JPS5810526B2 - Construction method of packed sand piles for improving soft ground under water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method of constructing bagged sand piles in the ground in order to improve soft ground under water.
In particular, the present invention relates to a method for constructing bagged sand piles in which the bagged sand piles, which are inserted into a casing penetrating into soft ground, are prepared in advance in a separate process to improve work efficiency.

When using drain piles to improve soft ground under water to the depth of a fracture, conventionally a casing was installed on the side of the leader of a driving machine installed on a platform floating above the water surface. Then, this casing is penetrated into the soft ground until its upper part reaches near the water surface, and after draining the water that has entered the casing, a net bag for the bagged sand pile is inserted directly into the casing itself, This net bag is filled with sand to create a bagged sand column inside the casing.Then, the lid attached to the bottom end of the casing is opened and the casing alone is pulled up while compressing air from the top of the casing. The method used was to construct bagged sand piles made of bagged sand pillars.

However, in the above conventional construction method, the work of setting the net bag into the casing and the work of filling the net bag with sand were incorporated in series into the series of bagged sand pile construction processes, so the bagged sand pile was sequentially installed in soft ground. There was a problem in that it was not possible to shorten the construction cycle time.

Moreover, the setting of the net bag and the filling of sand into the net bag are done inside the casing after penetrating the soft ground, so the net bag may be twisted in the middle of the casing when it is put in, or the net bag may not be filled with sand enough. Therefore, there was a problem that the construction of bagged sand piles was likely to be uncertain.

In addition, in the conventional construction method, in order to ensure the construction of net bag sand piles, it is necessary to drain water that has entered the casing before pouring sand into the casing, which complicates the process. There was a problem.

In order to solve the various problems mentioned above, the present invention performs the net bag setting work and sand filling work into the net bag in a separate process from the casing casting process, and then inserts the sand into the casing and penetrates into the ground. By forming wood sand piles, the length of the bagged sand pillar can be set arbitrarily, ensuring the production of bagged sand pillars, and significantly shortening the cycle time of the bagged sand pile creation process. The purpose of this study is to provide a method for constructing bagged sand piles for improving soft ground under water.

An embodiment of the construction method of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show a driving device for bagged sand piles constructed using the construction method of the present invention.

In the figure, 1 is a pack drain ship, 2 is an oar installed on the ship's gunwale,
3 is the leader.

Above the leader 3, a vibrohammer 4 that generates vertical vibration is lowered by a wire rope 7, and by connecting the end of the rope to a hoist via pulleys 5 and 6, the vibrohammer 4 can be raised and lowered. It is composed of

Further, the vibrohammer 4 is supported by a guide 8 of the leader 3 via a guide gib 9 so as to be freely slidable upward and downward.

At the lower end of the vibrohammer 4, an impact transmission rod 10 for transmitting the impact caused by the vertical vibration of the pyrohammer 4 is vertically installed, and at the lower end of the impact transmission rod 10, a support plate 11 is provided.

The support plate 11 supports the tops of two tubular casings 12 having the same structure.

The casing 12 has a lid 13 that can be sealed and opened at the lower end, and a charging scat 14 for charging the bagged sand column at the upper end.

A drain pipe 15 is attached to the casing 12, which communicates with the inside of the casing 12 at the lower part of the casing and rises up to the vicinity of the input skirt 14.

The length of the casing 12 is formed to be somewhat longer than the height including the ground improvement depth of the soft ground E and the two-way operation above the water surface.

Further, a compressed air introduction pipe (not shown) is attached to the upper part of the casing 12, so that the inside of the casing 12 can be pressurized from above.

On the other hand, on the platform 1 is a sand J pipe 16 for manufacturing tubular bagged sand pillars.
is provided so that the sand pipe 16 can reciprocate between a position above the casing 12 on the platform 1 and a sand charging position 60 to the sand pipe 16, which is horizontally separated from the above position of the casing. It has become.

A hopper 17 is provided at the upper part of the sand pipe 16 to facilitate receiving the sand when it is introduced, and a lid 18 that can be opened and closed is provided at the lower end to form the sand pipe 16 when the bagging column is introduced.

Although not shown, a vibrating feeder may be attached to the hopper 17.

19 is a belt conveyor for removing sand, 20.21 is a packet, and 22 is a hoist rail that conveys the packet 20.21 from the position of the belt conveyor 19 to the position directly above the hopper 17 of the sand pipe 16.

The sand pipe 16 is guided by a sand pipe running rail 23 so that it can move in the horizontal direction, and can be set at a position above the feeding skirt 14 of the casing 12.

The sand injection position A into the sand pipe 16 may be provided only on one side of the sand column injection position B into the casing 12, but desirably, as shown in FIG. Sand may be provided on both sides of the casing 12, and sand may be introduced into the sand pipe 16 at each position and transferred onto the casing 12 alternately.

Note that in order to convey the sand to the sand pipe 16, a belt conveyor may be installed at a high place and the sand from the belt conveyor may be directly thrown into the sand pipe 16. It is also possible to use means such as a hydraulic hinge that swings between two points without relying on the traveling rail 23.

Next, an embodiment of the construction method of the present invention will be described according to the construction order shown in FIGS. 5 and 6.

To describe the process of preparing the bagged sand column in advance, which is different from the process of casting the casing, as shown in Figure 5A, the lid 1 at the lower end is
A net bag 24 for a packed sand pile containing a small amount of sand as a weight is placed in a sand pipe 16 with a closed end 8, and the upper end of the net bag 24 is attached to a hopper 17.

Next, the sand put into the bucket) 20 from the belt conveyor 19 is raised by the hoist rail 22, the sand is put into the hopper 17, and the sand is put into the net bag 24 by the vibrating feeder as shown in the opening in Figure 5. After filling, the upper end of the net bag 24 is closed, and a packed sand column 25 is prepared in advance.

Separately from the above steps, the casing 12 is hammered using the vibrohammer 4 until the upper end of the casing 12 is slightly lower than the lower end of the sand pipe 16, that is, to the position where the bagged sand column 25 is introduced, as shown in FIG. 6A. In this way, it penetrates into the soft ground E.

Next, the sand pipe 17 having the bagged sand column 25 therein is moved to just above the feeding skirt 14 of the casing 12,
The lid 18 at the lower end of the sand pipe 17 is opened, and the bagged sand column 25 is allowed to fall into the casing 12, as shown in the opening in FIG.

Then, the empty sand pipe 17 is moved to the original position shown in FIG. 5A, and the process of producing the bagged sand column 25 is repeated again.

During the process shown in FIG. 6A, water that has entered the casing 12 is drained from the bottom of the casing 12 through the drain pipe 15 due to the falling pressure of the bagged sand column 25 when it falls. However, this water serves as a buffer against the falling of the bagged sand column 25.

After charging the bagged sand column 25 into the casing 12, the inside of the casing 12 is sealed, and the casing is further hammered into the soft ground E using the vibro hammer 4 to a predetermined penetration depth as shown in FIG. Drive 12 and penetrate.

After penetration, the lid 13 at the lower end of the casing 12 is opened, the lower end of the bagged sand column 25 is placed on the floor, and the casing 12 is pulled up as shown in FIG. 6-2 while compressing air from the upper part of the casing 12.

As a result, a packed sand pile consisting of the packed sand column 25 shown in FIG. 6 is constructed in the soft ground E.

Furthermore, the casing 12 is salvaged, the end of the casing 12 is sealed, a bagged sand column 25 made in advance with the sand pipe 16 is newly inserted into the casing 12, and the casing 12 is moved to the next soft ground on the water bottom using the vibro hammer 4. Bagged sand piles are created one after another by repeating the operation of driving and penetrating during E.

In the above embodiments, the bagged sand column was made using an upright sand pipe, but the bagged sand column may be made by laying the sand pipe horizontally or tilting it.

In addition, the casing used in the construction method is not limited to two as shown in the illustrated example, but it is also possible to create a bagged sand pile using a single or multiple casings, and in that case, the sand pipe can also be used as a casing. The corresponding number of stations will be obtained.

According to this construction method, it is expected that the speed will be further increased.

Furthermore, the bagged sand pillars may be of a cartridge type and may be manufactured in large numbers in advance.

The present invention is a construction method as described above, and is a method for bagging in soft ground improvement under water, in which a packed sand pillar is prepared in advance and then charged into the casing, and the process is separate from the casing casting process. Since it is a sand pile construction method, a pillar of packed sand can be formed inside the sand pipe while driving the casing, and the cycle time of the process of creating packed sand piles one after another can be reduced compared to the conventional method of pouring sand into the casing and driving the casing. It can be significantly shorter than the construction method that is built in series.

Furthermore, unlike the method of the present invention, there is an advantage that the bagged sand pillars can be reliably produced without causing variations or twists in the bagged sand pillars.

In addition, in the method of the present invention, the bagged sand column is produced in a sand pipe, so the length of the used net bag is equal to the length of the designed net bag, reducing loss of the used net bag, and reducing the length of the sand pipe. By changing the length of the bagged sand pillar, the design can be changed arbitrarily.

Furthermore, in the conventional method, it was necessary to drain the water that entered the casing during penetration, but in the method of the present invention, this water can be used as a buffer material when the bagged sand column falls, and moreover, Automatic drainage is possible due to the falling pressure of the sand column and its weight.

[Brief explanation of drawings]

Fig. 1 is a front view showing a driving device for bagged sand piles for construction using the method of the present invention, Fig. 2 is a side view of the bagged sand pile driving device shown in Fig. Fig. 4 is a plan view showing the arrangement of the casing and sand pipe, which is different from the arrangement shown in Fig. 3, and Fig. 5 is a plan view showing the arrangement of the casing and sand pipe according to the present invention. The process of making a sand column is shown. Figure 5A shows the state in which a net bag is set in the sand pipe, the opening of Figure 5 is a schematic diagram showing the state of sand filling work in Figure 5A, and Figure 6 is Fig. 1 shows the casing casting process of the method of the present invention, and Fig. 6 A shows the state in which the casing has penetrated into soft ground up to the position where the bagged sand pillar is introduced. Figure 6 shows the state where the pillar is inserted, Figure 6 shows the state where the casing has penetrated to a predetermined depth between the soft ground, Figure 6 2 shows the state where the casing is pulled up while pressurizing the inside of the casing from the top, Figure 6 is a schematic diagram showing a state in which packed sand piles are constructed in soft ground. 12...Casing, 13...Lid, 14...Charging skirt, 15...Drain pipe, 16...Sand pipe, 17...Hotsuha, 18...Lid, 19...Belt conveyor, 20.21
... Packet, 22 ... Hoist rail, E ... Soft ground, 24 ... Net bag, 25 ... Bagged sand pillar.

Claims (1)

[Claims] 1 After loading a net bag for the bagged sand pile into a sand pipe that has a lid that can be opened and closed at the lower end, the net bag is filled with sand, and the bagged sand pile is moved in a process separate from the casing penetration process. Fabricate the sand pipe,
Move to a position above a tubular casing that has a lid that can be opened and closed at the lower end, open the lid of the sand pipe, drop and insert the bagged sand column in the sand pipe into the casing, and insert the casing into soft ground. The construction method involves penetrating the casing to a predetermined depth, opening the lid at the lower end of the casing, applying pressure from the upper part of the casing, and pulling up the casing to create a packed sand pile in the soft ground.