JPH0321790A - Conduit retreat preventive method - Google Patents

Abstract

PURPOSE:To save the labor, to reduce the term and the cost of the work, and to improve the work efficiency, by suppressing the retreat of a conduit with a ring-form body to which plural fixing tools to release the restraining force when the conduit is advanced and to press down the conduit when it is retreated CONSTITUTION:At a starting cut-off wall 14 at the front side inside a starting vertical shaft, a ring-form body 1 made by combining six fixing tools 3 which furnish wedges 2 contacting to the outer surface of a conduit 12 by plural holding frames 13 is provided fixed with plural connecting members 4 so that its center line is coincident to the sheduled center line of the conduit 12 to be buried. And when the conduit 12 is advanced by the extension of a base pushing jack, the fixing tools 3 release the contact with the conduit 12 by the thrust of the jack. When the conduit 12 is stopped, the fixing tools 3 are contacted again to the outside of the conduit 12 to prevent the retreat of the conduit 12 owing to the earth pressure at a facing or a pressing-back force of the water pressure automatically.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a shield tunneling machine and a method for preventing retreat of a propulsion pipe in various propulsion works.

Conventional technology> A propulsion method in which a starting shaft is installed at a predetermined position and the pipes are pushed into the ground one after another by the thrust of a jack using a bearing wall installed at the rear of the shaft as a reaction force. Unlike the open-cut method, the excavation surface above ground is limited to vertical shafts, making it an effective method for construction on roads with heavy traffic or in urban areas. The general propulsion method is to attach a blade or a shield excavator to the tip of a buried pipe collection, reduce the propulsion resistance while excavating the earth and sand with human power or machinery, and use a main push jack installed in the starting shaft to shield the tunnel. Pressure is applied to the rear end of the machine and the rear end of the pipe to push the shield machine and pipe into the ground. Once the jack has been extended, the jack is reduced, a steel spacer that matches the jack stroke length is inserted into the front of the jack, the jack is extended again, and the shield machine and pipe are buried. . Furthermore, in recent years, excavation has become more common in soils with a lot of groundwater or soft soils that are not self-sustaining, and many mechanical excavation methods have been adopted. Mud water type shield machines and earth pressure balance type shield machines, which pressurized mud and excavated earth to counteract water pressure and face soil, suppress and excavate, have come to be used frequently.

However, when these shield excavators are used, the excavation chamber at the front of the shield machine is filled with pressurized mud water and excavated soil, which balances the face soil and water pressure. There is always a huge force trying to push you back. For this reason, at the beginning of propulsion, the frictional force of the shield tunneling machine and the outer periphery of the pipe is smaller than the force of the face earth pressure and water pressure, so when the main push jack is reduced or the next pipe is installed, the pressure of the main push jack is This often causes the shield excavator and pipes to retreat, and as the pipes retreat inside the shaft, sand and groundwater gush out from the outer circumference of the pipe, causing submergence inside the shaft and areas around the shaft. It is causing a collapse. Moreover, at the tip of the shield machine, as the shield machine retreats, the earth and sand on the top of the shield machine is drawn into the front part of the shield machine, causing subsidence and depression of the ground around the shield machine.

For this reason, in conventional technology, in order to prevent the shield tunneling machine and the pipe culvert from retreating, wires and chains are wrapped around the outer circumference of the shield tunneling machine and the pipe culvert inside the shaft, and both ends are tied to the sheet pile or starting point at the front of the shaft. Methods of fixing the tube to an ice-stopping wall and tightening the tube with a traction device, or tensioning both sides of the rear end of the tube and the front of the shaft with a traction device to prevent the tube from retreating are used.

Problems to be Solved by the Invention The method for preventing the tube from retreating according to the prior art described above is such that the tube moves forward and moves with the extension of the pusher jack, so the wires and chains tightening the tube and the traction The current situation is that the equipment becomes loose and the traction equipment is tightened every time the jack extends one stroke. As the traction device is tightened at the same time as the extension of one stroke of the pusher jack is completed, the reduction work of the jack must be interrupted while the traction device is being tensioned.
Currently, the propulsion speed is significantly delayed due to the frequent tightening work, resulting in longer construction periods and increased construction costs. In addition, the frequent tightening work makes the propulsion work complicated, leading to problems such as forgetting to tighten the traction device and lowering the propulsion accuracy. Therefore, the present invention provides a method for preventing the receding of pipes, which aims to solve such problems.

Means for Solving the Problems> The pipe retreat prevention method of the present invention which solves the above problems includes a method in which a plurality of fixing devices are attached to the outer surface of the pipe inside the annular body at the front part in the starting shaft. The fixture is characterized in that it releases the restraining force when the pipe moves forward, and presses against the pipe when it retreats to prevent the pipe from retreating.

Function: The plurality of fixing devices installed inside the annular body are installed so as to come into contact with the outer surface of the pipe, and when the pipe is moving forward due to the extension of the main push jack, the fixing devices are When the contact is released by the thrust and the pipe stops, the fixing device comes into contact with the outer circumference of the pipe again, and furthermore, the pipe retreats due to the pushing back force due to the face earth pressure and water pressure at the tip of the shield excavator. When started, the fixture can press against the culvert and prevent the culvert from backing up.

In this way, when the pipe recedes, it is automatically prevented from receding by the pressure contact mechanism of the fixture, and it is possible to reliably prevent the pipe from receding due to frequent tightening operations or forgetting to tighten as in the conventional method.

Embodiment> Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1, 2, 8, and 4.

Launch water stop wall 1 fixed to earth retaining wall l7 at the front of the launch shaft
At the rear of 4, fixing devices a equipped with wedge mechanisms at six locations in the circumferential direction are connected by a plurality of support frames l3 to form an annular body l, and the center line of the annular body l and the buried pipe l2 are connected. Place the annular body 1 on the front starting water stop wall l so that it matches the planned center line.
4 by fixing it in several places with connecting members 4. Annular body 1
The wedge 2 installed on the fixture 3 is the shield excavator I5.
and the outer surface of the pipe conduit I2.

To explain the mechanism of the fixture 3 in detail with reference to FIG. 3, the wedge 2 that comes into contact with the shield tunneling machine 15 and the pipe culvert 12 is constituted by a wedge holder 7 provided so as to be inscribed with the wedge 2. , wedge pull-back panels 8 are provided on both sides of the wedge 2 and the wedge holder 7 to hold the wedge 2 and the wedge holder 7 inward, and the wedge holder 7 is further provided with a plurality of contact adjustment screws 6. It has a mechanism for bringing the wedge 2 into contact with a pipe etc. via a wedge holder 7.

Now, to explain the operation status of the W culvert retreat prevention method according to an embodiment of the present invention, the shield excavator 15 and the pipe culvert 12 are
It is propelled underground by the thrust of the main thruster (not shown) installed at the rear of the starting shaft. At this time, the wedge 2 of the fixing device 3 that has come into contact with the pipe culvert 12 moves forward as the pipe 12 moves forward, and maintains a small space between it and the outer surface of the pipe culvert 12, and the wedge 2 of the fixture 3 that is in contact with the pipe culvert 12 moves forward. Release the contact. Therefore, the mechanism is such that the restraining force of the wedge 2 does not act on the pipe culvert 12 or the shield excavator 15 while the pipe culvert 12 and the like are moving forward. When one stroke of the main push jack is completed, the jack is contracted, a steel spacer for one stroke of the jack is inserted between the pipe culvert 12 and the jack, and the jack is extended again to connect the pipe culvert 12 and the shield tunneling machine. 15 will be promoted.

In the muddy water type shield construction method and the Tonosho type shield construction method, the shield machine 15 and the pipe culvert 12 are constantly pushed back by the tip face earth pressure and water pressure, and when the main push jack is reduced, the shield machine 16 and the pipe culvert are The force supporting l2 is released, and the shield machine 15 and pipe culvert 12 try to retreat toward the shaft side. At this time, the wedge 2 of each fixture 3 comes into contact with the pipe culvert 12 etc. by the wedge pullback panel 8 when the pipe culvert 12 etc. stops moving forward. When the pipe 12, etc. tries to retreat due to the contraction of the main push jack, each wedge 2 that has come into contact with the pipe 12, etc. tries to retreat backward together with the pipe 12, etc., but the wedge 2, etc. This is prevented by the wedge action with the wedge pedestal 7, and furthermore, pressing pressure is applied to the pipe culvert 12 side to press against the pipe culvert 12 and the like, thereby suppressing the retreat of the shield excavator 15 and the pipe culvert 12.

In this embodiment, a method for preventing the pipe from retreating using a wedge mechanism has been described, but as shown in FIG. 4, it is also possible to use a method using a cam mechanism or other known friction mechanisms.

Further, in this embodiment, the number of fixtures 3 is set to six, but it can be increased or decreased depending on the diameter of the propulsion pipe, the soil pressure, and the water pressure situation.

Effects of the Invention> According to the present invention, it is possible to automatically prevent the pipe culvert and shield excavator from retreating when the main push jack is reduced or when the pipe culvert is replaced, and it is possible to prevent the pipe culvert and the shield excavator from moving back frequently, unlike the conventional technology. There is no need to check the tools or be nervous, making it easy to save labor and shorten the construction period.

[Brief explanation of drawings]

FIG. 1 is a front view of a pipe backback prevention device showing one embodiment of the present invention. FIG. 2 is a side view showing the device. FIG. 3 is a detailed explanatory diagram of a pipe retreat device showing an embodiment of the present invention. N4
The figure is an explanatory diagram showing a method for preventing backward movement according to the present invention. FIG. 5 is an explanatory diagram showing a method for preventing backward movement in the prior art. In addition, 1 in the figure is a ring-shaped body. 2 is a wedge. 8 is a fixture. 4 is a connecting material. 5 is a presser plate. 9 is a contact adjustment spring. 10 is a support stand. 11 is cam. 16 is a towing device. 17 indicates a retaining wall.

Claims (1)

[Claims] (1) In a propulsion method in which a shield tunneling machine or a pipe culvert is launched from a starting shaft entrance installed at the front of the starting shaft, multiple fixing devices are arranged inside the ring so as to contact the outside surface of the pipe culvert. . A method for preventing the receding of a pipe conduit, characterized in that the fixing device releases contact when the conduit advances and presses against it when the conduit retreats to prevent the conduit from retreating.