JP5730717B2 - How to build a temporary bridge - Google Patents

Description

  The present invention relates to a construction method of a temporary bridge for enabling a vehicle or the like to pass quickly by passing a bridge over a river or a river in case of a disaster or an emergency.

  The Ground Self-Defense Force is equipped with erection equipment and erection vehicles for laying temporary bridges over rivers, moats, and isthmus that will hinder the movement of troops in an emergency, and for passing vehicles and personnel to the opposite bank. In addition, when an existing bridge collapses or is washed away due to a major earthquake or a huge tsunami, a temporary bridge is erected using an erection vehicle urgently in order to secure an initial rescue route. .

  As a conventional temporary bridge, for example, Patent Document 1 discloses an emergency bridge and a construction method thereof. As shown in FIG. 10, the emergency bridge described in Patent Document 1 is a bridge in which a plurality of bridge noses including a bridge nose, a bridge main girder, and a roadbed are connected. An erection vehicle for carrying and erection of bridges is equipped with erection arms and support devices.

  In the disclosed method, the erection rod first draws out the erection nose while sequentially connecting the erection nose to the opposite shore, and reaches the opposite shore, and is grounded. Next, while connecting the bridges, the bridge is supported by the erection nose and extended to the opposite bank, and both ends are landed to complete the emergency bridge. It is possible to construct a long temporary bridge while transporting the erection nose and bridge members by multiple erection vehicles and connecting them on site.

  According to this method, a temporary support bridge is constructed by extending a construction nose that is lighter than the main girder to the opposite bank, so that the reaction force applied to the construction vehicle can be made relatively small even when cantilevered from one bank. it can. In addition, the construction work can be performed without increasing the weight of the vehicle for stabilization or using a huge counterweight.

  In addition, since conventional emergency bridges supported the bridge by raising the pier from the riverbed, there was a problem that it could not be constructed if the ground strength of the riverbed was insufficient, or it was affected by the river flow velocity. However, the emergency bridge described in Patent Document 1 does not require a pier, and thus does not cause such a problem.

  On the other hand, there is a problem that the weight and height of the bridge main girder are increased because it is necessary to support the weight of the bridge and the load of the vehicle crossing the bridge. For example, a maneuvering support bridge (owned by the Ground Self-Defense Force) developed by developing the technology described in Patent Document 1 requires a construction vehicle with a total weight of 25 tons to construct a bridge with a maximum span of 60 m.

  Patent Document 2 discloses a method for constructing an emergency bridge by another method. As shown in FIG. 11 and FIG. 12, an auxiliary bridge for delivery and a delivery device equipped with a drive pinion are installed on one bank of the river, and a support for preventing overturning that supports the auxiliary bridge is fixed rearward. The auxiliary bridge is extended to the opposite bank by the sending device and grounded to secure a temporary bridge for the main bridge construction.

  Then, the fall prevention support is removed and replaced with a support base, and the feeding device is moved to the opposite bank and attached to the tip of the auxiliary bridge. The main bridge is connected to the end of the auxiliary bridge. After that, when the auxiliary bridge is pulled out to the opposite shore by the sending device, the main bridge connected to the end is drawn to the opposite shore, and the emergency bridge is bridged over the river. The main pier and main slope are installed on both sides of the main bridge, and the construction is completed.

  According to the technique disclosed in Patent Document 2, it is possible to construct a bridge with a simpler structure than the emergency bridge disclosed in Patent Document 1. However, the load must be supported by the mechanical strength of the main bridge, and the problem of increasing the weight and height of the bridge main girder in order to secure the rigidity of the main bridge cannot be solved.

Therefore, the inventor of the present application paid attention to the pneumatic structural element disclosed in Patent Document 3 as a member that forms a temporary bridge having a small total weight.
As shown in FIG. 13, the pneumatic structural element disclosed in Patent Document 3 has a configuration in which one compression strut and at least one pair of tension wires are arranged in a cylindrical air tube. The compression strut is a rod having the same length as the air tube, and is fixed to the upper surface of the air tube. The pair of tension wires are connected to the compression struts at the nodes at both ends, and surround the air tube symmetrically in the clockwise direction and the counterclockwise direction, respectively.

  The pneumatic structural element disclosed in Patent Document 3 balances the compression force of the compression strut and the tension of the tension wire to support the load and resist buckling. For example, as shown in FIG. 14, when a load Fm is applied to the center of the compression strut from above, the air tube is deformed, so that the tension wire is pulled by the tensile force Fz, and the compression force Fs is applied from the knot to the compression strut. Since the compressive force Fs, the tensile force Fz, and the load Fm and the vector component of the supporting force Fa applied to the nodule are always balanced to zero, the entire pneumatic structural element has large rigidity and buckling resistance and can support the load. .

  With this configuration, the mechanical stiffness required by the compression strut is significantly reduced compared to the case where the compression strut alone resists the load. Accordingly, the compression strut can be made of light weight and a small cross section, for example, composed of an aluminum alloy.

Since the other members do not use heavy objects, the overall weight is significantly smaller than that of conventional emergency bridges. Furthermore, since the air tube can be folded if compressed air is removed and the tension wire can be wound up, the air tube is not bulky and can greatly save storage and transportation costs.
In the bridge using the pneumatic structural element disclosed in Patent Document 3, as shown in FIG. 15, a plurality of pneumatic structural elements are juxtaposed, and a knot member called a yoke is arranged in the knot portion and connected in the lateral direction. A bridge slab such as a wooden board can be arranged on the upper surface.

  Further, as an extension of the pneumatic structural element disclosed in Patent Document 3, Patent Document 4 by the same inventor discloses an arch type support using fluid force. As shown in FIG. 16, the arch-type support disclosed in Patent Document 4 includes a road structure on the upper surface of a side boat-shaped air tube that is thick at the center and is tapered toward both ends, and a tension element on the lower surface. It has a different shape.

According to the arch type support body disclosed in Patent Document 4, in addition to having a high load support capability compared to the pneumatic structural element disclosed in Patent Document 3, a road structure such as a floor slab panel instead of a compression strut It is advantageous in terms of reducing material consumption and reducing weight and girder height, such as using as a vehicle road surface.
However, both Patent Document 3 and Patent Document 4 disclose a state in which a structural technique is applied when applied to a bridge, but the efficiency utilizing the characteristics of a pneumatic structural element or an arch-type support is disclosed. The general construction method and procedure are not disclosed.

Japanese Patent Laid-Open No. 7-259013 Japanese Patent Laid-Open No. 4-169611 Japanese Patent No. 3906079 JP-T-2006-528288

  Therefore, the problem to be solved by the present invention is to construct a temporary bridge that is lightweight and easy to transport and erection, especially for emergency bridges that are used during emergencies and disasters, especially emergency construction that utilizes the characteristics of pneumatic structural elements. It is to provide a bridge erection method.

  A method for constructing a temporary bridge according to the present invention that solves the above problem is a support body including a gas tube, a compression strut, a tension sling, and an anchor portion, and the compression strut is formed by connecting a plurality of rods, The tension sling connects the end points of the compression struts, the gas tube is disposed between the compression strut and the tension sling, and anchor portions are provided at both ends in the bridge axis direction of the support to expand the gas tube. This is a method of laying a temporary bridge that supports the load using a support that is stiffened by this, between this bank and the opposite bank, folding the compression strut together with the tension sling and gas tube in units of rods, and folding Folding process for forming the support, transporting process for transporting the folding support to the installation point, and folding An unfolding process that unfolds the folding support body in the direction of the bridge axis by traction means connected to the anchor part of the holder and passes it between this bank and the opposite bank, and a stiffening process that stiffens the support body by supplying gas to the gas tube And a fixing step of fixing the anchor portions at both ends to the ground.

The compression strut is installed along the axis on the surface of the gas tube, and is connected between both ends by a tension sling. The tension sling has a configuration in which an end is coupled to an end of the compression strut and generates a compressive force in the axial direction of the compression strut as the gas tube expands. A moderately long cable or belt wrapped around the cable, or a cable or belt that extends in the axial direction of the gas tube. When the gas tube expands due to gas, it is tensioned, and the axial direction of the compression strut is at both ends of the compression strut. It has a function of applying rigidity to compress and stiffening.
The support formed by the gas tube, the compression strut, and the tension sling having the above configuration is a strong support having a high resistance to buckling.

In the construction method of the temporary bridge according to the present invention, after the anchor portion on one end side is fixed to the ground on this bank, the folding support body can be unfolded by traction means connected to the anchor portion on the other end side.
In addition, it can comprise with the pulling wire which connected the pulling means to the winding machine. When using a pulling wire, after fixing the anchor part at one end to the ground at this bank, the folding support is lifted by winding the pulling wire hung on the anchor part at the other end with a hoist installed on the opposite bank. expand.
In addition, hang a traction wire on each anchor at both ends, connect each traction wire to a hoisting machine provided on each of this bank and the opposite shore, and then suspend the folding support and move it over the installation point Then, the folding support may be unfolded and passed between both banks by winding up the pulling wires stopped at the anchor portions at both ends.

  According to the construction method of the temporary bridge of the present invention, a support body (hereinafter referred to as a support body) formed into a columnar shape or an arch shape by a support body using a pneumatic structural element or fluid force is lightweight, and a compression strut is provided. Since it becomes small by separating into rods, extracting gas from the gas tube and folding each rod, it can be transported to an appropriate construction place even by a relatively small vehicle having a small transport force. In addition, at the construction point of the temporary bridge, the support body can be easily deployed by winding the tow wire with a winch, and the rod separated between this bank and the opposite bank is recombined and compressed. By forming the struts and filling the gas tubes with gas, the rigidity of the support increases and the compression struts are not easily deformed by the load, so that they can be installed between the two banks as a stable bridge structure. Become.

Furthermore, a deck panel can be arranged on the compression strut to support a vehicle that crosses the bridge. Alternatively, the deck panel can be handled in the same manner as a rod of a compression strut, and the compression strut can be formed by butting and joining the deck panels so that the vehicle or the like is directly supported by the compression strut.
Note that the rods are separated from each other, and the compression struts may be formed by abutting and connecting ends to each other at the time of installation. Moreover, the edge part for every rod may be couple | bonded with a hinge, and it turns around the bridge axis right-angled axis | shaft perpendicular | vertical to a bridge axis, and the compression strut formed with a rod may be folded.

The support is composed of a substantially cylindrical gas tube, and the tension slings arranged symmetrically and paired are formed so as to bind around the gas tube in a spiral in opposite directions. It may be a thing. A plurality of cylindrical supports may be installed in parallel, and the deck panel may be horizontally arranged so as to straddle the cylindrical support.
In addition, the support has a compression strut disposed on the ridge line of the gas tube, a tension sling is disposed along the bottom of the lower side of the gas tube, and the tension sling is coupled to the end of the compression strut. It has a structure in which the gas tube is sandwiched between the tension slings. By expanding the gas tube, it has an arch shape with a high central part and a low end at both ends, making it resistant to displacement and buckling. It may be elevated.

  According to the temporary bridge erection method of the present invention, a relatively lightweight support is developed and passed between this bank and the opposite bank to form a bridge, so that a temporary bridge can be quickly and easily installed in a disaster or emergency. It is possible to pass vehicles and the like.

It is a procedure figure explaining the construction method of the temporary bridge which concerns on this invention. It is process drawing explaining the construction method of the temporary bridge which concerns on 1st Example of this invention. It is a procedure figure explaining the construction method of the temporary bridge of 1st Example. It is a side view which shows one example of the folding support body used in 1st Example. It is sectional force figure in the support body applied to this invention. It is sectional force figure in the conventional cable truss girder. It is a conceptual diagram which shows the state in which the compression strut is supported by the continuous spring. It is process drawing explaining the construction method of the temporary bridge which concerns on 2nd Example of this invention. It is a procedure figure explaining the construction method of the temporary bridge of 2nd Example. It is a side view explaining the vehicle for erection of an emergency bridge concerning the prior art, and the erection method. It is drawing explaining the delivery process of the auxiliary bridge in the construction method of the emergency bridge which concerns on a prior art. It is drawing explaining the delivery process of the main bridge in the construction method of the emergency bridge which concerns on a prior art. It is a perspective view which shows the example of the pneumatic structural element which concerns on a prior art. It is explanatory drawing regarding the action force in the pneumatic structural element which concerns on a prior art. It is a partially notched perspective view which shows the example of the bridge using the pneumatic structural element which concerns on a prior art. It is a side view of the bridge to which the arch type support body concerning a prior art is applied.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a procedural diagram for comprehensively explaining a method for constructing a temporary bridge according to the present invention.
The temporary bridge erection method of the present invention is a method of rapidly bridging a lightweight and easy-to-assemble bridge using a support body using fluid force.

  As shown in FIG. 1, the erection procedure in the temporary bridge erection method of the present invention first forms a support body by assembling a compression strut, a tension sling, a gas tube, and an anchor part. At this time, the compression strut is disassembled into rods by the folding step, and the support body is folded in a bellows shape in units of rods to obtain a folding support body (S1).

Next, in the transporting process, the folding support is transported to the temporary bridge erection position on this bank, and in the unfolding process, the folding support is pulled with a pulling wire and unfolded and passed between this bank and the opposite bank (S2) for rigidity. In the process, a gas such as compressed air is supplied to the gas tube and inflated so that tension is applied to the tension sling that connects both ends of the compression strut, and the compression strut is subjected to compression force, and the support is stiffened. Stiffening is performed (S3).
In addition to air, the gas tube may be filled with an inert gas such as nitrogen, argon, carbon dioxide, or a gas that is easy to obtain and transport and economical to expand.
Further, in the fixing step, the anchor portions at both ends of the support are fixed to the ground, thereby completing the installation of the temporary bridge (S4).

  The expansion of the gas tube may be performed in conjunction with the expansion of the folding support. Further, the anchor portion on one shore can be fixed to the ground before the folding support body is deployed, and the fixed anchor portion can be used as a support point when the support body is deployed.

  FIG. 2 is a process diagram for explaining the construction method of the temporary bridge according to the first embodiment of the present invention, and FIG. 3 is a procedure diagram for explaining the first embodiment. In the present embodiment, the deck panel is arranged on the gas tube and joined so as to have the function of a compression strut. FIG. 4 is a side view showing an example of a folding support used in the present embodiment.

In the temporary bridge construction method according to the first embodiment of the present invention, first, the compression strut, the tension sling, the gas tube, and the anchor portion are assembled together, and the compression strut is folded for each rod to form the support 10 (S11). ). When inflating with air, the gas tube may be referred to as an air tube. If air is used as the expansion medium, the gas tube can be easily expanded by using a simple pump, and since it does not pollute the atmosphere, it can be easily thinned by directly releasing it into the atmosphere. Can do.
As illustrated in the side view of FIG. 4, the folding support body is formed by disassembling the compression strut 1 for each rod (here, the deck panel 6), and the support body 10 in a state in which the gas in the gas tube 3 has escaped is the rod. It is formed by folding in a bellows shape in units.

  The gas tube 3 is sandwiched between the compression strut 1 and the tension sling 2 in a state where the gas has escaped and is deflated. It is preferable to stop the gas tube 3 on the compression strut 1 at an appropriate interval so that the gas tube 3 does not hang down during conveyance or deployment. In addition, when the support body 10 is folded and when the gas tube 3 is inflated, the position where the gas tube 3 contacts the compression strut 1 may be shifted, so the gas tube 3 and the deck panel 6 of the compression strut 1 Can be loosely engaged. The gas tube 3 can be fixed to the compression strut 1 at an appropriate interval by using a hanger 5 so as not to hang down during conveyance or deployment.

The tension sling 2 is a belt coupled to the anchor portion 4 at both ends. It is preferable that the tension sling 5 is also fixed to the compression strut 1 and the gas tube 3 at an appropriate interval so that the tension sling 5 does not sag during conveyance or deployment. Moreover, you may hang together with the gas tube 3 using the hanger 5. FIG.
One end of the deck panel 6 disposed at the end of the compression strut 1 is fixed to the anchor portion 4.

As shown in FIG. 2A, the folding support 10 is transported to the site by a truck 11 or the like, and is lowered to the bridge position on this bank 21 (S12). The traction track 14 having the winch 13 is arranged on the opposite shore 22 and the traction wire 12 extended from the winch 13 is tied to the anchor portion 4 that is passed to the opposite shore 22 (S12).
As shown in FIG. 2B, the anchor portion 4 on this bank side is fixed to the ground (S13). Further, as shown in FIG. 2 (c), the traction wire 12 hung on the anchor portion 4 for the opposite shore is wound up by the winch 13 of the traction track 14 on the opposite shore 22 to extend the folding support 10 (S14).

As shown in FIG. 2 (d), when the folding support 10 is completely deployed and the anchor portion 4 on the opposite bank reaches a predetermined position on the opposite bank 22, the anchor portion 4 on the opposite bank 22 is stopped on the ground of the opposite bank 22. (S15).
The anchor portion 4 can be fixed to the ground using an anchor bolt or the like, but the tip of the support 10 is fixed to the ground by engaging with a member fixed to the ground in an appropriate manner. May be. Moreover, a bolt hole can be provided in the edge part of the rod and deck panel located in the front-end | tip of a support body, and it can also be set as an anchor part.

  In a state where the anchor portion 4 is stopped on the ground of the opposite shore 22, the unfolded folding support body 10 becomes the compression strut 1 sandwiched between the anchor portions 4 with the deck panels 6 facing each other, and the gas tube 3. Is placed under the compression strut 1 in a state in which the gas has escaped and is thinned, and is passed between the anchor portions 4 in a state where the belt-like tension sling 2 is supported at various points by means of hangers 5 or the like. Yes.

  The deck panels 6 are connected to each other while abutting each other at the edge surface in the step of expanding the folding support 10 to form an integrated compression strut 1. The abutting surface of the edge of the deck panel 6 that forms the joint portion of the compression strut 1 may be a flat surface or a combination of a concave surface and a convex surface that are pressed against each other. In addition, the abutting position can be prevented from shifting by sewing the adjacent parts with bolts or engaging pins. Note that the butted surfaces may be connected with a hinge so that the folding and unfolding can be performed smoothly.

Furthermore, the compression strut 1 is provided with a guide hole penetrating in the direction of the bridge axis in each of the rod or the deck panel 6, and a tightening rope such as a wire or a chain is serially connected to the guide hole of the rod or the like arranged in the bridge axis direction. The rods and the like can be integrated into one compression strut 1 by pulling and tightening the tightening rope, and each rod and the like can be folded by loosening the fastening rope. Also good.
Regarding the folding support body that is made to bend using the tightening rope, it is preferable to guide the tip of the support body to a desired position by a pulling wire tied to the anchor portion when the folding support body is deployed. .

Here, when gas is blown into the gas tube 3 with a gas cylinder (not shown), as shown in FIG. 2 (e), a compression force acts on the compression strut 1 due to the tension of the tension sling 2, and it becomes rigid and has great rigidity and buckling. An arch-shaped support body 10 having resistance is formed, and a bridge 20 that can withstand a large load is completed, in which the deck panel 6 is laid on the rigid support body 10 (S16). For safety, handrails may be provided on both sides of the bridge.
In addition, the deck panel 6 is directly used as the compression strut 1 that forms the support 10, but a lighter rod-like body connected with a thin rod made of aluminum alloy or the like is used to stiffen the support 10. Alternatively, the temporary bridge 20 may be provided by arranging the deck panels 6 side by side.

  In this example, the basic cylindrical support shown in FIG. 13 was used as the support 10. For cylindrical supports, the difference in height between the top and bottom surfaces at the end of the support is large, so it is necessary to devise a way to loosen the slope with a fixing member that hits the anchor, or to adjust the road surface of the mounting road to the top surface of the support. become. Moreover, when using a cylindrical support body, it is preferable to maintain the direction perpendicular to the bridge axis of the road surface horizontally by arranging a plurality of support bodies in parallel and arranging a deck panel thereon.

The support used in the construction method of the temporary bridge of the present embodiment converts the bending moment due to the load applied to the deck panel into the compression force of the compression strut and the tension force of the tension sling, and generates a drag force against the load. Can withstand heavy loads while being lightweight.
FIGS. 5 and 6 are sectional force diagrams comparing the support used in the temporary bridge construction method of the present invention and a general cable truss girder in a model manner. FIG. 5 is a sectional force diagram of a cylindrical support applied to the present invention, and FIG. 6 is a sectional force diagram of a cable truss girder model shown for comparison.

  In both cases, tension slings are connected to both ends of a compression strut having a length L. In the cylindrical support, two tension slings are spirally wound around an air tube having a height D. In the cable truss girder, tension slings are connected to the tips of many vertical struts and suspended.

When the girder height D is sufficiently smaller than the bridge length L (γ = L / D >> 1), the tensile force T applied to the tension sling when the load q is applied to the support and the cable truss girder is both It can be approximated by the following formula (1).
(1) T = 1/8 · qLγ

Since the tension sling is connected to the compression strut at both ends, the compression force P is generated in the compression strut by the tensile force T. When the compression force P exceeds the buckling resistance, the compression strut buckles. In cable truss girder, seat屈抗force P _b is represented by the below formula (2).
_{(2) P b = (n} + 1) 2 π 2 EI / L 2

  Here, I is the moment of inertia of the cross section of the compression strut, E is the elastic modulus, and n is the number of vertical struts. As expressed in Expression (2), the buckling resistance is inversely proportional to the square of the installation interval L / (n + 1) of the vertical struts. Therefore, the number of vertical struts must be increased to increase the buckling resistance. However, when the number of vertical struts increases, the bridge's own weight increases, and there is a dilemma that reduces the residual force against the load.

  On the other hand, in the support using fluid force, since the compression strut is held in close contact with the gas tube, it can be considered that it is supported by an infinite number of vertical struts and depends on the number of vertical struts n. Released from. Therefore, by arranging a light gas tube, a vertical strut is not necessary, and the weight of the bridge can be significantly reduced.

In the support, assuming that the compression strut is supported by a continuous spring, as shown in FIG.
(3) P _b = 2√ (kEI)
It can be expressed as. That is, since the gas tube supports the compression strut over its entire length, the buckling resistance of the compression strut is not affected by the bridge length L.

In the support, the spring constant k of the virtual spring depends on the gas pressure of the gas tube. When the spring constant k is k = πp using the gas pressure p of the gas tube,
(4) P _b = 2√ (πpEI)
It becomes.
When the moment of inertia I and the gas pressure p proper selection, seat屈抗force P _b is greater than the yield load of the compression strut. Therefore, it is possible to apply a compressive force up to the yield load without considering the buckling resistance with respect to the compressive struts, so that the degree of freedom of the material and shape is increased even in the longitudinal compressive struts. That is, since it is not necessary to consider the lateral stress applied to the compression struts, the cross-sectional area of the compression struts can be reduced and the structure can be made very light.

In a support using fluid force, the gas pressure of the gas tube is an important parameter.
In the case of a simple cylindrical gas tube not equipped with a compression strut and a tension sling, the gas pressure p required for the load q _a per area is expressed by Equation (5).
(5) p = 2 / π · q _a γ ²

γ represents the ratio of the length to the thickness of the gas tube (γ = L / D). The gas pressure p required for the gas tube strongly depends on the shape γ of the gas tube, and the gas pressure p must be considerably increased in the elongated shape used for the bridge. For example, in the gas tube gamma = _30, in order to withstand the load of q a = 1kN / ^{m 2,} it is necessary to gas pressure of about 570kN / ^{m 2.}

On the other hand, the gas tube was used for the support to be applied in the present invention, the gas pressure p required to resist the load q _a is given by equation (6).
^{(6) p = π 2/} 2 · q a

For example, the gas pressure p required to withstand a load of q _a = 1 kN / m ² is about 5 kN / m ² (50 mBar). Thus, the gas tube applied to the support can withstand the load with a low gas pressure regardless of the span. In a support using fluid force, the compression strut and tension sling are responsible for the load resistance, and the gas pressure is responsible for pretensioning the tension sling and fixing the compression strut. Even tubes can withstand practical use with low gas pressure. Moreover, the method of enclosing air using an air pump can also be utilized.

  Since the required gas pressure is as small as several hundred mBar, it is not necessary to use a gas tube cloth material with particularly high confidentiality, and a material that can be obtained at low cost may be used. Further, when the gas tube is damaged, there is no risk of rupture, and only gas such as air leaks from the damaged part. Therefore, the gas tube does not need to use a special material, and can be made thin, lightweight, and inexpensive. In addition, even if it is damaged, it can be dealt with by covering the damaged part with a patch or supplying a gas larger than the leaked gas amount with a cylinder or an air pump. Therefore, it is highly safe and easy to maintain.

  The support used in this example can be formed of aluminum alloy compression struts, steel wire rope tension slings, and PVC coated polyester gas tubes. The temporary bridge erected by the erection method of the present embodiment is, for example, 20 m and can withstand a load of several tens to 100 tons. Nevertheless, one support is very light at about 130 kg at 20 m, and the total weight of the bridge including the three supports and the floor slab panel is 500 to 700 kg. The weight is less than 1/10 compared to a conventional truss bridge with the same maximum load.

Therefore, the construction method of the temporary bridge according to the present embodiment can easily and smoothly expand the bridge, and can quickly construct the temporary bridge even in a situation where the working environment is poor. In addition, since the members to be used are lightweight and the required gas pressure or air pressure is low, it is sufficient that the winch, the air pump, etc. necessary for the development of the bridge are small. Therefore, the total weight of the members and tools necessary for erection is small and transportation is very easy, and it is not difficult to transport materials across a plurality of bridges.
Needless to say, a temporary bridge using a columnar support can be installed by the temporary bridge installation method of this embodiment.

FIG. 8 is a process diagram showing a work procedure of a temporary bridge erection method according to the deployment method of the second embodiment of the present invention, and FIG. 9 is a procedure diagram illustrating the procedure.
Compared with the method of the first embodiment, the construction method of the temporary bridge of the present embodiment is different from that of the first embodiment in that the folding support body is supported in the air and the pulling wire is pulled from both banks and deployed. There is no difference in the preparation process and the process after unfolding the support and passing it to both banks. FIG. 8 illustrates parts different from the first embodiment.

  As shown in the procedure diagram of FIG. 9, the temporary bridge construction method of the present embodiment is constructed by integrally assembling the compression struts, tension slings, gas tubes, and anchor portions composed of rods, as illustrated in FIG. 4. The folding support body 10 folded for each rod is formed (S21).

The folding support 10 is suspended from the helicopter 31 or the like by the transport wire 32, transported to the installation point, and held above the bridge position as shown in FIG. 8A (S22). At this time, the pulling wire 34 extended from the wire hoisting machine 33 installed on this bank 21 is tied to the anchor part 4 for this bank of the folding support.
The folding support 10 may be transported to a crossing position by a truck or the like, suspended by a crane, and supported on a construction point.

Further, the pulling wire 36 attached to the opposite shore anchor portion 4 is connected to the wire hoisting machine 35 installed on the opposite shore (S23).
Next, as shown in FIG. 8 (b), the traction wires 34, 36 on both sides are wound by the wire hoisting machines 33, 35 on this bank 21 and the opposite shore 22, and the helicopter 31 and the The folding support body 10 suspended from the crane is moved above the installation point (span center) (S24).

  When the pulling wires 34 and 36 are wound up while being suspended by the transport wire 32 and the folding support 10 can be maintained in the air by the tensile force from both sides, as shown in FIG. Then, as shown in FIG. 8 (d), the pulling wires 34 and 36 are wound up from both sides of the folding support 10 to expand the folding support 10 (S25). In addition, you may make it support in the air with the helicopter 31 or a crane until the folding support body 10 is fully developed.

After the unfolded folding support 10 is disposed so as to straddle between this bank 21 and the opposite bank 22, the anchor portion 4 is fixed to the ground at a predetermined position (S26).
Therefore, according to the same steps as in the first embodiment, when gas is supplied from the gas cylinder to the gas tube 3 of the developed support or compressed air is blown by an air pump, the tension is applied to the compression strut 1 by the tension of the belt-like tension sling 2. The temporary bridge 20 capable of withstanding a large load is completed by forming a support body having rigidity and buckling resistance by applying a compression force (S27).

Also in this embodiment, handrails may be provided on both sides of the bridge as in the first embodiment.
Further, as the compression strut 1 forming the support, a lighter rod-like body connected with thin rods made of aluminum alloy or the like is used, and the deck panel 6 is arranged side by side on the rigid support. Also good.

  Note that the flat boat-shaped arch-shaped support conceptually shown in FIG. 16 has higher load-bearing performance than the cylindrical support, and can withstand a load of several hundred tons, for example, on a 20 m bridge. Also in the present invention, an arch type support can be used instead of the columnar support. The arch-type support used in the present invention has a compression strut in which a deck panel is arranged on the upper surface of the gas tube of the support, and a tension sling on the lower surface, and has a boat-shaped longitudinal section. It may be. The anchor portion is provided with an inclined surface, and the inclined surface can also serve as a stepping plate. Temporary bridges formed using arch-type supports have high load-bearing performance, so large heavy machinery and main battle tanks can be handed over and the range of use is wide.

  The temporary bridge erection method of the present invention can easily and quickly deploy a lightweight air tube bridge, so that it is possible to pass a vehicle etc. by crossing a bridge over a river or river in case of a disaster or emergency. It can be used for the construction of temporary bridges.

DESCRIPTION OF SYMBOLS 1 Compression strut 2 Tension sling 3 Gas tube 4 Anchor part 5 Hanger 6 Deck panel 10 Support body 11 Truck 12 Towing wire 13 Winch 14 Truck 20 Temporary bridge 21 This bank 22 Opposite bank 31 Helicopter 32 Transport wire 33 Wire hoist 34 Pulling wire 35 Wire hoist 36 Towing wire

Claims (8)

A support comprising a gas tube, a compression strut, a tension sling, and an anchor portion, and stiffening the gas tube by gas expansion, wherein the compression strut is formed by connecting a plurality of rods. The tension sling connects the end points of the compression struts, the gas tube is disposed between the compression struts and the tension sling, and anchor portions are provided at both ends of the support in the bridge axis direction. A method of laying a temporary bridge between the shore and the opposite shore that supports the load using the support,
A folding step of folding the compression strut together with the tension sling and the gas tube in units of the rod to form a folding support;
A transporting process for transporting the folding support to a construction point;
An unfolding step of unfolding the folding support in the direction of the bridge axis and passing between this bank and the opposite bank by traction means connected to the anchor part;
A stiffening step for stiffening the support;
A fixing step of fixing the anchor portion to the ground,
How to build a temporary bridge.   The procedure in the unfolding step and the fixing step is that the anchor portion on one end side is fixed to the ground at this bank, and the folding support body is unfolded in the direction of the bridge axis by traction means connected to the anchor portion on the other end side. The construction method of the temporary bridge of Claim 1 characterized by the above-mentioned. The steps in the transporting process, the folding process and the unfolding process connect traction means to each of the anchor portions at both ends,
Suspend the folding support and stop it above the installation point,
The construction method of the temporary bridge according to claim 1, wherein the folding support body is developed in a bridge axis direction by the pulling means.   The construction method of the temporary bridge of any one of Claim 1 to 3 with which the said rod is comprised with a deck panel.   The construction method of the temporary bridge of any one of Claim 1 to 3 which arranges a deck panel on the said compression strut and makes it a floor slab.   The temporary bridge erection method according to any one of claims 1 to 5, wherein the support body includes two or more gas tubes arranged in a direction perpendicular to the bridge axis.   The support is configured such that the tension sling is passed between the end portions on the lower side of the compression strut, and the gas tube is sandwiched between the two, and the gas tube is expanded to expand the central portion of the span. 6. The method for constructing a temporary bridge according to any one of claims 1 to 5, characterized in that the arch shape is high in height and low at both ends.   The temporary bridge constructed by the construction method of the temporary bridge of any one of Claim 1 to 7.

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