JPH0730670B2 - Connection structure of buried pipe for propulsion method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a connection structure for a buried pipe buried in the ground,
More specifically, the present invention relates to a connection structure of a buried pipe for a propulsion method in which a horizontal shaft is formed in the ground and pipes are sequentially propelled in the horizontal shaft to be laid.

(Prior Art) Buried pipes that are buried in the ground, such as sewer pipes, water pipes, and cable protection pipes, are laid by the propulsion method, for example.
In this propulsion method, as disclosed in Japanese Patent Laid-Open No. 58-120996, a vertical shaft is formed in the ground, and a buried pipe having a drilling cutter attached to the tip is inserted from the vertical shaft, and the drilling cutter is inserted. While forming a shaft with a diameter slightly larger than the buried pipe,
The buried pipe is laid by propelling it into the horizontal shaft. A buried pipe is newly joined to the rear end of the buried pipe pushed into the underground shaft, and is pushed into the underground shaft and propelled in the shaft.

In the propulsion method disclosed in the above publication, an embedded pipe having a collar is used at the rear end portion in the propulsion direction, and the subsequent embedded pipe is joined by the collar.

(Problems to be Solved by the Invention) Since the collar of the buried pipe disclosed in the above publication has a diameter larger than that of the pipe main body excluding this collar, the buried pipe is propelled in a horizontal shaft formed in the ground. During the operation, the soil in the side pit may fall and accumulate at the bottom of the side pit. When soil accumulates in the side pit, the collar rides on the soil, and the propulsion direction of the buried pipe changes upward, which may cause a slight difference from the desired propulsion direction, or the buried pipe to be propelled may bend. is there. Further, when the buried pipe is laid, a gap having a size corresponding to the difference between the outer diameter of the collar and the outer diameter of the pipe main body exists around the buried pipe, and when the ground is soft, There is a possibility that the ground will subside by an amount corresponding to the gap. The same problem occurs when the buried pipes propelled in the horizontal shaft are joined by a pipe joint because the pipe joint has a larger diameter than the buried pipe.

In order to solve such a problem, for example, in a thick-walled buried pipe such as a Hume pipe, the outer peripheral portion of the end portion where the collar is fitted is cut and the collar fitted outside the end portion is cut. It is also possible not to project outward from the outer peripheral surface of the main body. However, if the buried pipe is a thin-walled synthetic resin pipe such as vinyl chloride, when cutting the outer peripheral part of the end part where the collar is fitted, the end strength of the pipe body part fitted inside the collar is cut. In order to hold the pipe, only 40% of the wall thickness of the pipe can be cut. Therefore, the wall thickness of the collar that is fitted on the cut end of the pipe body should be about 40% of the wall thickness of the pipe body in order to prevent it from protruding outward from the outer peripheral surface of the pipe body. It is said that If the collar is made of the same synthetic resin as the tube body,
With such a thin wall, sufficient strength cannot be obtained. Therefore, the collar may be damaged when propelling the buried pipe into the ground. Therefore, it is conceivable that the collar is made of metal or the like having excellent rigidity and is made separate from the pipe body. However, when a metal collar is externally fitted to the synthetic resin pipe body, it is difficult to bond the two in a liquid-tight manner in a short time. It cannot be used.

The present invention is to solve the above-mentioned conventional problems, and an object thereof is to change the propulsion direction by the soil accumulated in the bottom of the horizontal shaft even when it is propelled in the underground shaft by the propulsion method. Another object of the present invention is to provide a buried pipe connection structure for a propulsion method in which there is no risk that the laid buried pipe will bend, and further that the connection portion of the buried pipe has high strength and is not damaged.

(Means for Solving the Problem) The present invention is a connection structure for connecting buried pipes in a propulsion method in which a buried shaft is formed in the ground and the buried pipes are sequentially propelled and laid in the shaft, and each end surface is A fitting part is provided at each end of a pair of buried pipes that are butted against each other and has a smaller outer diameter than the outer diameter of the pipe main body with a constant outer diameter excluding each end of each buried pipe. A large number of axially projecting ridges protruding outward from the outer peripheral surface of the pipe body of each buried pipe are provided at appropriate intervals in the circumferential direction over the fitting portions of the buried pipes where the collars are butted against each other. They are connected in an externally fitted state, which achieves the above object.

Further, the present invention is a connection structure of buried pipes in a propulsion method in which a buried shaft is formed in the ground while the buried pipes are successively propelled and laid in the shaft, and a pair of end faces are butted against each other. A fitting part, which is provided at each end of the buried pipe and has an outer diameter smaller than the outer diameter of the pipe main body with a constant outer diameter excluding each end of each buried pipe, It is externally fitted over the fitting part, and a large number of axially extending projections projecting outward from the outer peripheral surface of the pipe main body are arranged in the lower part at appropriate intervals in the circumferential direction. The outer peripheral surface of the pipe has a collar projecting outward from the outer peripheral surface of the tube main body portion, whereby the above object is achieved.

(Example) Hereinafter, the present invention will be described with reference to Examples.

As shown in FIGS. 1 and 2, the connection structure of the buried pipe for the propulsion method of the present invention is composed of a pair of buried pipes 10 and 10 and respective collars 20. Each buried pipe 10 is made of, for example, a synthetic resin such as vinyl chloride, and has a fitting portion 11 provided at each end and a pipe main body 12 having a constant outer diameter excluding each fitting portion 11. . The outer diameter of each fitting 11 is the pipe body
It is smaller than the outer diameter of 12. And each buried pipe 10
The end faces of the fitting portion 11 of are abutted with each other.

The collar 20 is made of the same synthetic resin as the buried pipes 10, and is fitted over the fitting portions 11 of the buried pipes 10 that are butted. The collar 20 has a large number of projections 21, 21 ... Which project outward and extend continuously in the axial direction on the outer peripheral surface of a cylindrical main body portion 21 at appropriate intervals in the circumferential direction. . The thickness of the body portion 21 of the collar 20 is the same as that of the buried pipe 10
This corresponds to the difference between the outer diameter of the pipe main body 12 and the outer diameter of the fitting portion 11, and the outer peripheral surface of the main body 21 does not project outward from the pipe main body of the buried pipe 10. Therefore, each ridge 22 of the collar 20
Are projected outward from the outer peripheral surface of the pipe body 12 of the buried pipe 10.

Each of the protrusions 22 has a triangular shape in cross section which becomes narrower toward the tip, and the tip end on the propulsion direction side is chamfered and tapered.

The axial length of the collar 20 is slightly shorter than the axial lengths of the fitted fitting portions 11, so that the end surfaces of the fitting portions 11 are reliably abutted against each other.

The laying of buried pipes by the propulsion method is as follows. First, a vertical shaft 30 is formed between points where the buried pipe 10 should be laid, and a propulsion device such as a jack is arranged in one vertical shaft 30. In this state, the leading conduit with the excavation cutter 24 installed inside
43 is buried underground from the shaft 30 and the buried pipe 10 is inserted into the leading conduit 43.
The fitting portion 11 at the tip of is fitted.

Then, the fitting portion at the rear end of the buried pipe 10 is connected to the propulsion device.

In this state, the excavation cutter 41 is operated and the propulsion device pushes the entire tip conduit 40 into the ground. The excavation cutter 41 excavates the ground to form a side pit, and the propulsion unit pushes the leading conduit 40 into the formed side pit. When the front conduit 40 is pushed in, the buried pipe 10 fitted on the front conduit 40 is also pushed in. The soil excavated by the excavation cutter 41 is transferred to the vertical shaft by the screw conveyor 42 in the buried pipe 10.
It is discharged into 30. The outer peripheral surface of the pipe body (12) of the buried pipe (10) propelled in the horizontal shaft is in sliding contact with the inner peripheral surface of the horizontal shaft.

When the buried pipe 10 is inserted into the horizontal shaft except the fitting portion 11 at the rear end, the collar 20 is fitted into the fitting portion 11. At this time, the collar 20 is externally fitted to the fitting portion 11 of the buried pipe 10 such that the tapered end portion of each protrusion 22 is on the propelling direction side. Then, the fitting portion 11 at the tip of the subsequent buried pipe 10 is fitted into the collar 20, and the preceding buried pipe 10 and the succeeding buried pipe 10 are joined. At this time, the fitting portion 11 of each buried pipe 10
And the collar 20 are liquid-tightly bonded with an adhesive. And
Subsequent buried pipes 10 are pushed into the horizontal shaft by a propulsion machine,
It is propelled in the side pit. Thereafter, similarly, the buried pipes 10 are joined together, propelled in the side pit, and the buried pipe is laid over a predetermined length.

The connection between the buried pipes is not limited to the above procedure. The buried pipe having the collar 20 previously connected to the rear end is propelled into the horizontal shaft, and the collar 20 is joined to the subsequent buried pipe. May be.

When the buried pipe 10 connected by the collar 20 is propelled in the horizontal shaft, even if soil is deposited on the bottom of the horizontal shaft, the soil enters between the ridges 22 of the collar 20 and There is no danger of the propulsion direction changing upward.

The wall thickness t of the main body 21 of the collar 20 (see FIG. 2) is
The difference is about the difference between the outer diameter of the pipe body 12 of the buried pipe 10 and the outer diameter of the fitting portion 11. When the buried pipe 10 is made of a synthetic resin such as vinyl chloride, this difference must be 40% or less of the wall thickness of the pipe body 12 so that the fitting portion 11 becomes thin and the buried pipe 10 is The fitting portion 11 may buckle when propelled into the side shaft.

Therefore, the wall thickness t of the body portion 21 of the collar 20 is also about 40% of the wall thickness of the pipe body portion 11 of the buried pipe 10. For example, in the case of the vinyl chloride pipe VU250, its wall thickness is 8.4 mm × 0.4 =
It will be about 3.5 mm.

Each ridge 22 of the collar 20 improves the axial strength of the entire collar 20 and is also fitted to each fitting portion 11 of the pair of buried pipes 10 when propelled in the horizontal shaft. ， There is no possibility that the collar 20 will be damaged. The number and intervals of the ribs 22 are determined so that the collar 20 has sufficient strength in the axial direction.

The total cross-sectional area of each protrusion 22 having a triangular cross section in the collar 20 is about 6 to 20% of the cross-sectional area of the entire collar 20.

The ratio of the interval (pitch) of each ridge 22 to the width dimension of the bottom surface of each ridge 22 is about 1 to 3. If the width of the bottom surface of each protrusion 22 is reduced and the height thereof is increased, sink marks of synthetic resin (a phenomenon in which the resin is distorted during demolding) or the like occur when the collar 20 is injection molded.

Although the number of the ribs 22 of the collar 20 is determined so that the collar 20 has a predetermined strength as described above, when the number of the ribs 22 increases, when the collar 20 is propelled into the shaft along with the buried pipe 10. , The propulsion direction may change upward due to the soil deposited on the bottom of the shaft. As a result, the laid buried pipe 10 is curved so as to project upward. The inventors of the present application conducted an experiment on the relationship between the number of the projections 22 and the bending amount of the buried pipe laid. In this experiment, a vinyl chloride pipe VU250 was used as a buried pipe. Each ridge 22 of color 20
Has a triangular cross section, its height is about 40% of the wall thickness of the pipe body 12 in the buried pipe 10 (about 3.5 mm), and the width of its bottom is D / 2Sin6 with respect to the outer diameter D of the buried pipe. It is about °. The soil where the buried pipe was laid was sandy soil mixed with volcanic ash, N value was about 15 to 20, the buried depth was 4.5 m from the ground surface to the pipe top, and the groundwater level was 1.8 m underground. . When the buried pipes were laid by the propulsion method using the collars of which the number of each ridge was 60, 40 and 30 respectively, and the amount of deflection of the buried pipe was measured every 10m up to 50m, the results in Table 1 were obtained. was gotten. For reference, the buried pipe was laid by the propulsion method using a cylindrical collar whose outer diameter is larger than that of the main body of the buried pipe, which is disclosed in JP-A-58-120996. The amount of bending of the buried pipe at that time is also shown. In the table, "-" indicates that the experiment was discontinued.

From this result, it is preferable that the number of ridges in the collar is about 50 or less.

The interval between the protrusions 22 does not have to be constant, and the fourth
As shown in the figure, a pair of ridges 22 and 22 may be continuously provided at various places in the circumferential direction without an appropriate interval in the circumferential direction. Furthermore, the protrusions 22 do not have to be continuous in the axial direction, and may be intermittent in the axial direction as shown in FIG. In this case, each ridge 22
The bending strength of the collar 20 does not decrease if the intermittent positions of the collars do not match in the circumferential direction. Further, as shown in FIG. 6, each of the ridges 22 may be inclined so that the central portion in the axial direction becomes the highest. Further, an annular protrusion 21a with which the end surface of the fitting portion 11 of each embedded pipe 10 abuts may be provided on the inner peripheral surface of the central portion of the body portion 21 of the collar 20. In the above embodiment, the cross-sectional shape of each ridge 22 is triangular, but it is not limited to such a shape and may be semicircular, semielliptic, rectangular, or the like.

As the collar used in the buried pipe connection structure of the present invention,
The structure shown in FIG. 8 may be used. The main body portion 51 of the collar 50 has a lower half 51b similar to the collar 20 shown in FIGS. 1 and 2, in which the difference between the outer diameter of the pipe body portion 12 of the buried pipe 10 and the outer diameter of the fitting portion 11. The lower half 51b, and has a thickness corresponding to
2, 52 ... Are arranged at appropriate intervals in the circumferential direction.
The upper half 51a of the main body 51 has a constant wall thickness corresponding to the total thickness of the lower half 51b and the height of each protrusion 52 projecting from the lower half 51b. Therefore, color
When 50 is externally fitted to the fitting portion 11 of the buried pipe 10, the outer peripheral side portion of the upper half 51a of the main body 51 of the collar 50 is
The embedded pipe 10 is in a state of protruding further outward than the pipe body portion 12. The upper half 51a of the main body 51 of the collar 50 is chamfered at the end on the propulsion direction side to form a tapered shape.

When the buried pipe 10 is laid by the propulsion method using such a collar 50, the soil accumulated on the bottom of the shaft enters between the ridges 52 projecting on the lower half 51b of the collar 50 in the main body 51. , There is no fear that the propulsion direction of the buried pipe 10 will change upward. Moreover, since the upper half of the collar 50 is thick, the collar 50 has a large bending strength. as a result,
There is no fear that the buried pipe to be laid will be bent so as to project upward.

The number of the nuclear ridges 52 in the collar 50 is about the same as the number provided in the lower half of the collar 20. Further, the shape, size, etc. of each ridge 52 are the same as those of the above-described embodiment of the collar 20.

Although the buried pipe and the collar made of synthetic resin have been described above as examples, the present invention is not limited to the buried pipe and the collar made of synthetic resin. For example, the buried pipe made of cast iron or concrete. And a collar made of cast iron or concrete may be connected.

(Effects of the Invention) In the connection structure for the buried pipe for propulsion method of the present invention, the collar externally fitted to the fitting portion of the buried pipe extends in the axial direction so as to project outward from the pipe main body of the buried pipe. Since a large number of ridges are provided at appropriate intervals in the circumferential direction, when the buried pipes connected by the collar are propelled into the shaft, the soil accumulated in the shaft will be separated by the collar. There is no danger that the direction of propulsion of the buried pipe will change significantly upwards when it enters the ridge. Moreover, the collar has excellent bending strength and compressive strength due to each ridge, and there is no risk of the collar being damaged when the embedded pipe is propelled.

Furthermore, in the connection structure of the buried pipe for the propulsion method of the present invention, since the upper part of the collar is thick, the collar has high bending strength and high compression strength, and is damaged when the buried pipe is propelled. There is no fear, and furthermore, the bending of the laid buried pipe protruding upward can be suppressed as much as possible.

[Brief description of drawings]

FIG. 1 is a connection structure of a buried pipe for a propulsion method according to the present invention, FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, FIG. 3 is an explanatory view of a propulsion method using the connection structure, and FIG. FIG. 5 is a front view of another embodiment of the collar, FIG. 5 is an explanatory view of main parts of still another embodiment of the collar, and FIGS. 6 and 7 are sectional views of main parts of still another embodiment of the collar. FIG. 8 is a front view of still another embodiment of the collar used in the connection structure of the present invention. 10 …… Buried pipe, 11 …… Mating part, 12 …… Pipe body, 20,50 ……
Color, 21,51 …… Main body, 22,52 …… Ridge.

Claims (2)

[Claims] 1. A connection structure for connecting buried pipes in a propulsion method in which a buried shaft is formed in the ground and the buried pipes are successively propelled and laid in the shaft, and a pair of buried members whose end faces are butted against each other. The outer circumference of the pipe body of each embedded pipe is fitted to the fitting part that is provided at each end of the pipe and has an outer diameter smaller than the outer diameter of the pipe body with a constant outer diameter excluding each end of each buried pipe. A collar provided with a large number of axially extending ridges protruding outward from the surface at appropriate intervals in the circumferential direction is connected to each other while being fitted over the fitting portions of the abutting buried pipes. The connection structure of the buried pipe for the propulsion method. 2. A structure for connecting buried pipes in a propulsion method in which a buried shaft is formed in the ground while the buried pipes are successively propelled and laid in the shaft, and a pair of buried members whose end faces are butted against each other. Fittings that are provided at each end of the pipe and that have an outer diameter smaller than the outer diameter of the pipe main body with a constant outer diameter excluding each end of each buried pipe, and the fitting of each buried pipe that is butted. It is fitted over the joint part, and on the lower part, a large number of axially extending projections projecting outward from the outer peripheral surface of the pipe main body part are arranged at appropriate intervals in the circumferential direction, and on the upper part. A connection structure for a buried pipe for a propulsion method, which has a collar whose outer peripheral surface projects outward from the outer peripheral surface of the pipe body.