JP7224216B2 - Attitude control method when caisson frame is submerged - Google Patents

Description

TECHNICAL FIELD The present invention relates to a posture control method for setting a caisson frame, and more particularly to a method for stably setting a caisson frame at a great depth using a pneumatic caisson construction method.

Attitude control is performed by controlling the balance between the subsidence force of the caisson frame and the subsidence resistance force when the caisson frame is submerged. The subsidence force is related to the weight of the caisson frame itself, the weight of the water stored inside the caisson frame, the driving force of the anchor jack, etc. The subsidence resistance is related to the cutting edge resistance, the circumferential friction resistance of the caisson frame, the air pressure inside the box, etc. is related. Therefore, when sinking the caisson frame, the settlement of the entire caisson can be controlled by adjusting the amount of water stored inside the caisson frame, the driving force of the anchor jack, the excavation method at the cutting edge (excavation position), the air pressure inside the box, etc. Control. The posture (inclination) of the caisson frame is controlled by adjusting the driving force of the anchor jack, the excavation method (excavation position) at the cutting edge, and the like.

In recent years, there has been a demand for submerging the caisson frame at a great depth of about GL-80m. In the case of submerging the caisson frame at a great depth, even if a lubricant method (for example, a method of injecting bentonite mud into the outer periphery of the caisson frame) is implemented as in the past, the friction reduction effect of the lubricant (lubricant) will be low. , there is concern that it will be difficult to set the caisson frame and correct or suppress the inclination due to the frictional force on the peripheral surface from the ground.

Therefore, as described above, anchor jacks are used to increase the thrust of the caisson structure, insert injection pipes around the caisson structure from the ground to inject bentonite mud, and reduce peripheral friction. Countermeasures are taken to reduce peripheral friction by building a loose area around the caisson frame using a construction method and a high-pressure agitation injection method. In addition, various techniques have been proposed for reducing circumferential friction when setting down the caisson frame (see, for example, Patent Documents 1, 2, and 3).

The technology described in Patent Document 1 relates to a jet nozzle that injects a friction reducing agent onto the outer circumferential surface of a caisson frame. The jet nozzle includes a nozzle having a hole on the peripheral surface and a closed tip portion, and a nozzle arranged on the peripheral surface of the nozzle and deformed by the supply pressure of the friction reducing agent supplied to the nozzle to close or close the hole. It is provided with a chain opener that opens, and a protection tube that houses the chain opener and the nozzle while maintaining a certain interval on the side of the chain opener and restrains the amount of deformation of the chain opener.

The technology described in Patent Document 2 relates to an injection device for a multi-liquid cemented type lubricant for preventing air leakage in the pneumatic caisson construction method and preventing ground collapse due to excavation settlement. This multi-liquid consolidation type lubricant injection device has check valves respectively provided in a plurality of injection pipes for pressure-feeding the raw material of the multi-liquid consolidation type lubricant, and faces the plurality of injection pipes in the discharge direction of the raw material. It has a multi-liquid mixing plate positioned at the A plurality of raw materials are injected almost at right angles to a multi-liquid mixing plate provided near the tip of the cutting edge of the caisson frame through check valves from a plurality of injection pipes, and mixed and smoothed by stirring. A multi-liquid mixing chamber that generates lumber, a lubricant discharge port that discharges the lubricant generated by mixing multiple raw materials from the vicinity of the tip of the cutting edge of the caisson frame in the direction of the ground, and a lubricant discharge port. First and second dispersion guide walls sandwiched between and arranged in a belt shape around the entire periphery of the cutting edge of the caisson frame, for guiding and dispersing the lubricant discharged from the lubricant discharge port to the entire periphery of the cutting edge. I have.

The technique described in Patent Literature 3 relates to a method for reducing peripheral friction when penetrating into a caisson skeleton. This method of reducing peripheral friction when penetrating into the caisson frame is to inject high-pressure gas through the air supply passage provided in the caisson frame toward the seabed ground that the peripheral surface of the skirt is in contact with. The high-pressure gas is injected to mix the water sucked from the inside of the water supply passage with the earth and sand separated by the injection, and float them along the skirt portion.

Japanese Unexamined Patent Application Publication No. 2005-90022 JP 2012-136882 A JP-A-9-312095

However, when caisson structures are laid down at great depths, once the caisson structure is tilted, it is difficult to correct, and the correction work requires a great deal of time and money.

For example, in the method of improving the thrust by using an anchor jack, since it is necessary to sink at a great depth, a large amount of thrust is required, a large-scale thrust device must be used, and the thrust is not easy to control. rice field.

In addition, in the method of injecting bentonite mud around the caisson frame, the bentonite mud with low injection pressure flows into weak ground parts and does not efficiently flow into areas with high peripheral friction.

In addition, in the method of constructing a slack area around the caisson frame by the boring hole method or the high-pressure agitation injection method, when the caisson frame is set down, the surroundings of the caisson frame are in a compressed state by a high-pressure compressor, so the peripheral friction force In the immediate vicinity of the caisson frame, which is most effective in reducing air pollution, there was a risk that the air holes would communicate with the ground and cause groundwater to erupt.

Furthermore, the techniques described in the above-mentioned cited documents can reduce the peripheral friction when setting the caisson frame, but it is difficult to set the caisson frame while reliably and efficiently controlling the attitude. had room for further improvement.

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above-mentioned circumstances. It is an object of the present invention to provide an attitude control method for

In the posture control method when the caisson frame is set down according to the present invention, the installation locations are different in the circumferential direction and the vertical direction with respect to the outer peripheral surface of the caisson frame, and the injection ports directed upward to the outer peripheral surface of the caisson frame are set. It is assumed that a plurality of injection nozzles are provided, each with its own.

That is, in the posture control method when the caisson frame is set down according to the present invention, the installation points are different in the circumferential direction and the vertical direction with respect to the outer peripheral surface of the caisson frame, and the injection is directed upward on the outer peripheral surface of the caisson frame. A plurality of injection nozzles each having an orifice are provided.

The injection nozzle is substantially tangential to the outer peripheral surface of the caisson body and is rotatable in a range toward the upper side of the outer peripheral surface of the caisson body. is selected to inject liquid, and the direction of the injection port is changed in a range toward the upper outer peripheral surface of the caisson skeleton , and the liquid is injected with a predetermined width to control the attitude of the caisson skeleton. and

In the above-described attitude control method when the caisson frame is set down, the main body portion of the caisson frame which is above the friction cut portion provided near the lower end of the caisson frame and has an outer peripheral diameter smaller than the friction cut portion. By injecting the liquid from the injection nozzle in a range toward the upper side of the outer peripheral surface of the caisson frame into the gap formed between the ground and the outer peripheral surface of the caisson frame and the ground, the space between the outer peripheral surface of the caisson frame and the ground is filled. It is possible to control the posture of the caisson frame by stirring the sand that has settled in the liquid and controlling the frictional force between the outer peripheral surface of the caisson frame and the natural ground.

In the posture control method when the caisson frame is sunk according to the present invention, liquid is injected upward from the outer peripheral surface of the caisson frame from the injection nozzle provided near the place where the peripheral friction of the caisson frame shows an increasing tendency. By adjusting the circumferential friction, the attitude of the caisson frame can be controlled.

In addition, since the injection nozzles each have a plurality of injection ports, it is possible to widely spray the liquid from one injection nozzle. The liquid ejected from the caisson can be spread over a wide range of the outer peripheral surface of the caisson frame. As a result, the number of piping systems and injection nozzles can be reduced, and the liquid can be efficiently injected over a wide range on the outer peripheral surface of the caisson frame.

In addition, by making the injection nozzles rotatable, the liquid injection direction can be swung or changed within a predetermined range, so that the liquid injected from one injection nozzle can be spread over a wide range of the outer peripheral surface of the caisson frame. can let As a result, the number of piping systems and injection nozzles can be reduced, and the liquid can be efficiently injected over a wide range on the outer peripheral surface of the caisson frame.

By the way, the gap between the outer peripheral surface of the caisson frame and the ground is filled (filled) with lubricant (lubricant), muddy water, and groundwater. Sand that has been scraped off from the ground has settled in it, and frictional resistance acts on the outer peripheral surface of the frame due to the presence of this settled sand. In the posture control method when the caisson frame is set down according to the present invention, the liquid injected from the injection nozzle stirs the sand that has settled in the liquid that fills between the outer peripheral surface of the caisson frame and the ground, causing convection. Since the frictional force between the outer peripheral surface of the caisson frame and the ground is controlled, the frictional force acting on the caisson frame can be reduced and controlled.

In other words, while reducing the frictional force on the entire outer peripheral surface of the caisson frame, reducing only a part of the frictional force, or changing the order of reducing the frictional force in multiple places, when the caisson frame is laid down can control the tilting and rolling of the caisson frame.

As described above, according to the attitude control method for setting the caisson frame according to the present invention, the peripheral friction of the caisson frame can be appropriately controlled by simple injection control without using a large-scale device. It is possible to reliably and efficiently perform tilt correction and subsidence.

FIG. 2 is a schematic diagram of a caisson skeleton provided with injection nozzles used in the attitude control method when the caisson skeleton is lowered according to the embodiment of the present invention. FIG. 4 is an explanatory view of the action of the attitude control method when the caisson skeleton is set down according to the embodiment of the present invention. Explanatory drawing of the injection nozzle and piping used for the posture control method at the time of caisson frame sinking which concerns on embodiment of this invention. Explanatory drawing (1) of the injection nozzle used for the attitude|position control method at the time of the caisson building frame sinking which concerns on embodiment of this invention. Explanatory drawing (2) of the injection nozzle used for the posture control method at the time of caisson building frame sinking which concerns on embodiment of this invention. FIG. 3 is a schematic vertical cross-sectional view of a caisson skeleton provided with an injection nozzle and ancillary devices used in the posture control method when the caisson skeleton is laid according to the embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a caisson skeleton provided with an injection nozzle and ancillary devices used in the attitude control method when the caisson skeleton is laid according to the embodiment of the present invention.

Hereinafter, an attitude control method for setting a caisson skeleton according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 7 explain the attitude control method when the caisson skeleton is set down according to the embodiment of the present invention. FIG. 1 is a schematic diagram of the caisson skeleton provided with injection nozzles, FIG. is an explanatory diagram of the injection nozzle and piping, FIGS. 4 and 5 are explanatory diagrams showing the specific shape of the injection nozzle, FIG. and a schematic cross-sectional view of a caisson frame provided with ancillary devices. In addition, FIG. 4(a) shows the state of the injection nozzle viewed from the side, and FIG. 4(b) shows the state of the injection nozzle viewed from the top.

<Basic attitude control method when setting down the caisson>
As shown in FIGS. 1, 6, and 7, the posture control method when the caisson skeleton is set according to the embodiment of the present invention is such that the installation points are set in the circumferential direction and the vertical direction with respect to the outer peripheral surface of the caisson skeleton 10. Basically, the attitude control of the caisson frame is performed using a plurality of jet nozzles 20 which are provided differently. Each injection nozzle 20 has a plurality of injection ports 21 or is rotatably provided with respect to the caisson body 10 .

By injecting the liquid from the injection port 21 of the injection nozzle 20 toward the upper side of the outer peripheral surface of the caisson body 10, the liquid settled in the liquid filled between the outer peripheral surface of the caisson body 10 and the ground. The sand can be agitated to control the frictional force between the outer peripheral surface of the caisson body 10 and the natural ground. By selecting one or more injection nozzles 20 out of the plurality of injection nozzles 20 and injecting the liquid, the attitude of the caisson frame is controlled.

<Injection nozzle>
As shown in FIGS. 1, 6, and 7, the injection nozzles 20 are provided on the outer peripheral surface of the caisson body 10 at different positions in the circumferential direction and the vertical direction. Each injection nozzle 20 has a plurality of injection ports 21 directed upwards from the outer peripheral surface of the caisson body 10, as shown in FIG. A base end of the injection nozzle 20 is connected to a delivery pipe 40 provided inside the caisson body 10 . In addition, each injection nozzle 20 is preferably provided with a check valve (not shown), which permits injection of liquid from the injection nozzle 20 when the liquid is delivered at a predetermined pressure or higher.

In this embodiment, the liquid injected from the injection nozzle 20 in order to reduce the circumferential friction when setting the caisson frame 10 is a mixture of water, bentonite mud, lubricant (lubricant), cement milk, air, and the like. be. In this case, one type of these objects may be jetted, or a plurality of types of substances may be mixed and jetted.

As shown in FIG. 3 , each injection nozzle 20 is connected to a delivery pipe 40 . , and each injection nozzle 20 may be provided with an on-off valve (not shown). Since the injection nozzles 20 used in the embodiment of the present invention each have a plurality of injection ports 21 as shown in FIG. 4B, the number of injection nozzles 20 can be reduced. Therefore, even if a separate delivery pipe 40 is connected for each injection nozzle 20, the number of delivery pipes 40 can be reduced. Although not shown, the delivery pipe 40 is attached with a tank for storing the liquid ejected from the injection nozzle 20, a pumping pump, and the like.

The on-off valve is composed of, for example, an electromagnetic valve, and is a valve for opening and closing the delivery path to each injection nozzle 20. By opening and closing this on-off valve, injection and stop of liquid from each injection nozzle 20 are controlled. can do. Opening and closing of the on-off valve is controlled by liquid injection control means 50, which will be described in detail later.

Each injection port 21 of the injection nozzle 20 is set to an appropriate size according to the injection amount and injection pressure of the liquid to be injected. In addition, as shown in FIG. 4, each injection port 21 is provided so that the liquid injection direction is different. It is preferable that the direction of liquid injection is tangential to the outer circumferential surface of the caisson body 10 . That is, the liquid spreads and is sprayed from each injection port 21 of the injection nozzle 20 along the tangential direction of the outer peripheral surface of the caisson body 10 . Thereby, the liquid can be ejected in multiple directions from one ejection nozzle 20 .

In the example shown in FIG. 4B, the injection ports 21 are arranged in an arc so as to follow the outer peripheral surface of the cylindrical caisson body 10, but along the outer peripheral surface of the caisson body 10 The position where the injection port 21 is provided may be changed as appropriate as long as the liquid can be injected. For example, the injection ports 21 can be arranged concentrically or linearly. Also, the number of injection ports 21 can be appropriately changed according to the size and shape of the caisson frame 10, the soil quality of the surrounding natural ground, and the like.

Further, as shown in FIG. 5 , the injection nozzle 20 may be provided so as to be rotatable in the substantially tangential direction of the outer peripheral surface of the caisson body 10 . It should be noted that rotatable in the substantially tangential direction of the outer peripheral surface of the caisson body 10 means that the injection nozzle 20 is rotated so as to change the direction of the injection port 21 with the position at which the injection nozzle 20 is attached to the caisson body 10 as a rotation fulcrum. is to rotate. That is, for example, if the caisson body 10 has a cylindrical shape with a square cross section, the outer peripheral surface of the caisson body 10 is flat, and the injection nozzle 20 can be rotated in line with the tangential direction of the outer peripheral surface of the caisson body 10. .

However, for example, if the caisson body 10 has a cylindrical shape with a circular cross section, the outer peripheral surface of the caisson body 10 becomes a curved surface. requires a complicated mechanism. Therefore, when the outer peripheral surface of the caisson body 10 is a curved surface, it is preferable to rotate the injection nozzle 20 so as to approximate the tangential direction of the outer peripheral surface of the caisson body 10 . In this embodiment, such a configuration is provided so that the injection nozzle 20 can be rotated substantially tangentially to the outer peripheral surface of the caisson body 10 .

Although not shown, in order to rotate the injection nozzle 20, a rotation mechanism provided at the proximal end of the injection nozzle 20 and a rotation driving device for rotating the rotation mechanism are required. The rotation mechanism may be any mechanism as long as it can rotate the injection nozzle 20 in the tangential direction of the outer peripheral surface of the caisson body 10. For example, a gear attached to the rotating shaft of the injection nozzle 20 can be used. can be done. Further, the rotation drive device may be any mechanism as long as it can rotate the rotation mechanism. For example, an electric motor, or an actuator driven by air or oil can be used.

In the injection nozzle 20 provided rotatably with respect to the caisson frame 10, the number of injection ports 21 may be one, or two or more. That is, by rotating the injection nozzle 20, the liquid can be sprayed over a wide range. Moreover, when a plurality of injection ports 21 are provided, the liquid can be injected over a wider range.

In this embodiment, as shown in FIGS. 6 and 7, a friction meter 30 is provided near each injection nozzle 20 . Then, when the circumferential friction of the caisson body 10 measured by each friction meter 30 shows an increasing tendency (when the circumferential friction value exceeds a predetermined value continues for a predetermined time), the circumferential friction increases From the injection nozzle 20 provided near the friction meter 30 that measures the tendency, by injecting the liquid at high pressure toward the upper outer peripheral surface of the caisson body 10, the caisson body 10 is accelerated and the inclination is corrected. do it. Such liquid injection control can be carried out under the control of the liquid injection control means 50 .

<Liquid injection control means>
The liquid injection control means 50 is means for controlling the injection of liquid from each injection nozzle 20 based on the friction value measured by each friction meter 30. Specifically, the caisson body measured by each friction meter 30 10 shows an upward tendency, from the injection nozzle 20 provided near the friction meter 30 that measures the upward tendency of the circumferential friction, liquid is controlled to inject at high pressure. The threshold value of the peripheral friction that causes the liquid to be sprayed from the injection nozzle 20 at high pressure can be appropriately set based on various factors such as the size, shape, sinking depth of the caisson body 10, and the soil quality of the surrounding ground.

For example, the operator observes the measurement value of each friction meter 30 and performs an operation input based on the observation result to operate the opening/closing valve of the injection nozzle 20 for liquid injection. , and a device for transmitting a control signal for high-pressure injection of liquid from the injection nozzle 20 .

A computer, a control program installed in the computer, and peripheral devices of the computer constitute liquid injection control means 50, which receives measurement signals from each friction meter 30, and the measurement value (friction value) reaches a predetermined value. When it exceeds, the opening/closing valve of the injection nozzle 20 to which the liquid is to be injected may be automatically controlled to inject the liquid from the injection nozzle 20 at high pressure. In addition, the measured value (friction value) may rise transiently due to various factors such as the size, shape, sinking depth of the caisson frame 10, and the soil quality of the surrounding ground. The value (friction value) returns to a predetermined value or less. Therefore, it is preferable to perform control such that the liquid is jetted from the injection nozzle 20 at high pressure when the state in which the circumferential friction value exceeds the predetermined value continues for a predetermined time.

In the above-described embodiment, the measurement signal from the friction meter 30 is used as the input data for controlling the attitude of the caisson body 10, but the input data for controlling the attitude is not limited to this. For example, inclination data of the caisson frame 10, loose state data of the ground around the caisson frame 10, and the like may be used as input data.

As shown in FIG. 2, the caisson body 10 of the present embodiment has a friction cut portion 11 near the lower end, and the outer diameter of the main body located above the lower end of the caisson body 10 becomes smaller. ing. Therefore, a gap is generated between the main body of the caisson frame 10 and the ground, and the liquid (lubricant (lubricant), etc.) injected into this gap and the soil particles generated by the liquid injection is full.

At this time, if no measures are taken, soil particles (particularly sand) will settle in the liquid that fills between the ground and the ground, clogging the gap between the main body of the caisson frame 10 and the ground, resulting in a caisson. Friction between the frame 10 and the ground increases. Under such circumstances, the posture of the caisson skeleton 10 cannot be properly controlled.

In the posture control method when the caisson skeleton is set down according to the present embodiment, the liquid is jetted from the injection nozzle 20 toward the upper side of the outer peripheral surface of the caisson skeleton 10, thereby causing the gap between the outer peripheral surface of the caisson skeleton 10 and the natural ground. Soil particles (particularly sand) that settle in the permeating liquid are agitated, and the frictional force between the outer peripheral surface of the caisson body 10 and the natural ground can be controlled. The posture of the caisson body 10 is controlled by selecting the injection nozzles 20 for injecting the liquid and controlling the frictional force between the outer peripheral surface of the caisson body 10 and the natural ground.

10 caisson frame 11 friction cut part 20 injection nozzle 21 injection port 30 friction meter 40 delivery pipe 50 liquid injection control means

Claims (2)

A plurality of injection nozzles are provided at different positions in the circumferential direction and the vertical direction with respect to the outer peripheral surface of the caisson frame, and each have an injection port directed upward on the outer peripheral surface of the caisson frame,
The injection nozzle is substantially tangential to the outer peripheral surface of the caisson body and is rotatable in a range toward the upper side of the outer peripheral surface of the caisson body. The position of the caisson frame is controlled by selecting a nozzle to inject the liquid, and by jetting the liquid in a predetermined width while changing the direction of the injection port in a range toward the upper outer peripheral surface of the caisson frame. Posture control method at the time of caisson frame subsidence. In the gap between the main body of the caisson frame and the ground, which is above the friction cut portion provided near the lower end of the caisson frame and has a smaller outer diameter than the friction cut portion On the other hand, by injecting the liquid from the injection nozzle to the upper side of the outer peripheral surface of the caisson frame, sand settled in the liquid filling between the outer peripheral surface of the caisson frame and the ground is removed. 2. The attitude control of the caisson frame according to claim 1 , wherein the attitude of the caisson frame is controlled by stirring to control the frictional force between the outer peripheral surface of the caisson frame and the ground. Attitude control method.

Images