Air duct slab provided with a reinforced joint structure and the construction method thereof

Abstract

The present invention provides a reinforcement structure for the fastening portion of a ventilation duct slab, which is manufactured as a panel-shaped precast concrete structure and forms a ventilation passage such as a tunnel or underpass through a continuous fastening process at the site. In this invention, an insert anchor and a bolt fastening groove are formed at one end and the other end of the body of a pair of ventilation duct slabs connected to each other, respectively. During the construction process of fastening the ventilation duct slabs, a snap ring inserted into the bolt fastening groove reinforces the integrated fixing structure of a high-strength bolt inserted into the insert anchor of one ventilation duct slab and mortar filled in the bolt fastening groove of the other ventilation duct slab. This structure effectively prevents the mortar forming the joint portion of adjacent ventilation duct slabs from separating or detaching from the joint surface between the slabs, or the joint portions from separating due to damage to the mortar filled in the joint portion, even when sudden load changes, such as wind pressure applied to a cross-flow ventilation duct structure of an underground facility constructed through the continuous fastening of ventilation duct slabs occur.

Description

Technology Field

[0001] The present invention relates to a ventilation duct slab equipped with a fastening reinforcement structure, and more specifically, to a ventilation duct slab manufactured as a panel-shaped precast concrete structure to form a ventilation passage such as a tunnel or underpass through a continuous fastening process at the construction site. In this invention, at least two or more bolt fastening grooves are formed along a joint surface connecting to an adjacent ventilation duct slab at one end of the body of a connected ventilation duct slab, and at the other end of the body of the connected ventilation duct slab, insert anchors are installed at positions corresponding to the locations where the bolt fastening grooves are formed along the joint surface connecting to the connected ventilation duct slab. During the construction process of the ventilation duct slab at the construction site, high-strength bolts are fastened to the insert anchors of the connected ventilation duct slabs, and while the fastened high-strength bolts are deeply inserted into the bolt fastening grooves of the connected ventilation duct slabs, mortar is filled into the connection portion of the two ventilation duct slabs to fasten the two adjacent ventilation duct slabs. The present invention relates to a ventilation duct slab and a method of constructing the same, which is equipped with a fastening reinforcement structure that can reliably support the structural stability of a ventilation system under emergency conditions as well as normal conditions, by effectively preventing the mortar forming the joint portion of adjacent ventilation duct slabs from separating and detaching from the joint groove due to external forces, even when a strong load caused by external events such as wind pressure or vibration is applied to a ventilation duct slab structure constructed through the continuous connection of precast type concrete panels by inserting a snap ring on the inner side to prevent the mortar, which is filled inside the bolt fastening groove and hardens integrally with the high-strength bolt, from separating and detaching from the bolt fastening groove. Background Technology

[0003] Recently, the construction and operation of underground structures, including long underground roads and tunnels, have been very active. For such structures, establishing a ventilation system for the underground space is one of the most important factors.

[0004] Therefore, when constructing long underground roads or tunnels, establishing a ventilation system for internal air circulation is one of the important design elements. In terms of the method, there is a growing trend in design to establish a cross-flow ventilation system using air duct slabs, compared to the conventional method using jet fans.

[0005] Due to the installation form and structural characteristics of air duct slabs, construction methods involving the assembly and fastening of pre-fabricated concrete panel-shaped slabs on-site are mainly carried out rather than on-site casting. Accordingly, there is a continuous search for structural methods that allow for more convenient and rapid construction while maintaining the bonding strength of the joints of the air duct slabs forming the air duct through continuous assembly and fastening on-site.

[0006] In order to support such a continuous connection structure for duct slabs, conventionally, methods have mainly been used, such as the connection surface structure between duct slabs disclosed in Korean Registered Patent Publication No. 10-2516724, "Connection structure of duct slab segments with fire-resistant mortar attached by pre-construction and method of connecting the same," wherein a shear key protruding outward is formed on the connection surface of one duct slab that is joined to an adjacent one, and a key groove into which the shear key is inserted is formed on the connection surface of the other duct slab connected thereto, thereby joining the two interconnected duct slabs by fitting them together, and then filling the connection area with non-shrink fire-resistant mortar.

[0007] However, as described above, when shear keys and shear key grooves interlock to connect two adjacent duct slabs, the strength of the mortar filling and hardening at the joint can be configured to be similar to or even stronger than the strength of the duct slab body itself, which is prefabricated in the form of a precast concrete panel; however, even in this case, the bonding force between the concrete body forming the joint surface of the duct slab and the mortar filling and hardening at the joint is inevitably relatively weak. Consequently, if strong tensile forces are applied to the adjacent connected duct slabs, causing them to spread outward due to continuous wind pressure applied to the duct slab by the airflow passing through the duct, or due to sudden changes in airflow within the duct and / or vibrations transmitted to the structure in the event of an accident, the mortar filling and hardening at the joint between the duct slabs separates and detaches from the joint surface of the slabs, causing the joint between the two connected duct slabs to spread outward and [into] the ventilation passage Cracks occur, which not only degrade the performance of the overall ventilation system and increase the risk of safety accidents, but in severe cases, can also cause structural damage to the ventilation system itself.

[0008] Accordingly, there is a steady demand for effective fastening structures and construction methods for the on-site fastening of ventilation duct slabs prefabricated in the form of precast concrete panels, which can perform continuous fastening of ventilation duct slabs quickly and conveniently while effectively maintaining a solid connection at the joints between interconnected ventilation duct slabs. Prior art literature

[0010] 1. Korean Registered Patent Publication No. 10-2516724 (Registration Date: March 28, 2023) "Joining structure of a ventilation duct slab segment with fire-resistant mortar attached by pre-construction and method of joining the same" The problem to be solved

[0011] The present invention aims to solve the problems associated with the aforementioned prior art and provides a reinforcement structure for the fastening portion of a ventilation duct slab, which is manufactured as a panel-type precast concrete structure and forms a ventilation passage such as a tunnel or underpass through a continuous fastening process at the site. In this structure, an insert anchor and a bolt fastening groove are respectively provided on the joint surface of a pair of connected ventilation duct slabs. Through an integrated fixing structure in which a high-strength bolt fastened to the insert anchor of one ventilation duct slab and mortar filled in the bolt fastening groove of the other ventilation duct slab are used, the mortar forming the joint portion of adjacent ventilation duct slabs is separated or detached from the joint surface of the ventilation duct slabs, or the joint portions are separated due to damage to the mortar filled in the joint portion, even when a strong load caused by external events such as wind pressure or vibration is applied to the ventilation duct slab structure constructed through the continuous joining of precast-type concrete panel-type slabs. means of solving the problem

[0013] In the technical concept for achieving the above-mentioned purpose, the present invention relates to a ventilation duct slab manufactured as a panel-type precast concrete structure to form a ventilation passage such as a tunnel or underpass through a continuous fastening process at the construction site. In this slab, at least two or more bolt fastening grooves are formed along the joint surface connecting to an adjacent ventilation duct slab at one end of the body of a connected ventilation duct slab, and at the other end of the body of the connected ventilation duct slab, insert anchors are installed at positions corresponding to the locations where the bolt fastening grooves are formed along the joint surface connecting to the connected ventilation duct slab. During the construction process of the ventilation duct slab at the construction site, high-strength bolts are fastened to the insert anchors of the connected ventilation duct slabs, and while the fastened high-strength bolts are deeply inserted into the bolt fastening grooves of the connected ventilation duct slabs, mortar is filled into the connection portion of the two ventilation duct slabs to fasten the two adjacent ventilation duct slabs. In the inner side of the bolt fastening grooves, within the bolt fastening grooves The present invention provides a ventilation duct slab equipped with a fastening reinforcement structure and a method for constructing the same, characterized by effectively preventing the mortar forming the joint portion of adjacent ventilation duct slabs from separating and detaching from the joint groove due to external force, even when a strong load caused by external events such as wind pressure or vibration is applied to a ventilation duct slab structure constructed through the continuous connection of precast type concrete panels by inserting a snap ring to prevent the mortar, which is filled and hardens integrally with the high-strength bolt, from separating and detaching from the bolt fastening groove. Effects of the invention

[0015] The duct slab structure according to the present invention comprises an insert anchor and a bolt fastening groove formed respectively on the joint surfaces of one end and the other end of the body of a pair of interconnected duct slabs. Through an integrated fixing structure in which a high-strength bolt fastened to the insert anchor of one duct slab and mortar filled in the bolt fastening groove of the other duct slab are fixed, the duct slab structure constructed by the continuous connection of precast-type concrete panels is structurally prevented from easily separating or detaching the mortar forming the joint portion of adjacent duct slabs from the joint surface of the duct slabs even when a strong load caused by external events, such as wind pressure or vibration, is applied. At the same time, through a snap ring structure inserted inside the bolt fastening groove, the mortar integrated with the high-strength bolt inserted inside the bolt fastening groove is effectively suppressed from detaching from the bolt fastening groove even when the mortar filled inside the bolt fastening groove is damaged by tensile force transmitted by external events, thereby allowing adjacent ducts Through a connection reinforcement structure capable of maintaining a more robust connection between slabs, the overall structural integrity of the ventilation duct slab structure constructed through the continuous connection of precast-type concrete panels can be significantly improved. Brief explanation of the drawing

[0017] FIG. 1 is a drawing exemplarily showing the state in which a ventilation duct slab according to one embodiment of the present invention is applied to a tunnel structure. FIG. 2 is a diagram schematically showing the connection relationship of a ventilation duct slab according to an embodiment of the present invention. FIG. 3 is a drawing showing a plurality of bolt fastening grooves formed at regular intervals on one end of the body in a duct slab according to an embodiment of the present invention. FIG. 4 is a drawing showing a plurality of insert anchors installed at regular intervals on the other end of the body in a ventilation duct slab according to an embodiment of the present invention. FIG. 5 is a partial cross-sectional view showing the cross-section of a joint where two adjacent air duct slabs are connected according to an embodiment of the present invention. FIG. 6 is a partial cross-sectional view showing two adjacent air duct slabs connected and joined by filling with mortar according to an embodiment of the present invention. FIG. 7 is a drawing that exemplarily shows the structure of a snap ring inserted and fixed inside a bolt fastening groove of a duct slab according to the present invention, and the shape of a plurality of steel clips fastened at regular intervals along the inner surface of the snap ring. FIG. 8 is a drawing that exemplarily shows a shear key and a shear key groove, respectively, additionally formed on the joint surfaces on both sides of the body of the duct slabs connected to each other in a precast type duct slab according to the present invention. Specific details for implementing the invention

[0018] The present invention is capable of various modifications and may take various forms, and specific embodiments are illustrated in the drawings and described in detail in the text.

[0019] However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0020] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments without departing from the gist thereof.

[0024] FIG. 1 is a drawing exemplarily showing the state in which a ventilation duct slab according to one embodiment of the present invention is applied to a tunnel structure.

[0025] As illustrated in FIG. 1, an air duct slab (100) according to one embodiment of the present invention is installed on the upper part of a tunnel structure (1) and performs the function of forming an air duct that provides a cross-flow ventilation passage for the atmosphere inside the tunnel.

[0026] At this time, the duct slab structure installed in this manner is typically constructed by continuously connecting multiple duct slabs (100), which are manufactured in the shape of precast concrete panels, at the construction site in accordance with the design of the structure. Below, we will examine in more detail the connection structure provided in the duct slab according to an embodiment of the present invention during such a connection process.

[0028] FIG. 2 is a diagram schematically showing the connection relationship of a ventilation duct slab according to an embodiment of the present invention.

[0029] As briefly described in FIG. 1 above, the air duct slab (100) is installed on the upper part of a tunnel or underpass to form a cross-flow ventilation passage for the internal air. It is manufactured as a precast concrete structure in the shape of a panel (slab). During the construction process at the construction site, as shown in FIG. 2, a plurality of pre-manufactured air duct slabs (100a, 100b, 100c) are arranged along the length direction of the passage, and through the process of continuously connecting the plurality of air duct slabs (100a, 100b, 100c) arranged in this manner, an air duct structure is formed to form a cross-flow ventilation passage for the internal air of the tunnel.

[0030] At this time, when examining the connection relationship of the air duct slab (100) according to the present invention based on the configuration shown in FIG. 2, as shown in the drawing, at one end of the body of two air duct slabs (100a, 100b) connected to each other, a plurality of insert anchors (120) are installed at regular intervals along the joint surface connected to the adjacent air duct slab, and at the joint surface of the other end of the body of the air duct slab (100a, 100b), bolt fastening grooves (not shown) of the same number as the inserted insert anchors (120) are formed at the same intervals at positions corresponding to the positions where the insert anchors (120) of the adjacent air duct slabs are installed.

[0031] Through this configuration, among the two interconnected air duct slabs (100a, 100b), the joining surface of one air duct slab (100a) having a bolt fastening groove (not shown) and the joining surface of the other air duct slab (100b) having an insert anchor (120) installed are arranged to face each other, and a high-strength bolt (not shown) is fastened to the insert anchor (120) so that the head portion of the high-strength bolt is deeply inserted into the bolt fastening groove. After connecting and joining the two adjacent air duct slabs (100a, 100b), mortar is filled and hardened through a mortar injection groove (not shown) provided on one side of the air duct slabs (100a, 100b) to form the space between the joining surfaces of the two adjacent air duct slabs and the space inside the bolt fastening groove, thereby continuously connecting a plurality of adjacent air duct slabs (100). The structure of such fastening will be explained in more detail through Figures 3 to 7 described later.

[0032] At this time, as described above, in the interior of the body of the air duct slab (100) that is continuously connected, a number of steel wires may be inserted to prevent sagging caused by the self-weight of the slab, etc., due to the structural characteristics of the air duct slab, which is installed on the upper part of the tunnel with both ends fixed to the inner wall of the tunnel structure. The basic structure of such an air duct slab and / or the structure of inserting steel wires is a technology that is already widely applied and used in the field of technology, so a detailed explanation thereof will be omitted in this description.

[0034] FIG. 3 is a drawing showing a plurality of bolt fastening grooves formed at regular intervals on one end of the body in a duct slab according to an embodiment of the present invention, and FIG. 4 is a drawing showing a plurality of insert anchors installed at regular intervals on the other end of the body in a duct slab according to an embodiment of the present invention.

[0035] With reference to FIGS. 3 and 4, the connection surface joining structure and fastening method of a duct slab according to an embodiment of the present invention are examined in more detail. At one end of the body of a precast type duct slab (100a) that is pre-manufactured according to the present invention, as shown in FIG. 3, a plurality of bolt fastening grooves (110) are formed at regular intervals along the joint surface connected to an adjacent duct slab (100b). At the other end of the body of the duct slab (100b) connected thereto, as shown in FIG. 4, insert anchors (120) of the same number as the bolt fastening grooves (110) are installed at regular intervals on the joint surface at a position corresponding to where the bolt fastening grooves (110) of the adjacent duct slab (100a) are formed.

[0036] At this time, the bolt fastening groove (110) is formed in a shape that is recessed inwardly in a tapered form on the joint surface of the duct slab, so that during the process of fastening with an adjacent duct slab, the protruding head portion of a high-strength bolt (not shown) that is fastened to an insert anchor (120) provided on the joint surface of the adjacent duct slab is deeply inserted into the bolt fastening groove (110). This will be explained in more detail in FIGS. 5 and 6, which will be described later.

[0037] Through this configuration, in the process of constructing a duct structure by directly connecting multiple precast type duct slabs at the site, a high-strength bolt (not shown) is connected to an insert anchor (120) provided at one end of the body of a precast type duct slab, and two adjacent duct slabs are connected so that the head portion of the high-strength bolt is deeply inserted into a bolt connection groove (110) formed in the adjacent duct slabs. Then, mortar is filled and hardened through a mortar injection groove (not shown) provided on one side of the duct slabs to form the space between the connecting surfaces of the two adjacent duct slabs and the space inside the bolt connection groove (110), thereby continuously connecting multiple adjacent duct slabs (100). At this time, the specific connection structure between adjacent duct slabs will be described in more detail in FIGS. 5 and FIGS. 6.

[0038] Here, it is preferable to use a high-strength bolt that has a relatively higher tensile strength compared to a standard bolt for the bolt fastened to the insert anchor (120).

[0039] In addition, as described above, the bolt fastening grooves and insert anchors provided on each joint surface of the duct slab can be formed with at least two or more on each joint surface to increase structural stability. Generally, they are provided in an appropriate number according to the specifications of the duct slab, which is pre-fabricated as a precast type, and / or the design specifications of the underground structure where the duct slab is installed, and typically, they can be provided in a range of 2 to 20 to match the specific design specifications of the duct slab.

[0040] That is, according to the present invention, at one end of the body of a duct slab that is pre-fabricated as a precast type, a plurality of bolt fastening grooves are formed at regular intervals on the joint surface connected to an adjacent duct slab, and at the other end of the slab body, insert anchors are installed and provided at regular intervals at the same location on the joint surface corresponding to the location of the bolt fastening grooves. Through this configuration, a high-strength bolt is fastened to the insert anchor provided at one end of the body of one of the two adjacent duct slabs, and the head portion of the high-strength bolt is inserted deep into the bolt fastening groove formed at the other end of the body of the other duct slab connected to the one duct slab, thereby connecting the two adjacent duct slabs. Then, mortar is filled and hardened in the space between the joint surfaces of the two adjacent duct slabs and in the space inside the bolt fastening grooves, thereby connecting the two adjacent duct slabs to each other. The entire duct slab structure is constructed by continuously performing the above-described process.

[0041] In other words, as previously explained, when constructing a ventilation duct slab structure by connecting multiple ventilation duct slabs at a construction site, the strength of the mortar itself, which is filled between the joint surfaces of two ventilation duct slabs through the mortar injection grooves provided in the ventilation duct slabs, can be configured to have a strength similar to or even stronger than that of the concrete slab body itself, which is pre-fabricated as a precast type; however, the adhesion between the ventilation duct slab body forming the joint surface and the mortar filled between them exhibits a relatively weak bonding strength. Accordingly, the present invention provides a structure that effectively suppresses the occurrence of cracks between connected ventilation duct slabs by forming an irregular uneven structure on the joint surface of two adjacent ventilation duct slabs through a reinforced fastening structure using high-strength bolts fastened to the bolt fastening grooves and insert anchors described above, thereby preventing the hardened mortar filled in the joint area between two adjacent ventilation duct slabs from detaching from the ventilation duct slab body even when strong external forces are applied to the ventilation duct slab structure due to external events such as wind pressure or vibration. is presenting.

[0042] However, even with such a reinforced fastening structure, if the external force acting on the duct slab structure is concentrated significantly, cracks may eventually occur in the mortar filled and hardened inside the bolt fastening groove. Consequently, the mortar filled and hardened integrally with the high-strength bolt deeply inserted into the bolt fastening groove may separate and detach from the bolt fastening groove due to the cracks, thereby causing an accident in which the joint between two connected duct slabs separates. In this invention, an additional reinforcement structure is provided to effectively prevent the mortar hardened integrally with the high-strength bolt from detaching from the bolt fastening groove even when cracks occur in the mortar filled and hardened integrally with the high-strength bolt in the bolt fastening groove of the duct slab. This will be explained in more detail in FIGS. 5 and 6, which will be described later.

[0044] FIG. 5 is a partial cross-sectional view showing the cross-section of a joint where two adjacent air duct slabs are connected according to an embodiment of the present invention, and FIG. 6 is a partial cross-sectional view showing two adjacent air duct slabs connected and joined by filling with mortar according to an embodiment of the present invention. Hereinafter, the fastening structure of the air duct slab according to the present invention will be explained in more detail through FIG. 5 and FIG. 6.

[0045] As illustrated in FIG. 5, in the present invention, when connecting two air duct slabs (100a, 100b) that are fastened to each other, the end of one air duct slab (100a) having a bolt fastening groove (110) formed therein and the other end of the other air duct slab (100b) having an insert anchor (120) installed therein are arranged to face each other.

[0046] Next, as illustrated in FIG. 6, a step is performed to fasten a high-strength bolt (140) to an insert anchor (120) installed in the other air duct slab (100b) among the two air duct slabs (100a, 100b) facing each other, and the two air duct slabs (100a, 100b) are connected so that the head portion of the high-strength bolt (140) is deeply inserted into the bolt fastening groove (110) formed at one end of the body of the one air duct slab (100a). Then, by filling and hardening the space between the joint surfaces of the two air duct slabs connected in this way and the space inside the bolt fastening groove (110) with mortar (150), the two adjacent air duct slabs (100a, 100b) are configured to be connected to each other. By repeating the above-described process, an air duct is formed that provides a cross-flow ventilation passage for the internal atmosphere in an underground structure such as a tunnel.

[0047] However, as previously explained, when a strong external force is applied to the duct slab structure due to the influence of external events such as wind pressure or vibration, particularly when a large tensile force is applied to the duct slab structure, causing it to spread apart on both sides of the connection part due to strong downward wind pressure, cracks may occur in the mortar (150) that is filled inside the bolt fastening groove (110) and solidified integrally with the high-strength bolt (140) inserted inside the bolt fastening groove. Consequently, the mortar (150) that is solidified integrally with the high-strength bolt (140) inserted inside the bolt fastening groove (110) may separate and detach from the bolt fastening groove (110) due to the cracks, thereby causing an accident in which the joint part between the two connected duct slabs separates. In the present invention, even when cracks occur in the mortar (150) that is filled in the bolt fastening groove (110) of the duct slab and solidified integrally with the high-strength bolt (140), the mortar that is solidified integrally with the high-strength bolt An additional reinforcing structure is provided to effectively prevent the mortar from detaching from the bolt fastening groove.

[0048] That is, in the present invention, as shown in FIG. 6, a snap ring (160) is additionally provided on the inside of the bolt fastening groove (110) of a side air duct slab (100a) in which a bolt fastening groove (110) is formed, to prevent the mortar (150) that has been filled and hardened inside the bolt fastening groove (110) by an external force from separating and detaching from the bolt fastening groove (110) even when a crack occurs in the mortar (150) that has been hardened integrally with the high-strength bolt (140).

[0049] To this end, the inner wall of the bolt fastening groove (110) of the duct slab, which is pre-manufactured as a precast type according to the present invention, is provided with a snap ring mounting groove (111) into which the snap ring (160) is inserted and fixed, as shown in FIG. 5. The process of forming the snap ring mounting groove (111) described above can be performed relatively easily through methods such as fastening a rubber ring to a truncated steel formwork for forming the bolt fastening groove (110) during the manufacturing process of the duct slab.

[0050] In the construction process of a duct structure using precast duct slabs equipped with a fastening reinforcement structure according to the present invention through such a structure, a snap ring (160) made of steel or reinforced stainless steel, which is prepared in advance, is inserted and fixed into a snap ring mounting groove (111) formed on the inner wall of the bolt fastening groove (110), and then a fastening process is carried out by injecting mortar as described above, thereby completing the fastening structure of two adjacent duct slabs as shown in FIG. 6. At this time, regarding the structure of the snap ring (160) inserted and fixed into the snap ring mounting groove (111), it will be explained in more detail in FIG. 6, which will be described later.

[0051] That is, at one end of the other air duct slab (100b) connected to the one air duct slab (100a) equipped with the aforementioned bolt fastening groove (110), insert anchors (120) for fastening high-strength bolts (140) are installed at regular intervals on the joint surface between the slabs, along a position corresponding to the bolt fastening groove (110) formed in the one air duct slab (100a) as previously explained, and during the construction process of the air duct slab, after fastening the high-strength bolts (140) to the insert anchors (120), as shown in FIG. 6, the head portion of the high-strength bolt (140) is inserted deeply into the bolt fastening groove (110) formed at one end of the body of the one air duct slab (100a) and fixed along the inner circumference of the inner wall, such that a ring-shaped snap ring (160) is inserted and fixed therein. By connecting the two duct slabs (100b) and filling and hardening the space between the joint surfaces of the two connected duct slabs and the space inside the bolt fastening groove (110) with mortar (150), the two adjacent duct slabs (100a, 100b) are connected to each other. At this time, the head portion of the high-strength bolt (140) that is fastened to the insert anchor (120) provided on the other duct slab (100b) can be inserted as deeply as possible into the bolt fastening groove (110) formed in the one duct slab (100a) to induce a more solid connection. Preferably, as shown in FIG. 6, it is configured to be inserted deeply into the snap ring (160) that is inserted and fixed into the inner wall of the bolt fastening groove (110) to maintain a more solid connection between the connected duct slabs.

[0052] That is, as briefly explained above, when a large tensile force is applied to the wind duct slab structure due to sudden changes in wind pressure load caused by external events, a situation occurs in which cracks form in the mortar (150) that is filled inside the bolt fastening groove (110) and solidified integrally with the high-strength bolt (140) inserted inside the bolt fastening groove. At this time, the cracks that form in the mortar (150) that solidified integrally with the high-strength bolt (140) inserted inside the bolt fastening groove typically proceed at an angle of 30° to 45° downward from near the head end of the high-strength bolt (140) to the bolt body. In this process, if the head end of the high-strength bolt (140) is inserted deeply into the snap ring (160) that is inserted and fixed to the inner wall of the bolt fastening groove (110), the crack resistance that blocks the propagation of cracks occurring in the mortar (150) through the snap ring (160) can be increased. At the same time, the snap ring (160) provides a stopper function that prevents the mortar (150), which has been solidified integrally with the high-strength bolt (140) inserted into the bolt fastening groove (110), from separating and detaching from the bolt fastening groove (110) due to cracking, thereby allowing the bonding strength between adjacent air duct slabs to be maintained more firmly.

[0053] In addition, in the process of injecting mortar (150) into the space between the joint surfaces of two adjacent air duct slabs and the space inside the bolt fastening groove (110), an EVA foam (130) may be attached to one end of the joint surface of one of the two adjacent air duct slabs to prevent the mortar filled in the space from leaking out.

[0055] FIG. 7 is a drawing that exemplarily shows the structure of a snap ring inserted and fixed inside a bolt fastening groove of a precast type duct slab according to the present invention, and the shape of a plurality of steel clips fastened at regular intervals along the inner surface of the snap ring. FIG. 7 (a) exemplarily shows the general shape of the snap ring applied to the present invention, and FIG. 7 (b) exemplarily shows the shape of a plurality of steel clips fastened at regular intervals along the inner surface of the snap ring to prevent deformation of the snap ring due to external load.

[0056] As illustrated in FIG. 6(a), the snap ring (160) inserted and fixed into the bolt fastening groove of the air duct slab according to the present invention is formed in the shape of a circular ring with one side open, made of steel or reinforced stainless steel, and a pair of through holes (161) are formed at each end of the circular snap ring (160) that forms the opening.

[0057] In the present invention, through such a structure, during the construction process of the air duct slab, a gripping mechanism or the like is hooked onto the pair of through holes (161) and pulled inward to close them, and then moved to the position of the snap ring mounting groove (111) formed inside the bolt fastening groove (110). After reaching the mounting position, the gripping of both ends of the snap ring (160) that was pulled inward is released, and the snap ring (160) is returned to its original shape with both ends open, thereby allowing the snap ring (160) to be firmly inserted and fixed into the snap ring mounting groove (111) formed inside the bolt fastening groove (110).

[0058] In addition, the snap ring (160) applied to the present invention is formed in the shape of a circular ring with one side open, as shown in FIG. 7 (a). When a strong load is applied from the outside, a void may occur due to cracks in the mortar inside the bolt fastening groove, causing the snap ring (160) to contract inward and detach from the snap ring mounting groove (111). Therefore, the present invention adopts a reinforcing structure that effectively prevents deformation of the snap ring due to external load by fastening a plurality of steel clips (170) at regular intervals along the inner circumference of the snap ring, from the inner side to the outer side, as shown in FIG. 7 (b), and then inserting and fixing them into the snap ring mounting groove (111). At this time, the steel clips (170) fastened to the snap ring (160) may be arranged radially at regular intervals, with 3 to 8 clips, along the inner circumference of the snap ring.

[0060] In addition, in the present invention, in addition to the fastening structure using a bolt fastening groove and a snap ring as described above, a fastening structure using a conventional shear key and a shear key groove may also be included as an auxiliary structure, and the configuration thereof will be explained in more detail below through FIG. 8.

[0061] FIG. 8 is a drawing that exemplarily shows a shear key and a shear key groove being additionally formed on both joint surfaces of the body of a duct slab that is connected to each other in a precast type duct slab according to the present invention. FIG. 8(b) is a drawing showing a shear key (220) with a shape protruding outward from the body formed between insert anchors (120) inserted on the other side of the body of the duct slab (100b), and FIG. 8(a) is a drawing showing a shear key groove (210) into which the shear key (220) is inserted formed between bolt fastening grooves (110) formed on one side of the body of the duct slab (100a).

[0062] As illustrated in FIG. 8, in a duct slab prefabricated as a precast type with a fastening structure according to the present invention applied, a shear key (220) protruding outward from the body is additionally formed in the space between the insert anchors (120) inserted into the joint surface connecting the adjacent duct slab (100a) to the other duct slab (100b) placed on the other side, and a shear key groove (210) into which the shear key (220) is inserted is formed at a position corresponding to the position where the shear key (220) is formed on one side of the joint surface body of the adjacent duct slab (100a), so that during the fastening process of the adjacent duct slabs (100a, 100b), the shear key (220) formed on the joint surface of the other duct slab (100b) is inserted into the shear key groove (210) formed on the joint surface of the adjacent duct slab (100a). After connecting them so that they are inserted, the two adjacent duct slabs (100a, 100b) are connected by filling the space between the joint surfaces with mortar and allowing it to harden, thereby enabling the two adjacent duct slabs to be connected so that the bonding strength of the joint area between the two connected duct slabs can be maintained more firmly.

[0063] At this time, in the embodiment of FIG. 8 described above, during the process of pre-manufacturing the duct slab as a precast type, an example is shown in which a shear key (220) is formed on the side where the insert anchor (120) is inserted at the joint surfaces on both sides of the body of the duct slab, and a shear key groove (210) is formed on the side where the bolt fastening groove (110) is formed. However, the configuration of the present invention does not necessarily have to be the same as this, and it is of course possible to configure it so that a shear key (220) is formed on the side where the bolt fastening groove (110) is formed, and a shear key groove (210) is formed on the side where the insert anchor (120) is inserted.

[0065] As described above, the duct slab prefabricated as a precast type according to the present invention, when constructing a transverse-flow duct structure of an underground structure through the continuous connection of duct slabs, is provided with an insert anchor and a bolt fastening groove formed respectively on the joint surfaces of one end and the other end of the body of a pair of interconnected duct slabs, thereby preventing the mortar forming the joint portion of adjacent duct slabs from easily separating or detaching from the joint surface between the slabs even when a strong external tensile force due to wind pressure, etc., is applied to the duct structure constructed through the continuous connection of duct slabs through an integrated fixing structure of a high-strength bolt fastened to the insert anchor of one duct slab and mortar filled in the bolt fastening groove of the other duct slab, while simultaneously preventing the mortar inserted inside the bolt fastening groove from being easily separated or detached even when the mortar filled inside the bolt fastening groove is damaged by a tensile force applied by an external event through a snap ring structure inserted and fixed inside the bolt fastening groove By effectively preventing the mortar integrated with the high-strength bolt from detaching from the bolt fastening groove, the structural integrity of the cross-flow type air duct structure of the underground structure formed by the continuous connection of air duct slabs can be significantly improved through a fastening reinforcement structure that can maintain a more solid fastening state between adjacent air duct slabs.

[0067] The present invention described above is not limited by the aforementioned embodiments and attached drawings, and it will be obvious to those skilled in the art that various substitutions, modifications, and changes are possible within the scope of the technical concept of the present invention. Explanation of the symbols

[0069] 100, 100a, 100b, 100c: Air duct slab 110: Bolt fastening groove 111 : Snap ring mounting groove 120 : Insert anchor 130 : EVA foam 140 : High-strength bolts 150 : Mortar 160 : Snap ring 161 : Through hole 170 : Steel clip 210 : Shear key slot 220 : Shear key

Claims

Claim 1 In a duct slab that is pre-fabricated as a precast panel type and forms a cross-flow duct through continuous fastening at a construction site, at least two bolt fastening grooves are formed on a joint surface connected to an adjacent duct slab at one end of the body of the duct slab, and at the other end of the body of the duct slab, insert anchors equal in number to the bolt fastening grooves are installed in the body forming the joint surface connected to the adjacent duct slab, corresponding to the position of the bolt fastening grooves formed at one end of the body of the adjacent duct slab, and a snap ring mounting groove is formed along the inner circumference of the inner wall of the bolt fastening groove, and a snap ring having a circular ring shape with one side open and having a structure in which three to eight steel clips fitted from the inside to the outside of the snap ring along the inner circumference are integrally fastened in a radial manner at regular intervals is inserted and fixed into the snap ring mounting groove, thereby filling the inside of the bolt fastening groove and solidifying integrally with the high-strength bolt A ventilation duct slab characterized by being configured to prevent high-strength bolts and mortar solidified integrally with them from detaching from the bolt fastening grooves even when cracks occur in the mortar due to external force. Claim 2 A ventilation duct slab according to claim 1, characterized in that a pair of through holes are formed at both ends of the snap ring forming the open opening of the snap ring. Claim 3 A ventilation duct slab according to claim 1, wherein the snap ring is made of steel or reinforced stainless steel. Claim 4 delete Claim 5 delete Claim 6 A duct slab according to claim 1, wherein the bolt fastening grooves and insert anchors provided on each joint surface of the duct slab are characterized in that 2 to 20 bolt fastening grooves or insert anchors are formed at equal intervals on each joint surface. Claim 7 A duct slab according to claim 1, wherein at least one shear key having a shape protruding outward from the body is formed between the inserted insert anchors on the joint surface of the duct slab on which the insert anchors are installed, and a shear key groove into which the shear key is inserted is formed at a position corresponding to the position where the shear key is formed on the joint surface of the duct slab on which the bolt fastening grooves are formed. Claim 8 A duct slab according to claim 1, wherein at least one shear key having a shape protruding outward from the body is formed between the bolt fastening grooves formed on the joint surface of the duct slab having the bolt fastening grooves formed on the joint surface, and a shear key groove into which the shear key is inserted is formed at a position corresponding to the position where the shear key is formed on the joint surface of the duct slab into which the insert anchor is installed. Claim 9 A method for constructing a cross-flow type duct structure by continuously connecting duct slabs according to the configuration of claim 1, comprising: a step of fastening a high-strength bolt to the insert anchor; a step of fastening a plurality of steel clips radially at regular intervals from the inner side to the outer side of a snap ring, and then inserting and fixing the snap ring to which the steel clips are fastened into a snap ring mounting groove formed on the inner wall of the bolt fastening groove; and a step of connecting and joining two adjacent duct slabs so that the head portion of the high-strength bolt is inserted into the bolt fastening groove and passes through the snap ring. A method for constructing a duct slab, characterized by being configured to prevent the high-strength bolt and the mortar solidified integrally with it from detaching from the bolt fastening groove even when a crack occurs due to an external force in the mortar solidified integrally with the high-strength bolt and filled inside the bolt fastening groove, thereby forming a cross-flow type duct by continuously fastening adjacent duct slabs through the step of fastening and joining two adjacent duct slabs by filling and hardening mortar in the space between the joint surfaces of the two connected duct slabs and the bolt fastening groove. Claim 10 delete

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