transverse direction; and the split portion (3) in an inflated state defining an inflated chamber for housing water supplied to said split portion.
A flat hose as claimed in claim 1, characterized in that each of both end portions of the hose in the lengthwise direction thereof is sandwiched between a pair of keep members (10) and a flanged connection pipe (11) is watertightly inserted into the end portion between the keep members (10) so as to communicate with the hollow split portion (3).
A flat hose as claimed in claim 1 or 2, characterized in that the flexible plate body (2) is provided with a reinforcing layer (4) around the hollow split portion (3).
A flat hose as claimed in any of claims 1 to 3, characterized in that coupling holes (26) are formed in the solid fin portion (22;42a,42b) at given intervals in the lengthwise direction.
A method of compacting soft ground, which comprises arranging a plurality of flat hoses (1) as claimed in any of claims 1 to 4 side by side on a fill material (62) placed on soft ground (60) in a volume corresponding to a given settlement volume of the soft ground, to form a first stage (A) comprised of said flat hoses, piling a plurality of flat hoses on the first stage and arranging them side by side while shifting laterally from the first stage only by a given pitch to form a second stage (B) comprised of said flat hoses, providing a third (C) and a fourth stage (D) in the same way, and then successively supplying water into each of the flat hoses from the first stage to the fourth stage (D) to inflate said hoses.
A method as claimed in claim 5, characterized in that, when the flat hoses (1) are arranged side by side and piled one upon the other to form at least four stages (A-D) of pyramid form, the flat hose in the second stage (B) is shifted laterally by a half pitch from the flat hose in the first stage (A), and the flat hose in the third stage (C) is shifted laterally by 1/4 pitch from the flat hose in the second stage, and the flat hose is shifted laterally by a half pitch from the flat hose in the fourth stage (D).
A method as claimed in claim 5 or 6, characterized in that vibrations are forcedly applied to water filled in the inflated hoses.
A method as claimed in claim 7, characterized by forcedly applying vibrations to water filled in the inflated hoses by means of a vibrator (80) or pump (82).
A method as claimed in any of claims 5 to 8, characterized in that the flat hoses arranged in at least a first stage are connected to each other.
A method as claimed in claim 9, characterized in that at least three flat hoses located at each outward end of the first stage are connected to each other.
A method as claimed in any of claims 5 to 8, characterized in that two flat hoses located at each outward end of each stage are connected to each other.