JP5503219B2 - Middle push device - Google Patents

Description

  The present invention is provided in the middle of a steel shell that is connected in series between a drilling machine for excavating a natural ground and a main pushing device provided in a starting vertical shaft, and is located more than the installation position. The present invention relates to an intermediate pushing device that pushes forward a steel shell forward and absorbs the pushing stroke of the pushing device to reduce the driving force of the pushing device.

  As shown in FIG. 1, a plurality of steel shells 4 are interposed in series between an excavator 1 for excavating a natural ground and a main pushing device 3 arranged in the start shaft 2. A propulsion method is known in which the excavator 1 is pushed forward through the shell 4.

  In this propulsion method, when the excavation distance, that is, the distance from the main pushing device 3 to the excavator 1 is increased, the sliding contact area between the side surface of the steel shell 4 and the ground is increased, and the frictional resistance is increased. It may be necessary to increase the driving force of the pushing device 3 and the construction becomes difficult. Therefore, in the case of a long-distance propulsion method, an intermediate pushing device 5J is interposed in the middle of the steel shell 4, the steel shell 4 ahead of the interposed position is pushed forward by the intermediate pushing device 5J, and the extrusion stroke of the main pushing device 3 Is used by the intermediate pushing device 5J (see Patent Documents 1 and 2).

  As shown in FIG. 1, a conventional intermediate pushing device 5J includes a front cylinder 6J connected to a front steel shell 4, and a rear cylinder 7J connected to a rear steel shell 4 and whose front part overlaps with the rear part of the front cylinder 6J. And a seal 8J that is provided on the inner peripheral surface of the rear portion of the front cylinder 6J and closes the outer peripheral surface of the rear cylinder 7J, and an intermediate push jack 9J interposed between the front cylinder 6J and the rear cylinder 7J. Yes. When the main pushing device 3 pushes the front steel shell 4 forward, the middle pushing device 5J absorbs the extrusion stroke of the main pushing device 3 by contracting the middle pushing jack 9J. In this state, the intermediate push jack 9J is extended to push the steel shell 4 in front of the intermediate pusher 5J forward to advance the excavator 1.

JP-A-8-246789 Japanese Patent Laid-Open No. 7-18978

  In the conventional center pushing device 5J, since the seal 8J is provided between the front trunk 6J and the rear trunk 7J that receive the earth load from the natural ground, the front trunk 6J receives the earth load from the natural ground. The seal 8J may be crushed by bending inward. If the expansion and contraction of the intermediate push jack 9J is repeated in a state where the seal 8J is crushed in this way, the seal 8J may be damaged due to repeated sliding, and water stoppage may not be performed normally. In particular, when the construction is carried out at a deep depth or when a natural ground made of earth and sand having a heavy weight per unit volume is constructed, the earth load is increased, so that the seal 8J is easily crushed and the above-described problem is likely to occur.

  Moreover, when the cross section of the steel shell 4 is a rectangle, the front trunk | drum 6J and the rear trunk | drum 7J of the intermediate pushing apparatus 5J also become a rectangular cross section, and the bending amount of the center part of each side of a rectangle is compared with the bending amount of the corner part of four corners. Since it becomes large, crushing of the seal 8J in the center portion becomes remarkable, and the seal 8J is easily damaged. In this case, since the seal 8J is also in the shape of a rectangular ring, water stoppage tends to be unstable at the corners of the four corners.

  Accordingly, an object of the present invention is to provide an intermediate pressing device that can avoid the collapse of the seal due to earth load and that has improved the water-stopping property of the seal.

In order to achieve the above-mentioned object, the present invention is provided in the middle of a steel shell having a rectangular cross section arranged in series between a drilling machine for excavating a natural ground and a main pushing device arranged in a start shaft. An intermediate pushing device that pushes forward the steel shell forward from the interposed position, and is connected to the rear end of the front steel shell and is formed in a rectangular shape according to the shape of the steel shell; A rear wall connected to the front end of the rear steel shell and formed in a rectangular shape according to the shape of the steel shell, a front outer cylinder having a rectangular cross section attached to the front wall and in contact with a natural ground, and attached to the rear wall A front outer portion of the front outer cylinder that overlaps with the rear portion of the front outer cylinder in the axial direction with a gap in and out of the cylinder and has a rectangular cross section that touches the ground, and the front of the front outer cylinder inward a front inner tube of circular cross-section which is mounted at a space from the front outer cylinder on the wall, inwardly of the rear wall of the rear outer cylinder It mounted spaced the space from the rear outer sleeve, and the rear inner cylinder of circular cross-section which polymerize axially front portion across a gap to the rear and the cylindrical inner and outer direction of the front inner tube, and the front inner cylinder wherein A seal that closes a gap with the rear inner cylinder, and is interposed between the front wall inside the front inner cylinder and the rear wall inside the rear inner cylinder, and the front wall and the rear wall The space is formed by separating the front inner cylinder and the rear inner cylinder in the in-cylinder direction from the front outer cylinder and the rear outer cylinder, and the front outer cylinder. A rear outer cylinder, a front inner cylinder, a rear inner cylinder, a front wall and a rear wall, and a pipe for filling the space with the filler and for introducing and discharging the filler, the front wall and the rear wall Of at least one of them.

A plurality of steel shells connected in series between the excavator for excavating the natural ground and the main pushing device arranged in the start shaft are installed in the middle of the steel shell, and the steel shell in front of the installation position is inserted. An intermediate pushing device that pushes forward, a front wall connected to the rear end of the front steel shell, a rear wall connected to the front end of the rear steel shell, and a front outer cylinder attached to the front wall; A rear outer cylinder that is attached to the rear wall and whose front part overlaps the rear part of the front outer cylinder in the axial direction with a gap in and out of the cylinder, and the front wall inside the front outer cylinder. An attached front inner cylinder, and a rear inner cylinder attached to the inner rear wall of the rear outer cylinder, wherein the front part overlaps the rear part of the front inner cylinder and the inner and outer directions in the axial direction with a gap therebetween. A seal for closing a gap between the front inner cylinder and the rear inner cylinder; the front wall inside the front inner cylinder; and the rear wall inside the rear inner cylinder Interposed between, and a center push jacks adjacent separating the front wall and the rear wall above the front wall is divided into an outer front wall and the inner front wall to said tube inner and outer direction, the rear wall , Divided into an outer rear wall and an inner rear wall in the cylinder inner / outer direction, the front outer cylinder is attached to the outer front wall, the rear outer cylinder is attached to the outer rear wall, A cylinder is attached to the inner front wall, the rear inner cylinder is attached to the inner rear wall, and a front engagement / disengagement means for engaging / disengaging them is provided on the outer front wall and the inner front wall, A rear engaging / disengaging means for engaging / disengaging them may be provided on the outer rear wall and the inner rear wall.

  According to the intermediate pushing device according to the present invention, the seal can be prevented from being crushed by a soil load, and the water-stopping property of the seal can be increased.

It is explanatory drawing which shows an excavator, a main pushing apparatus, and the conventional intermediate pushing apparatus. It is a sectional side view of the intermediate pushing apparatus which concerns on one Embodiment of this invention. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. It is the IV-IV arrow line view of FIG. FIG. 5 is a view taken along line VV in FIG. 2. It is explanatory drawing showing the action | operation of the intermediate pressing apparatus which concerns on the said embodiment, (a) is the operation | movement process 1, (b) shows the operation | movement process 2, (c) shows the operation | movement process 3. FIG. It is explanatory drawing which shows a mode that the intermediate pushing apparatus which concerns on the said embodiment is disassembled and collect | recovering partially, (a) shows the disassembly process 1 and (b) shows the disassembly process 2. FIG.

  An embodiment of the present invention will be described with reference to the accompanying drawings.

  A plurality of intermediate pushing devices 5 according to the present embodiment are connected in series between an excavator 1 for excavating natural ground and a main pushing device 3 disposed in the start shaft 2 as in the conventional intermediate pushing device 5J shown in FIG. It is interposed in the middle of the steel shell 4 which is connected and disposed, and the excavator 1 is moved forward by pushing the steel shell 4 ahead of the interposed position to absorb the extrusion stroke of the main pushing device 3. Thus, the propulsive force applied to the main pushing device 3 is reduced.

  As shown in FIG. 2, the intermediate pushing device 5 includes a front wall 6 connected to the rear end of the steel shell 4 on the front side, that is, the side where the excavator 1 is arranged, and the rear side, ie, the side on which the main pushing device 3 is arranged. The rear wall 7 connected to the front end of the steel shell 4, the front outer cylinder 8 attached to the front wall 6, the rear wall 7 is attached to the rear wall 7, and the front part is the rear part of the front outer cylinder 8 and the in-cylinder direction. And a rear outer tube 9 that is superposed in the axial direction with a gap A therebetween.

  Further, the intermediate pushing device 5 is attached to the front inner cylinder 10 attached to the inner front wall 6 of the front outer cylinder 8 and the inner rear wall 7 of the rear outer cylinder 9, and the front part is the front inner cylinder. 10, a rear inner cylinder 11 that overlaps in the axial direction with a gap B between the rear and inner cylinders, a seal 28 that closes the gap B between the front inner cylinder 10 and the rear inner cylinder 11, and the inner side of the front inner cylinder 10. The intermediate wall jack 6 is interposed between the front wall 6 and the inner rear wall 7 of the rear inner cylinder 11, and has an intermediate pushing jack 12 that moves the front wall 6 and the rear wall 7 close to and away from each other.

  The steel shell 4 is a rectangular tube having a rectangular cross section as shown in FIGS. 3 to 5, has a predetermined length in the axial direction as shown in FIG. 1, and is connected in series by a fastener such as a bolt and nut. ing.

  The front wall 6 is formed in a rectangular shape in accordance with the shape of the steel shell 4 as shown in FIGS. 3 to 5, and as shown in FIG. 2, the outer front wall 6a and the inner front wall 6b are arranged in the cylinder outer direction. It is divided. Similarly, the rear wall 7 is also formed in a rectangular shape in accordance with the shape of the steel shell 4, and is divided into an outer rear wall 7a and an inner rear wall 7b in the cylinder inner / outer direction. A front communication port 13 is formed in a circular shape in the central portion of the inner front wall 6b, and a rear communication port 14 is formed in a circular shape in the central portion of the inner rear wall 7b. A line for supplying current, hydraulic pressure, and the like from the start shaft 2 to the excavator 1 is inserted into the front communication port 13 and the rear communication port 14.

  Further, the rear wall 7 includes an extension cylinder 7c formed in a square cylinder shape according to the outer shell shape of the steel shell 4, and a square ring attached to the rear end of the extension cylinder 7c according to the end shape of the steel shell 4. And a reinforcing rib 7e attached to the inner peripheral surface of the extension tube 7c, and the steel shell 4 is connected to the flange 7d. However, the extension cylinder 7c, the flange 7d, and the reinforcing rib 7e may be omitted, and the rear wall 7 may be configured similarly to the front wall 6.

  As shown in FIG. 2, the front part engagement / disengagement means 15 which engages / disengages them is provided in the junction part of the outer front wall 6a and the inner front wall 6b. The front engagement / disengagement means 15 includes a plurality of outer tapered holes 16 formed in the inner peripheral portion of the outer front wall 6a at intervals in the circumferential direction and a plurality of outer taper holes in the outer peripheral portion of the inner front wall 6b at intervals in the circumferential direction. The inner tapered hole 17 is formed, and the tapered pin 18 is inserted into and removed from the inner tapered hole 17 and the outer tapered hole 16 from the inside. Of course, the positions and taper angles of the outer tapered hole 16 and the inner tapered hole 17 are matched.

  Similarly, a rear engagement / disengagement means 19 for engaging / disengaging them is provided at the joint between the outer rear wall 7a and the inner rear wall 7b. A plurality of rear engagement / disengagement means 19 are formed in the inner peripheral portion of the outer rear wall 7a with a plurality of outer tapered holes 20 spaced in the circumferential direction, and a plurality of outer tapered portions 20 are formed in the outer peripheral portion of the inner rear wall 7b with a spacing in the circumferential direction. The inner tapered hole 21 and the tapered pin 22 inserted and removed from the inner tapered hole 21 and the outer tapered hole 20 from the inside.

  The front outer cylinder 8 is formed in a rectangular cross section as shown in FIG. 3 according to the outer shell shape of the steel shell 4, and its front part is attached to the outer front wall 6a as shown in FIG. . The rear outer cylinder 9 is formed in a rectangular section that is slightly smaller than the front outer cylinder 8, and the rear part is attached to the outer rear wall 7a. A predetermined gap A is formed between the outer peripheral surface of the rear outer cylinder 9 and the inner peripheral surface of the front outer cylinder 8. It should be noted that the inner and outer arrangements of the front outer cylinder 8 and the rear outer cylinder 9 may be reversed.

  A cover 23 is provided on the outer peripheral surface of the rear outer cylinder 9 as shown in FIG. The cover 23 is formed in a substantially rectangular tube shape, and its outer peripheral surface is formed so as to be flush with the outer peripheral surface of the front outer cylinder 8, the front end portion 23 a is formed in a slope shape, and the tip is outside the rear portion. The tube 9 is in contact with the outer peripheral surface. A plurality of reinforcing ribs 24 formed in a ring shape are provided inside the cover 23 at intervals in the axial direction. In addition, a plurality of reinforcing ribs 25 formed in a plate shape along the axial direction are provided on the inner peripheral surface of the rear outer cylinder 9 at intervals in the circumferential direction. The cover 23 and the reinforcing ribs 24 and 25 may be omitted.

  A front inner cylinder 10 and a rear inner cylinder 11 are disposed inside the front outer cylinder 8 and the rear outer cylinder 9.

  The front inner cylinder 10 has a circular cross section as shown in FIG. 3, and its front part is attached to the inner front wall 6b as shown in FIG. The rear inner cylinder 11 is formed in a circular shape that is slightly smaller than the front inner cylinder 10, and the rear part is attached to the inner rear wall 7 b. A stopper 26 for restricting the contraction stroke of the intermediate push jack 12 is detachably provided at a front portion of the rear inner cylinder 11 by a fastener 27 such as a bolt and nut. The stopper 26 restricts the contraction stroke of the intermediate push jack 12 by the tip (left end in FIG. 2) coming into contact with the inner front wall 6b, and prevents the front end of the rear outer cylinder 9 from coming into contact with the outer front wall 6a. . Note that the inside and outside arrangements of the front inner cylinder 10 and the rear inner cylinder 11 may be reversed.

  As shown in FIG. 2, a predetermined gap B is formed between the outer peripheral surface of the rear inner cylinder 11 and the inner peripheral surface of the front inner cylinder 10 in the cylinder inner and outer directions. 28 is disposed. The seal 28 is provided on the inner peripheral surface of the rear portion of the front inner cylinder 10, and is similarly disposed with a water stop seal 29 disposed in an annular shape along the circumferential direction and spaced apart in the axial direction. It is comprised from the water seal 30 made and the dust seal 31 similarly arrange | positioned at intervals in the axial direction. However, one water stop seal 29 or 30 and the dust seal 31 may be omitted. The seal 28 may be provided on the rear inner cylinder 11.

  Between the inner front wall 6b on the inner side of the front inner cylinder 10 and the inner rear wall 7b on the inner side of the rear inner cylinder 11, there is an intermediate push jack 12 that brings the inner front wall 6b and the inner rear wall 7b close to and away from each other. A plurality are provided at intervals in the direction. The intermediate pushing jack 12 is expanded when the excavator 1 shown in FIG. 1 is pushed forward, and is contracted when the extrusion stroke of the main pushing device 3 is absorbed.

  That is, when the intermediate push jack 12 is extended with the extension stroke of the main pushing device 3 fixed, the front outer cylinder 8 and the front inner cylinder 10 are pushed forward, and the excavator 1 moves forward. Further, when the main pushing device 3 is extended in a state where the stroke of the extended intermediate pushing jack 12 is made free, the rear outer cylinder 9 and the rear inner cylinder 11 move forward, and the pushing stroke of the main pushing device 3 is absorbed.

  As shown in FIG. 2, a pipe 32 is attached to the outer front wall 6a. This pipe 32 is filled with a filling material (water, earth and sand water, oil, in a space S defined by the front outer cylinder 8, the rear outer cylinder 9, the front inner cylinder 10, the rear inner cylinder 11, the front wall 6 and the rear wall 7. Etc.) is introduced and discharged. The installation location of the piping 32 may be the outer rear wall 7a.

  The outer rear wall 7 a is provided with a pipe 34 for supplying a filler to the gap A between the front outer cylinder 8 and the rear outer cylinder 9. The extension cylinder 7 c is provided outside the extension cylinder 7 c and the cover 23. A pipe 35 for supplying a filler is provided.

  As shown in FIGS. 3 and 4, the outer front wall 6 a is formed with a manhole 36 communicating with the inside of the mine and the space S, and a lid 37 is attached to the manhole 36 so as to be opened and closed.

  The operation of this embodiment will be described.

  6 (a), 6 (b), and 6 (c), the intermediate pushing device 5 extends and retracts the middle pushing jack 12 to push the excavator 1 forward and the main pushing device 3. When the extrusion stroke is absorbed alternately, the front outer cylinder 8 and the rear outer cylinder 9 are always partially superposed in the axial direction during expansion and contraction of the intermediate push jack 12.

  For this reason, while the intermediate push jack 12 expands and contracts, the earth load of the natural ground D is always supported by the front outer cylinder 8 and the rear outer cylinder 9, and the front inner cylinder 10 and the rear inner cylinder 11 disposed inward thereof. Has almost no effect. Therefore, the seal 28 disposed in the gap B between the front inner cylinder 10 and the rear inner cylinder 11 is not crushed by the earth load. Therefore, even if the seal 28 is repeatedly slid along with the expansion and contraction of the intermediate push jack 12, the seal 28 is not damaged, and the reliability and durability of the seal 28 can be improved.

  Since the gap A is separated between the front outer cylinder 8 and the rear outer cylinder 9, even if the front outer cylinder 8 bends inward due to earth load, the bent front outer cylinder 8 is the rear part. There is no contact with the outer cylinder 9. That is, the gap A is set to a size such that the bent front outer cylinder 8 does not contact the rear outer cylinder 9 in anticipation of the amount of bending of the front outer cylinder 8 due to earth load. In addition, the bending produced by the earth load on the rear outer tube 9 is suppressed by the reinforcing ribs 24 and 25.

  The intermediate pushing device 5 includes a front inner cylinder 10 and a rear inner cylinder 11 having a circular cross section inside the front outer cylinder 8 and the rear outer cylinder 9 formed in a rectangular cross section in accordance with the outer shell shape of the steel shell 4. The seal 28 is provided between the front inner cylinder 10 and the rear inner cylinder 11. Therefore, even when the steel shell 4 has a rectangular cross section, an annular seal 28 can be used. When the steel shell 4 has a rectangular cross section as in the conventional type shown in FIG. Compared with the case where it becomes a shape, the situation where the water stop becomes unstable at the four corners of the seal 8J can be avoided, and the water stop of the seal 28 can be increased.

  When the intermediate push jack 12 is contracted from the state of FIG. 6A as shown in FIG. 6B and FIG. 6C, the distance between the front wall 6 and the rear wall 7 is reduced, and the front outer cylinder 8, The volume of the space S defined by the rear outer cylinder 9, the front inner cylinder 10, the rear inner cylinder 11, the front wall 6 and the rear wall 7 is reduced. For this reason, unless the filler filled in the space S is smoothly discharged, the pressure in the space S increases excessively, making it difficult for the intermediate push jack 12 to contract, and applying high pressure to the seal 28 to stop it. Aqueousness will deteriorate. In the intermediate pushing device 5, a part of the filler in the space S is smoothly discharged from the pipe 32 into the mine as the distance between the front wall 6 and the rear wall 7 is narrowed, so that the pressure in the space S is excessively increased. The intermediate push jack 12 can be easily contracted, and the water stoppage of the seal 28 is not deteriorated.

  Further, when the intermediate push jack 12 is extended from the state shown in FIG. 6C as shown in FIGS. 6B and 6A, the space between the front wall 6 and the rear wall 7 increases, and the space S Since the volume increases, unless the filler is replenished in the space S, the pressure in the space S fluctuates low and the water stoppage by the seal 28 becomes unstable. In this intermediate pushing device 5, by introducing the filler from the pipe 32 into the space S as the distance between the front wall 6 and the rear wall 7 increases, the pressure in the space S is prevented from fluctuating extremely low, This prevents the water stoppage of the seal 28 from becoming unstable.

  In FIG. 6C, when the filler is injected from the pipe 32 into the space S, the outlet of the pipe 32 is in the gap A between the inner peripheral surface of the front outer cylinder 8 and the outer peripheral surface of the rear outer cylinder 9. The gap A is filled with a filler from another pipe 34, and a stopper 26 provided at the tip of the rear inner cylinder 11 is in contact with the front wall 6, so that the rear outer cylinder 9 Since the tip is separated from the front wall 6, the filler ejected from the pipe 32 flows into the space S through the gap between the tip of the rear outer cylinder 9 and the front wall 6.

  In FIGS. 6A to 6C, the fillers ejected from the pipes 32, 34, and 35 are represented by different dots. The coarsest dot represents the filler remaining in the space S, the finest dot represents the filler replaced by the pipe 32 in the space S, and the medium roughness dot represents the filler outside the space S. Represents. The material itself of the filler may be the same for each of the pipes 32, 34, and 35, or different ones may be used. A pipe 32 for introducing and discharging the filler into the space S is provided on both the outer front wall 6a and the outer rear wall 7a. One pipe is dedicated to supply and the other pipe is dedicated to discharge. The filler in S may be replaced little by little to replace the entire surface.

  Further, even if foreign matter such as gravel enters between the rear end of the front outer cylinder 8 and the front end of the cover 23 of the rear outer cylinder 9 in the state of FIG. When the intermediate push jack 12 is contracted as shown in FIG. 6C, the foreign matter is pushed outward by the sloped portion of the front end portion 23a of the cover 23, and the foreign matter is moved to the rear of the front outer cylinder 8. Biting between the end and the front end of the cover 23 is prevented.

  Now, if the excavator 1 shown in FIG. 1 has reached the pre-planned point by operating the intermediate pushing device 5 as described above, the stopper 26 is placed in the rear part as shown in FIG. The fastener 27 such as a bolt and nut attached to the cylinder 11 is loosened, and the front steel shell 4 is pushed out by the main pushing device 3 of FIG. 1, and the front end of the rear outer cylinder 9 is moved forward as shown in FIG. Press against the wall 6. At this time, the rear end of the front outer cylinder 8 is pressed against the sloped portion of the front end portion 23a of the cover 23, and a certain sealing effect is produced.

  In this state, a solidifying agent (such as mortar) is ejected from each of the pipes 32, 34, and 35 instead of a filler, and the gap A between the inner peripheral surface of the front outer cylinder 8 and the outer peripheral surface of the rear outer cylinder 9 is solidified. Fill with. Thereafter, an operator in the mine opens the lid 37 of the manhole 36 shown in FIG. 4, takes out the filler in the space S shown in FIG. 7A from the manhole 36, and surrounds the tip of the rear outer cylinder 9 around the front wall 6. Weld tightly along the direction. In the figure, 38 is a weld bead.

  After the completion of welding, as shown in FIG. 7B, the front and rear taper pins 18 and 22 are pulled out inward, and the front inner cylinder 10, the rear inner cylinder 11, the intermediate push jack 12, the inner front wall 6b and the outer front wall 7b. The assembly AS is pulled out rearward in the axial direction with respect to the outer front wall 6a and the outer front wall 7a. Here, since the distance from the tunnel center to the inner peripheral surface 7x of the outer rear wall 7a is longer than the distance from the tunnel center to the inner peripheral surface 6x of the outer front wall 6a, the assembly AS is moved rearward in the axial direction. When pulling out, the outer peripheral surface 6y of the inner front wall 6b is not caught on the inner peripheral surface 7x of the outer rear wall 7a.

  The pulled assembly AS is reused (diverted) as it is, or is disassembled and the intermediate push jack 12, the seal 28, etc. are reused.

DESCRIPTION OF SYMBOLS 1 Excavator 2 Starting shaft 3 Main pushing device 4 Steel shell 5 Middle pushing device 6 Front wall 6a Outer front wall 6b Inner front wall 7 Rear wall 7a Outer rear wall 7b Inner rear wall 8 Front outer cylinder 9 Rear outer cylinder 10 In front part Tube 11 Rear inner tube 12 Middle push jack 15 Front engagement / disengagement means 19 Rear engagement / disengagement means 28 Seal 32 Pipe A Clearance B Clearance S Space

Claims (2)

Between the excavator that excavates the natural ground and the main pushing device arranged in the starting shaft, a plurality of steel shells having a rectangular cross section arranged in series are arranged in front of the interposed position. An intermediate pushing device that pushes the steel shell forward,
A front wall connected to the rear end of the front steel shell and formed in a rectangular shape in accordance with the shape of the steel shell;
A rear wall connected to the front end of the rear steel shell and formed in a rectangular shape in accordance with the shape of the steel shell;
A front outer cylinder having a rectangular cross section attached to the front wall and in contact with a natural ground ;
A rear outer cylinder having a rectangular cross section that is attached to the rear wall, and whose front part overlaps with the rear part of the front outer cylinder in the axial direction with a gap in and out of the cylinder and in contact with the natural ground ,
A front inner cylinder with a circular cross section attached to the inner front wall of the front outer cylinder with a space from the front outer cylinder;
A circular cross-section that is attached to the inner wall of the rear outer cylinder with the space from the rear outer cylinder, and the front part overlaps with the rear part of the front inner cylinder in the axial direction with a gap in and out of the cylinder. A rear inner cylinder,
A seal that closes a gap between the front inner cylinder and the rear inner cylinder;
An intermediate push jack that is interposed between the front wall inside the front inner cylinder and the rear wall inside the rear inner cylinder and closes and separates the front wall and the rear wall ;
The space is formed by separating the front inner cylinder and the rear inner cylinder in the in-cylinder direction from the front outer cylinder and the rear outer cylinder, and the front outer cylinder, the rear outer cylinder, the front inner cylinder, Partitioned by a rear inner cylinder, a front wall and a rear wall;
An intermediate pushing device characterized in that a pipe for filling and discharging the filler in the space is provided on at least one of the front wall and the rear wall . A plurality of steel shells connected in series between the excavator for excavating the natural ground and the main pushing device arranged in the start shaft are installed in the middle of the steel shell, and the steel shell in front of the installation position is inserted. An intermediate pushing device that pushes forward,
A front wall connected to the rear end of the front steel shell;
A rear wall connected to the front end of the rear steel shell;
A front outer tube attached to the front wall;
A rear outer cylinder attached to the rear wall, wherein the front part overlaps the rear part of the front outer cylinder and the inner and outer directions in the axial direction with a gap therebetween; and
A front inner cylinder attached to the front wall inside the front outer cylinder;
A rear inner cylinder attached to the rear wall on the inner side of the rear outer cylinder, wherein the front part overlaps the rear part of the front inner cylinder and the inner and outer directions in the axial direction with a gap therebetween; and
A seal that closes a gap between the front inner cylinder and the rear inner cylinder;
An intermediate push jack that is interposed between the front wall inside the front inner cylinder and the rear wall inside the rear inner cylinder and closes and separates the front wall and the rear wall;
The front wall is divided into an outer front wall and an inner front wall in the cylinder inside / outside direction,
The rear wall is divided into an outer rear wall and an inner rear wall in the cylinder inner / outer direction,
The front outer cylinder is attached to the outer front wall;
The rear outer cylinder is attached to the outer rear wall;
The front inner cylinder is attached to the inner front wall;
The rear inner cylinder is attached to the inner rear wall;
A front engaging / disengaging means for engaging / disengaging them is provided on the outer front wall and the inner front wall,
Rear engagement / disengagement means for engaging / disengaging them is provided on the outer rear wall and the inner rear wall.
An intermediate pushing device characterized by that .

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