JP3957284B2 - Ground improvement method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground improvement method for improving a ground under the surface of the sea, such as the seabed, and in particular, deposits deposited on the seabed (water bottom) and fluid substances generated by excavation during the ground improvement work are submerged. The present invention relates to a technique for preventing diffusion in water.
[0002]
[Prior art]
For example, a technique for creating and improving a high-strength underground solid body on a soft ground can be achieved by using, for example, a stirring device 50 provided with a stirring shaft 52 and a stirring blade 54 (stirring blade) as shown in FIG. Done.
However, when ground improvement work is performed using such a stirring device, the shaft strength must be reinforced in the case of a large depth, and at the construction site where the height dimension in the construction equipment is limited, A telescopic structure must be provided for the shaft. Therefore, there is a problem that various costs increase during construction. In addition to this, the size and weight of the stirring device 50 provided with a stirring blade is also a problem.
Recently, the applicant has developed a technique to improve the subsurface ground using a high-pressure jet jet. In such a ground improvement technique (details will be described later), a solidified material and compressed air are injected at a high pressure, and mixed with agitation with the original ground to form an underground consolidated body. And if it is injection stirring, since the apparatus used for it is small compared with the machine which has a stirring blade, it can cope with the problem mentioned above.
[0003]
Here, in the ground improvement under the water surface (for example, the sea surface), it is necessary to prevent the sediment deposited on the sea bottom (water bottom) and the fluid material generated by excavation from diffusing.
Therefore, at the time of construction of the above-described technology (technique for improving the ground below the sea surface using a high-pressure jet jet), for example, the fluid substance generated with the construction of the ground improvement is once collected by land facilities, Carrying out to an industrial waste disposal facility is carried out.
[0004]
However, in the technology for improving the ground by injecting the solidified material and compressed air at a high pressure, the fluid (solidified material and compressed air) is injected at a high pressure. It is difficult to collect the sediment without diffusing it in water (in the sea). For this reason, there is a demand for a technique for recovering fluid substances and sediments generated by construction without diffusing into the water (underwater) even when high-pressure fluid is jetted on the seabed.
[0005]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-described problems of the prior art, and even when a high-pressure fluid is sprayed on the bottom of the water (sea floor), fluid substances and seabed generated along with the construction are generated. The purpose is to provide a ground improvement method under the surface of the water (the sea level) that allows the sediment to be collected without diffusing into the water (under the sea).
[0006]
[Means for Solving the Problems]
According to the present invention, in order to improve the ground (30) under the water surface (1), the solidified material excavated using the triple pipe rod (5) equipped in the work facility (2) and having the monitor (4) at the tip. In the ground improvement method for injecting water, a casing pipe (23) is inserted outside the triple pipe rod (5), a guide pipe (24) is installed outside the casing pipe (23), and the ground (30) A flat support base (8) is formed on the surface layer part (3) of the steel plate, and the triple pipe rod (5) is lowered to penetrate the support base (8). The underground tube solid body (10) is formed by pulling up the triple tube rod while jetting the mixed jet (J).
[0007]
According to the ground improvement method of the present invention of such a construction method, the surface layer portion (3) of the ground improvement region (30) is covered with a thin support base (8). This prevents the diffusion of fluid substances and seabed deposits that are generated during construction.
[0008]
In carrying out the present invention, the flat support base (8) acting as the lid can be formed using a stirring device as described in FIG.
[0009]
Alternatively, as will be described later with reference to FIG. 5, for example, a flat plate (8A) made in advance can be used.
[0010]
Furthermore, as will be described later with reference to FIG. 6, the flat support base 8 </ b> B may be formed by pouring underwater concrete or underwater soil mortar.
In addition, a conventionally known technique can be applied.
[0011]
According to the present invention, the box-shaped member (1c) is placed on the ground (30) in the construction area when the support base (8c) is created.
In this way, it is possible to prevent the diffusion of fluid substances and seabed deposits that are generated when the support base (8) is created.
[0012]
In carrying out the present invention, the support base (8) includes an artificial support base (8A) made in advance at a production base existing on land separated from the construction site.
At the time of construction, the artificial support base (8A) may be transported to a construction sea area by a transport ship or the like (2A) and installed in a predetermined position using various operation means (for example, a crane) in the sea area. If such an artificial support base (8A) is installed on the surface layer (3) of the seabed ground in the construction area, the work time on the sea with danger is reduced, which is preferable in terms of safety.
[0013]
Further, in the present invention, a mechanism (for example, a hopper 26, a crane 25, a crane 25, a mortar, concrete, fluidized soil, etc.) is charged into the offshore work facility (offshore work platform 2B). Equipped with treme tube 27, hose 28, pressure feed pump 29, etc.) When constructing the artificial support base (8B), the water-curing material is discharged to the bottom of the water (the sea floor) and placed in a flat plate shape. Can be done.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0015]
The first embodiment will be described with reference to FIG.
In FIG. 1, the trolley as the work facility 2 is equipped with a construction machine 21. The construction machine 21 is combined with a triple tube rod 5 that can be vertically added downward and has a monitor 4 at the tip, and controls excavation work by the monitor 4 at the tip of the triple tube rod 5.
[0016]
The triple tube rod 5 includes a first tube (not shown) for allowing high-pressure solidified material to flow through the center, a second tube (not shown) for surrounding the outside and allowing high-pressure air to flow, It is comprised by the 3rd pipe | tube (part visible as the triple pipe rod 5) which protects the whole on the outer side of 2 pipe | tubes.
The first tube and the second tube are connected to the nozzle at the tip of the monitor 4 at the tip, respectively, and the high-pressure solidified material pumped by the first tube is ejected from the center of the nozzle, and around the ejected solidified material. The high-pressure air pumped by the second pipe surrounds and jets a jet J with a stronger jetting force.
[0017]
The first pipe is the upper tip of the triple pipe rod and is connected to the solidifying material supply line L1 via the first swivel joint S1.
The second pipe is connected to the compressed air supply line L2 via the second swivel joint S2 below the first swivel joint S1.
[0018]
Further, the outside of the triple tube rod 5 is inserted with the casing pipe 23 up to the construction area on the seabed, and is solidified with a solidifying material such as cement so as not to leak a fluid substance from the outside of the casing pipe. The fluid material generated by excavation by the injection J from the monitor 4 rises in the casing pipe 23 by the air lift of the compressed air injected from the monitor 4 through the second pipe, and the fluid material recovery line. Removed by L3.
A guide pipe 24 is installed outside the casing pipe 23 to prevent the spread of contamination in the unlikely event.
In addition, the code | symbol 10 in FIG. 1 shows the underground solidified body which the injected solidified material and the cut | disconnected soil mixed and were formed.
[0019]
When the flat support base 8 is formed, although not clearly shown, for example, it is preferable to use the above-described stirring device (device of FIG. 8).
Since only the comparatively thin (for example, thickness 3 m-5 m) area | region H of the surface layer part 3 of the seabed ground 30 is stirred, even if it is the stirring apparatus 50 using a stirring blade, construction cost does not increase so much.
[0020]
Only the surface layer 3 at a predetermined location of the seabed ground 30 is improved and the flat support base 8 is formed. Then, an underground solid body is formed by the following procedure, and the region 30 below the surface layer 3 is formed. Improve sequentially.
[0021]
In FIG. 2, first, the rod 5 is lowered, penetrates the support base 8, digs into the soft layer 30, and reaches the end of the rod 5 to the support layer (a strong ground where the support force under the sea surface can be obtained) 6. Let
In the case shown in FIG. 2 to FIG. 4, the lower end of the underground solid body 10 is formed so as to reach the support layer 6, but when sufficient support force can be secured for the underground solid body 10, The lower end of the underground consolidated body 10 may not reach the support layer 6. In that case, it is not necessary for the tip of the rod 5 to reach the support layer 6 as well.
[0022]
In FIG. 3, a jet of ground improvement material and a high-pressure air jet surrounding it are ejected from the monitor 4 at the tip of the rod 5 reaching the support layer 6. In addition, the horizontal arrow J of illustration shows the mixed jet of injection of a ground improvement material and injection of a high pressure air jet.
While ejecting the mixed jet J, the rod 5 is rotated (arrow R), and the rod 5 is pulled up at a constant speed (arrow S).
As a result, the soft ground 30 is excavated, and the ground improvement material and the excavated soil are mixed and stirred.
[0023]
And as shown in FIG. 4, the ground improvement material and the mixture of soil are gradually solidified, and the column-shaped underground solid body 10 is created.
Here, the support layer 8 exists in the surface layer portion 3 as described above, and deposits deposited on the seabed (water bottom) and fluid substances generated by excavation during the injection of the high-pressure jet J are Since the support base 8 acts like a lid, it is prevented from spreading in the sea.
2 to 4, the symbol W indicates the sea area above the surface layer 3 on the seabed.
[0024]
The work facility 2 may be a self-lifting work platform ship (SEP) or a spat ship.
[0025]
In forming the flat support base 8, a conventionally known technique can be applied.
[0026]
Alternatively, for example, as shown in FIG. 5, it is possible to use a flat support base 8A made in advance.
[0027]
Here, the example of FIG. 5 will be briefly described.
In the embodiment of FIG. 5, for example, an artificial support base 8A previously made at another plant manufacturing base is transported to a construction sea area by a transport ship 2A or the like, and the artificial support base 8A loaded on the transport ship 2A or the like is transported in the sea area. In this embodiment, the crane 25 provided in the transport ship 2A is installed at a predetermined position while operating.
[0028]
Since the artificial support base 8A previously prepared in another place is only installed on the surface layer portion 3 of the seabed ground in the construction area, it is preferable from the viewpoint of safety because there is less work time on the sea with danger.
[0029]
Furthermore, as shown in FIG. 6, the flat support base 8B may be formed by pouring underwater concrete and underwater soil mortar.
[0030]
Here, the example of FIG. 6 will be briefly described.
In the embodiment of FIG. 6, the marine work platform ship 2 </ b> B is provided with a crane 25, a hopper 26 into which a material (for example, mortar, concrete, fluidized soil, etc.) that hardens in water, and a material from the hopper 26. Is provided with a pressure feed pump 29 for pressure-feeding the material M through a hose 28 to a tremy pipe 27 suspended on the crane 25.
[0031]
The offshore work platform ship 2B discharges the underwater concrete material M from the tip of the tremy pipe 27 while maneuvering from the end of the construction site in the right direction in the figure, and the material solidifies without mixing with seawater. Concrete is directly placed on the surface layer 3 of the seabed to form a flat support base 8B.
[0032]
According to an embodiment of such a method and apparatus, the underwater concrete material M is simply discharged from the tip of the tremy tube 27 without ejecting a high-pressure jet by the stirring device, and the sediment on the seabed is There is little diffusion and work can be performed efficiently. In addition, detailed control is unnecessary for placing concrete. [0033]
Next, a second embodiment will be described with reference to FIG.
1st Embodiment of FIGS. 1-4 forms the support base 8 over the whole area | region which should construct a ground improvement construction method.
On the other hand, the second embodiment of FIG. 7 creates a support base (acting as a lid) 8C for each predetermined region (for example, a region having a radius of 5 m to 6 m) when forming the support base. is there.
Construction of box-shaped member (cover member, surrounding member) 1C shown in Japanese Patent Application No. 2002-27584 is performed in order to prevent the diffusion of fluids and seabed deposits generated during construction when constructing the supporting base 8C. It covers the seabed ground 30 in the area.
The mechanical equipment used for other construction is generally the same as that of the first embodiment.
[0034]
According to the ground improvement construction method of the second embodiment of the construction method and the construction method, since the upper part of the construction area is covered with the cover member 1C, the flowable substance and the sediment on the seabed generated along with the construction. Can be prevented.
[0035]
The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
For example, there is a case where the lower end of the underground consolidated body 10 to be formed does not need to reach the support layer 6. Also, the shape of the cover member 1C shown in FIG. 7 is not limited to the illustrated umbrella shape.
[0036]
【The invention's effect】
The effects of the present invention are listed below.
(1) By creating a flat support base on the surface layer of the ground below the surface of the water, the surface layer part of the ground improvement area will be covered with a thin support base, so that the flowable material generated during construction And the spread of sediment on the sea floor.
(2) When an artificial support base made in advance elsewhere is installed on the surface layer of the seabed ground in the construction area, it is preferable from the viewpoint of safety because there is less work time on the sea, which is dangerous. There is little diffusion.
(3) When the underwater concrete material and the material discharge device are equipped on the offshore work platform ship, the underwater concrete material is discharged directly from the tip of the discharge pipe to the construction position while maneuvering. Concrete can be placed, high-pressure jets are not ejected by the agitator, and only the underwater concrete material is discharged from the tip of the discharge pipe. Can be carried out. Moreover, fine control is not required for placing concrete.
(4) When the support base is constructed, by disposing an enclosing member that surrounds a predetermined area of the ground surface layer portion, diffusion of fluid substances and seabed deposits generated when the support base is constructed is prevented. .
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a construction method according to a first embodiment of the present invention.
FIG. 2 is a boring drilling process diagram in an area where improvement work of the first embodiment is to be performed.
FIG. 3 is an excavation process diagram using a high-pressure jet in a region where improvement work of the first embodiment is to be performed.
FIG. 4 is a process diagram showing when an underground solid body is completed in an area where improvement work of the first embodiment is to be performed.
FIG. 5 is a schematic diagram showing an example of a construction method according to the first embodiment of the present invention.
FIG. 6 is a schematic view showing another example of the construction method according to the first embodiment of the present invention.
FIG. 7 is a schematic diagram showing a construction method according to a second embodiment of the present invention.
FIG. 8 is a view showing a stirring device attached to a tip of a drilling rod.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Sea surface 2 ... Work table ship 3 ... Surface layer part 4 ... Monitor 5 ... Triple pipe rod 8 ... Support base 30 ... Ground 1C ... Cover member

Claims (2)

    In order to improve the ground (30) under the surface of the water (1), the ground improvement method of injecting the solidified material excavated using the triple pipe rod (5) equipped in the work facility (2) and having the monitor (4) at the tip In this case, a casing pipe (23) is inserted outside the triple pipe rod (5), a guide pipe (24) is installed outside the casing pipe (23), and a surface layer portion (3) of the ground (30). A flat support base (8) is formed on the base plate, and the triple pipe rod (5) is lowered to penetrate the support base (8). From the monitor (4), a mixed jet of ground improvement material and high-pressure air (J) A ground improvement construction method characterized by forming a ground solid body (10) by rotating a triple pipe rod while spraying and rotating it.   The ground improvement method according to claim 1, wherein a box-shaped member (1c) is placed on the ground (30) in the construction area when the support base (8c) is formed.

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