KR101005605B1 - Arch type wind duct slab and method for constructing wind duct of tunnel - Google Patents

Abstract

PURPOSE: An arch precast concrete air duct slab and a construction method thereof are provided to reduce the tunnel inner section by using arch effect and to reduce the use of temporary installation materials including a staging and a mold. CONSTITUTION: An arch precast concrete air duct slab comprises a slab main body(11), and a horizontal displacement constraining member(12). The slab main body is board shape. The cross section of the slab main body has a fixed upward curvature radius. The slab main body has the length corresponding to the width of the installed tunnel.

Description

Arch type wind duct slab and method for constructing wind duct of tunnel}

The present invention relates to the airflow of a semi-crossflow or crossflow tunnel ventilation system, and more particularly to an arcuate precast concrete slab constituting the airflow and a construction method thereof.

Currently, the construction of long road tunnels is increasing in order to maximize land use due to the rapid growth of automobiles along with the economic growth.In addition, the environmental pollution of the driving environment in tunnels by natural ventilation due to the accumulation of pollutants in the tunnels due to the increase of traffic volume It is impossible to keep below the allowable value.

In road tunnels for automobiles, in order to provide a safe driving environment for the driver, it is necessary to secure the visible distance in the tunnel and to keep the air pollutants generated from the vehicle emissions below the allowable concentration level.

To this end, it is necessary to analyze the flow phenomena of the surrounding terrain and the airflow in the tunnel, and to comprehensively judge the field measurement results to maximize the natural ventilation performance due to the diffusion of airflow in the tunnel design, and allow air pollutants by natural ventilation. If it is difficult to maintain below the concentration level, forced ventilation should be installed and operated.

Natural ventilation is a ventilation method that relies on natural ventilation force (ventilation according to the chimney effect and air pressure arrangement) and the piston force generated by driving of the car without installing ventilation equipment in the tunnel. It is mainly used in small mountain tunnels (natural ventilation = natural wind + traffic wind (influenced by cars), and shorter tunnels (normal limit of 600m at 1,000 traffic / hour).

On the other hand, in the case of long tunnels, forced ventilation is designed to control pollutants inside the tunnel by installing pollutant control facilities such as forced ventilation and dust collection facilities in tunnels with long tunnel length and high traffic volume. It is mainly used because natural ventilation cannot sufficiently dilute the air inside the tunnel. Representative methods are divided into three types, type, semi-cross flow, and cross-flow type. Among them, semi-transverse ventilation and transverse ventilation require a space of duct.

The duct in the tunnel is formed by pouring the slab 100 or additional partition 300 after forming the lining 200 concrete as shown in FIG. The wind slab 100 and the bulkhead 300 are formed with linings and formwork in a tunnel in one step to form linings 200 in a cast-in-place manner (see (a)), and additionally in two steps with steel bars. By installing the formwork to pour the wind slab 100 is to form a duct for ventilation (see (b)).

In this case, in order to form the wind slab 100 and the partition 300, in the first step of forming the lining 200, the joint reinforcement 120 is exposed to the connection portion between the lining 200 and the slab 100. In addition, the wind slab 100 is the first stage lining (200) when the concrete is poured and cured, and then move forward, followed by the use of steel clubs and formwork in the tunnel to form the wind duct slab 100 in the field casting method Slab was formed.

By the way, the construction method of wind slab and bulkhead by the site casting method has the following disadvantages.

First, the slab reinforcement (120) or bulkhead reinforcement (310) is pulled out from the side, and about 20m of lining concrete should be cast and when curing is carried out in the direction of the tunnel progress by demolding the formwork, the progress is very difficult, There is a disadvantage that the construction period is long, and the work by manpower is greatly increased. In addition, the steel bar and formwork is a factor that greatly increases the construction cost because one set for the lining concrete and one set for the installation of the wind slab and bulkhead.

Secondly, if the wind-resistant slab is formed of cast-in-place concrete, the thickness thereof becomes large, and accordingly, the hole cross section of the tunnel becomes large. Therefore, the internal hole cross section of the tunnel becomes large, and the construction cost increases.

Third, the cast-in-place wind slab is deformed by creep and shrinkage due to the long-term behavior of concrete, which causes downward deflection due to its own weight. This deflection causes cracks in the weathering slab and lining concrete around the connection of the lining concrete with the weathering slab.

Fourth, the formation of the wind slab by spot casting has a high risk of safety accidents caused by copper bars.

On the other hand, as shown in Fig. 1b, if the wind duct slab is formed in an upward curve, securing of the driver's cigar on the road is greatly improved, traffic accidents can be greatly reduced, and the thickness of the wind duct slab is reduced, thereby making the tunnel's inner cross section small and costly. Can be greatly reduced. However, because the precast concrete weather slab is pretensioned, it can only be applied in a flat, flat structure, and thus an upward curved effect on the cross section of the tunnel cannot be obtained.

The present invention aims to solve the disadvantages of the conventional cast-in-place slab and the bulkhead construction and the disadvantages of the precast-style slab of the pre-tension method of the bottom surface is flat.

The present invention can reduce the cross-section of the airway slab by using the arch effect is possible to reduce the cross-section of the hole in the tunnel, and to provide a weathering slab using a precast concrete member that can omit the use of temporary materials, such as clubs and formwork The purpose.

Another object of the present invention is to provide a method for constructing an arcuate precast concrete weathering slab.

According to a preferred embodiment of the present invention, the cross-section is in the form of a plate having a constant upward radius of curvature and has a length and a constant width corresponding to the width of the tunnel to be installed, both ends are hinged or strongly coupled to the bracket formed on the inner surface of the tunnel An arcuate precast concrete weathering slab is provided which includes a precast concrete slab body having a stepped surface and a horizontal displacement restraining member that connects both ends of the slab body to each other to restrain horizontal displacement and is removed after construction.

According to another suitable embodiment of the present invention, the radius of curvature is 100 m or less.

According to another suitable embodiment of the present invention, the radius of curvature is 20 m or less.

According to another suitable embodiment of the present invention, protrusions are formed on the lower surface of the straddling surface.

According to another suitable embodiment of the present invention, the method includes: installing a bracket for connecting the weather slab to the tunnel lining concrete at the position where the weather slab is to be installed; The slab body has a length and a constant width corresponding to the width of the tunnel to be installed, the cross section is a plate shape having a constant upward radius of curvature, and at both ends formed a slab body formed by a hinged or rigidly coupled to the bracket formed on the inner surface of the tunnel; Hinge-bonding or rigidly coupling an arcuate precast concrete weather vane slab comprising a horizontal displacement restraint member which connects both ends of the slab body to each other to restrain horizontal displacement and is removed after hypothesis; And removing the horizontal displacement restraint member.

Arch-shaped precast concrete slab according to the present invention is composed of a precast concrete member can shorten the air, it is a member that receives only the axial force or at the same time receiving the axial force and the bending moment, compared to the flat slab of the cast-in-place concrete method The cross section can be reduced, which reduces construction cost, and there is no risk of safety accident since there is no need for grouping.

In addition, it is possible to prevent cracks around the connection between the weather slab and the lining concrete and the weather slab, and hardly cause long-term sagging caused by bending.

In addition, the curvature of the driver is greatly improved since the curvature of the driver is significantly increased, thereby greatly reducing the occurrence of traffic accidents.

The following drawings, which are attached in this specification, illustrate the preferred embodiments of the present invention, and together with the detailed description thereof, serve to further understand the technical spirit of the present invention. It should not be construed as limited.
1 is a cross-sectional view showing an arcuate precast concrete weathering slab according to the present invention.
2 is a view for explaining the manufacturing principle of the arched precast concrete weather wave slab according to the present invention.
Figure 3a to 3d is a graph of the analysis results for the seven from R = ∞ to R = 20m in Table 1 from top to bottom, Figure 3a shows the axial force according to the radius of curvature, Figure 3b is a moment according to the radius of curvature 3c illustrates the stress of the upper edge of the member according to the radius of curvature, and FIG. 3d illustrates the stress of the lower edge of the member according to the radius of curvature.
Figure 4 is an enlarged cross-sectional view showing the junction of the slab body and the bracket according to another embodiment of the present invention.
5 is a cross-sectional view schematically showing a method of constructing the wind speed according to the present invention.
Figure 6 is a cross-sectional view showing the construction process of the wind slab and partition wall according to the conventional cast in place method.

In the following the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings, but the embodiments presented are exemplary for a clear understanding of the present invention is not limited thereto.

1 is a cross-sectional view showing an arcuate precast concrete weathering slab according to the present invention.

Referring to FIG. 1, the arcuate precast concrete weather wave slab 10 according to the present invention has a plate shape having a constant upward curvature radius in cross section and has a length and a constant width corresponding to the width of a tunnel to be installed. Constrain the horizontal displacement by connecting the both ends of the slab main body 11 and the slab main body 11 formed with the engaging surface 111 hinge-coupled or strongly coupled to the bracket formed on the inner surface of the tunnel, and then removing the horizontal displacement. And a member 12.

That is, according to the present invention, the slab is arcuate with a constant upward curvature, and the horizontal displacement restraint member is coupled so that the bending moment does not act on the slab during the construction, and the slab is hinged or rigidly coupled to the bracket formed on the inner surface of the tunnel. The horizontal displacement restraint member is then removed so that the arcuate slab is subjected to axial force only or to both axial and bending moments.

This will be described in more detail below.

As shown in (a) of FIG. 2, the slab in the form of a flat plate having a boundary condition of simple support and infinite curvature, that is, a flat plate type, has no bending force and no axial force. On the contrary, as in (b), when the slab in the form of plate has a constant curvature, it becomes a member that receives axial force or simultaneously receives axial force and bending moment according to the curvature. In other words, the member shown in (a) is a member that is completely deflected against the applied load, and when the curvature of the member is gradually raised upward as shown in (b) and (c), the bending moment acting decreases and compressive force is generated to reduce the curvature. Increase accordingly.

The formation of such arch members should be such that the boundary condition of both ends restrains the horizontal displacement of the support point against the load acting downwards by both hinges or both ends fixing. If the horizontal displacements (Rah, Rbh) are not constrained, the arch member loses its characteristics and behaves as a flexure member as in (a), and the cross section of the member designed as the arch member causes cracking and eventually breakage. This leads to.

The arch member, which resists the applied load by the compressive force, can greatly reduce the material cost and the cross section, and can greatly reduce the construction cost and structural safety.

Therefore, in the present invention, the slab is configured in an arc shape having a constant upward curvature, and the horizontal displacement is restrained in the horizontal direction by the horizontal displacement restraint member during the construction, and after the construction is hinged or strongly coupled to the bracket formed on the inner surface of the tunnel, the horizontal displacement The slab was allowed to behave as an arch member during and after the construction.

In the present invention, the slab is made of precast concrete member produced by pouring concrete using a mold in the factory and is transported to the site by the transport vehicle after curing and assembled at the final position. Precast concrete can be reinforced by reinforcing bars as well as known reinforced concrete, and can also be reinforced by post tension using tension members.

The thickness of the slab may be formed to have the same thickness except for the intersecting surface of both ends, that is, the portion having a constant upward curvature, and the length (intersection) of the slab is determined corresponding to the width of the tunnel to be installed. May be arbitrarily determined in consideration of lifting capacity and workability.

The curvature of the slab body can be determined as follows.

Table 1 below analyzes the effect of curvature using MIDAS CIVIL 6.1, a general structural analysis program, and summarizes the results from the central part.

The curvature radius was gradually reduced in a straight member. A total of seven cases, R = ∞, R = 500m, R = 100m, R = 80m, R = 60m, R = 40m, and R = 20m, were examined. The unit is 100cm in width (length in tunnel direction), 20cm in thickness, and 27MPa in general concrete. The width is 10.0m and the boundary condition is applied by both hinges. The load was applied to the weight of the concrete member. In the case of the sign "+" indicates tension and "-" indicates compression.

Radius
(mm) Axial force
(kN) moment
(kNm) Stress (MPa)
Stage
(compression) Ha Yeon
(Seal) R = ∞ 0.0 61.3 -9.194 9.194 R = 500,000 -221.5 55.8 9.471 7.256 R = 100,000 -351.5 17.6 -4.401 0.886 R = 80,000 -313.8 12.6 -3.459 0.322 R = 60,000 -258.6 7.8 -2.468 -0.233 R-40,000 -185.3 3.8 -1.497 -0.458 R = 20,000 96.3 1.1 -0.651 -0.407

Figure 3a to 3d is a graph of the analysis results for the seven from R = ∞ to R = 20m in Table 1 from top to bottom, Figure 3a shows the axial force according to the radius of curvature, Figure 3b is a moment according to the radius of curvature 3c illustrates the stress of the upper edge of the member according to the radius of curvature, and FIG. 3d illustrates the stress of the lower edge of the member according to the radius of curvature.

As can be seen in Table 1 and Figure 3, when the radius of curvature is less than about 100m, the stress acting on the upper edge of the member is reduced to less than about 50% of the compressive stress compared to the simple supporting conditions, and the lower edge of the member It can be seen that a stress occurs. In addition, when the radius of curvature is less than 20m it can be seen that the stress generated in the upper and lower edges of the member is sharply reduced to generate a very small stress.

Therefore, in the present invention, the slab radius of the slab body is preferably 100 m or less, and more preferably 20 m or less.

As described above, in the present invention, the slab main body 11 may be a reinforced concrete structure or a prestressed concrete structure, but by using the principles described above, the slab main body 11 may have a compressive force or a small compressive force over the entire length. Because the bending moment is applied, it can be applied to the tunnel section of the wide source without introducing prestress. However, of course, prestress can be introduced to prevent cracks that may occur due to wind pressure due to the passage of the vehicle.

The engaging surface 111 formed at both ends of the slab body 11 may have a thicker thickness than a portion having a predetermined upward curvature, and an insertion groove formed in the bracket 21 formed in the tunnel inner surface thereof. A protrusion 111a that can be inserted into 211 may be formed. The protrusion 111a may be formed over the entire width of the straddling surface 111 or a plurality of the protrusions may be spaced from each other. By inserting the protrusion 111a into the insertion groove 211, the hinge is coupled to restrain the horizontal displacement of the slab so that the slab can behave as an arch member as described above (see FIG. 5 (b)).

Alternatively, as shown in FIG. 4, the slab main body 11 is formed by forming a through hole 111c in the engaging surface 111 and penetrating the fastening means 111d through the through hole 111c to fix it to the bracket 21. It can be strongly coupled to the bracket (21). The fastening means 111d may be a steel rod or a screw rod having a length that can be fixed to the bracket 21 by penetrating the engaging surface 111. When the steel bar is used as a fastening means, non-shrink mortar or resin may be filled between the steel bar and the through hole, and when the screw bar is used as the fastening means, the nut 111e may be inserted into the through hole 111c and the bracket 21. It may be purchased in advance. In addition, a method of fixing the latching surface 111 to the bracket 21 by using a steel rod and a screw rod may be any method known in the art.

The reason why the hinge and the bracket are hinged or stiffened is not only to obtain the arch effect by restraining the horizontal displacement, but also to provide a simple wind pressure on the lower surface of the slab due to the wind pressure acting upon the movement of the large direction. This is because there is a possibility that the slab may come off if the bracket is placed on the bracket.

The arch effect can only be achieved by constraining the horizontal displacement with both ends constrained or hinged. That is, the arched slab can ensure the safety of the structure when the formwork supports the concrete weight below the fabrication and when the structure is completed in the tunnel and the horizontal displacement is constrained. If the displacement in the horizontal direction is not constrained, it is obvious that the arch-shaped slab manufactured by the arch-like structure also behaves the same as the bending member, and cracks or failure of the destroyed door will be lost.

However, it is impossible to manufacture a hinge structure or a rigid structure at the manufacturing and transportation stages. There is no stress on the concrete until the arch formwork is installed on the floor and the reinforcing bar is placed on top and concrete is poured to cure. When the formwork is demolded and the end of the arcuate slab is supported on the bottom surface, it behaves as a flexural member by downward load, and the member may be destroyed during transport and construction by acting as a flexural member.

Accordingly, in the present invention, the horizontal displacement restraint member 12 connecting both ends of the slab body 11 is installed to restrain the horizontal displacement during transportation and construction. The horizontal displacement restraining member 12 is removed because the slab body 11 is coupled to the bracket 21 when the slab construction is completed.

The horizontal displacement restricting member 12 may have an overall length corresponding to the distance between the engaging surfaces 111 of both ends of the slab body 11, and both ends thereof are fixed to the engaging surfaces 111. Since the horizontal displacement restraint member 12 is removed after the slab is installed, the nut 111b is embedded in the latching surface 111 for convenience of removal, and the screw is machined at both ends of the horizontal displacement restraint member 12 for screwing. can do. The horizontal displacement restraint member 12 is divided into at least two parts, and a screw opposite to each other is configured to be divided by connecting both threaded nuts 121 processed on the inner circumferential surface thereof. Therefore, the horizontal displacement limiting member 12 may be formed of a steel bar or steel pipe, and a screw may be machined at the position where the horizontal displacement restraint member 12 is coupled with the nuts 111b and 121. Of course, the horizontal displacement restraint member 12 may be composed of reinforcing bars divided into at least two, and the ends of each of the reinforcing bars are fixed to the latching surface 111 and connected by a coupler. The horizontal displacement restraint member is not limited to the above description, and is not particularly limited as long as it is a configuration that can restrain the horizontal displacement of the slab body during the construction and can be removed after the construction. In addition, the number of horizontal displacement restraint members is also not particularly limited as long as it can restrain the horizontal displacement of the slab body during construction.

Therefore, the slab body is arched by the horizontal displacement is constrained by the horizontal displacement constraint member during transport and construction.

The following describes a method of constructing the wind by using the arcuate precast concrete wind slab configured as described above.

5 is a cross-sectional view schematically showing a method of constructing the wind speed according to the present invention.

First, as in (a), the bracket 21 for connecting the wind slab to the tunnel lining concrete 20 at the position where the wind slab is to be installed is installed. The bracket 21 is provided with a latching surface 111 formed at both ends of the slab body 11. At this time, when the protrusion 111a is formed on the lower surface of the latching surface 111, the protrusion 111a is formed on the upper surface of the bracket 21. An insertion groove 211 into which the groove can be inserted may be formed. The bracket 21 may be formed over the entire length of the tunnel and the insertion groove 211 may be continuously or over the entire length or discontinuously formed in a number corresponding to the number of the protrusions 111b. On the other hand, when the latching surface 111 is fixed to the bracket 21 using the fastening means 111d, the insertion groove 211 does not need to be formed in the bracket 21, and instead the fastening means 111d may be fastened. The nut 111e may be installed in advance.

Next, as in (b), the arcuate precast concrete weatherproof slab 10 according to the invention described above is connected to the bracket 21. As a connection method, a hinge coupling method for inserting the protrusion 111a to be formed on the bottom surface of the engaging surface 111 into the insertion groove 211 formed in the bracket 21 or a rigid coupling method through the fastening means 111d may be used. Can be. Alternatively, the slab may be mounted on the bracket, and may be integrally formed using concrete or non-shrink mortar to be strongly bonded. The slab assembly is completed by repeating the connection of the arched precast concrete weather slab to the bracket.

Finally, as in (c), the horizontal displacement restraint member 12 is removed. The horizontal displacement constraining member 12 can be removed by removing both screw nuts 121 or couplers connecting the constraining members to each other and disconnecting the brackets 21 at both ends. Alternatively, the horizontal displacement restraint member may be cut and removed. If necessary, the partition wall 30 may be installed on the upper surface of the slab body 11 as in (D).

Since the weather slab according to the present invention configured as described above is composed of precast concrete member can shorten the air, and can reduce the internal cross section of the tunnel, the construction cost is reduced, there is no risk of safety accident because no copper claws are required. .

In addition, it is possible to prevent cracks around the connection between the weather slab and the lining concrete and the weather slab, and hardly cause long-term sagging caused by bending.

In addition, the curvature of the driver is greatly improved since the curvature of the driver is significantly increased, thereby greatly reducing the occurrence of traffic accidents.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention . The invention is not limited by the invention as such variations and modifications but only by the claims appended hereto.

11: slab body
111: spreading
111a: turning
111c: through hole
111d: fastening means
111b, 111e: nuts
12: horizontal displacement constraint member
121: double-nut
20: lining
21: Bracket
211: insertion groove
30: bulkhead

Claims (5)

Precast concrete slab body with a cross section of a plate shape with a constant upward radius of curvature, a length and a constant width corresponding to the width of the tunnel to be installed, and a stepped surface that is hinged or rigidly coupled to a bracket formed on the inner surface of the tunnel at both ends Wow,
An arcuate precast concrete weathering slab comprising: a horizontal displacement restraining member which connects both ends of the slab body to each other during the construction to restrain the horizontal displacement and is removed after the construction. The method according to claim 1,
An arcuate precast concrete weather slab characterized by a radius of curvature of less than 100 m. The method according to claim 1,
An arcuate precast concrete weathering slab, characterized by a curvature radius of 20 m or less. The method according to claim 1,
An arcuate precast concrete weathering slab, characterized in that a projection is formed on the lower surface of the cladding surface. Installing a bracket for connecting the abundance slab to the tunnel lining concrete at a location where the abundance slab is to be installed;
The slab body has a length and a constant width corresponding to the width of the tunnel to be installed, the cross section is a plate shape having a constant upward radius of curvature, and at both ends formed a slab body formed by a hinged or rigidly coupled to the bracket formed on the inner surface of the tunnel; Hinge-bonding or rigidly coupling an arcuate precast concrete weather vane slab comprising a horizontal displacement restraint member which connects both ends of the slab body to each other to restrain horizontal displacement and is removed after hypothesis; And
And removing the horizontal displacement restraint member.

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