JP4213090B2 - Tunnel branch construction method and equipment - Google Patents

Description

  The present invention excavates a branch tunnel by a shield excavator toward an existing tunnel built in the ground, reaches the vicinity of the existing tunnel, and then stops the shield excavator to stop the existing tunnel from the branch tunnel. The present invention relates to a method for constructing a tunnel branch portion that communicates with the device and an apparatus for carrying out the method.

  Conventionally, in order to build a tunnel that branches from an existing tunnel, a shield excavator excavates a branch tunnel from the start shaft side toward the existing tunnel toward the existing tunnel, and the shield excavator is installed in the existing tunnel. After stopping the shield excavator when it reaches the vicinity of the tunnel, excavate the ground between the shield excavator and the existing tunnel and dismantle the wall of the existing tunnel to communicate with the branch tunnel from the existing tunnel Is being built. At this time, the ground between the existing tunnel and the shield excavator reaching the vicinity of the existing tunnel is consolidated using an auxiliary method such as a chemical injection method or a freezing method, and the cutter head of the shield excavator is attached. After demolition and removal, while forming the tunnel part to the outer peripheral wall surface of the existing tunnel while excavating the consolidated ground by manpower from the shield excavator side and lining the excavated wall surface with sprayed concrete, etc. By dismantling the outer wall of the tunnel, a branch tunnel is built that communicates with the existing tunnel in a crossing manner.

  However, in such a construction method of the branch part of the branch tunnel, the auxiliary construction method for solidifying the ground between the existing tunnel and the shield excavator requires a lot of time and labor, and the amount of ground excavation by human power increases. As a result, there is a problem that work efficiency is remarkably lowered.

  For this reason, a shield excavator for branch tunnel excavation described in Patent Document 1 has been developed. This shield excavator is provided with a cutter head 32 for excavating the front ground at the open end of a skin plate 31 consisting of front and rear body portions 31a and 31b connected to each other in a refractive manner as shown in FIGS. In the main body A ′, a plurality of rectangular hood plate pieces 33a curved in an arc shape in the circumferential direction of the skin plate are combined in a cylindrical shape on the outer peripheral surface of the front body portion 31a of the skin plate 31, and adjacent hood plate pieces are combined. A hood body 33 is provided in which the opposite side end faces of 33a and 33a are individually movably connected forward.

And this tunnel excavator digs the tunnel T 'while constructing the segment lining on the excavation wall toward the existing tunnel T, and when the cutter head 32 reaches the existing tunnel T, the shield excavator is stopped, The hood plate pieces 33a are propelled while being press-fitted into the front ground by a propulsion jack (not shown) mounted in the excavator body, and the tips of the respective hood plate pieces 33a are placed on the outer peripheral wall surface of the existing tunnel T. By abutting, the ground taken in the hood body 33 and the outer ground are cut off, and then the ground in the hood body 33 is excavated and removed, and the tip of the hood body 33 is in contact with the ground. By disassembling the outer peripheral wall surface of the tunnel T, the tunnel T ′ is communicated so as to be branched from the existing tunnel T.
JP-A-8-86187

  However, according to this shield excavator for excavating a tunnel tunnel, the plurality of hood plate pieces 33a constituting the cylindrical hood body 33 are made of a single rectangular plate material and thus have low rigidity. Therefore, when press-fitting into the ground from the front end of the skin plate 31, there is a concern that the ground may collapse in a soft ground due to bending deformation in the diameter increasing direction or the diameter reducing direction due to the resistance force from the ground side. On the other hand, in the construction on the hard ground, it is difficult to propel the hood plate piece 33a, and the construction work of the branch tunnel with respect to the existing tunnel T cannot be performed efficiently.

  Further, a cylindrical hood body 33 is formed by a plurality of hood plate pieces 33a reaching the outer peripheral wall surface portion of the existing tunnel T from the shield excavator, and the ground taken in the hood body 33 and the outer ground side However, since the hood body 33 has a low water-stopping property, there is a risk that groundwater may enter the hood body 33. In particular, the outer peripheral wall surface of the existing tunnel T is curved in an arc shape. On the other hand, since the front end surface of each hood plate piece 33a in contact with the outer peripheral wall surface is straight, there is a gap between them, and groundwater enters through this gap, which hinders the construction of the tunnel branch. There was a problem of bringing about.

  The present invention has been made in view of such problems, and the object of the present invention is to make a tunnel branch from a tunnel excavator that reaches the vicinity of the existing tunnel while excavating the branch tunnel to communicate with the existing tunnel. It is in providing the construction method of the tunnel branch part which can construct a part efficiently and correctly, and the apparatus for implementing the method.

  In order to achieve the above object, according to the tunnel branching method of the present invention, as described in claim 1, after the branch tunnel is constructed by the shield excavator toward the existing tunnel before crossing the existing tunnel. , A method for constructing a tunnel branch portion that communicates with the existing tunnel from the branch tunnel, and sequentially a plurality of sheet pile members arranged side by side along the inner peripheral surface of the skin plate of the shield excavator, After driving the tip until it touches the outer peripheral surface of the existing tunnel, the tip of the hardener injection pipe arranged at predetermined intervals in the circumferential direction of the skin plate reaches the existing tunnel along the outer surface of the sheet pile member. And then pulling it out to the inside of the machine while injecting the hardening material from the hardening material injection pipe toward the ground around the sheet pile member. After improving the surrounding ground of the material to hardened ground, then excavating the unexcavated part surrounded by the sheet pile member, dismantling the wall of the existing tunnel surrounded by the tip of the sheet pile member and branching from the existing tunnel It is characterized by building a tunnel branch that communicates with the tunnel.

  In this tunnel branch construction method, the invention according to claim 2 is directed to driving the sheet pile member toward the existing tunnel while spraying pressure water from the tip of the sheet pile member, and then driving toward the ground around the tip. It is characterized by forming a water-stopping ground layer that stops the gap between the existing tunnel and the end of the sheet pile member by injecting a chemical solution.

  In addition, as the construction device for the tunnel branching section, as described in claim 3, a branch tunnel that communicates with the existing tunnel in an intersecting manner toward the existing tunnel while excavating the front ground of the skin plate with a cutter head. A construction device for a tunnel branch portion provided in a machine of a shield excavator for branch tunnel excavation for building, wherein a plurality of sheet pile members are formed in a cylindrical shape in the circumferential direction along the inner peripheral surface of the skin plate, and A plurality of hardener injection pipes are provided at predetermined intervals in the circumferential direction in the gap between the outer surface of these sheet pile members and the inner peripheral surface of the skin plate. The structure is such that it can be propelled and retracted.

  In the construction device for the tunnel branching portion configured as described above, the invention according to claim 4 includes: a pressure water injection nozzle that injects pressure water toward the front at the time of driving, and an existing tunnel after driving; A chemical solution injection nozzle for injecting a chemical solution for forming a water-stopping ground layer from between the tips of the sheet pile members toward the surrounding ground is provided.

  Furthermore, the invention which concerns on Claim 5 forms the said sheet pile member and the hardening | curing material injection | pouring pipe | tube by adding a plurality of short division | segmentation sheet pile members and a hardening | curing material injection | pouring pipe | tube sequentially in the length direction, respectively. A thrust jack connected to the rear end of the sheet pile member on the inner peripheral surface of the skin plate of the shield excavator and pushing out the sheet pile member; and pushing out the hardening material injection pipe connected to the rear end of the hardening material injection pipe; The propulsion jack to be pulled back is detachably arranged.

  According to a sixth aspect of the present invention, the branch tunnel is formed so that the cutter head of the excavation sul shield excavator can be enlarged or reduced in diameter, and after the branch tunnel is excavated, the diameter is reduced through the skin plate. It is configured to be removable.

  According to the present invention, a plurality of sheet pile members are juxtaposed in a circumferential and cylindrical manner along the inner circumferential surface of the skin plate in a tunnel excavator, and these sheet pile members are sequentially arranged in the order. Since it is configured to drive until the tip reaches the existing tunnel, these sheet pile members can form a cylindrical partition body that reaches the outer peripheral wall of the existing tunnel from the tunnel excavator. Of course, the ground that is taken in and the ground on the outer peripheral side can be surely edged, and the gap between the outer surface of these sheet pile members and the inner peripheral surface of the skin plate is set at a predetermined interval in the circumferential direction. Since a plurality of hardener injection pipes are arranged so as to be propelled and pulled back each time, after the sheet pile member is placed, the hardener injection pipe is driven along the outer surface of the sheet pile member until reaching the existing tunnel. The future To improve the ground around the sheet pile member to a stable hardened ground layer with water-stopping property, while leaving the ground surrounded by the sheet pile member as it is, by injecting the hardening material from the hardening material injection pipe and sequentially pulling it out to the inside of the machine. Can do.

  Therefore, it is possible to reliably prevent the intrusion of groundwater into the inside of the sheet pile member through a gap between adjacent sheet pile members, and therefore the excavation of the ground surrounded by the sheet pile member can be efficiently performed and the sheet pile member It is possible to smoothly dismantle the wall portion of the existing tunnel surrounded by the tip of the tunnel, and it is possible to efficiently build the tunnel branch portion that communicates from the existing tunnel to the branch tunnel.

  Further, when the sheet pile member is driven from the tunnel excavator side toward the existing tunnel, pressure water is injected from the pressure water injection nozzle provided at the tip of the sheet pile member as described in claim 2 and claim 4. However, since the front ground of the sheet pile member is reformed into a mud with fluidity by pressure water, the sheet pile member's driving resistance becomes extremely small, so that the sheet pile member bends and deforms. It can be driven with a small propulsive force accurately and quickly until its tip reaches the outer peripheral wall surface of the existing tunnel. Furthermore, a chemical solution injection nozzle is provided at the tip of the sheet pile member, and after the sheet pile member is placed, the chemical solution such as cement is injected toward the ground around the tip, so the outer periphery of the existing tunnel The gap formed between the wall surface portion and the front end surface of the sheet pile member and the surrounding ground can be reformed to a hard water-stopping ground layer, and therefore the ground side where the groundwater is surrounded by the sheet pile member through the gap. It is possible to surely prevent intrusion into the water and to smoothly perform the construction work of the branch portion.

  According to the invention which concerns on Claim 5, the said sheet pile member and hardening material injection | pouring pipe | tube are each formed by sequentially adding several short division | segmentation sheet pile members and hardening | curing material injection pipe | tubes to a length direction. A thrust jack connected to the rear end of the sheet pile member on the inner peripheral surface of the skin plate of the shield excavator and pushing out the sheet pile member; and pushing out the hardening material injection pipe connected to the rear end of the hardening material injection pipe; Since the propulsion jack to be pulled back is detachable, even if the work space in the machine is small like a small-diameter shield excavator, a short divided sheet pile member and divided hardener injection pipe are added. It is possible to perform the driving operation while simply assembling the sheet pile member or the hardener injection pipe having a length from the shield excavator to the existing tunnel.

  According to the invention of claim 6, the outer diameter of the cutter head of the shield excavator for excavating the branch tunnel is formed so as to be able to expand and contract, and the rear diameter is reduced through the skin plate by reducing the diameter after excavation of the branch tunnel. The excavator can reach the existing tunnel, of course, when the tunnel is excavated, the diameter of this cutter head can be expanded to smoothly dig the ground in front of the skin plate. Sometimes, if the diameter of the cutter head is reduced, a large gap can be provided between the outer peripheral end surface of the cutter head and the inner peripheral surface of the open end of the skin plate. The hardener injection tube can be easily placed on the front ground from the skin plate, and the skin plate remains. Recovery backwards through the branch tunnels construction equipment such as the cutter head and propulsion jacks, by removal, can pass through a branch tunnel branching from existing tunnel through the tunnel bifurcation.

  Next, a specific embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal side view of a shield excavator A for branch tunnel excavation, and FIG. 2 is a partial longitudinal front view thereof. The circular plates 4a and 4b are arranged on the front inner peripheral surface of the front body 1a of the skin plate 1 composed of the front and rear body 1a and 1b connected to the front and rear, with a certain distance in the front and rear. The outer peripheral end surfaces of the ring plates 4a and 4b are fixed integrally to the inner peripheral surface of the front body 1a of the skin plate 1, and the hardening material is injected into the front and rear ring plates 4a and 4b at predetermined intervals in the circumferential direction. Guide holes 3a and 3b are provided as guides for propelling the tube 2 to the front ground. Further, a short cylindrical inner body 11 is provided which is integrally fixed to an outer peripheral end surface of a partition wall 15 of a cutter head 14 to be described later with a certain distance inward from the inner peripheral surfaces of the front and rear annular plates 4a and 4b. The annular space 13 formed between the outer peripheral surface of the short cylindrical inner body 11 and the inner peripheral surfaces of the front and rear annular plates 4a, 4b has a constant width, a constant thickness, and a constant length. A plurality of leading portions of the rigid sheet pile member 5 having a hollow rectangular shape in cross section are combined and arranged side by side in a cylindrical shape in an inserted state.

  Each sheet pile member 5 is configured to form a sheet pile member 5 having a predetermined length as shown in FIG. 4 by sequentially adding a short divided sheet pile member 5b in series to the top portion. The leading portion is also formed on the short divided sheet pile member 5a. Further, as shown in FIG. 2, a pressure water injection nozzle that injects pressure water toward the front when the sheet pile member 5 is driven into the front end portion of the sheet pile member 5, that is, the front end portion of the divided sheet pile member 5 a on the leading side. 6 and a chemical injection nozzle 7 for forming a water-stopping ground layer, which will be described later, are provided in the divided sheet pile member 5b, which is sequentially added to the divided sheet pile member 5a on the front side, and these pressure water injection nozzles. A pressure water supply hose and a chemical liquid supply hose (not shown) connected to and in communication with 6 and the chemical liquid injection nozzle 7 are provided. A long pressure water supply hose and a chemical liquid supply hose are respectively connected to the pressure water injection nozzle 6 and the chemical liquid injection nozzle 7 and each time the divided sheet pile member 5b is added, the pressure water is supplied into the divided sheet pile member 5b. The supply hose and the chemical solution supply hose may be inserted.

  In addition, the annular space 13 between the front and rear annular plates 4a and 4b and the short cylindrical inner body 11 has several locations on the opposing surface between the front and rear annular plates 4a and 4b and the short cylindrical inner body 11. Are divided into several pieces by a partition plate 12 (shown in FIG. 2) that is integrally connected at predetermined intervals in the circumferential direction, and several pieces of the divided sheet pile members 5a are provided in each divided space portion (three pieces in the figure). They are arranged in parallel as a set. Each group of divided sheet pile members 5a can be propelled forward independently using the opposing end face of the adjacent divided sheet pile member 5a as a guide surface. The leading ends of the divided sheet pile members 5a on the leading side are formed with a tapered pointed end.

  As described above, the outer peripheral surfaces of the front and rear annular plates 4a and 4b are integrally fixed to the front inner peripheral surface of the front body portion 1a of the skin plate 1, and therefore the short cylindrical inner body 11 is connected to the partition plate 12. It is connected to and supported by the skin plate 1 through the front and rear annular plates 4a and 4b. Further, the hardened material injection tube 2 driven into the front ground using the front and rear guide holes 3a and 3b as guides, like the sheet pile member 5, a plurality of short divided hardened material injection tubes 2a and 2b are sequentially arranged in series. The hardened material injection tube 2 having a predetermined length is formed by adding it in a shape, and the divided hardened material injection tube 2a on the front side is inserted into and supported by the front and rear guide holes 3a and 3b. Yes.

  As shown in FIG. 2, the hardening material injection pipe 2 includes a small diameter hardening material injection pipe 201 and an air injection pipe 202, a pressure water injection pipe 203, a mud discharge pipe 204 having a larger diameter than these injection pipes, and the like. The hardened material injection pipe 201 and the air injection pipe 202 are provided on the peripheral ground side wall portion of the front peripheral wall portion of the hardened material injection pipe 2 in the head divided hardened material injection pipe 2a. The hardened material and the air are respectively ejected from the jet port toward the surrounding ground by communicating with the jet port (not shown). In addition, the above-mentioned hardened material injection pipe, air injection pipe, pressure water injection pipe, and mud discharge pipe having a length corresponding to the length of these injection pipes 2a and 2b are provided in each divided hardened material injection pipe 2a and 2b. It may be configured to connect these pipes at the same time as adding the divided hardener injection pipes, but each of the long pipes is connected to the leading split hardener injection pipe 2a. Each time the divided hardener injection pipe 2b is added, these pipes may be inserted into the split hardener injection pipe 2b.

  Pushing the hardener injection pipe 2 and the sheet pile member 5 to the front ground is performed by the propulsion jacks 8 and 9 as shown in FIGS. 4 and 5. This extruding operation is performed by the shield excavator A for branch tunnel excavation. After the branch tunnel T ′ reaching the vicinity of the existing tunnel T is excavated by the above, the shield excavator A is stopped and the tunnel branch portion t for connecting the branch tunnel T ′ to the existing tunnel T is constructed. . The propulsion jacks 8 and 9 remove equipment such as the earth and sand discharging means 20 comprising the screw conveyor in the tunnel excavator A, the erector 21 and the shield jack 22 supported by the ring gutter 26, and the bent jack 23. After that, the skin plate 1 is detachably mounted on the inner peripheral surface side of the bent portion 24 that flexibly connects the front and rear body portions 1a and 1b of the skin plate 1.

  Specifically, as shown in FIG. 4, the pushing jack 9 for pushing out the sheet pile member 5 is inserted into a support hole 25a provided in a support ring 25 which is detachably attached to the inner peripheral surface of the rear end of the front body 1a. The rear end is detachably connected to and supported by a bracket 26a attached to the front surface of the ring garter 26 that is supported in the inserted state and fixed to the inner peripheral surface of the front end of the rear trunk 1b. A divided sheet pile member 5b on the rear end side of the sheet pile member 5 is configured to be detachably coupled to the piston rod of the propulsion jack 9 via a coupling fitting 9a. The support holes 25a and the brackets 26a are provided at small intervals in the circumferential direction so as to correspond to the rear of the sheet pile members 5 arranged side by side in the circumferential direction. Every time the sheet pile member 5 is pushed out, the sheet pile member 5 is used instead of the next sheet pile position. The sheet pile member 5 may be configured to be pushed out by one propulsion jack 9.

  On the other hand, as shown in FIG. 5, the pushing jack 8 for pushing out the hardener injection tube 2 is a supporting hole provided in the outer peripheral portion of the supporting ring 25 after the pushing jack 9 for pushing the sheet pile member 5 is removed. (Not shown) has its front end portion supported in an inserted state, and its rear end portion is detachably connected to and supported by a bracket 26b attached to the front outer peripheral portion of the ring gutter 26. Further, a support base 27 is disposed inside the propulsion jack 8 and the rear end portion of the support base 27 is detachably fixed to the inner peripheral end surface of the ring gutter 26, and a motor is installed on the support base 27. A table 28 is disposed so as to be movable in the front-rear direction. The last hardened material injection pipe 2b of the hardened material injection pipe 2 connected to the rod end of the propulsion jack 8 through the rotary joint 30 and the connecting fitting 8a is installed on the support base 28. The motor 29 is configured to reciprocate within a certain angle range via an appropriate drive mechanism 29 ′.

  A cutter head 14 for excavating the ground in front of the skin plate 1 is rotatably inserted through the central shaft 16 into the central portion of the partition wall 15 whose outer peripheral end face is fixed to the inner peripheral surface of the short cylindrical inner body 11. , And is configured to be rotated by a drive motor 17 attached to the partition wall 15. The cutter head 14 has a plurality of cutter bits 18a projecting forward from both sides of the front surface in a direction (outer diameter direction) orthogonal to the center axis 16 from the front end of the center axis 16. The spoke body 14a is provided radially, and each spoke body 14a is formed in a cylindrical hollow spoke body whose outer end face is opened, and the outer spoke piece 14b is accommodated therein, and the spoke body 14a The outer spoke piece 14b is configured to protrude from the open end of the hollow spoke body 14a by the operation of a jack (not shown) mounted therein. The outer spoke piece 14b is also provided with a cutter bit 18b projecting forward on both sides of the front surface.

  The spoke length when the outer spoke piece 14b protrudes in the outer diameter direction is formed to reach the front of the outer peripheral surface of the skin plate 1, while the outer spoke piece 14b is formed as the spoke body 14a. The outer diameter of the cutter head 14 when housed inside is formed to have a diameter substantially equal to the outer diameter of the short cylindrical inner body 11. In addition, arm members 19 are protruded rearward at several locations on the outer periphery of the back surface of the cutter head 14, and the rear ends of these arm members 19 are integrally connected by an annular frame member 31 to form an annular shape. A frame member 31 is rotatably supported on the outer peripheral portion of the front surface of the partition wall 15. Further, an internal gear 32 is fixed to the rear end surface of the annular frame member 31, while the rotation shaft of the drive motor 17 is fixed. The fixed small gear 33 is engaged with the internal gear 32 and the cutter head 14 is rotated by the drive motor 17.

  Further, a space between the rear surface of the cutter head 14 and the front surface of the partition wall 15 is formed in the earth and sand chamber 34 that takes in the earth and sand excavated by the cutter head 14 and temporarily retains the earth and sand. The excavated sediment is discharged rearward through the soil removal means 20.

  In addition, the bent jack 23 includes a bracket 35 whose front and rear ends are detachably attached to the inner peripheral surface of the rear end portion of the front barrel portion 1a and a bracket which is detachably attached to the inner peripheral surface of the front end portion of the rear barrel portion 1b. 36, while the shield jack 22 is supported by the ring garter 26 in a penetrating manner, the spreader attached to the tip of the rod is pressed against the front end face of the segment lining S constructed on the tunnel excavation wall surface. By extending the rod, the shield excavator A is advanced. The erector 21 for assembling the segment S is disposed on the rear surface side of the ring gutter 26.

  In order to excavate the branch tunnel T ′ for communicating with the existing tunnel T by the shield excavator A for excavating the branch tunnel constructed as described above, the shield excavator A is started with its cutter head 14 having its diameter expanded. As shown in FIG. 1, the tunnel T ′ is excavated from the vertical shaft (not shown) toward the existing tunnel T and the cutter head 14 is rotated, and the segment S is assembled on the excavation wall surface by the erector 21. The excavation wall is lined by

  Then, the spreader attached to the tip of the rod of the shield jack 22 is pressed against the front end face of the segment S, and the rod is extended to extend the shield excavator A for a certain length, so that the excavation wall surface is covered with the segment S. I do. At this time, the propulsive force of the shield jack 22 is transmitted to the front body portion 1a via the ring garter 26 and the bent jack 22, and is further fixed from the front body portion 1a to the front inner peripheral surface of the front body portion 1a. The front and rear annular plates 4a and 4b, the short cylindrical inner body 11 fixed to the annular plates 4a and 4b via the partition plate 12, and the partition wall 15 integral with the short cylindrical inner body 11 are connected to the cutter head 14. The excavation reaction force that is transmitted and acts on the cutter head 14 can be supported on the skin plate 1 side.

  Further, when the direction of the shield excavator A is corrected or the curved tunnel portion is excavated while the tunnel T ′ is being excavated, the front trunk portion 1a of the skin plate 1 is moved rearward by operating the jack jack 23. The body part 1b is refracted by a predetermined angle in a direction in which the direction is desired to be changed from the middle bent part 24. The excavated earth and sand are sent from the earth and sand chamber 34 to the earth discharging means 20 and discharged from the earth discharging means 20 to the start shaft side through the tunnel T ′.

  Thus, the tunnel excavator A is propelled while excavating the front ground of the skin plate 1 with the cutter head 14 to build the tunnel T ′, and the shield excavator A intersects the existing tunnel T at a predetermined angle. When it reaches the side vicinity of the existing tunnel T, it stops at that position. After that, a tunnel branching portion t for connecting and communicating the tunnel T ′ excavated and constructed by the shield excavator A with the existing tunnel T is constructed, and the branch tunnel T ′ is branched from the existing tunnel T. Next, the construction method of this tunnel branch part t is demonstrated.

  First, when the shield excavator A reaches the existing tunnel T, as shown in FIG. 3, the screw conveyor as the earth removing means 20 is removed, and the erector 21 is also dismantled and removed, and the shield jack 22 and the bent jack are also removed. 23. Remove and remove equipment such as the cutter drive motor 17 and carry it back through the branch tunnel T '. After collecting it, a support ring is attached to the inner peripheral surface of the rear end of the front body 1a as shown in FIG. A propulsion jack 9 is attached between the support ring 25 and the ring gutter 26 so as to face the rear of the sheet pile member 5 to be driven into the front ground of the shield excavator A. In addition, the outer spoke piece 14b of the cutter head 14 is immersed in the spoke body 14a to reduce the diameter of the cutter head 14.

  Then, with the piston rod of the propulsion jack 9 contracted, the space between the inner peripheral end surfaces of the front and rear annular plates 4a, 4b fixed to the front inner peripheral surface of the skin plate 1 and the short cylindrical inner body 11 is reduced. One to several sheets corresponding to the length of the gap between the rear end surface of the divided sheet pile member 5a on the leading side of the sheet pile member 5 disposed in the annular space 13 and the tip of the piston rod. A piston rod of the propulsion jack 9 is connected to the front end face of the divided sheet pile member 5b following the rear end face of the leading divided sheet pile member 5a with the divided sheet pile member 5b interposed therebetween and the rear end face of the rearmost divided sheet pile member 5b. Are connected to each other through the connecting metal 9a, and then the piston rod of the propulsion jack 9 is extended to pass the outer periphery of the cutter head 14 whose diameter of the sheet pile member 5 is reduced, so that the front ground of the tunnel excavator A I will be working on it.

  At this time, pressure water is jetted from the jet nozzle 6 at the tip of the sheet pile member 5 to fluidize the front ground in a muddy state, and the pressure resistance of the sheet pile member 5 is reduced by fluidization of the ground to Driving straight and smoothly without bending and deforming. If the leading end of the divided sheet pile member 5a on the leading side of the sheet pile member 5 does not reach the outer peripheral wall surface of the existing tunnel T even if the piston rod of the propulsion jack 9 is extended to the maximum extent, the propulsion with respect to the rearmost divided sheet pile member 5b After releasing the connection of the piston rod of the jack 9, the piston rod is contracted, the divided sheet pile member 5b is added and the piston rod is extended to propel the sheet pile member 5, and if necessary, the divided sheet pile member 5b is added again. As a result, the tip of the leading divided sheet pile member 5a is brought into contact with the outer peripheral wall surface of the existing tunnel T.

  Similarly, after connecting the propulsion jack 9 between the support ring 25 and the ring gutter 26 at the rear of the sheet pile member 5 to be driven next, the sheet pile member 5 is divided while jetting pressure water from its tip. Placing a plurality of sheet pile members 5b, using the side face of the sheet pile member 5 that has been previously placed as a guide surface, is driven until the tip abuts against the outer peripheral wall surface of the existing tunnel T. By repeating the propulsion and driving work of the sheet pile member 5, all the sheet pile members 5 are brought into contact with the outer peripheral wall surface of the existing tunnel T, and the ground B 1 in front of the cutter head is placed inside by the sheet pile members 5. The short cylindrical partition wall body 10 taken in is formed.

  In addition, the hose for supplying pressure water and a chemical | medical solution through the inside of the sheet pile member 5 to the said pressure water injection nozzle 6 or the chemical | medical solution injection | pouring nozzle 7 provided in the front-end | tip part of the division | segmentation sheet pile member 5a of the head side in the sheet pile member 5 is divided | segmented. A lead-out hole is provided in the rear end portion of the sheet pile member 5b or the connection fitting 9a, and the lead-out member is drawn into the machine from the lead-out hole and connected to a supply source of pressure water or a chemical solution via a pump or the like.

  After all the sheet pile members 5 have been driven in this way, next, the setting work of the hardener injection tube 2 and the modification work of the surrounding ground of the cylindrical partition 10 are performed. First, as shown in FIG. 5, a propulsion jack 8 is attached between the support ring 25 and the ring gutter 26 so as to face the rear of the hardened material injection pipe 2 to be driven into the front ground of the shield excavator A, and the piston rod is attached. In a contracted state, the split hardener injection pipe 2a on the front side of the hardener injection pipe 2 inserted and supported between the front end of the piston rod and the guide holes 3a and 3b of the front and rear annular plates 4a and 4b. 1 to several divided hardener injection pipes 2b corresponding to the length of the gap are interposed in the gap between the rear end face and the rear end face of the split hardener injection pipe 2a on the top side. The front end face of the divided hardener injection pipe 2b is connected and the rear end face of the rearmost split hardener injection pipe 2b is connected to the piston rod of the propulsion jack 8 via the rotary joint 30 and the connecting fitting 8a.

  After that, by extending the piston rod of the propulsion jack 8, the hardener injection tube 2 is driven into the front ground along the outer peripheral surface of the cylindrical partition body 10 formed by the sheet pile member 5. At this time, pressure water is jetted from the pressure water injection pipe 203 disposed in the hardener injection pipe 2 toward the front front ground of the hardener injection pipe 2 to fluidize the front ground. The hardened material injection tube 2 is driven straight and smoothly while discharging the mud that has passed through the discharge tube from the rear end of the hardened material injection tube 2 to the inside of the machine.

  If the tip of the hardener injection pipe 2 does not reach the outer peripheral wall surface of the existing tunnel T even when the piston rod of the propulsion jack 8 is extended to the maximum extent, the divided hardener injection pipe 2b is added to the front side. The tip of the divided hardener injection pipe 2a is brought into contact with the outer peripheral wall surface of the existing tunnel T. Subsequently, the surrounding ground outside the sheet pile member 5 is improved by the hardening material injection pipe 2.

  First, a support base 27 is attached to the ring gutter 26, and a hardener injection that reaches the existing tunnel T through the rotation axis of a motor 29 on a motor installation base 28 that is arranged on the support base 27 so as to be movable back and forth. The hardener injection tube 2 is connected to the rear end portion of the tube 2 through a rotational drive mechanism so as to reciprocate. Thereafter, the hardened material injection pipe 201 and the air injection pipe 202 in the hardened material injection pipe 2 are supplied with cement-type hardened material such as cement milk and air from the inside of the machine, and the peripheral wall at the front end of the hardened material injection pipe 2. As shown in FIG. 6, the hardener injection pipe 2 is reciprocally rotated within a predetermined angle range by a motor 29 via a rotational drive mechanism 29 'while spraying the hardener and air from the portion to the surrounding ground. By retracting the piston rod of the propulsion jack 8, the hardener injection pipe 2 is gradually pulled back toward the inside of the machine.

  Then, a cylindrical partition wall formed by the sheet pile member 5 is cut into a deep portion by the air jetted toward the surrounding ground, and the hardened material is injected into the cutting trace while being disturbed and stirred and mixed with the ground. It is improved so that it becomes a stable hardened ground layer B2 having water-stopping property over a wide range from the body 10 to the deep ground layer. At this time, each time the hardener injection pipe 2 is pulled back to the inside of the machine by a length corresponding to the retracted length of the piston rod of the propulsion jack 8, the split hardener injection pipe 2b is cut off and removed. The hardener injection pipe, the air injection pipe, the pressure water injection pipe, the mud discharge pipe and the like disposed in the hardener injection pipe 2 are the rear end portion of the hardener injection pipe 2 or the connecting fitting 8a. A lead-out hole is provided, and the lead-out hole is pulled out into the machine and connected to a supply source of a hardener or the like, mud unloading means and the like.

  Thus, when the work of injecting the hardener from the existing tunnel T to the tunnel excavator A into the outer peripheral ground is completed, the next hardener injection pipe 2 adjacent in the circumferential direction is the same as described above. Then, the propulsion jack 8 is driven until its tip reaches the outer peripheral wall surface of the existing tunnel T, and then the hardening material and air are sprayed from the peripheral wall portion of the tip of the hardening material injection pipe 2 to the surrounding ground while the hardening material is injected. The injection tube 2 is reciprocated within a predetermined angle range by a motor 29 via a rotational drive mechanism, and is gradually pulled back toward the inside of the machine by the propulsion jack 8 so that the circumferential direction and A hard ground layer B2 continuous in the length direction is created.

  In the same manner, after the other hardening material injection pipe 2 is driven until its tip reaches the outer peripheral wall surface of the existing tunnel T, the hardening material is poured into the surrounding ground while being pulled back and is surrounded by the sheet pile member 5. The surrounding ground of the partition wall 10 is reformed to a stable hard ground layer B2. It should be noted that a bent jack 23 may be adopted as the propulsion jacks 8 and 9 for the hardener injection pipe 2 and the sheet pile member 5. Next, the chemical solution injection hose disposed in each sheet pile member 5 forming the partition wall 10 is supplied from the inside of the machine with a cement-based chemical solution such as cement milk same as the above-mentioned hardener, and the tip of the sheet pile member 5 is supplied. 7 is injected into the surrounding ground from the existing tunnel T to the tip of the sheet pile member 5 to inject the outer peripheral wall surface of the existing tunnel T and the sheet pile member 5 as shown in FIG. The ground in the gap between the tip surfaces is reformed to the still water ground layer B3.

  Thus, when the construction work of the still water ground layer B3 is completed, the earth and sand B1 in front of the cutter head 14 surrounded by the partition wall body 10 made up of a large number of sheet pile members 5 arranged side by side in a cylindrical shape is appropriately excavated. Then, the inner body 11 of the partition wall 15 supporting the cutter head 14 is cut off by fusing from the skin plate 1 side, and this cutter head 14 together with the inner body 11 is appropriately removed. Tow back and remove by simple traction means, leaving only skin plate 1 on the excavation wall surface of branch tunnel T ′.

  After that, the outer peripheral wall portion of the existing tunnel T facing the front side of the skin plate 1 is disassembled and removed from the existing tunnel T or from the branch tunnel T ′ side, and the tunnel branch between the existing tunnel T and the skin plate 1 is removed. A tunnel branching portion t that extends from the existing tunnel T to the branching tunnel T ′ through the portion t is constructed.

The longitudinal side view of the whole shield excavator excavating the branch tunnel. FIG. The vertical side view of the state which has removed the earth removal means. The vertical side view of the state which has laid the sheet pile member. The vertical side view of the state which laid the hardening material injection pipe. The vertical side view of the state which has created the hardened ground layer. The vertical side view of the state which has created the still water layer. The vertical side view of the state which penetrated the tunnel branch part. The simplified sectional view which shows the connection state of an existing tunnel and a branch tunnel. The simplified vertical side view which shows a prior art example. The simplified top view which crossed the part.

Explanation of symbols

A Shield excavator T Existing tunnel
T 'branch tunnel t tunnel branch 1 Skin plate 2 Hardener injection pipe 5 Sheet pile member 8, 9 Propulsion jack
14 Cutter head

Claims (6)

  A method of constructing a branching tunnel that leads from the branching tunnel to the existing tunnel toward the existing tunnel toward the existing tunnel by a shield excavator, and constructing a tunnel branch portion that communicates with the existing tunnel from the branching tunnel. A plurality of sheet pile members arranged side by side in a cylindrical shape along the inner peripheral surface of the skin are sequentially driven until their tips abut against the outer peripheral surface of the existing tunnel, and then are arranged at predetermined intervals in the circumferential direction of the skin plate. The hardener injection pipes that have been installed are sequentially driven along the outer surface of the sheet pile member until the tip reaches the existing tunnel, and then the hardener is introduced from the hardener injection pipe toward the ground around the sheet pile member. The ground around the sheet pile member was improved to hardened ground by sequentially pulling it inside the machine while injecting, and then the unexcavated part surrounded by the sheet pile member was excavated. , Method of constructing a tunnel bifurcation, which comprises construction of and dismantle the wall of the existing tunnels that are surrounded by the tip of the sheet pile member tunnel branching portion communicating the branch tunnel from the existing tunnel.   While spraying pressure water from the tip of the sheet pile member, the sheet pile member is driven toward the existing tunnel, and after the injection, a chemical solution is injected toward the ground around the tip to stop the gap between the existing tunnel and the tip of the sheet pile member. The construction method of the tunnel branch part according to claim 1, wherein a water-stopping ground layer is formed.   The tunnel branching portion provided in the shield tunnel excavator for branch tunnel excavation for constructing a branch tunnel communicating with the existing tunnel in an intersecting manner toward the existing tunnel while excavating the front ground of the skin plate with the cutter head. It is a construction device, and a plurality of sheet pile members are juxtaposed in a cylindrical shape in the circumferential direction along the inner circumferential surface of the skin plate so as to be propelled forward, and the outer surfaces of these sheet pile members A construction apparatus for a tunnel branching section, wherein a plurality of hardener injection pipes are disposed in the gap between the inner peripheral surface of the skin plate at predetermined intervals in the circumferential direction so as to be able to propel and pull back. .   At the tip of the sheet pile member, there is a pressure water injection nozzle that injects pressure water toward the front when driven, and a chemical solution for forming a water-stopping ground layer from between the existing tunnel and the tip of the sheet pile member to the surrounding ground after driving. 4. The tunnel branch construction apparatus according to claim 3, further comprising a chemical solution injection nozzle for injection.   The sheet pile member and the hardener injection pipe are formed by sequentially adding a plurality of short divided sheet pile members and the hardener injection pipe in the length direction, and the inner circumference of the skin plate of the shield excavator A propulsion jack connected to the rear end of the sheet pile member to push out the sheet pile member, and a propulsion jack connected to the rear end of the hardener injection pipe to push out and pull back the hardener injection pipe are detachably disposed. The construction apparatus of the tunnel branch part of Claim 3 or Claim 4 characterized by the above-mentioned.   The cutter head of the shield excavator that excavates the branch tunnel is formed so that its outer diameter can be expanded and contracted, and it can be removed backward through the skin plate by reducing the diameter after excavation of the branch tunnel. The construction apparatus of the tunnel branch part of Claim 3 characterized by the above-mentioned.

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