JP7121108B2 - Open shield construction method combined with jacking method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an open shield construction method used in combination with a jacking method for constructing underground structures such as water supply and sewage systems and underground passages in urban areas.

The open shield construction method is a highly rational construction method that takes advantage of the advantages of the open cut construction method and the shield construction method. This is a construction method in which the box is laid inside.

As described in the following patent documents, the outline of the open shield construction method is to form a cutting edge at the front, rear, and top surfaces of the side wall plate and the bottom plate, which are composed of left and right side wall plates and a bottom plate connected to these side wall plates. An open shield machine is used in which shield jacks are arranged vertically in the center or near the rear end of the open shield machine body facing rearward.
JP 2009-108570 A

This open shield machine is installed in the starting pit, the shield jack of the open shield machine is extended, the reaction force is applied to the reaction wall in the starting pit, and the open shield machine is advanced to form the underground structure. Lower the concrete box from above and set it behind the contracted shield jack in the tail part of the open shield machine. A strut is placed between the shield jack and the reaction wall to adjust the spacing as appropriate.

In addition, the starting hole is composed of a retaining wall, and in order to start the open shield machine, a part of this retaining wall is cut off, but if necessary, the ground in front of the starting hole is improved by injecting chemicals etc. Sometimes.

An excavator such as a shovel is used to excavate and discharge earth and sand from the front or top surface of the open shield machine 1 . Simultaneously with or after this discharging process, the shield jack is extended to move the open shield machine 1 forward. In the case of this forward process, a press bar consisting of a frame made of box steel or shaped steel is arranged in front of the concrete box 4, and the open shield machine takes reaction force from the concrete box set behind.

Then, the second concrete box is lowered in the tail part of the open shield machine in front of the first concrete box. Thereafter, the same earth-discharging process, forwarding process, and concrete box setting process are repeated as appropriate, and the concrete boxes are sequentially left in the ground in series as the open shield machine 1 advances. Put backfill soil on top.

In this way, when the open shield machine reaches the arrival pit, it is removed and the construction is completed.

By the way, as described in the following patent documents, there are cases where a jacking method for propelling a concrete box with a jack is used together with the open shield method as described above.
Japanese Patent No. 2759445

The open shield construction method combined with the jacking method will be described below. 27 to 31 show a schematic construction flow. The open shield machine 1, as shown in FIGS. It is a shield machine with an open rear surface and an upper surface.

In the open shield machine 1, the width of the concrete box 4 to be laid and the width of the shield machine are the same. The shield jacks 3 are arranged vertically facing rearward. Of the cutting edge, the side wall portion is divided and formed as a slide type earth retaining 16 so as to be movable, and the bottom plate portion is formed as a movable split bottom plate 18 and a bottom plate jack 19 is provided. The slide-type earth retaining 16 is for preventing the collapse of the ground at the side during excavation, and extends and contracts from the tip of the open shield machine 1 up to 1.0 m.

Reference numeral 14 in the figure denotes a partition provided at the back of the cutting edge, which may be used as a drainage gate. Reference numeral 15 in the figure denotes a press bar 15 which is placed between the shield jack 3 and the leading concrete box 4 to transmit thrust to the leading concrete box 4, and which is formed of a steel frame.

As shown in Figures 23 and 24, a starting shaft 8 was constructed at the starting base for the installation and assembly of the box and the shield machine. An arrival shaft 13 is constructed for the dismantling and removal of the machine. Earth retaining methods for constructing vertical shafts include the steel sheet pile method, the main pile horizontal sheet pile method, the liner plate method, and the like.

In the starting vertical shaft 8, the bearing wall 22 for supporting the reaction force of the main pushing jack 23 is constructed at the innermost part by a method of assembling steel materials in a grid pattern, or by a method of using plain concrete or reinforced concrete, and a steel material are assembled and the original pushing jack 23 is installed.

In the starting shaft 8, the shield machine is assembled by first arranging H steel in a rail shape and installing an iron plate on the entire surface to form a cradle 25, and in order to maintain the straightness of the shield machine and the box, A guide steel 26 made of H steel is installed on both sides of the machine.

After completing the assembly of the open shield machine 1, the concrete box 4 is suspended into the vertical shaft by the lifting machine 31 (see FIG. 27) on the starting shaft 8, and the concrete box 4 is placed between the main pushing jack 23 and the shield machine. is installed, and the open shield machine 1 and the installed concrete box body 4 are propelled by the original pushing jack 23.

As shown in FIGS. 21 and 22, behind the open shield machine 1 are the press bar 15, the front concrete box 4, and the concrete box 4 behind them. It is tied with a PC steel bar and becomes fixed.

The press bar 15 is connected to the open shield machine 1 by a PC steel wire 29 and a traction jack 30. In order for the open shield machine 1 to move forward with the reaction force of the press bar 15, the PC steel wire 29 is loosened by the traction jack 30. When the open shield machine 1 advances together with the concrete box 4 by propelling the entire concrete box 4 with the press bar 15, the PC steel wire 29 is tensioned by the traction jack 30, and the open shield machine 1 and the press bar 15 are separated. be united.

A strut 24 is provided when the extension width of the original pushing jack 23 is insufficient. (See Figure 23)

For excavation, as shown in FIGS. 19 and 20, the ground in the face is excavated by an excavator 6 such as a backhoe, and side earth retaining is carried out by a slide type earth retaining 16 to prevent the side of the natural ground from collapsing. While excavating, the open shield machine 1 is propelled.

In FIG. 21, 20 is a friction cut plate installed to cut the edges of the box and backfill material and to propel only the box. Install from place.

Propulsion of the open shield machine 1 is carried out by a shield jack 3 mounted inside the shield machine, which transmits a propulsive reaction force to the top concrete 4a via a press bar 15, which is then transmitted to the box 4 laid behind it to propel it forward. The press bar 15 is tied to the open shield machine 1 by PC steel wires 29 .

Next, the main pushing jack 23 is used with the bearing wall as a reaction force to move to box propulsion in which all the laid concrete boxes 4 are propelled. As the open shield machine 1 is advanced, backfill soil 5 is applied to the upper part of the box behind the open shield machine 1 with sand or the like.

In this way, the step of excavating and discharging earth and sand in front of the front or top opening of the open shield machine 1, and the front concrete box 4 connected to the rear via the press bar 15 by extending the shield jack 3 , the step of advancing the shield machine by using the subsequent concrete box 4 as a reaction force, pushing out the concrete box 4 with the pushing jack 23 installed in the starting shaft 8, and pushing out the pushing jack 23 and the pushed concrete box A new concrete box body 4 is arranged between 4 and the process of repeating extrusion is repeated, and the open shield machine 1 is made to reach the arrival shaft 13.例文帳に追加

19 and 20 when the thrust for pushing the open shield machine 1 and the concrete box 4 is insufficient or the reaction force of the bearing wall is insufficient only with the main pushing equipment with the main pushing jack 23. A middle pressing facility 21 is provided as follows.

As shown in FIGS. 16 and 17, the center pushing equipment 21 has a collar 21a, which is a cylindrical steel body, as its main body, and has a center pushing jack 27 disposed therein. After determining whether the thrust of the primary pushing jack 23 is insufficient and propelling a predetermined number of propulsion boxes, the intermediate pushing equipment 21 is installed, the primary pushing jack 23 is extended, and the intermediate pushing equipment 21 is arranged. The entire concrete box body 4 is propelled while it is held.

A press bar 28 is arranged between the concrete box 4 and the intermediate pushing jack 27 also in the case of this intermediate pushing equipment 21 .

In addition, when using this intermediate pushing equipment 21, the steel collar 32 may be arranged in the connection part of concrete box 4 comrades.

In this way, the concrete boxes 4 are propelled one by one, and at the stage of laying and propelling the boxes in places where the propulsive force of the original pushing jack 23 is assumed to be insufficient, after the open shield machine 1 is propelled, The shield jack 3 is returned, the intermediate pushing jack 27 is extended by the vacant space, and all the concrete boxes 4 ahead of the intermediate pushing equipment are pushed forward.

After propulsion, the intermediate pushing jack 27 is returned, the original pushing jack 23 in the starting shaft 8 is extended, and all the concrete boxes 4 behind the intermediate pushing equipment 21 are pushed forward.

When the concrete box 4 is propelled, a lubricant 35 is injected to reduce the friction between the concrete box 4 and the natural ground. (See Figure 21)

After the promotion and installation of the box 4 are completed and the open shield machine 1 reaches the arrival shaft 13, the shield machine 1 is dismantled and removed in the arrival shaft. (See Figure 30)

Finally, when the concrete box 4 is completely laid, a back-filling injection material such as cement milk is injected so as to replace the lubricant 35 in the slight gap between the concrete box 4 and the natural ground. As shown in FIG. 31, injection filling is performed from the inside of the concrete box 4 through the grout holes 34 of the concrete box 4 using the injection nozzle 36 . If there is a friction cut plate 20, backfill the top plate as well.

In such an open shield construction method in combination with the jacking method, the open seal machine 1 and the press bar 15 are connected to the towing jack 30 and the PC so that the press bar 15 can be fixed and released as necessary in the open seal machine 1 as described above. They are connected by steel wires 29 .

Also, the press bar 15 is tightly fixed to the leading concrete box 4 with a PC steel bar.

For propulsion of the open shield machine 1, first, the traction of the traction jack 30 attached to the press bar 15 is loosened, the tightness of the PC steel wire 29 is loosened, and the jack cylinder of the shield jack 3 is extended backward. It is transmitted to the front concrete box 4 at the rear through the main body press bar 15, and the open shield machine 1 is propelled.

After the open shield machine 1 propels the predetermined length, the shield jack 3 is shortened, the main push jack 23 in the starting shaft 8 is extended, and the concrete box 4 that has been laid, the concrete box at the top, and the press bar 15 All are pushed forward, the press bar 15 is pushed into the rear end of the open shield machine 1, and the loosened PC steel wire 29 is brought into close contact with the predetermined position of the rear end of the open shield machine 1 by the pulling jack 30. . Repeat the above operations.

The operation of the intermediate pushing equipment 21 is as follows. As described above, after the concrete box 4 is thrown into the starting shaft 8 by the lifting machine 31 and installed at a predetermined position, the main pushing jack 23 is extended to propel the box sequentially forward. 16 and 17 show the laid concrete box 4 in front of the intermediate pushing equipment 21 shown in FIGS. It is propelled by an intermediate pushing jack 27 arranged in the intermediate pushing equipment.

After propulsion, the cylinder of the intermediate pushing jack 27 is contracted, the rearward laying box is pushed forward from the intermediate pushing equipment 21 shown in FIG. Push the 27 cylinder into the space created by shrinking it.

By the above-described propulsion of the open shield machine and the operation of the intermediate pushing equipment, the concrete box 4 is successively thrown into the starting pit 8, installed and then propelled, and this operation is repeated.

When the open shield machine 1 is used for propulsion or when the concrete box 4 is extruded by the intermediate pressing equipment, the concrete box 4 is attached to the fitting skirt portion of the press bar, which is a tubular steel member, or to the collar body of the intermediate pressing equipment. When the outer circumference is surrounded and the operation of the open shield machine and the operation of the intermediate pressing equipment are performed while repeating the above operation, the fitting parts come into contact with each other, so chipping and cracking of the fitting part of the concrete box 4 may occur. Such damage may occur, and the durability of the concrete box 4 may be lowered.

Although the press bar 15 is tightly fixed to the front concrete box 4 with a PC steel bar, if a cushioning material such as rubber is interposed between the press bar 15 and the concrete box 4, the fit may be displaced, and the chipping may occur. and damage such as cracks.

In addition, the concrete box 4 is rectangular, and the fitting skirt portion of the press bar, which is a steel cylindrical member that is fitted to the concrete box 4, and the collar body of the intermediate pressing equipment are also rectangular. The protruding corner of the part is easily chipped.

It is an object of the present invention to eliminate such conventional inconveniences and prevent deterioration in the durability of the fitting portion of the leading concrete box and the deterioration of the durability of the fitting portion of the concrete box that is fitted to the intermediate pushing equipment. To provide an open shield construction method combined with a jacking method and a concrete box used for the method.

In order to achieve the above object, the present invention uses an open shield machine, which is an open top shield machine, as an open shield construction method combined with a jacking method, and excavates and discharges earth and sand in front of the front or top opening of the open shield machine. , the process of extending the shield jack and using the concrete box as a reaction force to advance the open shield machine, and the concrete box to fill the advance of the advanced open shield machine Push out with a pushing jack or a middle pushing jack of a middle pushing facility provided between the concrete box to be laid and the concrete box, and then arrange a new concrete box between the original pushing jack or middle pushing jack and the pushed concrete box. In the open shield construction method that combines a concrete box promotion process in which the concrete box is repeatedly pushed out, a press bar having a skirt part for fitting to the concrete box is arranged between the shield jack and the concrete box head, and the concrete box is pushed out. A steel member is attached to the protruding corner of the fitting part at the front end of the box, and this is fitted into the fitting skirt part of the press bar, and the shield jack of the open shield machine propels the press bar and concrete box. It can be extended as a reaction force, or the middle pushing equipment has a collar that is a steel cylinder with one end as the fitting part of the concrete box, and the concrete box is at the outer corner of the fitting part at the front end. A steel member is attached, and this is fitted into the collar of the intermediate pressing equipment in which the press bar is placed. The gist of this is to push out.

According to the present invention of claim 1, since the steel members are attached to the protruding corners of the corners of the fitting portion at the front end of the concrete box, even if the fitting portion of the press bar is made of steel, the Even if contact occurs due to repeated movements, the contact portion is made of the same material, so there is no risk of chipping or cracking of the concrete.

According to the second aspect of the present invention, since the steel mold member is attached to the outer corner of the corner of the fitting portion of the concrete box that is fitted to the intermediate pressing equipment, the collar of the intermediate pressing equipment made of steel is attached. As for the concrete box to be fitted, even if the fitting part of the concrete box 4 is repeatedly moved back and forth, even if the fitting part of the intermediate pressing equipment and the concrete box 4 come into contact repeatedly, the steel members will not contact each other. Therefore, there is no risk of chipping or cracking of the concrete.

As described above, the open shield construction method in combination with the jacking method of the present invention reduces the durability of the fitting portion of the leading concrete box and the durability of the fitting portion of the concrete box that is fitted to the intermediate pushing equipment. can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal side view showing an embodiment of an open shield construction method combined with a jacking method and a concrete box body used therein according to the present invention; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional plan view showing an embodiment of an open shield construction method combined with a jacking method and a concrete box body used therein according to the present invention; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional front view of an essential part showing an embodiment of an open shield construction method combined with a jacking method and a concrete box body used therein according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional side view of a main part showing an embodiment of an open shield construction method combined with a jacking method of the present invention and a concrete box body used therein. FIG. 5 is an enlarged vertical cross-sectional side view of FIG. 4; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged vertical cross-sectional front view of an essential part showing an embodiment of an open shield construction method combined with a jacking method and a concrete box body used therein according to the present invention; FIG. 2 is a cross-sectional plan view showing a second embodiment of the open shield construction method combined with the jacking method of the present invention and a concrete box body used therein. It is a longitudinal side view which shows 2nd Embodiment of the open shield construction method of this invention combined with the jacking method and the concrete box body used for it. It is a longitudinal front view showing a second embodiment of the open shield construction method combined with the jacking method of the present invention and the concrete box body used therefor. It is a longitudinal side view of the principal part which shows 2nd Embodiment of the open shield construction method of this invention combined with the jacking method and the concrete box body used for it. 11 is an enlarged vertical cross-sectional side view of FIG. 10; FIG. It is an enlarged longitudinal front view of the main part showing the second embodiment of the open shield construction method combined with the jacking method of the present invention and the concrete box used therefor. It is a longitudinal side view showing a conventional example. It is a horizontal vertical plan view showing a conventional example. It is a longitudinal front view showing a conventional example. and FIG. 11 is a longitudinal side view showing another conventional example. and FIG. 11 is a cross-sectional plan view showing another conventional example. FIG. 11 is a longitudinal front view showing another conventional example; BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal side view which shows the outline|summary of the open shield construction method of a jacking method combination. It is a cross-sectional plan view showing the outline of the open shield construction method combined with the jacking method. It is a longitudinal side view of the open shield machine used by the open shield construction method. It is a horizontal vertical plan view of the open shield machine used by the open shield construction method. It is a longitudinal side view of the starting shaft of the open shield construction method combined with the jacking method. It is a cross-sectional plan view of the starting shaft of the open shield construction method combined with the jacking method. It is a longitudinal front view of the starting shaft of the open shield construction method combined with the jacking method. It is a longitudinal front view of the main part of the starting shaft of the open shield construction method combined with the jacking method. It is a side view which shows the 1st process of the open shield construction method of a jacking method combination. It is a side view which shows the 2nd process of the open shield construction method of a jacking method combination. It is a side view which shows the 3rd process of the open shield construction method of a jacking method combination. It is a side view which shows the 4th process of the open shield construction method of a jacking method combination. It is a vertical front view which shows a lubricating agent injection|pouring condition.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a vertical cross-sectional side view showing one embodiment of the open shield construction method combined with the jacking method of the present invention, and FIG. 2 is a cross-sectional plan view of the same. As a construction method, it is the case of the open shield construction method combined with the jacking method.

Using an open shield machine 1, which is a top open shield machine, a process of excavating and discharging earth and sand in front of the front or top opening of the open shield machine 1, and extending the shield jack 3 to turn back the concrete box 4. A step of advancing the open shield machine 1 by force, and a concrete box and a concrete box for laying a concrete box 4 as a main pushing jack of the starting pit or laying it to fill the advanced portion with respect to the advanced open shield machine 1. Pushing out with a middle pushing jack of a middle pushing equipment provided between, after that, a new concrete box 4 is arranged between the main pushing jack or the middle pushing jack and the extruded concrete box, and pushing out is repeated. This is an open shield construction method that combines processes.

In the figure, 3 is a shield jack, 16 is a slide type earth retainer, and 17 is a slide jack for moving the slide type earth retainer 16. The details of the open shield machine 1 are as described with reference to FIGS. 21 and 22. .

Between the concrete box 4 and the shield jack 3 of the open shield machine 1, a press bar 15, which is a cylindrical member made of steel, is set. It is tightened and fixed to the box 4 .

In addition, the press bar 15 and the open shield machine 1 are fixed and released by a PC steel wire (not shown) for fixing the towing jack 30 to the press bar 15 and one end thereof to the open shield machine 1 as necessary. connected as possible.

The press bar 15 is provided with a skirt portion 38 for fitting to the concrete box 4 . This fitting skirt portion 38 is a tubular frame made of steel.

On the other hand, steel members 40 which are angle members having anchors 40a were attached to four protruding corners of the corners of the fitting portion of the concrete box 4 . The steel member 40 of the angle material is installed so that the outer surface of the external corner of the fitting portion of the concrete box 4 is on the same plane.

The anchor 40a is fixed toward the inner surface of concrete of the leading concrete box 4, and the other end is fixed to the inner surface of the steel member 40 by welding. Although two anchors 40a are shown in the figure, it is necessary to increase the length of the steel member 40 when the head concrete box 4 is large and the fitting portion of the concrete box 4 is long. , three or more may be installed.

Although illustration is omitted, a separate plate is installed, welded and fixed so that it fits inside the cross section of the steel member 40 shown in FIG. It is also possible to increase the rigidity of the reinforcing steel material by increasing the rigidity of the reinforcing steel material and prevent the fitting part of the front concrete box 4 from repeatedly moving and the tip of the reinforcing steel material from coming into contact with the fitting skirt part 38 of the press bar 15 and peeling off.

A cushioning material 39 made of rubber is attached to the front end face of the concrete box 4, and this cushioning material 39 is interposed when the press bar 15 is fitted to the fitting portion of the leading concrete box 4 via the skirt part 38 for fitting.

The concrete box 4 and the press bar 15 are tightly fixed with a PC steel bar (not shown), and when the concrete box 4 is propelled by the main pushing jack of the starting pit, both are propelled together.

The open shield machine 1 is propelled by extending the shield jack 3 and excavating only the open shield machine 1 with the reaction force of the concrete box 4 and the press bar 15, and when the open shield machine 1 is a concrete box with the press bar 15. Both cases of moving forward together with the concrete box 4 by propulsion of the whole body 4 can be selected.

In the latter case, the PC steel wire is tensioned by a pulling jack 30, and the open shield machine 1 and the press bar 15 are integrated.

In this way, even if the fitting portion of the front concrete box 4 moves and contacts within the fitting skirt portion 38 of the press bar 15, it is protected by the steel member 40, so chipping or cracking of the concrete can occur. None.

Next, a second embodiment of the invention will be described. FIGS. 7 and 8 show the case of using the intermediate pushing equipment 21. The intermediate pushing equipment 21 has a collar 21a, which is a cylindrical steel body, as its main body, and has an intermediate pushing jack 27 inside.

An end portion of the collar 21 a serves as a fitting portion 43 to the concrete box 4 .

Reference numeral 28 in the figure denotes a press bar arranged on the end surface of the concrete box 4 when installing the intermediate pressing equipment 21 .

When the press bar 28 is installed, a buffer material 39 made of rubber is attached to the front end face of the concrete box 4, and the press bar 28 is pressed thereon.

In this case as well, the concrete box 4 is attached with steel members 40 which are angle members having anchors 40a at four protruding corners of the corners when connecting/fitting to the intermediate pushing equipment 21 .

The steel member 40 is installed with a length up to the fitting portion 43 of the collar 21a. In order to insert the concrete box into the intermediate pushing equipment 21 up to the tip of the collar 21a, the steel members 40 may be intermittently installed at predetermined intervals up to the steel collar side.

In this way, the concrete box 4 is propelled by the intermediate pushing jack 27 of the intermediate pushing equipment 21, but even if the fitting portion of the concrete box 4 moves or comes into contact with the intermediate pushing equipment 21, it is protected by the steel member 40. Therefore, chipping and cracking of concrete do not occur.

DESCRIPTION OF SYMBOLS 1... Open shield machine 1a... Side wall plate 1b... Bottom plate 3... Shield jack 4... Concrete box 5... Backfilling soil 6... Excavator 8... Starting pit 13... Arrival pit 14... Partition wall 15... Press bar 16... Sliding soil Fastening 17 Slide jack 18 Operation split bottom plate 19 Bottom plate jack 20 Friction cut plate 21 Intermediate pushing equipment 21a Collar 22 Bearing wall 23 Primary pushing jack 24 Strut 25 Catch 26 Guide steel 27 Intermediate pushing Jack 28 Press bar 29 PC steel wire 30 Traction jack 31 Lifting machine 32 Steel collar 34 Grout hole 35 Lubricant 36 Injection nozzle 38 Fitting skirt 39 Cushioning material (rubber) 40 Steel Made member 40a... Anchor 43... Fitting part

Claims (2)

Using an open shield machine, which is a top open type shield machine, the process of excavating and removing earth and sand in front of the front or top opening of the open shield machine, and extending the shield jack to open the concrete box by reaction force. The process of advancing the shield machine, and the intermediate pushing equipment provided between the concrete box to be laid and the concrete box to fill the advance of the forwarded open shield machine. In the open shield construction method, a step of pushing out with an intermediate pushing jack, then placing a new concrete box between the main pushing jack or the pushing jack and the extruded concrete box, and pushing out the concrete box repeatedly, is combined. A press bar with a skirt portion for fitting to the concrete box is arranged between the shield jack and the front end of the concrete box, and the concrete box is a steel member at the outer corner of the fitting part at the front end. and inserting it into the fitting skirt of the press bar, and the shield jack of the open shield machine extends the press bar and concrete box as a propulsive reaction force. Using an open shield machine, which is a top open type shield machine, the process of excavating and removing earth and sand in front of the front or top opening of the open shield machine, and extending the shield jack to open the concrete box by reaction force. The process of advancing the shield machine, and the intermediate pushing equipment provided between the concrete box to be laid and the concrete box to fill the advance of the forwarded open shield machine. In the open shield construction method, a step of pushing out with an intermediate pushing jack, then placing a new concrete box between the main pushing jack or the pushing jack and the extruded concrete box, and pushing out the concrete box repeatedly, is combined. The main body of the intermediate pressing equipment is a collar, which is a steel cylinder with one end fitted to the concrete box. The concrete box has a steel member attached to the outer corner of the front end fitting part, and is pressed. The jacking method is characterized in that the bar is fitted into the collar of the intermediate pushing equipment placed inside, and the intermediate pushing jack of the intermediate pushing equipment extends the rear concrete box as a propulsion reaction force, pushing out the press bar and the front concrete box. open shield construction method.

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