JP7061773B2 - Construction method of underground structure and friction reducing material used for it - Google Patents

Description

INDUSTRIAL APPLICABILITY According to the present invention, the present invention can construct an underground structure that can be constructed without hindering upper traffic when excavating and constructing a large number of underground structures in the lower ground such as a railway or a road in the transverse direction. It relates to the method and the friction reducing material used in it.

In order to dig a large number of underground structures in the lower ground such as railroads and roads in the crossing direction, protective work is required to support the upper traffic, and a pipe roof for horizontally paralleling steel pipes, etc. is required. Can be given.

However, if a pipe roof was formed as a separate work first and then excavated under and inside to construct an underground structure, or if the underground structure was dug under the pipe roof, this pipe roof would be used. The overburden becomes thicker as much as it exists. Moreover, the protection work for the pipe roof construction is a separate work from the main work for burying the underground structure, and the construction cost and construction period are large.

As a solution to such inconvenience, there is a box-shaped roof construction method as described in Patent Document 1 below.
Japanese Patent No. 2789523

As shown in FIG. 10, a starting shaft 3 and a reaching shaft 4 are constructed by placing a steel sheet pile 2 on the side of the upper traffic 1 such as a railroad, and a press-fitting machine 5 is installed in the starting shaft 3. With this, the box-shaped roof cylinder 6 is press-fitted toward the reaching shaft 4 to form a roof as a protective work.

The box-shaped roof cylinder 6 is a box-shaped cylinder having a substantially square cross section made of a steel pipe, and a friction cutter plate (hereinafter referred to as FC plate) 7 made of a flat plate is placed on the upper surface thereof. (See Fig. 14)

The box-shaped roof cylinder 6 is for press-fitting unit cylinders one by one. As shown in FIG. 14, a joint flange 6c is formed at an end portion, and the joint flanges 6c are fastened to each other with bolts and nuts 19. By doing so, the required length from the starting shaft 3 to the reaching shaft 4 is buried by adding one piece at a time in the length direction, and further, the second, third, and so on are sequentially buried in parallel with the first one buried in this way. In the figure, 17 is a box punch for fastening with bolts and nuts 19.

The press-fitting machine 5 has an extrusion mechanism using a jack or the like for the box-shaped roof cylinder 6.

The arrangement of the box-shaped roof cylinders 6 is appropriately selected according to the underground structure to be arranged later, such as a gate type as shown in FIG. 13, a single character type, a box type, etc., although not shown.

Next, as shown in FIG. 11, a reaction force wall 8 and an underground structure 9 made of a concrete box are set in the starting pit 3, and a propulsion jack 10 is provided between the reaction force wall 8 and the underground structure 9. A cutting edge 11 is provided at the tip of the underground structure 9, and a small jack 12 is interposed between the tip of the underground structure 9 and the box-shaped roof cylinder 6.

In the figure, 13 is a support member for the box-shaped roof cylinder 6, 14 is a stop member for the friction cutter plate 7, and these are provided on the starting shaft 3 side, while a pedestal (pedestal) 15 is provided on the reaching shaft 4 side.

The small jack 12 was extended and the underground structure 9 was used as a reaction force to push forward the box-shaped roof cylinders 6 one by one while leaving the friction cutter plate 7, and all the box-shaped roof cylinders 6 moved forward. Then, the small jack 12 is shrunk and the propulsion jack 10 is extended this time to dig up the underground structure 9. 16 in the figure shows a strut interposed between the propulsion jack 10 and the underground structure 9.

In this way, while alternately repeating the advance of the box-shaped roof cylinder 6 and the advance of the underground structure 9, as shown in FIG. 12, the unit 1 piece of the box-shaped roof cylinder 6 is completed in the reaching shaft 4. If this happens, the joint flanges 6c are not fastened together with the bolts and nuts 19, and the joint flanges 6c are divided in the length direction and removed in sequence.

Then, when the tip of the underground structure 9 reaches the reaching shaft 4, the cutting edge 11 and the like are removed, and the backfill grout is performed as appropriate to complete the construction.

In the underground structure 9, precast concrete boxes may be sequentially suspended and connected in the starting shaft 3, or concrete may be placed in the starting shaft 3 to increase the required length. You may do so.

Further, regarding the propulsion method of the underground structure 9, a reaction force wall and a center hole type traction jack are provided on the reaching shaft 4 side, and one end thereof is a traction member made of PC steel wire fixed to the underground structure 9 with this traction jack. By pulling, the underground structure 9 can be pulled in from the reaching shaft 4 side.

In the construction method of the underground structure using the box-shaped roof construction method as described above, the construction method is carried out while the business line is running directly above the site.

Therefore, a box-shaped roof is installed in the ground under the railroad track to temporarily protect it, and then a concrete box (box culvert) is propelled to construct a crossing structure under the railroad track.

However, in recent years, with the increase in the size of the cross section of the box in the under-track cross-section method, the propulsion and traction force of the box has increased, and a large frictional force is generated at the interface between the box and the ground. It is necessary to secure the thrust by.

In particular, in the construction method that replaces the box-shaped roof installed in the cross section and the box body, the frictional resistance due to the consolidation of the surrounding ground during the re-propulsion of the box-shaped roof installed in the cross section for a long period of time (during the box body propulsion). As a result, unexpected propulsive force was required, which may affect the surrounding ground (vibration and noise) during edge cutting, box propulsion, and towing.

An object of the present invention is to eliminate the inconvenience of the above-mentioned conventional example, and to eliminate the friction between the box-shaped roof and the friction cutter (FC) plate, which occurs during the propulsion and towing of the box body, or the peripheral surface of the box body in the construction of the crossing structure under the railroad track. By effectively reducing the friction between the FC plate and the FC plate, the propulsion / towing force at the time of edge cutting and the influence on the surrounding ground at the time of box propulsion / towing can be reduced. The purpose is to provide a friction reducing material used for it.

In order to achieve the above object, the present invention is to match the outer edge of the concrete box to be installed as a protective work when propulsion of the concrete box to be installed as the underground structure as a construction method of the underground structure. In addition, a box-shaped roof, which is a steel pipe of a box-shaped cylinder with a rectangular cross section, is passed through in advance between the starting shaft and the reaching shaft, which is a crossing section, and a friction cutter plate is placed on the box-shaped roof to place the starting shaft. A concrete box is installed in the concrete box, the box-shaped roof is pushed out while leaving the friction cutter plate, and the concrete box is propelled. In the installation method of the underground structure that replaces and installs the box, between the box-shaped roof and the friction cutter plate, a metal sphere or roller such as rigid iron and the roller are covered with mortar as a covering material that can be sheared. The gist is that a friction reducing material having a hexahedral block shape having a height, width, and depth that matches the diameter of the sphere or roller is placed.

As a friction reducing material used in the construction method of underground structures, there is a space between the box-shaped roof, which is a protective work when propelling a concrete box to be installed as an underground structure, and the friction cutter plate on it. It is a friction reducing material that is placed in a friction-reducing material, and is covered with a metal sphere or roller such as rigid iron and a covering material that can be sheared and broken , and has a height, width, and depth that matches the diameter of the sphere or roller. The gist is that the block shape is a hexahedron .

According to the present invention, when the box body is propelled, the covering material is sheared and broken due to the forced displacement due to the friction, so that the friction at the time of edge cutting and the friction generated at the time of box body propulsion / towing can be reduced. ..

If only a sphere or roller is installed at the interface between the FC plate and the box-shaped roof, the interface friction between the ground and the box can be almost zero, but the behavior of the box during construction is extremely large due to the influence of train load and ground pressure. Although it becomes unstable, the destabilization of construction is suppressed by rolling on the fragments of the covering material in which the sphere or roller can be sheared and broken while receiving resistance.

Also, the friction reducing material can be formed as a block or flat plate by covering it with a shear-breakable coating, and a sphere or roller rolls out to be placed between the box roof and the friction cutter plate. Can be installed stably without any need.

Further, since the FC plate and the box-shaped roof are not displaced in the height direction due to a sphere such as rigid iron or a roller, the vertical displacement in the displacement of the track / road can be suppressed.

In addition to this, mortar is optimal in terms of formability, price, etc. as a coating material that undergoes forced displacement due to friction and undergoes shear failure.

As described above, the construction method of the underground structure of the present invention and the friction reducing material used thereof are the box-shaped roof and the friction cutter (FC) plate generated at the time of box propulsion / towing in the construction of the crossing structure under the railroad track. By effectively reducing the friction of the box body or the friction between the peripheral surface of the box body and the FC plate, the propulsion / traction force at the time of edge cutting and the influence on the surrounding ground during the box body propulsion / towing are reduced. Can be done.

It is a side view which shows 1st Embodiment of the construction method of the underground structure of this invention. It is a side view which shows the 2nd Embodiment of the construction method of the underground structure of this invention. FIG. 1 is a view taken along the line AA of FIG. It is a front view of the main part which shows the 3rd Embodiment of the construction method of the underground structure of this invention. It is a BB line arrow view of FIG. It is a perspective view which shows an example of the friction reducing material of this invention. It is a perspective view which shows the other example of the friction reducing material of this invention. It is explanatory drawing which shows the change in the box body propulsion of the construction method from the time of installing the friction reducing material which shows one Embodiment of the construction method of the underground structure of this invention. It is a graph which shows the relationship between a jack thrust and a propulsion amount. It is a side view which shows the 1st process of the construction method of the underground structure by the box-shaped roof construction method. It is a side view which shows the 2nd process of the construction method of the underground structure by the box-shaped roof construction method. It is a side view which shows the 3rd process of the construction method of the underground structure. It is a front view which shows an example of the arrangement state of a box-shaped roof cylinder. It is a partial perspective view which shows an example of the cylinder for a box-shaped roof.

Hereinafter, embodiments of the present invention will be described in detail with respect to the drawings. FIG. 1 is a vertical sectional side view showing a first embodiment of a construction method for an underground structure of the present invention. In the figure, 6 is a box-shaped roof cylinder, 7 is a friction cutter plate, and 9 is an underground structure made of a concrete box. Is.

The box-shaped roof construction method using the box-shaped roof cylinder 6 is as described with reference to FIGS. 10 to 14 showing the conventional example, and the box-shaped roof cylinder 6 is provided with the starting pit 3 and the reaching pit 4. An underground structure that is horizontally pressed into the ground between them and placed in parallel, and an underground structure is placed at the end of the box-shaped roof cylinder 6 that goes out to the starting pit 3, and the box-shaped roof and the underground structure are promoted. How to build.

A starting shaft 3 and a reaching shaft 4 are constructed by placing a steel sheet pile 2 on the side of the upper traffic 1 such as a railroad, and a press-fitting machine 5 is installed in the starting shaft 3 to form a box-shaped roof cylinder. 6 is press-fitted toward the reaching shaft 4 to form a roof as a protective work.

As shown in FIG. 14, the box-shaped roof cylinder 6 is a box-shaped cylinder having a substantially square cross section made of a steel pipe, on which a friction cutter (FC) plate 7 made of a flat plate is placed.

The box-shaped roof cylinder 6 is for press-fitting unit cylinders one by one, and a joint flange 6c is formed at the end, and a box punch 17 is formed behind the joint flange 6c to bolt the joint flanges 6c to each other. By fastening with nuts 19, the required length from the reaching pit 4 to the starting pit 3 is buried by adding one piece at a time in the length direction, and then the second, third, and so on are buried in order for the first pit buried in this way. And parallelize.

The friction cutter plate 7 is fixed to the box-shaped roof cylinder 6 by welding or the like only at the head portion, and then connected by welding, and is stretched so as to cover the box-shaped roof cylinder 6 by press-fitting. To go.

The present invention is a box-shaped cylinder, and when a friction cutter (FC) plate 7 made of a flat plate is placed on the box-shaped cylinder, a friction reducing material 20 is provided between the box-shaped roof cylinder 6 and the friction cutter plate 7. installed.

Only the front part of the friction cutter plate 7 is fixed to the box-shaped roof cylinder 6 by welding, and then the friction cutter plate 7 is connected by welding, and is extended so as to cover the box-shaped roof cylinder 6 by press-fitting. In order to sandwich the friction reducing material 20, a gap is secured between the friction cutter plate 7 and the box-shaped roof cylinder 6, and the welding is also performed with the friction cutter plate 7 floating so that the gap width can be secured.

The friction reducing material 20 is made by covering a sphere 21 such as rigid iron with a mortar 22 as a covering material capable of shear failure. As shown in FIG. 6, the height and width of the mortar 22 match the diameter of the sphere 21. , A hexahedron block shape with depth.

When molding the friction reducing material 20, the sphere 21 may be housed in the mold, then the mortar 22 may be filled in the mold, and the mold may be removed after curing.

The friction reducing material 20 having such a block shape is arranged between the friction cutter plate 7 and the box-shaped roof cylinder 6 at intervals.

Further, as another embodiment, the friction reducing material 20 can be configured as a block in which a plurality of spheres 21 are covered with mortar 22.

Further, as shown in FIG. 4, the friction reducing material 20 may be formed by arranging a large number of spheres 21 made of small spheres and embedding them in the mortar 22 to form a plate as a whole.

As another embodiment, instead of the sphere 21 as shown in FIG. 7, a roller 23 made of a steel rod can be used as a rigid one.

In this case as well, in addition to the case where the mortar 22 has a hexahedron shape having a height, width, and depth that match the diameter of the roller 23, the length of the roller 23 is assumed to be long, and this is covered with the mortar 22 to form a long rod. You may.

The long rod-shaped friction reducing material 20 is placed at intervals on the box-shaped roof cylinders 6 arranged side by side at intervals, and is sandwiched between the friction cutter plates 7.

As shown in FIG. 1, a unit of the box-shaped roof cylinder 6 is set by setting the underground structure 9 made of a concrete box, and alternately repeating the advance of the box-shaped roof cylinder 6 and the advance of the underground structure 9. If one piece comes out to the reaching shaft (not shown), remove it in sequence, and if the tip of the underground structure 9 reaches the reaching shaft 4, perform backfill grout as appropriate to complete the construction, but friction The change of the reduction material 20 is shown in FIG.

From the initial state, the friction reducing material 20 receives forced lateral displacement due to the propulsion of the underground structure 9 by the concrete box, and the mortar 22 undergoes shear failure.

That is, not only is the vertical direction of the track supported by the friction reducing materials 20 installed in large numbers before the start of the underground structure 9 by the concrete box, but also during propulsion, the rolling of the sphere 21 causes the concrete box and the ground. The friction that occurs can be reduced.

As a result, the jack thrust at the time of propelling the box can be reduced as compared with the existing method. Since the rigid sphere can propel the box under the condition that the displacement in the height direction does not occur, the construction can be performed under the condition that the track displacement does not occur.

FIG. 9 shows the relationship between the jack thrust and the propulsion amount u when the conventional FC plate and the roof are in contact with each other and when the present invention is used.

The coefficient of friction between steels is about 27 °, but the coefficient of friction when an iron ball with a diameter of 40 cm rolls on the steel surface is 0.001 °. Can be reduced to 0.004%.

When the iron ball rolls on the mortar fragments, the rolling friction coefficient can be adjusted by the compressive strength of the mortar, and the thrust of the jack can be effectively reduced as shown in FIG. The compressive strength of the mortar can be 200 MPa at high strength and 10 MPa or less at low strength.

In FIG. 2, the box-shaped roof 6 is assembled and arranged in a rectangular arrangement on the lower, side, and upper stages so as to correspond to the outer shape of the underground structure 9 to be propelled, and after being press-fitted into the ground, the box-shaped roof 6 This is a case where the present invention is applied to a construction method of an underground structure in which the tip portion of the underground structure 9 is arranged at the end of the underground structure 9 and pushed out together with the box-shaped roof 6 and the internal earth and sand together with the propulsion and towing of the underground structure 9. ..

The friction cutter plate 7 is left behind when the box-shaped roof 6 is extruded at the same time as the propulsion and towing of the underground structure 9, thereby cutting the edges between the box-shaped roof 6 and the underground structure 9 and the surrounding earth and sand. Is taken into the concrete box together with the friction cutter plate.

In this case, the friction cutter plate 7 is also arranged on the lower side of the box-shaped roof 6 arranged side by side on the lower stage, but the friction reducing material 20 is the box-shaped roof 6 and the friction cutter plate 7 on the lower stage. It is also placed between and.

Further, although not shown, the friction cutter plate 7 is also used on the side side of the box-shaped roof 6 which is arranged in a rectangular arrangement in the lower, side, and upper stages so as to correspond to the outer shape of the underground structure 9. A friction reducing material 20 may be arranged between them.

As yet another embodiment, as the friction reducing material 20, a synthetic resin such as Styrofoam or clay such as bentonite is used instead of the mortar 22 as a covering material capable of shear breakage covering a sphere such as rigid iron or a roller. It is also possible to do.

1 ... Upper traffic 2 ... Steel sheet pile 3 ... Starting shaft 4 ... Reaching shaft 5 ... Press-fitting machine 6 ... Box-shaped roof cylinder 6c ... Joint flange 7 ... Friction cutter plate 8 ... Reaction force wall 9 ... Underground structure 10 ... Propulsion Jack 11 ... Blade edge 12 ... Small jack 13 ... Support material 14 ... Stopping member 15 ... Cradle 16 ... Strut 17 ... Boxing 19 ... Bolts, nuts 20 ... Friction reduction material 21 ... Sphere 22 ... Mortal 23 ... Coro

Claims (2)

As a protective work when propelling a concrete box to be installed as an underground structure, a box-shaped roof, which is a steel tube of a box-shaped cylinder with a rectangular cross section, is crossed in advance so as to match the outer edge of the concrete box to be installed. Penetrate between the starting shaft and the reaching shaft, which is a section, place the friction cutter plate on the box-shaped roof, install the concrete box on the starting shaft, and push out the box-shaped roof leaving the friction cutter plate. In the installation method of the underground structure where the concrete box is propelled together, the box-shaped roof that is extruded and goes out to the reaching shaft is sequentially removed, and the box-shaped roof and the concrete box are replaced and installed in the ground, the box-shaped roof and friction A hexahedral block with a height, width, and depth that matches the diameter of the sphere or roller, with a metal sphere or roller such as rigid iron and a mortar covering it as a shear-breakable coating between the cutter plate. An underground structure installation method characterized by arranging a friction-reducing material in a shape . It is a friction reducing material that is placed with a gap between the box-shaped roof, which is a protective work when propelling a concrete box to be installed as an underground structure, and the friction cutter plate on it, such as rigid iron. An underground structure characterized by covering a metal sphere or roller with mortar as a covering material capable of shear fracture, and forming a hexahedral block shape having a height, width, and depth matching the diameter of the sphere or roller. Friction reduction material used in the installation method.

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