JPS5944452B2 - Method for creating bagged sand piles in soft ground under water using an underwater vibrohammer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved construction method for constructing net-bagged sand piles in soft ground under water in order to improve the soil quality of soft ground under water. This invention relates to a construction method for sand piles filled with net bags in soft ground under water using an underwater vibrohammer, which allows the use of a casing that is shorter in height than the water depth, and can save the net bag for sand piles by the length corresponding to the water depth.

When using drain piles to improve the soft ground under water to a predetermined depth, conventionally, as a casing,
Net bagging method uses a device with a vibrohammer attached to the upper end of a casing that has a total length that is slightly longer than the sum of the water depth, the pile length in soft ground, and the operation type above the water surface. They were building piles.

Therefore, when driving the casing into soft ground along the leader for guiding the lifting and lowering of the casting machine installed on a platform floating on the water surface, the upper part of the casing and the vibro hammer are always above the water. In addition to being able to insert the net bag into the casing and pouring sand into the casing on the water, it also had the advantage of not allowing water to enter some of the mechanical parts of the bigronometer and impeding its function.

However, in the above conventional construction method, the upper part of the casing is always above the water, so the length of the casing is at least the length of the water depth that is truly necessary for constructing the sand pile, that is, the length of the net-bagged sand pile. As the length of the drain pile increased, the net bag for the drain pile had to be longer than the length of the drain pile, which was a waste.

The present invention is intended to solve the above-mentioned problems, and aims to provide a method for constructing sand piles filled with net bags in soft ground under water, which makes it possible to use casings and net bags that are shorter by the water depth than conventional methods. purpose.

In order to achieve such an object, the construction method of the present invention suspends a tubular casing, which has a lid that opens both the lower end opening and the upper end opening, and is equipped with an underwater vibrohammer on the upper part, from the ship's platform, and also connects a leader and the leader. Guided by a sub-leader that reaches the soft ground below the water surface,
The tubular casing is placed underwater with the lower end opening closed, and with the sand inlet of the casing near the water surface, water that has entered the casing is discharged by pressurized air through a drain pipe extending from the lower end of the casing to the upper end. After that, the net bag is hung down so as to reach the bottom of the casing, and the upper end of the net bag is positioned at the upper end of the casing, and sand is poured into the net bag to produce a net bag filled sand pile, After closing the upper end of the casing with a lid, the casing is lowered using a sub-leader, and the casing is penetrated into the soft ground below the water surface to a predetermined depth using an underwater vibrohammer, and the lower lid of the casing is opened. The method is characterized in that the casing is pulled out (at the same time, air is pumped from above the casing, and a net-filled sand pile with a length approximately equal to the length of the casing is created in the soft ground below the water surface).

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

FIG. 1 shows a bagged sand pile driving device used to carry out the method of the present invention.

This device includes a tubular casing 1 that is driven into soft ground E below the water surface.

Casing 1 is made to be equal to or slightly longer than the length of sand piles to be constructed in soft ground E, and is shorter than the length of conventional casings by the amount of water depth. .

The casing 1 has a lid 2 that can be opened and closed at the lower end, and a sand inlet 4 at the upper part for introducing sand from the hopper 3, and the sand inlet 4 is sealed and opened by a lid (not shown). It has become.

The casing 1 is provided with a small-diameter drain pipe 5 at its lower end 1 and extending to the vicinity of its upper end.

A compressed air introduction pipe (not shown) is attached to the upper part of the casing 1, so that the inside of the casing 1 can be pressurized from above.

A pack drain ship 6 that supports the casing 1 has an oar 7 erected on the gunwale, and a leader 8 fixed to the oar 7 and extending in the vertical direction is connected to a sub-leader 1 extending in the vertical direction.
0 is attached so as to be movable up and down along the leader 8 via a sub-leader guide gib 9.

This sub-leader 10 is designed so that its lower end reaches close to the surface of the soft ground E when descending.

The sub-leader 10 supports an underwater vibro-hammer 12 via an underwater vibro-hammer guide gib 11 so that it can move along the sub-leader 10, and a support plate 13 fixed to the lower end of the underwater vibro-hammer 12.
As shown in FIG. 3, the upper ends of the two casings 1, 1 are fixed.

However, the casing 1.1 is not limited to two, and may be a single casing.

The underwater vibrohammer 12 includes pulleys 14aj14b, 1
The sub-leader 10 is vertically suspended by a winch 17 via pulleys 16, 16b and 16c.

In the figure, 18 is a shock amplifier, and 19.20 is a wire rope.

The underwater vibrohammer 12 has a structure in which a motor 22 and an exciter 23 consisting of a non-uniform rotating body are placed in a sealed box 21 as shown in FIG.

The motor 22 is connected to the exciter Boo' through the pulley 22a.
The casing 1.1 is driven downward by rotating the exciter 23a and activating the exciter 23 to generate vibrations.

The vibrator 23 is a machine for generating vertical vibration.

Note that cooling oil pipes 30 and 31 are connected to the motor 22 from the outside in order to remove heat generated by the motor.

Next, an example of the construction method of the present invention carried out using the above-mentioned net bagged sand pile driving device will be explained with reference to FIG.

First, the casing 1 is held vertically from the back drain vessel 6 until the sand inlet 4 reaches near the water surface. If the water is deep, the leader 8 and sub-leader 10 are operated by the winches 15 and 17. guide the lower end opening of the casing 1 to the lid 2 as shown in Figure 3A.
position it in the water in a closed state.

When the water depth is shallow, the underwater vibrohammer 12 is operated to penetrate the lower part of the casing 1 into the soft ground E, bringing the sand inlet and the sand inlet close to the water surface.

Then, compressed air is introduced from an inlet pipe (not shown) to pressurize the inside of the casing 1, and water that has entered the inside of the casing 1 is discharged from the drain pipe 5.

Next, as shown in Figure 3, a small amount of sand is charged into the tip of a cylindrical net bag A for bagging sand piles with a closed tip.
This is charged into the casing 1 as a weight.

The upper part of the net bag A is attached to the hopper 3, and sand is put into the hopper 3 using a belt conveyor or the like, and the net bag A is filled with sand.

Through this operation, a net bagged sand pile is produced.

The net bag A is a net bag made of synthetic resin such as polyvinyl chloride or nylon, and the diameter of the net bag A is approximately the same as the inner diameter of the casing 1. The length is such that when the lower part of the net bag A is positioned, the upper part of the net bag A slightly faces outside the hopper 3, as shown in the illustrated example.

Next, as shown in FIG. 3, after sealing the sand inlet 4 of the casing 1 with a lid (not shown), the sub-leader 10 in FIG. 1 is lowered along the leader 8 to near the soft ground E. , the motor 22 of the underwater vibrohammer 12 is operated and the exciter 23 is interlocked to activate the exciter 2.
The vertical vibration generated in step 3 moved casing 1 to soft ground E.
Penetrates to the desired depth for consolidation.

After penetration, the lid 2 of the casing 1 is opened, the net bag A filled with sand is placed vertically, and compressed air is introduced into the casing 1 from the introduction pipe as shown in FIG. 1. Pull up the casing 1 while applying pressure from the top.

As a result, the packed sand pile made of the net bag A filled with sand as shown in FIG. 3E is constructed in the soft ground E.

By sequentially performing the above operations at different locations, a large number of net-filled sand piles will be constructed in the soft ground E to be improved.

An embodiment of the construction method of the present invention has been described above, but
The configuration of the embodiments described above may be varied in various ways within the scope of the claims of the present invention.

For example, in the above embodiment, there are two casings,
It may be a single series or a plurality of series of two or more series.

The present invention is a construction method as described above, which is carried out by combining a sub-leader and an underwater vibrohammer with the bag-packed sand pile driving device used in the conventional construction method, and furthermore, the bag-packed sand piles are tightened after water is drained from the casing. Since this is a method of manufacturing inside the casing, the following effects can be obtained.

(i) Compared to the conventional construction method, it is possible to use a casing that is shorter by the water depth at the location where the net-bagged sand pile is constructed. This has the advantage of reducing waste by saving the net bag for the sand pile by approximately the length of the water depth.

The length of the company casing and the length of the net bag are related to strengthening the consolidation of soft ground, so it is necessary to reliably form a sand pile of a predetermined length (the length of the net bag). If this is not done, a water layer will be formed in the sand pile, and the ground will not be strengthened in that area, causing a problem in which the specified reinforcement cannot be achieved. Since punching is performed, there is no such problem and it is possible to reliably create net-filled sand piles with a length approximately equal to the length of the casing in the soft ground.

Qii) The total length of the casing is so short that most of it is driven into soft ground, so the exposed part of the casing is much smaller than in the case of conventional construction methods, and the influence of water pressure from the water is reduced. The verticality of the net-filled sand pile constructed in soft ground is ensured, and even if the constructed net-bag sand pile is bent due to the pressure exerted from the soft ground during the consolidation process, the sand pile will remain stable. Since it does not break apart like sand piles, it can smoothly dehydrate pore water in the ground and more robustly strengthen the consolidation of soft ground.

[Brief explanation of drawings]

Fig. 1 is a side view showing a bagged sand pile driving device for construction using the method of the present invention, Fig. 2 is a longitudinal side view showing the underwater vibrohammer of Fig. 1, and Fig. 3 is a side view showing the driving device for bagged sand piles used for construction using the method of the present invention. This is a front view of the casing part showing the order. Figure 3A shows the casing built on soft ground under water, and the opening in Figure 3 shows the state in which sand is filled into the net bag inserted into the casing. Figure 3C shows the state in which the casing has been penetrated into soft ground to a predetermined depth using an underwater vibrohammer, Figure 3B shows the state in which the casing is pulled up while pressurizing the inside of the casing from the top, and Figure 3 Figure E shows the condition in which net-filled sand piles were constructed in soft ground. 1...Casing, 2...Lid, 4...Sand inlet,
5... Drain pipe, 12... Underwater vibronommer,
A: Net bag, E: Soft ground, L: Water surface.

Claims (1)

[Claims] 1. A tubular casing having a lid for opening and closing the lower end opening and the upper end opening and equipped with an underwater vibrohammer on the upper part is suspended from the ship's platform, and a leader and a sub-leader that extends along the leader to the soft ground beneath the water surface are attached. The tubular casing is guided by the casing and placed in the water with the lower end opening closed, and with the sand inlet of the casing near the water surface, the water that has entered the casing is drained by pressurized air from the lower end of the casing to the upper end of the casing. After discharging the sand through the pipe, the net bag is lowered down to reach the bottom of the casing, the upper end of the net bag is positioned at the upper end of the casing, sand is poured into the net bag, and the sand pile is filled with the net bag. After the casing is manufactured and the upper end of the casing is closed with a lid, the casing is lowered using a sub-leader, and the casing is penetrated into the soft ground below the water surface to a predetermined depth using an underwater vibro hammer, and the lower lid of the casing is closed. An underwater vibro characterized in that when the casing is opened and the casing is pulled out, air is pressurized from the upper part of the casing to create a net-filled sand pile with a length approximately equal to the length of the casing in the soft ground below the water surface. A method for constructing net-filled sand piles in soft ground under water using a hammer.