JPH033107B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for replacing old pipes buried underground, such as water pipes and gas pipes, with new pipes, particularly for replacing old and new pipes without digging up the ground surface. It is about the method.

[Conventional technology] When old pipes, especially cast iron pipes, become obsolete after being buried and become difficult to perform their functions, or when demand increases and capacity is insufficient to replace them with new pipes, it is necessary to completely excavate above ground. Digging out old pipes is expensive and labor-intensive, and it also obstructs surface traffic, so it is preferable to replace the old and new pipes without digging up the ground.

This is the case with the so-called pipe-less pipe method, in which a new pipe is inserted into an old pipe underground, but the inner diameter of the new pipe is naturally smaller than the inner diameter of the old pipe, resulting in a reduction in gas and water transport capacity.

The prior art on which the present invention is based is an invention that solves this problem and is disclosed in detail in "Method and Apparatus for Replacing Existing Main Pipe with New Main Pipe" (Japanese Patent Publication No. 60-27873, Figure 3). There is.

In this conventional technology, a new pipe, etc. is attached to the rear end of an excavator, which has a body with a larger outer diameter than the old pipe, and both move forward together, and the tip of the excavator enters the old pipe, crushing it and filling the gap. This is a method and device for expanding old pipes and replacing them with new ones.

Since FIG. 4 shows an example of the prior art,
Let me say a few words about this specific content.

The excavator consists of a front part that enters into the inner wall of the old pipe 4a and breaks this wall, and a rear part that is fastened to pull the new pipe etc. The front part has a head that includes a movable blade 2a as a cutting surface, and its front end is pulled forward by a winch (not shown) via a cable 8a that has been inserted through the tube row of the old pipe. It is sent. A plurality of movable blades 2a are mounted diagonally on the head of the excavator so that they can rotate radially outward away from the body of the excavator in order to effectively crush the wall of the old pipe. As an example of the rotation of the movable blade 2a, as shown in FIG. Push up the provided piston 3a,
This piston pushes up one end of the blade, increases the angle of inclination, and causes the action of pushing the old tube 4a outward in the radial direction from the inner wall. A hydraulic hose may be connected to the rear end of the excavator.

[Problems to be Solved by the Invention] The present invention is based on the above-mentioned prior art and has developed related technologies so that it can be implemented more effectively.

If we consider the force when the movable blade rotates diagonally and hits the pipe wall to crush the old pipe, and consider it by breaking it down into vertical and horizontal components, the vertical component is the same as the old pipe. The pipe wall is pressed vertically to overcome the mechanical strength of the pipe material and attempt to break it. On the other hand, the horizontal component force acts as a reaction force that tends to move the excavator backward, which acts to reduce the breaking force.

As shown in FIG. 5, the excavator 1a has a cable 8a
It is forced forward according to the capacity of the winch. When the movable blade diagonally bites into the old pipe and tries to push it up, a horizontal reaction force acts rearward, countering the lifting force of the winch and increasing the load on the winch. As a result, the force originally used for crushing is reduced by that amount, deteriorating crushing efficiency. Additionally, extra loads are applied to the front end of winches and excavators, so unless they are constructed with higher strength, there is a risk that work will stop or they will be damaged. This effect poses a problem in construction when a mechanically strong part such as a joint ring is reached in an old pipe, and there is not enough force to break this part. This is a case where the process stops and ends here. The biggest problem with this replacement method occurs when the excavator remains underground and stops in the middle of the pipeline (actually between the starting shaft and the destination shaft).

In other words, it becomes necessary to dig up the stopped part from the ground surface and dig out the stuck excavator, which of course causes a significant delay in replacement work and a major cause of traffic obstruction.

In order to solve the above problems, the present invention provides a method for suppressing the rearward reaction force generated when the movable blades of the excavator body bite into the old pipe and preventing the crushing force from decreasing. Its purpose is to.

[Means for Solving the Problems] The method of replacing an old pipe with a new pipe, etc. according to the present invention solves the above problems by attaching an auxiliary blade that presses the inner wall of the old pipe in front of the movable blade so as to be able to move forward and backward. Resolved the point.

[Operation and Examples] The operation of the method of the present invention will be explained based on FIGS. 1A and 1B showing an example. Figure A is a front sectional view in which a movable blade 2 is attached to the body of an excavator 1, and this movable blade pushes up the old pipe 4 obliquely upward by the operation of a piston 3 in a cylinder (not shown). Attempt to crush the wall.

The feature of the present application is that, in addition to this prior art, the auxiliary blade 5 is attached to the head of the excavator ahead of the movable blade. It is essential that this auxiliary blade be attached to the head so that it can move forward and backward, and FIG. 1 shows an example of a preferred implementation. The head of the piston is formed with an inclined surface so that the sliding movement of the piston can be converted into the raising and lowering of the auxiliary blades 5.

This excavator is towed from the head into the old pipe by a cable 8 connected to the leading edge. At this time, the auxiliary blades have retracted into the head. When the excavator advances further and reaches the position where the movable blade contacts the end of the old pipe, it slides the piston 7 and advances the auxiliary blade 5, strongly pressing against the wall of the old pipe and causing the blade tip to bite ( (double-dashed line in FIG. 1A). At the same time, when the movable blade is rotated and the tip of the pipe wall is thrust strongly diagonally, the vertical component of force exceeds the mechanical strength and attempts to break it, and the horizontal component of force is the reaction force that attempts to move the excavator backward. However, the auxiliary blades bite into the pipe flesh in front of it and counteract this horizontal force, so the reaction force disappears and only the breaking force acts strongly, effectively crushing the old pipe. The crushed pieces of the old pipe are further pushed open by the diameter-expanding body, making it easy to replace them with new pipes, etc.

FIG. 1B is a side cross-sectional view of this embodiment as seen from direction A. In this embodiment, two movable blades 2 and two auxiliary blades 5 are installed, and they are attached so as to form a right angle to each other. There is. The auxiliary blades are attached as shown in this diagram. The auxiliary blades may be wedge-shaped as shown in this figure, but they may also be pin-shaped like a sharpened pencil.

Figure 2 shows another embodiment in which the entire hydraulic mechanism including the auxiliary blades can be rotated within the head of the excavator, and the hydraulic motor (or electric motor)
The auxiliary blade rotates under the driving force of 9 and changes the position of the auxiliary blade, making the relative relationship with the movable blade variable. Note that 10 in the figure is a ball bearing that pivotally supports the hydraulic mechanism.

[Effects of the Invention] Since the present invention produces the effects described above, when the movable blade obliquely pushes up the end of the old pipe, the horizontal reaction force is suppressed by the pressure of the auxiliary blade, and as a result, the crushing capacity is increased. Strengthen. Even if conventional technology would have been stuck midway through construction due to lack of capacity due to failure in crushing, the enhanced capacity as in the present application allows construction to proceed without any problems. Conversely, it is now possible to break something that was previously impossible to break, and the distance that can be constructed at one time (one span) can be extended. This will significantly reduce other causes of construction delays and traffic disruptions that may result.

A unique effect of this embodiment is that when the auxiliary blades are made rotatable, when the crushing strength varies in the circumferential direction of the old pipe, the auxiliary blades can be placed opposite the weakest point to crush it most effectively. can be mentioned.

For example, when the saddle distribution faucet 11 is screwed onto the old pipe with the upper and lower bolts 12 as shown in Fig. 3, rather than pushing the blades apart in the direction B-D, it is better to
It is easier to crush the material if it is pushed and expanded in the C direction. Furthermore, by pressing and fixing the auxiliary vane against the old pipe and driving the hydraulic motor, the movable vane can be rotated to any position on the circumference.

[Brief explanation of the drawing]

Figures 1A and B are a front sectional view and a side sectional view showing an embodiment of the present invention, Figures 2A and B are a front sectional view and a side sectional view showing another embodiment, and Figure 3 is a view of an old pipe. FIG. 4 is a side sectional view showing an example of a case where the crushing strength varies in circumference; FIG. 4 is a front sectional view showing a conventional technique;
FIG. 5 is an explanatory diagram showing the operation of the prior art. 1...excavator, 2...movable blade, 4...old pipe,
5...Auxiliary blade.

Claims (1)

[Claims] 1. A pipe having a body whose maximum outer diameter is larger than the outer diameter of an existing main pipe installed underground (hereinafter referred to as "old pipe"), and a movable blade is pivotally attached to the body. A new main pipe or its protective liner (hereinafter referred to as "new pipe, etc.") is attached to the rear end of the excavator, and the excavator and new pipe, etc. are pulled forward and move forward as one, and the movable blade rotates to remove the old main pipe. In the method of replacing an old pipe with a new pipe, etc. by biting into the wall of a pipe and pushing through it while expanding the gap, an auxiliary vane for pressing the inner wall of the old pipe is attached in front of the movable vane so that it can move forward and backward. A method of replacing old pipes with new ones, characterized by: 2. A method for replacing an old pipe with a new pipe according to claim 1, in which the auxiliary blade can rotate and change its position around the trunk of the excavator.