JP2717874B2 - Open caisson construction method and device - Google Patents

Description

[Detailed Description of the Invention] [Industrial application field] The present invention improves the uncertainty and the poor construction accuracy, which were the drawbacks of the conventional open caisson premised on underwater excavation, regardless of the ground conditions. In addition to enabling reliable and accurate construction, excavation and earth removal and building of the skeleton are advanced simultaneously,
TECHNICAL FIELD The present invention relates to an open caisson construction method and apparatus improved by shortening the construction period so as to be suitable for submerging at a large depth on the premise of underwater excavation.

[Conventional technology]

Conventional construction techniques applied to large-scale shafts for deep utilization of underground space and large-scale large-scale foundations include the underground continuous wall method, the pneumatic caisson method, and the open caisson method.

The underground diaphragm wall method involves placing concrete in muddy water, so the quality of the skeleton is lower than other methods, and the construction time must be longer because the entire structure must be divided into elements. In addition, the ground having pressurized water below the bottom of the excavation has a drawback such that an extremely long rooting depth is required under the floor.

In the pneumatic caisson method, excavation is carried out in a pressurized working room, and there is a limit to the pressure and pressure at which workers can enter the working room. However, since the opening for discharging the soil cannot be made large, the efficiency of discharging the soil is poor, and as with the underground continuous wall method, there are drawbacks such as a long construction period.

The open caisson method is generally an inexpensive method with a shorter construction period than the two methods described above.However, when underwater excavation is performed, there is uncertainty in the excavation of the cutting edge, which causes settlement of the surrounding ground. Or, it is difficult to control the attitude, the inclination can not be fixed, in some cases it may not be possible to sink, the application examples tend to decrease gradually, especially for deep construction under the assumption of underwater excavation, There was a problem in adoption due to uncertainty and poor accuracy. However, recently, an open caisson method that can reliably excavate below the cutting edge has been put into practical use.

An overview of the construction method of open caisson based on conventional underwater excavation is as follows.

The most common construction method is to add a load such as a steel material to the body's own weight or its own weight while performing underwater excavation with a bucket such as a clam shell, hammer grab, etc. There is a construction method (first construction method) in which the slab is laid.

As a step forward from the above method, a caisson top is equipped with a press-fitting device using a ground anchor or other reactive force at the top of the caisson to prevent settlement of the surrounding ground and ensure construction accuracy. While penetrating the mountains,
Underwater excavation and digging with buckets such as clamshells and hammer clubs that also serve as digging (second construction method)
There is.

In recent years, a method of excavating and submerging using an excavator (arm-type underwater excavator) that includes a press-fitting device at the top end and has a rotary cutter and excavates earth and sand together with water by an airlift method (arm type underwater excavator) (third method) Method).

In the case of a small open caisson using a precast product as the body, a special excavator equipped with a planetary-drive type bottoming bit measures the press-in excavation by the press-in support girder provided at the top end of the caisson, After excavation to a diameter larger than the diameter, the caisson frame is temporarily supported by the suspension support device, and is gradually laid down after completion of the excavation (No. 4
Method).

[Problems to be solved by the invention]

In the above-mentioned conventional open caisson construction method, no matter which of the first to fourth construction methods is used, rebar assembly,
When building a frame such as formwork assembly and concrete casting, excavation and unloading were stopped, and it was necessary to perform the work one step at a time so that the work did not interfere with each other. For this reason, there is a disadvantage that the construction period is long, and particularly in a deep caisson where the procedure is repeated frequently, it becomes a serious problem in terms of process and economy.

When constructing a caisson at a large depth, the caisson must be laid in a relatively hard stratum (sand, gravel, siltstone, etc.) at a point where the groundwater level is high. In the second method, too, there is a problem in submerging the cutting edge into the ground where the ground reaction force is large. For example, in the case of sinking in sand and gravel, it is impossible to settle only by pressing in if the soil just below the cutting edge is not removed.Therefore, the area near the cutting edge is dug with a clamshell, and the gravel ground at the cutting edge is dug out It has to be laid down while collapsed, which makes it difficult to stably manage the excavated surface, leading to the collapse of the caisson's surrounding ground and causing the surrounding ground to sink significantly. In addition, in a relatively hard and highly self-sustaining ground such as mudstone, it is not only difficult to excavate with a bucket such as a clamshell or the like, but even if it is possible to excavate the vicinity of the cutting edge, the ground directly below the cutting edge is difficult. Cannot be collapsed into the digging part, and the sinking is impossible.

For these reasons, there is a problem in applying the first and second construction methods, which cannot accurately excavate the cutting edge, to a deep caisson.

In the third and fourth construction methods, since the excavator and its mounting base are large, there is a problem in application to a large caisson. The third construction method has an outer diameter of up to 10 m, and the fourth construction method has a problem. It has only a track record of caisson of relatively small diameter up to 4m in outer diameter.

Further, in the conventional open caisson, it is difficult to correct the slope when the slope starts to be inclined, and therefore, there is a limit to the depth of work that can be performed, particularly when the stratum configuration is complicated. In the case of deep construction, it is essential to overcome this problem.However, it is necessary to catch the inclination of the caisson at an early stage and quickly control the posture against it. Control is not performed.

In addition to the above problems, there are the following problems when laying an open caisson at a large depth.

First, when submerging an open caisson at a large depth against low consolidated ground such as silt rock and consolidated sand, the peripheral friction acting between the back of the lower cutting edge and the ground, especially by friction cut May become very large, hindering the subsidence and making the subsidence impossible, and it is necessary to provide a means for reliably reducing the peripheral friction of this portion.

In addition, in order to ensure the deep sedimentation, it is necessary to reduce the peripheral friction acting between the outer periphery of the caisson and the ground above the friction cut. It is necessary to reliably fill the gap between the outer periphery of the caisson and the ground.

However, the caisson blade back earth and sand is excavated outside of the blade,
In some cases, a thin layer is excavated by the jet to reduce the peripheral friction on the back side of the cutting edge, which may create a gap on the back side of the cutting edge.Bentonite liquid interposed between the caisson and the ground There is also a problem that the sliding material such as leaks from the above-mentioned gap, and the effect of reducing the peripheral surface friction and the effect of preventing the settlement of the surrounding ground cannot be sufficiently exhibited.

It is an object of the present invention to provide an open caisson construction method and apparatus suitable for deep construction by solving these problems.

[Means for solving the problem]

The present invention has been made to solve the above problems and to achieve the object.

First, to solve the problem of shortening the construction period for deep construction, a caisson depressing device was installed to be able to move around the outer periphery of the caisson body after a sufficient training period after concrete placement,
After the caisson is pushed down to a predetermined position by the caisson pushing device, the underwater excavator provided on the lower inner wall of the caisson body is used to excavate by operating below the cutting edge from the ground. The assembly of rebar, the assembling of formwork using a sliding formwork device, and the subsequent concrete casting work are to be performed simultaneously at the upper part of the caisson.

The above works can be achieved by arranging the caisson depressing device on the outer periphery of the caisson frame sequentially and movably on the caisson frame to be built.This caisson depressing device is a straight steel girder. Install several so as to surround the caisson, and install a center hole jack with a reaction force such as an earth anchor or reaction force pile at the connection between the steel girders or the center of the span of the steel girder, Center hole jacks are arranged at equal intervals using the same reaction girder instead of straight steel girder. Further, instead of using the holding frame system as described above, a system in which reaction force stands are individually provided at the center hole jack positions can be adopted.

Next, in order to solve the problem of accurate and reliable underwater excavation of the cutting edge soil, an excavator of a known means such as a backhoe is mounted on a mounting base movably installed on a rail horizontally installed on a lower inner wall of the caisson body. By excavating the excavator tip and operating it from the ground while constantly checking the excavator tip position with the sensor, the earth and sand at the cutting edge and the central part of the caisson shall be excavated. This makes it possible to reliably remove the soil at the cutting edge,
The excavation shape can be changed depending on the location.

The caisson is laid down by pressing the jack while maintaining the balance between the squatting load and the squatting resistance while leaving the tip of the cutting edge close to the ground.

Furthermore, caisson construction accuracy shall be ensured by the following means.

The caisson that is being laid is equipped with sensors that detect the inclination and depth of the caisson.The values of the caisson are processed by computer to quickly grasp the attitude and position of the caisson. By using the measured values to determine the caisson's settlement load and settlement resistance as accurately as possible, the pressure input of each jack installed in the caisson press-down device and the excavation shape under the cutting edge are determined, and At the same time, the attitude is controlled.

This attitude control is performed by changing the individual press input of the jack provided on the side surface or by changing the excavation shape of the blade opening portion depending on the location.

When the posture and position are corrected more effectively, the following means shall be used. That is, a plurality of jacks are arranged in the lateral direction along the outer peripheral portion on the upper part of the cutting back surface of the caisson, and the pressure of each jack is changed to cause horizontal movement of the lower part of the caisson. This can be used in combination with biased loading by a jack on the ground, or in conjunction with a change in the excavation shape of the cutting edge by an underwater excavator.

The jack on the back side of the caisson lower cutting edge used above must be as flat as possible so as not to reduce the effective cross-sectional area of the caisson wall body, must have a simple structure, and must not be damaged by the sinking of the caisson. As a means for that, a flat, expandable bag body made of metal, rubber or high-strength fiber is used, and the function of a jack is provided by controlling the amount of the injection material injected into the bag body. . The jack shall be covered with a thin steel plate connected to a caisson blade so that the jack will not be damaged by the sinking of the caisson.

The following measures shall be used for other problems when the caisson is laid at a large depth, an increase in circumferential friction on the back of the cutting edge, and leakage of the sliding material from the back of the cutting edge.

To increase the circumferential friction on the back side of the cutting edge, a gantry movably mounted along the rail on the lower inner wall of the caisson has a telescopic mechanism along the cutting edge, and a bending mechanism above the pipe tip nozzle. , The high-pressure water jet peripheral friction removing device capable of accurately directing the nozzle above the back surface of the cutting edge is engaged.

For leakage of lubricating material used to reduce the peripheral friction above the caisson's friction cut and to prevent the settlement of the surrounding ground, the lower end immediately above the friction cut pipe immediately below the lubricating material injection pipe and the lower end bolted to the blade fitting or concrete And the like, and the upper end is widened by the same diameter as the ground at the outer peripheral portion.

This lubricating material leakage prevention member uses a high-strength material such as a thin iron plate or wire, and the lower end is bolted to the blade fitting or concrete with a bolt, so that the upper end follows the ground by the injection liquid pressure, It shall be arranged on the outer periphery of the caisson without any gap.

(Operation)

In order to install the caisson depressing device movably on the outer periphery of the caisson skeleton after a sufficient training period after casting the concrete, the caisson depressing device is used to set up the caisson siding work, and the caisson skeletal construction work to be added to the upper part and Equipment (rebar assembly work, formwork assembly work, scaffolding for work, etc.)
Does not hinder

Therefore, the caisson can be settled, excavated and excavated, and the frame can be constructed at the same time. Furthermore, since the concrete at the connection between the caisson press-down device and the skeleton has passed a sufficient training period after casting, the push-down device is set and pushed down after securing the training period after placing the upper concrete as in the past. No need. Therefore, workability is improved and the construction period can be significantly reduced.

In addition, the excavation machine, which is movably mounted along the rail extending horizontally to the lower inner wall of the caisson frame, can securely remove the soil under the cutting edge by using an excavating machine. The caisson can be reliably laid down at a large depth.

The posture and position of the caisson during subsidence and the factors of subsidence resistance (cutting edge reaction force, peripheral surface friction, buoyancy) can be quickly grasped by computer processing of the sensor values, and the jack installed in the push-down device Since the press input and the excavation shape of the cutting edge can be determined, it is possible to correct the posture before the posture is largely changed, and the construction accuracy of the caisson can be improved.
In addition, the lower end of the caisson is moved by the jack provided at the upper part of the friction cut on the back side of the caisson blade, and this is used together with the partial pressure loading by the jack arranged in the upper pressing device, or the location of the ground at the blade opening If it is changed and used together with excavation, a more effective posture and position correction effect can be obtained. With the above attitude control mechanism, not only the poor construction accuracy, which is a drawback of the conventional open caisson, can be overcome, but also construction at a large depth can be performed.

If the peripheral friction of the back of the cutting edge is large and hinders the settlement, a high-pressure water jet with a telescopic mechanism and a bending mechanism attached to the above-mentioned horizontally movable frame attached to the lower inner wall of the caisson body By using a peripheral friction removing device, the soil at the back of the cutting edge can be reduced by thinly shaving off the sand.

Leakage of the leaked material from the back of the cutting edge can be prevented by the slippery leakage prevention member provided on the friction cut straight material, ensuring a reduction in peripheral friction and sufficiently preventing the settlement of the surrounding ground. It can be expected.

In this way, the sinking resistance is reliably reduced, and the excavation and construction work are carried out at the same time while controlling the attitude, enabling smooth submersion even at large depths. Can be constructed.

〔Example〕

Hereinafter, a method and an apparatus for constructing an open caisson according to the present invention will be described based on the illustrated embodiment.

 FIG. 1 shows an overall view of the construction method of the present invention.

In the figure, K is a concrete caisson frame having a required diameter and height. The lower caisson 1 has a cutting edge 1a.

The lower caisson 1 having the cutting edge 1a at the lower end is built by a conventional method or manufactured by another method. A rail R extends horizontally on the lower inner wall 1b of the caisson skeleton K.

As shown in FIG. 2, the rail R is fixed to the caisson skeleton K by an anchor 31, and a plurality of horizontally movable frames 21 are engaged with the rail R, and the rail R is operated from the ground. An excavator 2 by a known means such as a backhoe is installed to excavate earth and sand at a cutting edge portion and a central portion of a lower end of a caisson.

The earth and sand excavated and collected by the excavator 2 is discharged from the upper opening by a known means such as a clam shell or an earth and sand bucket.

FIG. 3 shows the details of the sliding formwork device in the basic configuration of the construction method of the present invention (the underwater excavator at the cutting edge, the sliding formwork device, and the caisson pressing device).

Lower caisson 1 Steel bars 10 established at regular intervals around the circumference
, A sliding form device 4 having a lifting function is supported. The sliding form device 4 is of the same kind as that used for building silos and the like, and the entire sliding form device is raised while supporting the load along the steel bar 10 and the clamping means 41 for clamping the steel bar 10. An inner formwork 43, an outer formwork 44, and a work floor 47 are provided opposite to each other in accordance with the inner and outer diameters of the caisson to be built. Then, if necessary, a sheath tube 45 that is fitted to a steel rod for supporting and raising the sliding form device is used. Further, the yoke 46 is provided with a steel bar clamping and lifting means, and inner and outer molds suspended from the lower part.

A caisson depressing device 8 having a ground anchor or a reaction force pile as a reaction force is disposed at an outer peripheral position of the caisson frame K which is sequentially added to the upper part of the lower caisson 1.
The caisson pressing device 8 includes a holding frame 81 for holding the outer peripheral surface of the caisson frame K, and the holding frame 81 is
It is composed of a bracket 82 or a wedge 85 provided at a position close to the outer periphery, and a center hole jack 83 provided at a predetermined position for pushing down the holding frame. The push-down device grasps the rod 84 connected to the earth anchor, reaction force pile, etc. in the center hole jack hollow part, extends the hydraulic cylinder of the jack, pushes down the entire holding frame, and uses the bracket or wedge. Or caisson body K by frictional force with the outer peripheral surface by tightening the holding frame
Press down. The holding frame depressed together with the caisson skeleton K is raised to a predetermined position required for the next depressing and re-installed.

 An example of a caisson pressing device is shown in FIGS.

In the embodiment shown in FIG. 4, several straight steel girders are installed so as to surround the caisson to form a holding frame 81, and a center hole jack 83 is provided on the pin bearing at the connection between the individual steel girders. The transmission of the force between the holding frame and the caisson skeleton K is performed by the bracket 82. In the embodiment shown in FIG. 5, the span of the steel girder is shortened and the connecting portion is connected with the connecting pin 86 to form a polygonal holding frame having almost the same shape, and the center hole jacks 83 are arranged at equal intervals at the center of the span of the steel girder. The transmission of force between the holding frame and the caisson frame K is by wedge 85. The wedge 85 can be brought into a state where an effect is obtained before the press-fitting by a screw-in method or a press-fitting method. In the embodiment shown in FIG. 6, the holding frame is circular, and the caisson body K is tightened by the fastening jack 87 attached to the holding frame, and the pressing force is transmitted to the caisson by the frictional force between the holding frame and the outer wall of the caisson. It is a method to do.

While the caisson is being set, a fixed inclinometer 9
1. The position and occurrence of caisson can be quickly grasped by computer processing the data of the sinker 92 or by using a laser launcher provided at a fixed point on the ground and a target installed below the caisson body K. In addition, the ratio of the own weight and the pressure input to the sinking load and the change in the values measured by various sensors such as the cutting edge load 93 provided on the caisson body K, the peripheral surface friction meter 94, and the pressure gauge 95 of the hydraulic jack, Accurately grasp the ratio of peripheral friction and buoyancy and reaction force of the cutting edge to the resistance, and the individual pressure of the jack installed in the optimal press-down device for posture correction and the excavation shape under the cutting edge Excavation and press-fitting are repeated while determining the locational change of the computer by computer processing.

The caisson is laid down while controlling the attitude by the above method.

If it is desired to correct the posture or position more effectively, as shown in FIG. 7, a metal, rubber or high-strength fiber provided on the upper part of the friction cut 11 is formed into a flat and inflatable bag body 14. A lower blade position correcting jack 12 which can inflate or deflate the liquid by pumping the liquid and use it as a jack to move the position of the lower blade is used in combination with a ground jack on the side of the caisson. This lower jack is protected by a thin plate connected to the blade iron plate so as not to be destroyed during the caisson laying.

When the friction of the peripheral surface of the rear surface of the friction cut lower cutting edge is extremely large and hinders the caisson laying down, using a high-pressure water jet peripheral friction removing device 7 as shown in FIG.
The surface friction under the friction cut is removed by thinly shaving the earth and sand behind the cutting edge. This engages the guide 72 with the underwater excavator mounting base that is movable along the rail extending laterally on the lower wall of the caisson, making the high-pressure water jet pipe 71 extendable along the guide 72, Hydraulic jack device 73 has a mechanism to bend the nozzle 74 upward so that it can be accurately positioned under the back of the cutting edge, and if necessary, scrapes the sand and sand on the back of the cutting edge into a thin layer to remove peripheral friction I do.

The high-pressure water jet peripheral friction removing device 7 can be used for excavation under a cutting edge when delicate thin layer excavation is required during attitude control or final settlement.

In addition, the use of the above-described lower jack on the back side of the blade allows the blade position to be more effectively corrected.

In order to prevent leakage of the lubricating material such as bentonite injected from the lower part of the cutting edge to reduce the friction of the peripheral surface above the friction cut and to prevent the subsidence of the surrounding ground, the caisson has a ninth
As shown in the figure, a slip material leakage prevention member 13 is provided. The slipper leakage prevention member 13 is formed by stacking thin iron plates in a strip shape or using a tightly bundled wire, and the lower end is locked to concrete or blade fitting immediately above the caisson friction cut, and By following the ground by the injection pressure of the sliding material and arranging it without gaps, it is possible to exhibit the effect of preventing leakage of the sliding material.

By using the construction device as described above, the excavated earth and sand is discharged to the outside of the caisson using a conventional discharging means such as a clamshell or a sediment bucket while performing excavation, press-fitting, and posture control in the lower part and the side part. At the same time, after assembling the rebar at the top, the sliding form is raised to a predetermined position, and concrete is poured between the inner and outer forms. At this time, the sliding form device is sequentially raised while pouring concrete only at a height where the rebar has been assembled.

In this way, different operations can be performed simultaneously in the upper and lower directions, so that the operation efficiency is extremely improved, and the posture control mechanism, the peripheral surface friction reducing mechanism, and the like enable reliable and highly accurate construction.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, while excavating the blade part of a lower caisson and laying a caisson, different works can be performed simultaneously at the upper and lower parts of the caisson, such as rebar assembly at the upper part, concrete placing work, and the like. Since frame assembling and dismantling operations are not required, workability is improved, and the construction period can be significantly reduced.

In addition, the reliable excavation under the cutting edge, the reduction of the peripheral friction, and the posture control mechanism ensure reliable and accurate construction regardless of the properties of the ground.

As described above, a reliable and accurate open caisson that is suitable for large depth construction, has a short construction period, and can be constructed.

[Brief description of the drawings]

The drawings show the construction method of the open caisson of the present invention, FIG. 1 is an overall explanatory view, FIG. 2 is a sectional view of an underwater excavator mounting portion, FIG. 3 is an enlarged sectional view of a sliding formwork device, FIG. Figure, fifth
FIG. 6 and FIG. 6 are explanatory views of different caisson pressing devices. FIG. 4 (A) is a plan sectional view, FIG. 4 (B) is a front view,
5 (A) is a plan sectional view, (B) is a front view, (C) is an enlarged view, FIG. 6 (A) is a plan sectional view, (B) is a front view,
FIG. 7 is an explanatory view of a caisson lower posture and position control device, FIGS. 8 (A) and (B) are explanatory diagrams of a high-pressure water jet peripheral surface friction removing device, and FIGS. 9 (A) and 9 (B) are slippers. It is explanatory drawing of a material leakage prevention member.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location E02D 23/14 102 E02D 23/14 102 E02F 3/30 E02F 3/30 Z E04G 11/20 E04G 11 / 20 (72) Inventor Shuzo Fukumoto 1779-3 Ikeda Shitamachi, Izumi City, Osaka Prefecture 1-301 Familie Plaza Komeiike (72) Inventor Katsuhiro Moriyama 1117-2 Oishi Nishiyuma, Omiya City, Saitama Prefecture (72) Inventor Yutaka Nakajima Kanagawa 3-1-14-106, Higashi-Yurigaoka, Aso-ku, Kawasaki City, Japan (72) Inventor Yoshitomo Tani 4-1-1, 503-503, Tsurugashima-cho, Iruma-gun, Saitama Prefecture (56) References JP-A-48-19014 (JP, A) JP-A-63-44019 (JP, A) JP-A-1-190876 (JP, A) JP-A-60-172896 (JP, U) JP-B-48-14087 (JP, B1) JP-B-61 −27527 (JP B2) Tokuoyake Akira 54-9809 (JP, B2)

Claims (8)

(57) [Claims] An underwater excavation machine operable from the ground movably along a rail extending laterally on a lower inner wall of a caisson skeleton, a sliding formwork with a work floor on an upper part of the caisson skeleton,
A caisson presser is provided movably on the outer periphery of the caisson frame after a sufficient training period after concrete placement, and underwater excavation is carried out by the underwater excavation machine at the bottom of the caisson to discharge this excavated soil. A method for constructing an open caisson, comprising: simultaneously discharging the steel by means, assembling a reinforcing steel formwork on the upper part of the caisson, and subsequently placing concrete, while laying the caisson with the caisson pressing device. 2. The attitude and position of the caisson during sinking and the reaction force of the cutting edge, peripheral friction, and peripheral earth pressure acting on the caisson are constantly detected, and an offset load is applied by a caisson pressing device.
2. The method for constructing an open caisson according to claim 1, wherein the posture and the position of the excavation are controlled simultaneously with the subsidence by changing the shape of the excavation under the cutting edge depending on the location. 3. A plurality of jacks are arranged laterally along the outer periphery of the upper portion of the cutting edge rear surface friction cut at the lower part of the caisson, and the horizontal movement of the lower part of the caisson is caused by changing the pressure of each jack. 3. The method for constructing an open caisson according to claim 2, wherein the caisson attitude and position are controlled. 4. Using a high-pressure water jet pipe nozzle movable from the ground along a rail extending laterally to the lower inner wall of the caisson, thinly remove the earth and sand on the back side of the blade from immediately below the blade of the caisson. The method according to claim 1 or 2, wherein the friction of the peripheral surface of the back of the caisson blade is removed. 5. A lower end of a sliding material leakage prevention member, whose upper end spreads so as to follow the ground, is laterally locked along an outer peripheral portion of the skeleton on an upper portion of a cutting edge rear surface friction cut at a lower portion of the caisson. The construction method for an open caisson according to claim 1 or 2, wherein leakage of the sliding material interposed between the outer periphery of the caisson and the ground is prevented. 6. An underwater excavation machine operable from the ground movably along a rail extending laterally on a lower inner wall of a caisson body, a sliding formwork with a work floor installed on an upper part of the caisson body, and concrete casting An open caisson construction system, comprising a caisson depressing device movably installed on the outer periphery of the caisson frame after a sufficient training period after installation, and a device for detecting the position, posture, and settlement resistance of the caisson . 7. An inflatable bag made of metal, rubber or high-strength fiber is formed on the upper part of the cutting back surface of the caisson at the upper part of the cutting edge, and the jack is controlled by controlling the amount of the injection material injected into the bag. A plurality of sack-shaped jacks with the function of arranging them along the outer periphery of the caisson, changing the pressure of each jack from the ground, and moving the lower part of the caisson horizontally, a position control device The construction apparatus for an open caisson according to claim 6, comprising: 8. An upper and lower end of the caisson is located just below the back surface of the caisson and is extendable and contractable along the blade opening engaged with a base movably mounted on a lower inner wall of the caisson along a rail extending laterally. The open caisson construction apparatus according to claim 6, further comprising a high-pressure water jet peripheral friction removing device that can be bent freely.