JP2002146768A - Vacuum consolidated-drained improvement construction method by utilizing scaffold bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method and a work structure capable of advantageously conducting an improvement by vacuum consolidation at the points of the term of works and construction cost even in an extremely soft ground. SOLUTION: The work structure has a plurality of scaffold bridges 4 prepared in approximately parallel at regular intervals in a zone to be improved 2, a frame 13 stretched on a pair of the scaffold bridges in a traveling movable manner, a drain driving machine 11 installed onto the frame laterally movably, a plurality of vertical drains 7 driven into a ground to be improved between the scaffold bridges at regular intervals approximately vertically by the drain driving machine, a horizontal drain material 27 laid on the head sections of a plurality of the vertical drains extended up to a ground surface, an airtight sheet 21 covering a plurality of the vertical drain head sections and the horizontal drain material in an airtight manner, and a vacuum pump 40 secured so as to be communicated with the horizontal drain material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum consolidation drain improvement method for draining water contained in soft ground which cannot be easily accessed by a worker or construction machine to improve the hardened ground, and a method therefor. A construction structure for implementing the method.

[0002]

2. Description of the Related Art A vacuum consolidation ground improvement method for sucking and discharging moisture and air from soft ground using a vertical drain, a horizontal drain, an airtight sheet, and a vacuum pump is disclosed in, for example, JP-A-2000-54358 and JP-A-2000-54358. 2000-104
No. 242. These methods are methods for systematically improving soft ground by vacuum consolidation, but the method described in JP-A-2000-54358 is
It is intended for soft ground that can run on a mud such as a drain driving machine or a working vehicle.
The construction method described in JP-A-104242 targets soft ground under water.

[0003] However, among soft grounds that require ground improvement, there are also ultra-soft grounds that are difficult to work with a muddy vehicle equipped with a floating body. In such grounds, the area to be improved is immersed in water and construction on water is performed. Although it is necessary, underwater construction is difficult depending on construction conditions, and it is hard to say that it is advantageous in terms of construction period and construction cost.

[0004] In addition, in the case of an extremely soft ground such as a landfill just after dredging, in order to secure a working ground, a civil engineering stabilizing sheet and a sand mat, which are net-like sheets, are laid on the entire ground, or at a depth of one to three. It is also practiced to mix cement powder with a surface soil up to about 2 m to improve the entire area. Each of these methods has a drawback in that it requires a great deal of cost since it is carried out over the entire area of the target ground, and that the construction period is long. In addition, regarding sand mats, in recent years, there are many obstacles to the procurement of materials due to the depletion of sand.

[0005]

SUMMARY OF THE INVENTION The present invention focuses on the above-mentioned problems of the prior art and attempts to solve them.
The problem is that even on extremely soft ground where it is expected to be difficult to work with vehicles on mud, it is necessary to perform all work on water, improve the surface soil throughout the area, and lay civil engineering stable sheets and sand mats all over the area. It is an object of the present invention to provide a construction method and a construction structure capable of advantageously improving the target ground by vacuum consolidation in terms of construction period and construction cost without necessity.

[0006]

According to the present invention, there is provided a ground improvement method for draining water contained in soft ground to improve the hard ground by providing a plurality of grounds. Forming a pier at predetermined intervals substantially parallel to each other, and bridging a first gantry supported by traveling means capable of traveling on the pair of piers between the piers, and draining the pier on the first gantry. A step of laterally moving the driving machine and driving the drain material substantially vertically into the ground to be improved between the piers;
Laying horizontal drainage material on a plurality of vertical drain heads extending to the ground surface, extending a pipe communicating with the horizontal drainage material to a vacuum pump, the plurality of vertical drain heads and A vacuum, comprising: a step of airtightly covering a horizontal drainage material with an airtight sheet; and a step of operating the vacuum pump to guide water from the vertical drain to the ground through the horizontal drainage material and drain the water. A method for improving the consolidation drain is provided. The construction method of the present invention includes a case where a drain material is cast on soft ground for river improvement and the like, and ground improvement is performed.In such a case, a plurality of piers are connected to the flow of the river. In some cases, it may be provided on both sides along a parallel curve.

In the method for improving the vacuum consolidation drain according to the present invention, a second platform supported by a traveling means capable of traveling on a pair of the piers is bridged between the piers, and the second platform is connected to the first pier. And moving the horizontal drainage material, laying the pipe to a vacuum pump, and covering with a hermetic sheet on the second gantry.

According to the present invention, there is provided a construction structure for discharging water contained in soft ground to improve the hard ground, comprising a plurality of piers formed substantially in parallel at predetermined intervals in an area to be improved, and a pair of the piers. A gantry movably mounted on the gantry, a drain laying machine movably mounted on the gantry, and a vertical laying of the drain laying machine into the ground to be improved between the piers at a predetermined interval. A plurality of vertical drains, a horizontal drainage material laid on a plurality of vertical drain heads extending to the ground surface, an airtight sheet airtightly covering the plurality of vertical drain heads and the horizontal drainage material, And a vacuum pump provided to communicate with the horizontal drainage material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the drain material may be any material that can guide moisture contained in the ground to an upper horizontal drainage material. For example, a cardboard drain material, a flexible pipe material Although a drain material or a sand drain can be used, the cardboard drain material is most suitable because it is relatively easy to handle and cast and is economical.

The horizontal drainage material may be any material having water permeability. For example, a perforated drainage pipe in which a nonwoven fabric is wound around a perforated pipe made of vinyl chloride, a drain material in which a net is wound with a nonwoven fabric, Possible non-woven sheets, sand, gravel, etc. are available.

[0011] The pier is a temporary structure in which a girder is crossed over a leg that is cast on soft ground so that the upper end protrudes above the ground. To support the gantry, the gantry for transporting the material of the legs and the girder. Here, there are a pile system and a sheet pile system as the legs, and a pile system is preferable in terms of economy,
In particular, if a steel material such as an H-section steel is used for the pile, the pile can be easily driven into and pulled out of the ground, and the pile head can be easily machined. The construction method of the pier by the pile method
A girder is spanned over the head of the pile previously set and a track is provided on this girder. A gantry is placed on the track of a pair of piers located substantially in parallel, a pier erection device having a vibratory hammer, etc. is mounted on the pier, and the pier is sequentially constructed by driving a pile in front and erection of a girder. To construct. On the other hand, the sheet pile method
When it is necessary to ensure the vertical and horizontal bearing capacity of the legs, when there is a thin permeable layer in the ground to be improved, or when deformation such as land subsidence due to ground improvement is minimized. It is preferable to use it if you want to
It is used for relatively small and medium-sized ground improvement. As one of the construction methods of the pier by the sheet pile method, there is a method using a conventional press-fitting sheet pile driving machine that can move along the head of the sheet pile, and the head of the sheet pile placed on the ground to be improved, This press-fitting sheet pile driving machine is installed, and adjacent sheet piles are sequentially press-fitted while moving. Another construction method using the sheet pile method is to bridge a girder over the head of the previously piled sheet pile, provide a track on this girder, place the mount on the track of a pair of piers that are located almost in parallel, It can also be carried out by a pier erection device having a vibro hammer or the like from above.

The gantry is a steel beam having a fulcrum on a pier and having a span of about 10 to 20 m and having a main girder made of an H-beam or an I-beam, and a plurality of H-beams or I-beams. A combination, a steel truss assembled in a truss shape, or a temporary assembly type bridge can be used. The gantry has running means such as wheels and endless tracks at a fulcrum, and a construction device such as a drain driving machine is provided on the gantry. In addition, an electric motor, an engine, a winch, or the like can be used as the traveling means of the gantry. Further, when the construction of one lane is completed, the gantry is moved to an adjacent lane using a large crane or a separate track, and performs the construction of the adjacent lane.

In the present invention, a sheet material, a net-like material or a net-like sheet material may be laid at least on the ground to be improved between the piers, whereby the vertical drain head is prevented from being buried, and the worker is soft. There is an advantage that burial in the ground can be prevented. Further, in the present invention, the vacuum pump applies a vacuum pressure to the ground to be improved through a vertical drain, a horizontal drainage material, etc., to promote consolidation settlement of the ground and to release moisture and air from the ground to the surface. Although it plays a role of sucking and discharging, it is also possible to separately discharge water from below the airtight sheet to the surface of the ground using a submersible pump or the like.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. FIG. 1 is a plan view of a target area in which ground improvement is performed according to the present invention. Here, the ground to be improved is road 3a along the coast and seawall 3
The pier 4 is constructed by reclaiming the area surrounded by b. In the improvement target area 2, a plurality of piers 4 are constructed substantially in parallel at predetermined intervals. FIGS. 2A, 2B, and 3 are a plan view, a side view, and a side view, respectively, showing a state in which the method of the present invention is applied to such a landfill ground. FIGS. It is a side view and a front view of an apparatus used for the present invention. 2 and 3, the construction structure according to the present invention includes a plurality of piers 4 constructed substantially in parallel at predetermined intervals with the improvement target area 2 interposed therebetween.
And a gantry 1 movably mounted on a pair of piers 4
3, a drain driving machine 11 movably provided on the gantry, and a plurality of vertical driving devices which are driven by the drain driving device 11 substantially vertically at predetermined intervals in the ground 2 to be improved between the piers 4 and 4. The drain 7, a horizontal drain material 27 and a perforated drainage pipe 26 laid as a horizontal drainage material laid on the head of the vertical drain that emerges from the ground surface, and the vertical drain 7, the perforated drainage pipe 26, and the horizontal drain material 27 are hermetically sealed. Airtight sheet 21 covered with
And a vacuum pump 4 communicating with the vertical drain 7 via a drain pipe 41, a perforated drain pipe 26 and a horizontal drain material 27.
0 is provided as a main part, and a track for running the gantry 13 is provided on the pier 4.

In FIGS. 3 and 6, the gantry 13 and the drain driving machine 11 are provided as constituting a construction apparatus 10, and in addition to this, the construction apparatus 10 has a reticulated sheet material 14 wound thereon. A drum 14a and a work scaffold 15 are provided. Here, the gantry 13 has wheels 16 on its lower surface for traveling on the pier 4, and rails (not shown) for traveling and laterally moving the drain driving machine 11 on its upper surface in the erection direction. It has been extended. The drain driving machine 11 has wheels 11d, which are driven by a motor (not shown) and travel on rails of the gantry 13, provided on a lower surface of a base plate 11c. The casing 11b is erected substantially vertically to support the casing 11b so that it can move up and down.
It is configured to be driven up and down by a driving device 11e provided at the lower end of the. Also, on the base version 11c,
A drum 12a around which the drain material 12 is wound is provided,
The drain material 12 is unwound from the drum 12a and supplied from the upper end to the lower end of the casing 11b.

In the construction apparatus 10, the gantry 13 is
While running in the direction of arrow M, the net-like sheet material 14 is unwound from the drum 14a and laid on the ground surface, and the drain driving machine 11 travels on the gantry 13 to move between the piers 4 and 4 as shown in FIG. Move laterally in the S direction, and sequentially drain material 12
To be improved with the casing 11b almost vertically
, A plurality of vertical drains 7 penetrating the mesh sheet material 14 are formed in the soft ground. Therefore, in the construction apparatus 10, the gantry 13 traveling and moving on the pier 4 is supported upward without touching the ultra-soft ground, and the drain driving machine 11 strikes the drain material 12 while moving laterally on the gantry 13. Therefore, if the pier 4 is constructed in the area 2 to be improved, it becomes possible to perform the construction of a vertical drain, and it is not necessary to improve the surface layer over the entire ultra-soft ground as in the related art. In addition, in addition to the above-described construction apparatus 10, the vertical drain installation step may be performed by using an arm of a shovel base machine equipped with a casing or a press-fitting device.

Next, the work platform 2 shown in FIGS.
0 will be described. The work platform 20 is a net-like sheet material 1
Steps following the laying step of 4 and the placing step of the vertical drain 7,
For example, it is an apparatus for performing a laying process of a perforated drain pipe 26, a horizontal drain material 27, an airtight sheet 21, and the like.
Wheels 24 are provided on the lower surfaces at both ends of a gantry 23 bridged between the pair of piers 4, 4, and the drums 22 run on the pier 4 with the wheels 24 and wind the horizontal drain material 27 on the gantry 23. An airtight sheet 21, a perforated drainage pipe, and the like are loaded thereon, and a work scaffold 28 for laying the horizontal drain material 27 and the like on the extremely soft ground is provided.

An electric motor, an engine, a drawer using a winch, or the like can be used as a driving means for moving the construction apparatus 10 and the work platform 20 on the track 17.

Next, the pier 4 and the crane 50 for pier construction will be described with reference to FIG. The pier 4 is composed of a pile 4b in which H-shaped steel is cast in a row on the ground 2 to be improved, and a girder 4a in which one H-shaped steel is bridged over the pile head. It is shown, but besides this,
For example, a pier may be a pile and a girder arranged in a plurality of rows and a floor slab stretched over the girder. Although not shown, a track for guiding the wheels of the gantry is provided on the upper surface of the spar 4a.

As shown in FIG. 2, the apparatus for erection of the pier 4 includes pedestals 55, 57 laid over a pair of piers 4, 4, and a pier installed on the pedestal 55. The cranes 55 and 57 have wheels 16 for traveling on the pier 4 on the lower surface thereof, and the gantry 57 is loaded with materials 4 ′ such as pile materials and H-beams as girder materials. The pier-building crane 50 is driven to follow. Here, the jetty erection crane 50 includes a crawler 53 for traversing on a gantry 55, a base machine 52 rotatably provided on the crawler 53, and a boom 51a which is raised and lowered from the base machine 52. , A vibratory hammer 51c suspended at the tip of a boom 51a via a wire rope 51b, and the H-section steel as the pile 4b is gripped by the vibratory hammer 51c and driven into the ground to be improved. An H-section steel as the spar 4a is bridged over 4b.

Next, a pier 9 and a pier erection apparatus different from those in FIG. 4 will be described with reference to FIG. In FIG. 5, the pier 9 is a sheet pile 9b which is cast in a line on the ground 2 to be improved.
And a girder 9a having one H-shaped steel bridge over the head. Here, as in the case of the pier 4, it is also possible to arrange a sheet pile and a girder in a plurality of rows and put a floor slab on the girder to form a pier.
A track for guiding the wheels of the gantry is provided on the upper surface of a.

As a device for erection of the pier 9 using the sheet pile 9b, there are a conventional sheet pile crane 60 and a sheet pile press-in machine 62, both of which are mounted on the head of a sheet pile continuously installed in the ground. It is configured to be able to travel along and not to fall from the sheet pile head. Here, sheet pile cranes 6
0 is a base machine 63 running along the head of the sheet pile
And a boom 61a attached to the base machine 63 so as to be able to raise and lower, a telescopic cylinder 61b for raising and lowering the boom 61a, and a hook 61d suspended from the tip of the boom 61a by a wire rope 61c. On the other hand, the gantry 57 has wheels 57a on the lower surface, is bridged over a pair of piers 9, 9 constructed in advance, and loads a material 9 'such as a sheet pile or a H-beam as a girder material. Both the sheet pile building crane 60 and the sheet pile press-in machine 62 make the machine follow-up. When the pier 9 is erected, the sheet pile 9b loaded on the pedestal 57 is lifted by the sheet pile crane 60 and supplied to the sheet pile press-in machine 62, thereby driving the sheet pile 9b into the ground to be improved. Next, after the sheet pile press-in machine 62 is advanced using the sheet pile crane 60, the sheet pile crane 60 is advanced with the built-in cylinder. When the number of sheet piles is about 15 in this way, an H-section steel as the spar 9a is bridged over the head of the continuous sheet piles 9b and fixed. Next, after the gantry 57 is advanced, the same operation is repeated to construct a pier.

FIG. 10 is a sectional view of the improved structure.
Here, the ground cross section after construction by the construction apparatus 10 and the work stand 20 is shown. FIG. 8A is a plan view of the improved structure according to the present invention, and FIG. 8B is an enlarged plan view showing details of a vertical drain head. 8 and 10, the improved structure includes piers 4, 4, which are formed approximately parallel to the ground to be improved at a predetermined distance, and a mesh sheet material 14 laid in the area 2 to be improved between the piers 4, 4. And mesh sheet material 1
4, a plurality of vertical drains 7 laid substantially vertically at predetermined intervals so as to penetrate through the ground 4, a horizontal drain material 27 and a perforated drainage pipe 26 laid on the ground surface, and these vertical drains 7.
Airtight sheet 21 laid so as to airtightly cover the head, horizontal drain material 27 and perforated drain pipe 26, etc.
And a vacuum pump 40 connected to the perforated drain pipe 26 via a drain pipe 41.

Here, the horizontal drain material 27 is a horizontal drain material having a width of about 30 cm in which a net is wound with a non-woven fabric, and the airtight sheet 21 is formed by laminating two vinyl chloride sheets. Use a 5mm one. The pier 4 includes a stake 4b as a leg and a girder 4a bridged over the stake 4b. Further, the airtight sheet 21 is provided with a structure shown in FIG.
The edge processing is performed by the structure shown in FIGS. 9 (a) shows the airtight sheet end 21a inserted into a groove 35a having a depth of 30 to 80 cm and backfilled with mud 35b, and FIG. 9 (b) shows the airtight sheet end 21.
FIG. 9 (c) shows a fluidized soil 36 obtained by adding a thickening material such as CMC, MC, HEC, guar gum or a glue material to earth and sand, and an airtight sheet end 21.
9 (d) shows the airtight sheet end 21a pressed into the ground with a tool or the like, and FIG. 9 (e) shows the sandbag 37 or water bag with the airtight sheet end 21a.
a. As described above, FIGS.
May be provided singly or in combination of two or more.

In addition to the embodiment shown in FIG. 10, an improved structure can be formed as shown in FIG. 11 or FIG. That is, in FIG. 11, the pier 4 is constructed using the piles 4 b, the improvement structure similar to that of FIG. 10 is provided in the improvement target area 2 between the piers 4, 4, and water is stored on the airtight sheet 21. Alternatively, a loading embankment 43 is provided, and the drainage capacity is increased by interposing a jet pump 44 in the middle of the drainage pipe 41. Also, FIG. 12 shows that the pier 9 is constructed using the sheet pile 9b, and the improvement target area 2 between the piers 9 and 9 is shown in FIG.
In addition to providing the same improved structure as above, water is stored in the area surrounded by the sheet pile 9b. When the sheet pile 9b is used as described above, even if the water permeable layer 70 exists in the improvement target area 2, since the water permeable layer 70 is blocked by the sheet pile 9b, the pressure is not reduced through the water permeable layer 70. Is prevented.

Next, the method of improving the vacuum consolidation drain will be described. First, as shown in FIG. 1, a plurality of piers 4 are constructed at predetermined intervals, for example, approximately in parallel with each other at a predetermined interval, for example, about 14 m in the improvement target area. Next, as shown in FIGS. 6 and 7, by installing the construction apparatus 10 and the work platform 20 on adjacent piers 4 and 4 so as to be able to travel, the respective platforms 13 and 2
3 is laid between the piers 4 and 4, the netting sheet material 14 unwound from the drum 14a is laid on the ground while the construction apparatus 10 travels in the direction of arrow M in FIG. 3, and the construction apparatus 10 travels at a predetermined position. To stop. When the traveling of the construction device 10 is stopped, the vertical drain 7 is driven into the ground 2 to be improved at predetermined intervals while the drain driving machine 11 is moved laterally in the direction of the arrow S in FIG.

The work platform 20 is run on the ground 2 to be improved on which the mesh sheet material 14 and the vertical drain 7 are installed, and the horizontal drain material 27 and the perforated drain pipe 26 are vertically separated from the work platform 20. The airtight sheet 21 is laid out so as to communicate with the head of the drain 7, the vertical drain 7, the horizontal drain material 27, the perforated drainage pipe 26, etc., and the embankment 8 is loaded on the end 21 a thereof. Airtightly covers the ground to be improved.

When the laying of the airtight sheet 21 is completed as described above, the drain pipe 41 is connected to the perforated drain pipe 26, the drain pipe 41 is connected to the vacuum pump 40, and a measuring instrument (not shown) is installed. After performing the adjustment operation, the main operation is started. Here, the vacuum pump 40 may be installed for each lane (for each ground 2 to be improved between the piers 4 and 4) or may be installed collectively for a plurality of lanes. After the installation of the vertical drain 7 at a predetermined position is completed, the airtight treatment of the airtight sheet end 21a, the installation of the vacuum pump 40, and the like are performed, and then the vacuum operation is started. By the vacuum operation, a vacuum pressure of 60 kPa to 80 kPa acts on the ground 2 to be improved, and the vacuum pressure has a height of about 4 to 5 kPa.
m, which corresponds to an embankment load of m.

The groundwater discharged by the vacuum operation is
As shown in FIG. 11, the airtight sheet 21 may be stored on the airtight sheet 21, thereby increasing the airtightness and contributing to an increase in the vacuum pressure inside the airtight sheet 21. This is because water has a viscosity coefficient about 50 times greater than that of air, and the blocking effect increases.

When the vertical drain 7 is not cast on the ground around each pier 4 and the airtight sheet 21 is not covered, there are some places where the vacuum pressure does not act directly. Since the consolidation effect extends to the peripheral portion, an increase in ground strength can be expected in a plane range of about 20 to 30% of the improved depth, as in the improved area.

After about two weeks have passed since the operation of the vacuum pump, the ground strength increased until a person could walk on the airtight sheet. At this time, embankment on the airtight sheet became possible. Embankment can be performed on the airtight sheet to create a work road. Further, the embankment may be loaded on the airtight sheet while operating the vacuum pump, and this improves the ground improvement effect, which is advantageous in terms of increasing the strength.

[0032]

According to the present invention, a pier is constructed substantially parallel to the area to be improved, a gantry is bridged between the piers, a vertical drain, a horizontal drainage material, an airtight sheet, and the like are laid, and covered with an airtight sheet. By applying vacuum pressure to the area to be improved, even if the ground is extremely soft, where workers and construction machines cannot easily enter, the civil engineering stable sheet and sand mat can be applied to the entire area of the ground to be improved as before. It is no longer necessary to provide such equipment, and processing on the surface ground prior to vertical draining work etc. can be limited to only the pier, so that compared to the conventional method, materials and construction costs such as sand mats can be reduced, The use of sand for sand mats can be minimized.

Further, since the system can be implemented systematically from the installation of the vertical drain to the installation of the airtight sheet, it is easy to improve the quality of the process control and the ground improvement, and the worker's construction ability can be mastered and the safety can be improved. The above is also advantageous. Further, the improvement strength of the ground can be increased by storing water on the airtight sheet or by using embankment together.

According to the present invention, a movable platform is mounted on a pier constructed in the area to be improved and construction is performed from this pedestal. For example, a work road is provided in place of the pier, and the pedestal is provided here. It is particularly advantageous in the following three points, as compared with the case of bridging. The hermetic sheet can be laid in one step without leaving substantially unmodified parts. If the improvement depth is about 12 m or less, the construction cost of the pier is lower than that of the work road. Improvement of the ground under several tens of centimeters of water is also easy.

[Brief description of the drawings]

FIG. 1 is a plan view of a target area in which ground improvement is performed according to the present invention.

FIGS. 2A and 2B are a plan view and a side view showing a method of the present invention.

FIG. 3 is a side view showing the method of the present invention.

FIG. 4 is a side view showing a pier construction crane and the like used in the construction method of the present invention.

FIG. 5 is a side view showing a sheet pile building crane and the like used in the method of the present invention.

FIG. 6 is a front view of a construction apparatus used in the method of the present invention.

FIG. 7 is a front view of a work table used in the method of the present invention.

8 (a) is a plan view of the improved structure according to the present invention, and FIG. 8 (b) is an enlarged plan view showing details of a vertical drain head.

FIGS. 9A to 9E are cross-sectional views illustrating an airtight structure at an end of an airtight sheet.

FIG. 10 is a sectional view of an improved structure according to the present invention.

FIG. 11 is a sectional view showing an improved structure different from that of FIG. 10;

FIG. 12 is a sectional view showing an improved structure different from FIGS. 10 and 11;

[Explanation of symbols]

 2 Area for improvement 4, 9 Pier 7 Vertical drain 11 Drain driving machine 13 Mount 21 Airtight sheet 26 Perforated drain pipe (horizontal drain) 27 Horizontal drain (horizontal drain) 40 Vacuum pump

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isamu Mitsubata 2-58 Kitaaoyama, Minato-ku, Tokyo Inside the company group (72) Inventor Kaio Kumamoto 2-5-2 Kitaaoyama, Minato-ku, Tokyo No. Aoyama Kiko Co., Ltd. (72) Inventor Kazuo Todoro 2-5-8 Kita-Aoyama, Minato-ku, Tokyo Aoyama Kiko Co., Ltd. F-term (reference) 2D043 CA04 CB08 DA03 DA09 DC00 DD01

Claims (3)

[Claims] 1. A ground improvement method for draining water contained in soft ground to improve it into hard ground, comprising the steps of: installing a plurality of piers at predetermined intervals substantially in parallel in an improvement target area; Bridging the first gantry supported by the traveling means capable of traveling on the pier between the piers,
A step of laterally moving a drain driving machine on the first gantry and driving a drain material substantially vertically in the ground to be improved between the piers, and a plurality of vertical drain heads extending to the ground surface; Laying a horizontal drainage material, extending a pipe communicating with the horizontal drainage material to a vacuum pump, and airtightly covering the plurality of vertical drain heads and the horizontal drainage material with an airtight sheet. Operating the vacuum pump to guide and drain water from the vertical drain to the ground via the horizontal drainage material, and drain the water. 2. A second gantry supported by a traveling means capable of traveling on a pair of the piers is bridged between the piers, and the second gantry is caused to travel in a process subsequent to the first gantry. hand,
The method according to claim 1, wherein a step of laying the horizontal drainage material, a step of extending the pipe to a vacuum pump, and a step of covering with a hermetic sheet are performed on the second gantry. 3. A construction structure for draining water contained in soft ground to improve it into hard ground, comprising: a plurality of piers formed substantially in parallel at predetermined intervals in a region to be improved; A gantry movably bridged, a drain laying machine movably provided on the gantry, and a lay-down machine that is laid substantially vertically at predetermined intervals in the ground to be improved between the piers by the drain laying machine. A plurality of vertical drains, a horizontal drainage material laid on a plurality of vertical drain heads extending to the ground surface, an airtight sheet airtightly covering the plurality of vertical drain heads and the horizontal drainage material, and the horizontal drainage And a vacuum pump provided to communicate with the material.