JPH028146Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial field of application] This invention relates to propulsion pipes, including intermediate push pipes, used in tunnel excavation work using the propulsion method. Concerning a prestressed concrete propulsion tube that has been given.

[Conventional technology]

The so-called propulsion method is a construction method in which propulsion pipes are successively joined together and then press-fitted into the soil to construct a tunnel. Generally, a vertical shaft is provided at the starting point and the destination point (destination point), and while the front face of the face is excavated with the cutting edge at the tip, the reaction force is taken by the main pushing side of the starting shaft and the middle pushing part in the middle, and propulsion is carried out. Use jacks to press the propulsion tubes sequentially from the starting shaft to the destination shaft to construct a tunnel.

Conventionally, centrifugal reinforced concrete pipes have been mainly used as the propulsion pipes used in this construction method, but ductile pipes have been used especially for waterways with high internal pressure. However, this ductile pipe has a relatively low propulsion allowable stress and is easily corroded. For this reason, they have many disadvantages compared to centrifugal reinforced concrete pipes, such as being difficult to propel over long distances and requiring anticorrosive coating and secondary lining.

Against this background, it has been desired to use so-called prestressed concrete pipes, which are made by winding prestressed steel wire and applying stress in the circumferential direction of the concrete pipes, for propulsion work on waterways with relatively high internal and external pressures.

[Problem that the invention attempts to solve]

However, in the case of a propulsion tube that receives strong frictional resistance from the ground during propulsion, consideration must be given to damage and corrosion of the PC steel wire. In general prestressed concrete pipes, the outer periphery of the concrete pipe containing the PC steel wire is protected with a mortar coating, but this mortar coating is more brittle than a concrete pipe compacted by centrifugal force. It is easily peeled off by stones and gravel contained in the ground. Therefore, this point is considered to be the biggest difficulty when applying prestressed concrete pipes, and in fact, conventional prestressed concrete pipes are used exclusively for tunnel construction using the open-cut method, where the outer circumference is not subjected to strong friction. This is the reality.

The purpose of this invention is to solve the above problems of conventional prestressed concrete pipes and to provide a prestressed concrete pipe that can be used as a propulsion pipe.

[Means to solve the problem]

That is, in the present invention, in order to achieve the above-mentioned purpose, by wrapping and tightening a prestressed steel wire around the outer circumference of a concrete pipe, stress is applied in the circumferential direction of the pipe, and the outer circumferential side of the concrete containing the prestressed steel wire is , a prestressed concrete propulsion tube covered with a mortar coating formed by adhering and curing mortar, wherein the mortar coating includes a wire such as a metal wire, inorganic fiber, or organic fiber. .

[Effect]

As already mentioned, the mortar coating, which is formed by attaching mortar to the outer periphery of a concrete pipe and hardening it, rather than by centrifugal molding of concrete, is vulnerable to friction.
However, as in the present invention, by incorporating a wire rod into this mortar coating, it becomes resistant to friction, and as described later, tests by the present inventor have shown that it can withstand the friction received from the ground during propulsion. It is becoming clear. This makes it possible to use prestressed concrete pipes as propulsion pipes.

Hereinafter, an embodiment of this invention will be explained with reference to the drawings. First, a prestressed steel wire 2 is wound around the outer periphery of a concrete pipe 1 formed by a known method, and this is tightened to apply stress in the circumferential direction of the pipe 1. give.
Then, the outer circumferential side of the concrete pipe 1 containing the PC steel wire 2 is covered with a mortar coating 3 containing the wire rod 4. In addition, in FIG. 1, the symbols 7, 7, . . . indicate through holes for backfill injection.

To explain this configuration in more detail along with an embodiment, the concrete pipe 1 is a centrifugally reinforced concrete pipe that is centrifugally formed with reinforcing bars arranged inside. This concrete pipe 1 is formed so that the outer diameter of the middle part excluding both ends is made one step thinner, and the pipe is slightly thinner than a predetermined wall thickness. For example, inner diameter D=
In the case of a propulsion tube having specifications of 800 to 3000 mm and wall thickness T of 80 to 250 mm, the wall thickness of the intermediate portion of the concrete tube 1 is finished to be approximately 25 mm thinner than the value of the wall pressure T mentioned above.

Next, this concrete pipe 1 is cured and hardened, and after being demolded, a PC steel wire 2 is wound around the outer circumferential side of the thinner middle part. This is then tightened to apply stress to the concrete pipe 1 in the circumferential direction. In the case of a propulsion tube of the above standard, the PC steel wire 2 used is 3.5 to 6 mm depending on the design internal pressure and external pressure, etc.
It is particularly desirable to use galvanized steel wire, etc., which has high corrosion resistance.

Next, if necessary, a resin paint 5 such as epoxy resin is applied to the outer peripheral surface of the concrete pipe 1 around which the PC steel wire 2 is wound to cover the PC steel wire 2. Thereafter, a wire rod 4 is placed on top of this, mortar is sprayed onto it, and this is hardened to provide a mortar coating 3. Finally, except for both ends including the steel collar 6,
Finish the surface smooth with concrete paste so that the outer diameter is as uniform as possible between them.

As the wire 4, metal wires such as a so-called metal lath made of thin steel wire knitted into a mesh shape, and a so-called steel fiber made of intertwined steel wires with a length of about 30 mm are suitable. Furthermore, inorganic fibers such as glass fibers and carbon fibers, organic fibers such as synthetic resin fibers, etc. can also be used.

When using a knitted wire rod 4 such as metal lath or a long wire rod 4, the mortar coating 3 can be provided by winding the wire rod 4 around the outside of the PC steel wire 2 and then spraying mortar on the wire rod 4. In this case, the metal lath can be arranged in several layers in the mortar coating 3. On the other hand, when using short chip-shaped wire rods 4 such as steel fiber, mix the wire rods 4 into raw mortar in advance, and then
A mortar coating 3 can be provided by spraying on the outside of the PC steel wire 2.

In the prestressed concrete propulsion pipe made in this way, the mortar coating 3 covering the PC steel wire 2 is extremely tough and exhibits high durability against friction received from the ground during propulsion. In the actual propulsion method, some peeling of the mortar coating 3 was observed in the leading propulsion tube, which bears most of the propulsion resistance, but the damage to the mortar coating 3 in the second and subsequent propulsion tubes was extremely slight, and was not used in practical applications. It was confirmed that there were almost no problems.

[Effect of idea]

As explained above, according to this invention, the PC steel wire 2 wrapped around the outer circumference of the concrete pipe 1 can be sufficiently protected even in tunnel excavation work using the propulsion method, so it can be applied to the propulsion pipe of prestressed concrete pipes. becomes possible. Therefore, it is possible to provide an excellent propulsion tube that can be used under conditions of high internal and external pressure and that can withstand long-distance propulsion. Furthermore, by using this propulsion pipe, construction can be performed more easily than conventional ductile pipes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a prestressed concrete pipe showing an embodiment of this invention, and FIG. 2 is an enlarged sectional view of the main part of the same pipe. 1... Concrete pipe, 2... PC steel wire, 3...
... Mortar covering, 4... Wire rod.

Claims (1)

[Scope of utility model registration request] By wrapping and tightening a prestressed steel wire around the outer circumference of a concrete pipe, stress is applied in the circumferential direction of the pipe, and the outer circumferential side of the concrete, including the prestressed steel wire, is coated with mortar formed by adhering and hardening mortar. 1. A covered prestressed concrete propulsion tube, wherein the mortar coating includes a wire such as a metal wire, an inorganic fiber, or an organic fiber.