Box roof and its construction method

Abstract

To provide a box-shaped roof capable of surely pushing out the box-shaped roof without causing deflection even when the construction length is long, and a construction method thereof. [Solution] In a box-shaped roof 17 formed to a predetermined length by connecting unit cylinders 17a, which are box-shaped cylinders with an approximately square cross section, an expandable box-shaped cylinder 40 that has the same outer diameter as the unit cylinders 17a and expands and contracts in the longitudinal direction is incorporated in the middle of the box-shaped roof 17 where the unit cylinders 17a are lined up vertically.

Description

[Technical field]

[0001] The present invention relates to a box-shaped roof used for constructing underground structures, which allows existing crossing structures to be constructed without interfering with traffic above when excavating large underground structures in a transverse direction below the ground for railways, roads, etc., and a construction method thereof. [Background technology]

[0002] In the case of railways, the construction methods for underground crossing structures were initially mainly open-cut construction methods such as temporary line construction and track temporary support construction (construction girder construction method). However, as the number of trains increased, it became difficult to adopt the open-cut construction method, which involves a lot of work inside the tracks.

[0003] Therefore, a trenchless construction method was developed to build crossing structures under the tracks while ensuring train service. This method is called the tunneling method, and involves pushing forward a precast concrete box culvert as a large-width underground structure made of reinforced concrete.

[0004] This pushing is done by attaching a cutting edge made of a steel hood to the tip of a precast concrete box culvert, excavating inside the cutting edge to create a gap in front, and then pushing the concrete box forward with a main thrust jack installed in the starting shaft.

[0005] However, when digging a large precast concrete box (box culvert) in a transverse direction beneath a railway, road, etc., protective work is required to support the traffic above. One such protective work is the pipe roof method, in which a pipe roof is installed by arranging steel pipes horizontally in parallel.

[0006] The pipe roof method involves inserting a pipe roof (steel pipes) under the railway tracks in advance as a protective measure for the tracks. After the tracks are temporarily supported by each steel pipe using shoring, the soil from under the pipe roof is excavated and a concrete box is constructed.

[0007] In the pipe roof method, the main structure is excavated inside a roof or wall made of pipes (steel pipes) cast horizontally in an arch or column shape. As a result, in addition to the soil covering and the diameter of the pipes (steel pipes), the top of the concrete box is low, and the excavation must be done at a deep position.

[0008] Furthermore, there is a problem that the pipes that form the pipe roof cannot be removed, resulting in high construction costs.

[0009] Therefore, a box roof has been proposed as a protective work when using the concrete box jacking method. The box roof protects railway tracks instead of a pipe roof, and the box roof method uses a box roof to install the structure under the railway tracks while pushing out the box roof. Since the protective work for the underground structure to be excavated into the ground is not carried out as a separate work, but is carried out at the same time as the underground structure is excavated, the work can be carried out safely, reliably, and inexpensively, and the earth covering can be shallow.

[0010] As shown in Figure 15, the box-shaped roof is formed to a specified length by connecting unit cylinders 17a. These unit cylinders 17a are box-shaped cylinders with an approximately square cross section of 800 x 800 (mm) or 1000 x 1000 (mm). Unit cylinders 17a are 3 to 6 m long and can be connected sequentially in the lengthwise direction to the required length, and can be further arranged in parallel horizontally via joints.

[0011] The unit cylinders 17a of the box-shaped roof 17 form connection flanges 17c at the corners of their ends, and these connection flanges 17c are fastened together with bolts and nuts 19, or the fastening with the bolts and nuts 19 is carried out at the part of the box cutout 20, which is open outward at the end corner of the unit cylinder 17a.

[0012] When the box punch 20 is provided in this manner, the bolts and nuts 19 can be fastened or released from the outside of the box-shaped roof.

[0013] A friction-cut plate 21 made of a strip-shaped steel plate with a thickness of 9 to 12 mm is placed on the upper and other outer surfaces of the box-shaped roof 17. The length of this friction-cut plate 21 is approximately the same as that of the unit cylindrical body 17a, and is lengthened by welding when connecting the unit cylindrical body 17a.

[0014] Retaining members such as steel sheet piles are cast next to overhead transportation such as railways to construct a starting shaft and a arrival shaft 9. As shown in FIG. 17, a push jack 4 is installed in the starting shaft 3 as a propulsion device, and this is used to press the box roof 17, unit cylinder 17a at a time, into the arrival shaft.

[0015] The box-shaped roof 17 has a cutting edge pipe 18 attached to the tip, and the face is excavated by hand or by a machine such as an auger, and is advanced. In the figure, 14 is a soil discharge pipe that discharges the excavated soil.

[0016] In addition, a friction cut plate 21 is attached to the upper surface of the box-shaped roof 17 and is disposed underground by being pushed out together with the box-shaped roof 17, and the friction cut plate 21 is fixed to the starting shaft 3 side by a fixing member 26.

[0017] The friction cut plate 21 is welded only at its tip to the tip of the box-shaped roof 17, for example to the cutting edge tube 18, and the other parts are not fixed but simply placed on top of it, and are extruded together with the box-shaped roof 17.

[0018] The box-shaped roof 17 is made by pressing in the unit cylindrical bodies 17a one by one, and each piece is added lengthwise to bury the required length from the starting shaft 3 to the arrival shaft 9, and then the second, third, etc. are buried in sequence in parallel with the first one thus buried. Next, as shown in Figure 15, a concrete box 1 as an underground structure is set in the starting shaft 3, a thrust jack 4 is installed between the reaction wall 5 and the concrete box 1, and a cutting edge 2 is provided at the tip of the concrete box 1.

[0019] The earth and sand in the cutting edge 2 and in front of the face are excavated. A box roof 17 acts as a protection.

[0020] Since a gap is created by excavation and removal of soil, the main jack 4 is extended to push the concrete box body 1 forward, and at the same time, the box roof 17 is pushed forward through the concrete box body 1 while leaving the friction cut plate 21 behind.

[0021] The concrete box body 1 advances inside the friction cut plate 21, and the friction cut plate 21 cuts friction with the ground when the concrete box body 1 is advanced.

[0022] In the drawing, 6 indicates a strut interposed between the main jack 4 and the reaction wall 5. In this way, the box roof 17 and the concrete box body 1 are advanced simultaneously, and when one piece of unit cylindrical body 17a of the box roof 17 has completely emerged into the arrival shaft 9, the fastening of the bolts and nuts 19 between the connecting flanges 17c is released, the unit is divided lengthwise, and each piece is removed one by one.

[0023] Then, when the tip of the concrete box 1 reaches the arrival shaft 9, the cutting edge 2 and the like are removed and backfill grout is applied appropriately to complete the construction.

[0024] In this way, the box roof allows the structure to be covered shallowly with soil, making the approach road slope gentler and allowing the installation of a safe and easy-to-use underpass; the approach road section can be shortened, making it easier to apply in existing urban areas; the excavation depth for the entire work is shallower, so the overall construction cost of the underpass is cheaper; the structure can be constructed in a light state that is easy to manage; the protective work can be a box-shaped rigid frame structure, so it can be applied even when the cross-sectional length is long; and the box roof as protective work can be reused, making it economical.

[0025] The following patent document proposes a device and method for preventing subsidence of a roof cylinder in a method for constructing an underground structure, which can prevent the roof cylinder from bending downward and improve workability. [Patent Document 3] Patent No. 3702265

[0026] In a method for constructing an underground structure, a box-shaped roof with a friction cutter plate on top is pressed into the ground from a starting tunnel to be aligned in parallel, an underground structure is placed at the rear of the box-shaped roof cylinder remaining in the starting tunnel, and the underground structure is excavated while the friction cutter is left in the ground, and a lifting rope for lifting up the downwardly bent portion of the box-shaped roof cylinder is passed through the inside of the box-shaped roof cylinder along its length.

[0027] By pulling horizontally the rope that passes through the length of the inside of the box-shaped roof cylinder, the upper and lower vertical force components acting on the rope are transmitted to the box-shaped roof cylinder, and the sagging portion of the box-shaped roof cylinder is pulled up, eliminating the sagging. Summary of the Invention [Problem to be solved by the invention]

[0028] When the construction length of the box-shaped roof is long, the box-shaped roof is more likely to bend as described above, and a larger pushing force is required.

[0029] There is a risk that the thrust (pushing jack or towing jack) used to propel the concrete box may not be sufficient to push out the box roof from the concrete box.

[0030] In addition, although not shown in the figure, a thrust tube with a small jack attached is installed at the base of the box-shaped roof, and the box-shaped roof is pushed out using the thrust of the small jack. However, there are cases where this is not enough force to push out the entire box-shaped roof.

[0031] SUMMARY OF THE PRESENT INVETION The object of the present invention is to provide a box-shaped roof and a construction method thereof which can reliably push out the box-shaped roof without causing deflection even when the construction length is long, thereby eliminating the inconveniences of the conventional examples. [Means for solving the problem]

[0032] In order to achieve the above object, the box roof of the present invention is, firstly, a box roof formed to a predetermined length by connecting unit cylinders, which are box-shaped cylinders having a substantially square cross section, and a telescopic box-shaped cylinder that can be telescopically expanded and contracted in the length direction and has the same outer diameter as the unit cylinders is provided in the middle of the box roof where the unit cylinders are arranged vertically. This expansion box-shaped cylinder is composed of a front cylinder and a rear cylinder that fits into it, and jacks are provided at the four corners to span between the front and rear cylinders. The gist of the invention is that it has been incorporated.

[0033] Secondly, the expandable box-shaped cylindrical body consists of a front cylindrical body and a rear cylindrical body that fits into it, and one of the cylindrical bodies is reduced in diameter and inserted into the other. Thirdly, the part of the cylindrical body that is reduced in diameter that does not reduce in diameter extends partially to form a rectangular convex portion above the reduced diameter portion, and this is inserted into the rectangular concave notch of the other cylindrical body.

[0034] The construction method of the box roof of the present invention is to arrange a box roof, which is a box-shaped cylindrical steel pipe with a rectangular cross section, so as to match the outer edge of the concrete box to be installed as a protective work when advancing a concrete box to be installed as an underground structure, and this box roof is previously pushed through between the departure shaft and the arrival shaft, which is the entire length of the crossing section, and the concrete box is installed behind it, and the box roof is pushed out while the concrete box is advanced, and when the box roof and the concrete box are replaced and installed, an expandable box-shaped cylinder with the same outer diameter as the unit cylinder and which expands and contracts in the length direction is inserted into the box roof where the unit cylinders are vertically arranged, This expansion box-shaped cylinder is composed of a front cylinder and a rear cylinder that fits into it, and jacks are provided at the four corners to span between the front and rear cylinders. The gist of this method is that an expandable box-shaped cylinder that has the same outer diameter as the unit cylinder and expands and contracts in the lengthwise direction is incorporated, and during the process of pushing out the entire box-shaped roof, a process of pushing out only the front part of the box-shaped roof by extending the expandable box-shaped cylinder is inserted.

[0035] According to the present invention as described in claim 1, by incorporating an expandable box-shaped cylinder with the same outer diameter as the unit cylinders and which expands and contracts in the longitudinal direction in the middle of a box-shaped roof in which unit cylinders are lined up vertically, the row of unit cylinders in front of it can be pushed out by extending this expandable box-shaped cylinder, and by adding this extrusion to the extrusion of the box-shaped roof using the propulsion force that propels the concrete box body, even a box-shaped roof with a long construction length can be divided into front and rear parts and pushed out reliably without causing deflection of the entire structure.

[0036] In addition, when the expansion box-shaped cylindrical body is fully extended, if the box-shaped roof at the rear portion is pushed out, the expansion box-shaped cylindrical body will shrink and become ready for further pushing out.

[0037] Furthermore, the telescopic box-shaped cylinder can be reliably extended and retracted by using a jack to slide the front cylinder and the rear cylinder that fits into it, and since the jacks are placed at the four corners, space is secured in the center for workers and earth-removal carts to pass through. Furthermore, by using the jacks at the four corners, the propulsive force of the jacks can be transmitted evenly to the box-shaped roof at the front of the telescopic box-shaped cylinder, allowing the front box-shaped roof to be pushed out stably without any unevenness.

[0038] According to the present invention described in claim 2, the expandable box-shaped cylindrical body comprises a front cylindrical body and a rear cylindrical body that fits into the front cylindrical body, and one of the cylindrical bodies is reduced in diameter and inserted into the other, so that no gap is generated between the front cylindrical body and the rear cylindrical body when the expandable box-shaped cylindrical body is extended or contracted, and there is no risk of soil or sand getting mixed inside.

[0039] According to the present invention described in claim 3, the portion of the cylinder being contracted that does not contract is extended to form a rectangular convex portion above the contracted portion, and this is inserted into the rectangular recessed notch of the other cylinder, so that the rectangular convex portion acts as a guide when the expandable box-shaped cylinder contracts, allowing it to contract and expand smoothly.

[0040] According to the present invention as described in claim 4, a box roof is made by incorporating an expandable box-shaped cylinder with the same outer diameter as the unit cylinders and which expands and contracts in the longitudinal direction in the middle of the box roof where unit cylinders are lined up vertically, and by inserting a process of pushing out only the front part of the box roof by extending the expandable box-shaped cylinder during the process of pushing out the entire box roof, it is possible to push out the row of unit cylinders in front of it, and by adding this pushing out to the pushing out of the box roof with the propulsion force used to propel the concrete box body, even a box roof with a long construction length can be pushed out in front and back parts, and can be pushed out reliably without causing deflection of the entire box roof. Effect of the Invention

[0041] As described above, the box-shaped roof and the construction method thereof of the present invention can reliably push out the box-shaped roof without causing deflection even when the construction length is long. [Brief description of the drawings]

[0042] [Figure 1] FIG. 2 is a side view showing a first step of the box roof construction method of the present invention. [Diagram 2] FIG. 4 is a side view showing a second step of the box roof construction method of the present invention. [Diagram 3] FIG. 4 is a side view showing the third step of the box roof construction method of the present invention. [Figure 4] FIG. 4 is a side view showing the fourth step of the box roof construction method of the present invention. [Diagram 5] FIG. 4 is a side view showing the fifth step of the box roof construction method of the present invention. [Figure 6] FIG. 11 is a side view showing the sixth step of the box roof construction method of the present invention. [Figure 7] FIG. 2 is a side view showing the final step of the box roof construction method of the present invention. [Figure 8] FIG. 2 is a cross-sectional plan view of the telescopic box-shaped cylindrical body of the box-shaped roof of the present invention when contracted. [Figure 9] FIG. 2 is a cross-sectional plan view of the telescopic box-shaped cylindrical body of the box-shaped roof of the present invention when extended. [Figure 10] FIG. 2 is a front view of the telescopic box-shaped cylinder of the box roof of the present invention. [Figure 11] 9 is a view taken along line BB in FIG. 8. [Figure 12] 9 is a view taken along the line CC in FIG. 8. [Figure 13] FIG. 2 is a plan view of the telescopic box-shaped cylindrical body of the box-shaped roof of the present invention when contracted. [Figure 14] FIG. 2 is a plan view of the telescopic box-shaped cylindrical body of the box-shaped roof of the present invention when extended. [Figure 15] FIG. 1 is a side view showing an overview of the box roof construction method. [Figure 16] FIG. 13 is a perspective view showing the box roof connection. [Figure 17] FIG. 13 is a side view showing the launch of the box roof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Figures 1 to 7 are side views showing each step of the construction method of the box-shaped roof of the present invention, in which 17 is a box-shaped roof formed to a predetermined length by connecting unit cylindrical bodies 17a, which are box-shaped cylindrical bodies with a substantially square cross section, and the details of this box-shaped roof 17 are as explained in the conventional example.

[0044] In the present invention, an expandable box-shaped cylinder 40 that has the same outer diameter as the unit cylinders 17a and expands and contracts in the length direction is installed in the middle of the box-shaped roof 17 where the unit cylinders 17a are arranged vertically. The expandable box-shaped cylinder 40 is also a box-shaped cylinder with a substantially square cross section.

[0045] As shown in Figures 10 to 14, this expansion box-shaped cylinder 40 consists of a front cylinder 41 and a rear cylinder 42 that fits into it, and hydraulic jacks 43 that span between the front cylinder 41 and the rear cylinder 42 are arranged at the four corners.

[0046] Either the front cylinder body 41 or the rear cylinder body 42 that fits thereto (rear cylinder body 42 in the figure) consists of an outer cylinder wall 42a and an inner cylinder wall 42b that is narrower in diameter than the outer cylinder wall 42a and protrudes forward, the outer cylinder wall 42a has the same outer diameter as the front cylinder body 41, and the inner cylinder wall 42b is inserted into the front cylinder body 41.

[0047] The rear cylinder body 42, which is the cylinder that is reduced in diameter, has a portion of its outer cylinder wall 42a that does not reduce in diameter extended onto the inner cylinder wall 42b, which is the reduced-diameter portion, to form a rectangular convex portion 45, which is inserted into the rectangular concave notch 46 of the other front cylinder body 41 as a guide for expansion and contraction.

[0048] A jack base 44 is formed on each of the front cylinder body 41 and the rear cylinder body 42, and a hydraulic jack 43 is axially attached to a flange protruding from the jack base 44 by a pin.

[0049] The hydraulic jacks 43, including the jack bases 44, are arranged at the four corners, top, bottom, left and right, and a space is secured in the center of the expandable box-shaped cylindrical body 40 to allow passage of a truck 47 for removing soil.

[0050] Next, the construction method of the box roof of the present invention will be explained. As shown in Figure 1, earth retaining members 13 such as steel sheet piles are cast next to overhead traffic such as railways to construct starting shaft 3 and arrival shaft 9. A push jack 4 is installed as a propulsion device in starting shaft 3, and box roof 17 is pressed into arrival shaft 9 for each unit cylinder 17a.

[0051] A cutting edge pipe 18 is attached to the tip of the box roof 17, and the face is excavated by hand or by a machine such as an auger and advanced.

[0052] The box-shaped roof 17 is formed by pressing in unit cylindrical bodies 17a one by one, and each piece is added lengthwise to bury the required length from the starting shaft 3 to the arrival shaft 9.

[0053] The box-shaped roof 17 is positioned to match the outer edge of the concrete box to be installed as a protective structure when the concrete box is advanced to be installed as an underground structure. An expansion box-shaped cylinder 40 is incorporated in the middle of the vertical row of unit cylinders 17a of the box-shaped roof 17 (see Figure 4 and onwards), and this expansion box-shaped cylinder 40 is also advanced by the main jack 4.

[0054] Then, when the box-shaped roof 17 has been constructed to a certain length, a process of pushing out only the front portion of the box-shaped roof 17 by extending the expansion box-shaped cylindrical body 40 is inserted during the process of pushing out the entire box-shaped roof 17.

[0055] That is, by extending the hydraulic jack 43, the expansion box-shaped cylindrical body 40 extends as shown in FIG. 8 to FIG. 9, thereby pushing out the box-shaped roof 17 at the front portion.

[0056] Also, once the telescopic box-shaped cylindrical body 40 has been extended, the hydraulic jack 43 can be released to push the rear box-shaped roof 17, thereby causing the telescopic box-shaped cylindrical body 40 to return to its original contracted state.

[0057] Once the box roof 17 has been installed in this manner, the concrete box 1 is set as an underground structure in the departure shaft 3 (in the arrival shaft 9 in the drawing), a thrust jack is installed, and the cutting edge 2 is provided at the tip of the concrete box 1. The soil inside the cutting edge 2 and at the front face is excavated. The box roof 17 acts as a protective work.

[0058] Since a gap is created by excavation and removal of soil, the main jack is extended to push the concrete box body 1 forward, and at the same time, the box roof 17 is pushed forward through the concrete box body 1 while leaving the friction cut plate 21 behind.

[0059] When pushing forward the box roof 17, a small jack 22 may be interposed between the concrete box body 1 and the box roof 17. A jack housing pipe 24 housing the small jack 22 is disposed on the installation side of the concrete box body 1 of the box roof 17.

[0060] The small jack 22 is extended and the box-shaped roof 17 is pushed forward one by one, using the concrete box body 1 as a reaction force while leaving the friction cut plate 21 behind. Once all the box-shaped roofs 17 have advanced, the small jack 22 is retracted and the concrete box body 1 is excavated using the main push jack.

[0061] During the process of pushing forward the box-shaped roof 17 together with the concrete box body 1, a process of pushing out only the front part of the box-shaped roof 17 by extending the expansion box-shaped cylindrical body 40 can be interposed. [Explanation of symbols]

[0062] 1...Concrete box 2…Blade mouth 3…Departure shaft 4...Push jack 5…Reaction wall 6…Strut 7…Concrete foundation 9…Achievement shaft 13...Earth retaining material 14...Soil removal pipe 17...Box roof 17a...Unit cylinder 17c…Connection flange 18…Blade mouth tube 19...Bolts and nuts 20...Unboxing 21…Friction cut plate 22...Small jack 24...Jack housing tube 26…Fixing member 40…Extendable box-shaped cylinder 41…Front cylinder 42...Rear cylinder 42a…Outer cylinder wall 42b…Inner cylinder wall 43...Hydraulic jack 44…Jack base 45…Rectangular convex part 46...Rectangular recessed notch 47…Trolley

Claims

1. This box roof is formed to a predetermined length by connecting unit cylinders, which are box-shaped cylinders with a substantially square cross section, and is characterized in that an expandable box-shaped cylinder that expands and contracts in the longitudinal direction and has the same outer diameter as the unit cylinders is incorporated in the middle of the box roof where the unit cylinders are lined up vertically, this expandable box-shaped cylinder consisting of a front cylinder and a rear cylinder that fits into it, and jacks that span between the front cylinder and the rear cylinder are arranged at the four corners.

2. 2. The box-shaped roof according to claim 1, wherein the expandable box-shaped cylinder comprises a front cylinder and a rear cylinder fitted thereto, either one of the cylinders being reduced in diameter and inserted into the other.

3. 3. A box-shaped roof according to claim 2, wherein the cylindrical member to be reduced in diameter has a portion that is not reduced in diameter extended to form a rectangular convex portion above the reduced diameter portion, which is inserted into the rectangular concave notch of the other cylindrical member.

4. As a protective measure when advancing a concrete box to be installed as an underground structure, a box roof, which is a box-shaped cylindrical steel pipe with a rectangular cross section, is arranged to match the outer edge of the concrete box to be installed. This box roof is inserted between the departure shaft and the arrival shaft, which is the entire length of the crossing section, and the concrete box is installed behind it. The box roof is pushed out while the concrete box is advanced. When the box roof and the concrete box are replaced and installed, the box roof is a unit cylindrical structure that is vertical. A construction method for a box roof in which an extendable box-shaped cylinder with the same outer diameter as the unit cylinders and which extends and contracts in the lengthwise direction is inserted in the middle of a box roof in which unit cylinders are lined up vertically, this extendable box-shaped cylinder consisting of a front cylinder and a rear cylinder which fits into it, and jacks which span between the front cylinder and the rear cylinder are disposed at the four corners, and during the process of pushing out the entire box roof, a process of pushing out only the front part of the box roof by extending the extendable box-shaped cylinder is inserted.

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