KR100421703B1 - a tunnel ventilation structure using spancrete and the construction method thereof - Google Patents

Abstract

The present invention provides a tunnel ventilation structure and its installation to secure a safe and comfortable traffic environment by maintaining the concentration of pollutants in the tunnel below the allowable level by discharging or diluting the exhaust gas generated by the vehicle inside the tunnel outside the tunnel. It is related to the construction method, and in the prior art in which the construction of the formwork on the site and the installation of the slab through the reinforcement and concrete casting to form a slab through the semi-flow air flow tunnel ventilation structure of forming a duct slab on the upper part of the tunnel After laying lining concrete in the tunnel, formwork and copper bars for the formation of structures must be manufactured and installed at the site, and reinforcement is also required at the site. Curing after pouring concrete Since the entry into the tunnel is restricted for some time, it interferes with the progress of other work processes, resulting in a long tunnel construction period and a high cost of tunnel construction. Therefore, both sides of the upper portion of the tunnel 10 The lining bracket 11 is formed, and the air supply space 30 is formed in the upper portion of the spancrete 20 by installing the sprocket 20 having the air supply port 21 between the concrete lining brackets 11. According to the present invention, characterized in that the filling concrete 12 is placed between the span concrete 20 and the concrete lining bracket (11), with a less manpower than the field casting method of placing the slab in the field Not only can the work be greatly shortened, but the construction time is also reduced, and the structure is formed from the factory-made spancrete (20). It is possible to obtain a section, and to reduce the material cost required for the formwork and the round bar, it is possible to significantly reduce the work costs and construction costs.

Description

Tunnel ventilation structure using spancrete and its construction method

The present invention provides a tunnel ventilation structure and its installation to secure a safe and comfortable traffic environment by maintaining the concentration of pollutants in the tunnel below the allowable level by discharging or diluting the exhaust gas generated by the vehicle inside the tunnel outside the tunnel. More specifically, the construction of a semi-cross-flow ventilation system for forming fresh air into the tunnel by forming a duct slab having an air supply in the upper part of the tunnel can be more easily constructed using spancrete. It's about making things happen.

In general, the ventilation system of the road tunnel is to ensure safe and comfortable traffic environment by keeping the concentration of pollutants in the tunnel below the allowable level by discharging or diluting the exhaust gas generated by the vehicle in the tunnel outside the tunnel. In the case of such ventilation system, it is necessary to thoroughly examine the characteristics of the extension of the tunnel, topography, features, geology, traffic conditions, weather conditions, environmental conditions, etc., and then select a more effective and economical method.

Conventionally, many tunnel ventilation facilities employ forced exhaust systems by jet pans installed in the ceiling of the tunnel. Such a jet fan type tunnel ventilation is only applicable to short-length tunnels. In addition, since the tunnel top is open in an open space, there is a problem in that the capacity of the jet fan or the number of jet fans must be increased for the complete discharge of polluted air.

In addition, when the capacity of the jet fan is increased in the above, a great stress is applied to the connection between the tunnel ceiling and the jet fan, and when the number of jet fans is increased, it becomes expensive to maintain and manage.

Of course, the connection between the tunnel ceiling and the jet fan will be constructed in consideration of certain safety values in the structural design, but the fatigue load will be applied to the joint due to the constant vibration caused by the jet fan's operation, and the influence of the wind on the vehicle's driving is certain. It is unclear and always has an unsafe element.

In the ventilation method using the jet fan, when the reciprocation of the vehicle is performed in one tunnel, the ventilation force direction due to the vehicle progress and the boost pressure direction by the jet fan do not coincide properly.

In other words, it is not possible to apply the ventilation system by jet fan when the vehicle is reciprocating in one tunnel.

As a result, in the case of long tunnels with long tunnel lengths, and in many tunnel ventilation systems that have been recently constructed, a separate duct slab is formed at the upper part of the tunnel, and a predetermined interval of air supply is provided on the slab to provide a damper. It is a situation that the anti-flow air flow method is adopted to induce the circulation of the air inside the tunnel by supplying air through it after installation.

The anti-cross flow ventilation system is a system in which the sacred air supplied into the tunnel through the air supply duct and the air supply is diluted with polluted air generated in the tunnel and discharged to the shaft by the traffic ventilation force inside the tunnel.

When the anti-cross flow is used, the same pressure is supplied by the air supply holes installed at equal intervals in the long length tunnel, so that the distribution of polluted air in the tunnel is much better than that of other methods.

On the other hand, in the conventional tunnel ventilation structure of the semi-flow flow method of forming the duct slab on the upper part of the tunnel, it is common to construct and install the formwork directly on the site, and to construct the slab through reinforcement and concrete casting. Bar, such as the site casting method, after laying lining concrete in the tunnel, the formwork and dongbari for the formation of the structure must be manufactured and installed in the site, and the reinforcement is also required at the site. Due to the construction and installation of temporary products, the entry into the tunnel is restricted during the curing period after the concrete is placed, which hinders the progress of other work processes, resulting in a long tunnel construction period and a large tunnel construction cost. .

The present invention has been devised in view of the above-described conventional situation, and its object is to provide a slab quickly without interfering with the progress of other work processes in installing a tunnel ventilation structure of a transverse flow type having a duct slab. The purpose of the present invention is to provide a tunnel ventilation structure structure using spancrete and its installation method that can reduce the construction cost as well as shorten the construction period of the tunnel by allowing installation.

1 is a longitudinal cross-sectional view of one embodiment of the present invention;

Figure 2 is a plan view of the sprocket concrete joint of the embodiment

3 is a longitudinal sectional view of another embodiment of the present invention;

4 is a cross-sectional view taken along the line A-A of FIG.

5 is a front view of the moon according to the embodiment;

Figure 6 is a 3D structural analysis of the embodiment

<Description of Symbols for Main Parts of Drawings>

10 tunnel 11 concrete lining bracket

12: filled concrete 13: ceiling surface

20, 20a, 20b, 20c: Spandcrete

21: air supply port 30: air supply space

40: CT section steel 50: Moon stand

51: turnbuckle 52a, 52b: wire rope

60: heavy load anchor

The present invention is characterized in that to install a spancrete having an air supply in the lining bracket concrete formed on the upper sides of the tunnel in order to achieve the above object, the following detailed description of the technical details based on the accompanying drawings As follows.

That is, Figure 1 is a longitudinal cross-sectional view of one embodiment of the present invention, the present invention is to form a concrete lining bracket 11 on both sides of the inner upper portion of the tunnel 10, as shown in Figure 1, both concrete lining bracket ( 11) between the sprocket 20 having the air supply port 21 is provided between the 11 to form an air supply space 30 in the upper portion of the sprit 20, the sprocket 20 and the concrete lining bracket (11) The filling concrete 12 is placed between the air supply ducts installed at regular intervals after installing the structure for the ventilation facility using the spun concrete 20 having the air supply port 21 in the upper portion of the tunnel 10. By injecting fresh air into the tunnel 10 through the air supply port 21 (not shown), the polluted air may be diluted, and the polluted air may be discharged to the outside by the ventilation force caused by driving the vehicle.

In the present invention, the spancrete 20 is widely used as a structural floor material or exterior wall material of a general building, and hollow hollow cores are formed at the center of a concrete cross section, and a hollow stress applied to a prestressed strand as a tensile reinforcement material of concrete. It is a kind of hollow core slab.

The feature of the spancrete 20 is that the core is formed at the center of the cross section, and because of its small weight and prestressed steel wire, there is an advantage that a long span is possible with a thickness smaller than that of a general precast panel.

In addition, as a factory-made product is produced through strict quality control, you can expect high-quality products in quality and accurate construction schedule management in accordance with the process management.

On the other hand, when installing Precast Concrete Panel products, solid PCs without cores in the cross section have a relatively heavy weight compared to the spancrete with hollow sections. Since it becomes larger, when the spancrete is applied to the same span, it is advantageous in terms of self-weight reduction, thereby reducing the size of the cross section.

For example, a width of 1m and a thickness of 200mm can reduce the weight of the member by about 37% compared to the solid section, and reduce the overall thickness of the member by the reduced weight. The cost of installation can be significantly reduced.

As described above, the present invention in which the slab through the spancrete 20 is formed in the upper portion of the tunnel 10 to block the vehicle driving paths at the upper and lower portions thereof reduces the ventilation space and provides a heavy exhaust gas by installing an exhaust facility on the formed slab. It is possible to prevent accidents caused by the fall of heavy exhaust equipment.

The polluted air purifying effect of the cross-flow air flow method of the present invention is far superior to the jet fan method of discharging the polluted air to the outside by installing a jet fan on the upper side.

Meanwhile, the construction method and order of the present invention are as follows.

① As shown in FIG. 1, the concrete lining bracket 11 for pouring the end of the spancrete 20 is poured in accordance with the height at which the spancrete 20 is formed on both inner sides of the tunnel 10.

② Do the filling work for the installation of spancrete 20.

③ When the filling operation is completed, transport the spancrete (20) produced under strict quality control in the factory to the site and install it exactly where it is. At this time, the length spand over the concrete lining bracket 11 is, for example, 150mm, and the air supply port 21 formed in the spancrete 20 is 1000mm × 200mm in size every 5m.

④ Fill the space between the end concrete lining bracket (11) and span concrete (20) by filling concrete (12) to fix the span concrete (20).

⑤ The joint between the spancrete 20 is caulked with a joint of a certain interval (for example 15mm) as shown in Figure 2 to finish the treatment.

In the case of using the single member spancrete 20 as shown in FIG. 1, the span in the tunnel is 8.5 m, for example, and the thickness of the spancrete 20 is 200 mm.

In the above embodiment, the ventilation structure is constructed by using the single member spancrete 20 without an intermediate support point. When the width of the tunnel 10 is one-way lane, that is, reciprocating lane, the required width of the ventilation structure is about 8.5 m. (In the case of pure lane width), the above embodiment can be applied.

However, if the emergency parking lot section or the entire lane is more than three lanes, the required width of the ventilation structure exceeds 11m, and for the section to which the long span is applied, the ventilation structure is made of a single member spancrete 20 without intermediate support points. There will be a structural crowd to construct the bar, and setting a support point in the middle of the structure will interfere with the traffic in the tunnel.

As a solution to this, the present invention proposes a technique for forming a support point in the middle by dividing into two or three short members instead of installing a single member for a section in which the width of the ventilation structure exceeds 8.5m.

In the present invention, a method for providing an intermediate support point is to be attached to the ceiling surface of the tunnel by using a CT beam and a lanyard for spancrete end support, and such a method is most optimal for supporting a light weight product such as spancrete. It can be called a method.

3 to 5 show another embodiment of the present invention, which is applied to an emergency parking lot section or a tunnel having a width of three lanes or more, which embodiment is divided into three sections 20a, 20b, and 20c. To hang on the ceiling using the moon 50 has a form installed.

In other words, this alternative embodiment divides the spancrete 20a, 20b and 20c into three parts, while the right end and the center spancrete 20a of the left splint 20a, which is supported by the lower left side on the left-lining concrete bracket 11, The CT-shaped steel 40 is installed between the left end of the 20b) and between the left end of the right spancrete 20c on which the right lower end is supported by the right lining concrete bracket 11 and the right end of the center spancrete 20b. The stand 50 is installed between the CT-shaped steel 40 and the ceiling surface 13 to suspend and support each of the spancretes 20a, 20b, and 20c.

In the embodiment, the moon 50 is coupled to the wire rope 52a, 52b at both ends of the turnbuckle 51, as shown in Figure 5, the anchor shackle 53a and the connecting plate (top) of the upper wire rope (52a) 54a), and the upper CT steel 55 fixed to the ceiling surface through the high load anchor 60 is installed, the lower end of the lower wire rope 52b to the anchor shackle 53b and the spancrete CT steel 40 The connecting plate 54b to be welded is provided.

On the other hand, the construction method and order of this other embodiment are as follows.

① After drilling the mounting position of the high load anchor 60 on the ceiling surface (13) of the tunnel (10).

② Fix the upper CT section (55) welded anchor shackle connecting plate (54a) to the correct position using the high load anchor (60).

At this time, the high load anchor 60 is tightened exactly by a predetermined torque value.

③ using the turnbuckle 51 connects the upper wire rope 52a assembled by a predetermined length with the upper anchor shackle 53.

④ Connect the lower spancrete supporting CT-shaped steel 40 welded with anchor shackle connecting plate 54b to the lower wire rope 52b.

⑤ Correctly adjust the height of the connected lower CT section 40 using the turnbuckle 51.

⑥ Spancrete 20a, 20b, 20c is installed on the flange of lower CT section steel 40.

⑦ Finally, correct the height of the spancrete 20a, 20b, 20c using the turnbuckle 51.

Structural safety of the spancrete used in the installation of the ventilation structure of the present invention has already been verified in the structural flooring of many buildings that have already been constructed using the spancrete, an example of the properties of the prestressed spancrete As follows.

* Concrete: 28 days target strength-350kg / cm ²

Strength when introducing wire tension-270kg / cm ²

* PS steel wire: Domestic 2 ~ 9mm-3 and 9.3mm-3 have 250ksi grade and 12.7mm-3 have 270ksi grade. In addition, the strength and stress of the steel wire is as follows.

<Strength and Stress by Steel Type>

Type of PS steel wire Extreme time When introducing tension In case of loss Remarks Ton Stress, f _pu (ton / cm ² ) Ton Stress, f _pu (ton / cm ² Ton Stress, f _pu (ton / cm ² ) 2.9mm-3 book 3.90 19.67 2.73 13.77 2.13 10.74 22% loss estimate 9.3mm-3 pattern 9.05 17.54 6.34 12.28 4.95 9.58 22% loss estimate 12.7mm-3 book 18.46 18.70 12.92 13.09 10.08 10.21 22% loss estimate

Next, the principle of the prestressed structure applied to each spancrete in the present invention is as follows.

In other words, the prestressed structure is a pre-stressed wire that uses a prestressed steel wire as a reinforcement for tensile strength, which is a material weakness of concrete. In the present invention, the use of spun concrete to which the pre-tension structure is applied, and can be classified again according to the arrangement method of the steel wire, but the span concrete of the present invention is an inner product, the attachment steel wire structure.

Producing the spancrete is as follows.

① Place the steel wire in the correct position on the prestress bed.

② Use hydraulic jack on the placed steel wire to tension the steel wire by the predetermined tension.

③ Concrete is poured into the prestressed bed using concrete pouring equipment.

④ Curing concrete with steam curing machine for early strength development and excellent quality control.

⑤ When the predetermined target concrete strength is reached to introduce the tension force of the prestressed steel wire, the steel wire is cut by using saw cutting.

⑥ Machine the spancrete using cutting equipment as long as the required length.

Spancrete produced as described above is transported to the yard for curing.

The stress distribution at each load in the case of the application of the tension of the spancrete, the application of self-weight, and the application of the working load is a stress distribution that is simultaneously subjected to deflection by the eccentricity between the axial compression force and the central axis of the axial compression force. The maximum compressive and tensile stresses should not exceed the allowable compressive and tensile stresses of the concrete.

However, if the upper maximum tensile stress exceeds the allowable tensile stress of the concrete due to the tension transfer of the lower steel wire during the introduction of the tensile force, it can be reinforced against the tensile stress by the excess by arranging the appropriate steel wire on the upper part.

If the tensile stress at the lower end of the cross section is designed to be within the allowable range until the non-factored load is applied in the use load application step, a full prestressed structure can be realized.

The design of the bending moment of the spancrete cross section is based on the ultimate strength design method of the ACI Code.

In other words, Arrange the cross section size and PS steel wire so that

Where M _u = design bending moment generated by an external force with a load factor

ΦM _n = Nominal flexural strength and strength reduction factor of section through deflection analysis are applied to 0.9.

The nominal flexural strength of the cross section is

Where A _p = total cross-sectional area of the steel wire (cm ² )

f _ps = design stress of steel wire (kg / cm ² )

d _p = effective depth of steel wire (cm)

a = depth of equivalent stress block in cm

In the case of general RC structures, the reinforcement stresses are calculated based on the yield stress when calculating the nominal strength of the cross section. In the case of prestressed structures, the yield strength of steel wires depends on various factors such as the reinforcement ratio.

For this reason, the ACI Code specifies the design stress f _ps for steel wires as follows.

Where f _pu = ultimate stress of the steel wire (kg / cm ² )

V _p = 0.4 (for general PS steel wire)

ρ _p = A _p / bd _p

The design of the shear of the prestressed spancrete is based on the ACI Code as well as the flexural design.

The resistance of the cross section to the shear of the one-way slab concept is determined by the cross-sectional composition of the effective width and the effective depth excluding the hollow part. Like general slabs, it is designed to eliminate the need for a separate shear rebar.

In other words, Determine the cross-sectional size to be

Where V _u = design shear force generated by an external force with a load factor

ΦV _n = Nominal shear strength and strength reduction factor of the section through analysis apply 0.85.

Here, the nominal shear strength shared by the spancrete cross section is divided into two types according to the shear force pattern causing the crack in the cross section.

* Shear forces causing abdominal shear cracking

* Shear forces causing flexure-shear cracking

The smaller value of the shear force causing the two types of cracks at any position along the span is the shared shear force by the concrete at that position.

In addition, the ACI Code specifies the maximum and minimum shear stress due to the concrete cross section as follows.

* Maximum shear stress,

* Minimum shear stress,

Meanwhile, in the present invention, as shown in FIG. 3, in the case of a long span, that is, an emergency parking lot section, the plate concrete 20a, 20b, and 20c are installed using the CT steel 40. In this case, the CT steel 40 and The moon 50 to be connected uses wire ropes 52a and 52b, and the junction with the tunnel ceiling surface 13 uses a heavy duty anchor 60 to terminate the spancrete 20. Directionally supported CT section 40 obtains the applied stress through structural analysis for the load applied to the member, and then selects an appropriate member to fall within the allowable stress range.

In other words,

Where M = design bending moment for external force

Z = section modulus of cross section (cm ³ )

f _b = permissible bending stress (kg / cm ² )

Q _max = design shear force against external force

A _w = cross-sectional area of the web part

τ = permissible shear stress (kg / cm ² )

The following allowable bending stress is considered in consideration of transverse buckling which may occur due to uneven loading of CT steel.

Where l _b = span length

h = part height

A _f = flange cross section

As described above, the size of the cross section is determined by selecting the smaller of the two allowable bending stresses.

The CT-shaped steel 40 supporting the spancrete 20 is joined to the tunnel ceiling surface 13 by a lunar stand 50 having wire ropes 52a and 52b. The high load anchor 60 will be used.

The following table details the types of heavy duty anchors (60).

<Specification table of high load anchor>

Anchor Size Details M8 / 20 M8 / 40 M10 / 20 M10 / 40 M12 / 25 M12 / 50 M16 / 25 M16 / 50 M20 / 30 M20 / 60 M24 / 30 M24 / 60 d ₀ (mm) Drill bit diameter 12 15 18 24 28 32 h ₁ (mm) hole depth 80 90 100 125 155 180 h _nom (mm) Minimum insertion depth 65 75 80 105 130 155 t _fix (mm) 20 40 20 40 25 50 25 50 30 60 30 60 l (mm) Anchor Length 95 115 107 127 120 145 148 173 183 213 205 235 h _{n (} mm) height + washer 7.5 10 11 14 17 19 T _inst (kg * m) Tightening torque HSL 2.5 5.0 8.0 20.0 38.0 50.0 HSLG-R 12.0 20.0 - Distance (mm) 4 5 8 9 12 16 S _w (mm) HSL-R 13 17 19 24 30 36 HSLG-R - - 24 30 36 41 d _h (mm) Maximum tolerance hole 14 17 20 26 31 35 d _w (mm) washer diameter 20 25 30 40 45 50 h (mm) Minimum thickness of base material 120 140 160 180 220 270

The following table shows the allowable values of high-load anchors for uncracked concrete with a concrete compressive strength (fck) of 300 kg / cm2 and Poisson's ratio (υ) 3.0.

Anchor size M8 M10 M12 M16 M20 M24 Tensile force 0 ° 0.69 1.04 1.5 2.57 3.46 4.55 Composite load 30 ° 0.79 1.25 1.82 3.13 4.26 5.59 45 ° 0.84 1.36 1.98 3.42 4.66 6.11 60 ° 0.88 1.46 2.13 3.70 5.06 6.62 Shear force 0 ° 0.98 1.67 2.45 4.26 5.86 7.66

The design of the high load anchor is based on the values in the table above and is designed as follows.

Where f _B = correction factor for concrete strength

,

f _T = correction factor for anchor insertion depth

Anchor size M8 M10 M12 M16 M20 M24 h _nom (mm) 65 75 80 105 130 155

The table above is the standard insertion depth according to the bolt diameter.

f _A = correction factor according to the distance between anchors

f _R = correction factor according to the edge distance

<Reduction factor (f _A ) according to the distance between bolts and correction factor (f _R ) according to the edge distance>

Reduction factor (interanker spacing) f _A Reduction Factor (Edge Distance) f _R Draw / shear Drawing f _RN Shear f _RN Distance S (cm) Anchor size Corner distance (cm) Anchor size Anchor size M8 M10 M12 M16 M20 M24 M8 M10 M12 M16 M20 M24 M8 M10 M12 M16 M20 M24 6.5 0.70 0 6.5 0.70 0 0.30 0 7.5 0.72 0.70 0 7.5 0.73 0.70 0 0.37 0.90 0 8.0 0.73 0.71 0.70 0 8.0 0.75 0.71 0.70 0 0.40 0.44 0.30 0 10.5 0.79 0.76 0.74 0.70 0 10.5 0.82 0.78 0.76 0.70 0 0.59 0.59 0.44 0.30 0 13.0 0.85 0.81 0.79 0.73 0.70 0 13.0 0.90 0.85 0.83 0.74 0.70 0 0.77 0.74 0.59 0.41 0.30 0 15.5 0.90 0.86 0.84 0.77 0.72 0.70 15.5 0.97 0.91 0.88 0.79 0.73 0.70 0.95 0.78 0.74 0.52 0.39 0.30 17.5 0.95 0.90 0.87 0.80 0.75 0.71 16.2 1.0 0.93 0.90 0.80 0.75 0.71 1.0 0.92 0.78 0.55 0.41 0.32 19.5 1.0 0.94 0.91 0.82 0.77 0.73 18.7 1.0 0.96 0.85 0.78 0.74 1.0 0.92 0.66 0.50 0.39 22.5 1.0 0.97 0.87 0.80 0.76 20.0 1.0 0.88 0.80 0.75 1.0 0.72 0.55 0.43 24.5 1.0 0.89 0.82 0.78 22.5 1.0 0.92 0.84 0.79 1.0 0.83 0.64 0.51 27.5 1.0 0.94 0.86 0.81 26.5 1.0 0.91 0.84 1.0 0.79 0.63 31.5 1.0 0.91 0.85 27.5 1.0 0.92 0.85 1.0 0.82 0.66 35.0 0.95 0.88 30.0 1.0 0.96 0.88 1.0 0.91 0.73 39.5 1.0 0.92 32.5 1.0 0.92 1.0 0.81 43.0 1.0 0.96 35.0 1.0 0.95 1.0 0.89 47.0 1.0 39.0 1.0 1.0

The above table shows various reduction factors according to the bolt type and when designing, it should be designed with the net design load value reduced from the standard allowable tension with reference to the above values.

<Application example>

The performance example of the present invention as described above is as follows.

That is, the anti-flow ventilating structure of the present invention in a pole tunnel having a lane width of 7.3m, a total length of 1620m, and an emergency parking lot provided in the middle two places, the span of the main line section of 8.48m and the span of the emergency parking lot section of 10.716m. It will be described for the case of applying.

When the lining concrete is poured in the above example, the length of the concrete lining bracket 11 for supporting the spancrete 20 is 350 mm in total, and the span length of the spancrete 20 is 150 mm and the remaining 200 mm is Backfill with concrete.

The width of the spancrete was 1 m for all members and a stretch joint was provided every 5 panels, i.e. every 5 m.

The air supply port 21 was formed to have a size of 1180 × 220 every 5m intervals, and the air supply port 21 is produced at the factory and then assembled at the site through the air supply process.

The load applied to the ventilation structure is a facility installed on top of the slab in addition to the self-weight of the spancrete, and a load of 0.3t / m ² is applied.

The thickness of the spancrete 20 of 8.48m span used for main line segment was 200 mm.

In the case of the emergency parking lot section where the total span reaches 10.716m, three concrete slabs 20a, 20b and 20c having a total length of 3.572m and a thickness of 200mm are provided with concrete lining brackets 11 and CT steels 40 at the tunnel edges It was supported on the top of the tunnel with a turnbuckle (51) and a turn bar (51a, 52b, 52b) to the top of the tunnel to support the applied load.

The spacing of the moon 50 was 1.5m considering the sufficient safety factor in addition to the load applied through the structural design, the wire ropes 52a and 52b have a diameter of 24mm and the turnbuckles 51 have the diameter of the eye type. 24 mm was applied.

The joint between the moon 50 and the tunnel ceiling was M24 / 30 high load anchor 60, and CT-shaped steel 40 used CT-300 * 200 * 11 * 17.

FIG. 6 shows the results of 3D structural analysis of the emergency parking lot section using MIDAS / GENw.

As a result of the structural analysis, when the stress generated in the CT steel 40 with respect to the external force is examined, the maximum stress generated in the CT steel 40 becomes σ _max = 0.2045 t / m ² in the entire section.

This value is appropriate for members adopted with values smaller than the allowable bending stress value fb = 1.6 t / cm ² of SS41.

Referring to the axial force value of the truss-tension element of FIG. 6, the maximum tension force of 3.6 tons is applied to the second element from the outermost part.

In the KSD 3514 standard, wire rope 3 (configuration; 6 × 19, 19 twisted pairs of 6 twisted wires) adopted a wire rope with a diameter of 20 mm, which is larger than the applied tensile force.

For 25mm diameter wire ropes, the cutting load is 36.6 tons for class B, and the design safety load is 9.15 tons, 25% of the cutting load.

In the case of the turnbuckle 51, the shape of the hook for hooking the wire ropes 52a and 52b on both sides should be EYE type, and in the case of casting, the diameter 25mm and the safety type of the turnbuckle for the eye type Since the load is 4.54ton, the working tension is greater than 3.6ton, which is appropriate.

The welding size and length calculation for connecting the upper and lower portions of the moon 50 to the CT-shaped steel 40 are designed safely based on the structural analysis results.

The high load anchor 60 is used to join the CT-shaped steel 40 and the stand 50 supporting the spancrete 20 to the tunnel ceiling surface 13, and the design thereof is as follows.

First, the safety load value is calculated by applying various reduction factors based on the reference load value when the concrete strength is 300kg / cm ² .

The design of the high load anchor is designed by the following equation as described above.

,

Adopting a 2-M24 high load anchor to counter the maximum tension of 3.6 tons applied to the moon, one M24 has an allowable safety tension of 4.55 tons.

First, when the correction factor for concrete strength is calculated, the strength of lining concrete applied is 240kg / cm ² and axial tensile force is a = 0.

Therefore, the reduction factor f _B is Becomes

The correction factor for anchor insertion depth is 155mm for M24, so if this 155mm insertion depth is applied during construction, the reduction factor f _T is

Becomes

On the other hand, the distance between two M24 bolts is 150mm in the field, so the correction factor according to the distance between anchors is f _A = 0.7.

And since the anchor bolt position is applied to the tunnel ceiling, the correction factor according to the corner distance is f _R = 1.

Therefore, the safety tensile load of one M24 heavy load anchor is

Becomes

Therefore, the safety tensile load of 2-M24 heavy load anchor is 2.8ton * 2 = 5.6ton, which is larger than 3.6ton of tension applied to the moon.

As described above, the present invention provides a concrete lining bracket 11 on both sides of the inner upper portion of the tunnel 10, and installs the sprocket 20 between the concrete lining brackets 11 to spread the concrete 20. According to the present invention, the air supply space 30 is provided at the upper portion of the slab, and according to the present invention, it is possible to quickly work with less manpower than the on-site casting method of placing the slab in the field, thereby greatly shortening the construction period, as well as the factory produced product span. Since the structure is formed of the crete 20, it is possible to obtain an excellent effect in terms of quality control, and to reduce the material cost required for formwork and ridges, thereby significantly reducing work and construction costs. You can get it.

Claims (4)

delete delete The concrete lining bracket 11 is poured to support the span of the end of the spancrete 20 in accordance with the height at which the spancrete 20 is formed in the upper portion of the tunnel 10, and the filling work for installing the spancrete 20 is performed. After carrying out the span concrete 20 is transported to the site and installed precisely at the location of the filling, and filling the space between the concrete lining bracket 11 and the span concrete 20 with the filled concrete (12) span concrete (20) Fixing, and the joint between the spancrete 20, the construction method of the tunnel ventilation structure using a spancrete, characterized in that the finishing treatment by caulking with a joint of a certain interval. 4. The turnbuckle (51) and the wire rope (52a) (52b) are provided in order to install a plurality of split concrete (20a) (20b) (20c) between the concrete lining bracket (11). At the same time, after installing a plurality of CT beams (40) supported by the moon 50 fixed to the tunnel ceiling surface 13 with a high load anchor 60 between the two concrete lining brackets 11 (20a) (20b) The construction method of the tunnel ventilation structure using a spancrete, characterized in that the support via both concrete lining brackets (11) and the CT-shaped steel (40) located between them.