KR102565884B1 - Connector structure for changeable extension in the tunnel lattice girder and system constructing the tunnel lattice girder thereof - Google Patents

Abstract

The present invention relates to a variable expandable connection structure of a tunnel grid support and a tunnel grid support installation system according to the minimization of the overexcavation distance using the same. More specifically, in installing the grid support, the crown apex (J ), the arched tunnel section is divided into left and right symmetrical half sections with respect to the vertical line of gravity, and the half sections are divided into upper half sections (SA) and lower half sections (SB) based on the upper and lower connection points (E), and the upper and lower half sections Install lattice supports on both symmetrical sides of (SA) (SB), but between the crown ceiling point (J) and the top and bottom connection points (E) where the lattice supports are assembled and connected, a variable expandable ceiling connector (400A) and a variable expandable top and bottom connector (400B) ) is inserted and connected to the lattice supports on both sides, thereby extending the length in the horizontal direction by the variable expansion type ceiling connector (400A) at the top point (J) of the crown, and the variable expansion type top and bottom connector (400B) at the top and bottom connection point (E) The height expansion in the vertical direction is made by the "design construction line" where the factory-manufactured lattice support will be installed is moved as close as possible to the "tunnel excavation section line", minimizing the overexcavation distance (d) "actual lattice support installation" space-time line” is an invention.

Description

Tunnel lattice support installation system according to variable expansion type connection structure of tunnel lattice support and overexcavation distance minimization using the same

The present invention relates to a variable expandable connection structure of a tunnel grid support and a tunnel grid support installation system according to the minimization of the overexcavation distance using the same. More specifically, in installing the grid support, the crown apex (J ), the arched tunnel section is divided into left and right symmetrical half sections with respect to the vertical line of gravity, and the half sections are divided into upper half sections (SA) and lower half sections (SB) based on the upper and lower connection points (E), and the upper and lower half sections Install lattice supports on both symmetrical sides of (SA) (SB), but between the crown ceiling point (J) and the top and bottom connection points (E) where the lattice supports are assembled and connected, a variable expandable ceiling connector (400A) and a variable expandable top and bottom connector (400B) ) is inserted and connected to the lattice supports on both sides, thereby extending the length in the horizontal direction by the variable expansion type ceiling connector (400A) at the top point (J) of the crown, and the variable expansion type top and bottom connector (400B) at the top and bottom connection point (E) The height expansion in the vertical direction is made by the "design construction line" where the factory-manufactured lattice support will be installed is moved as close as possible to the "tunnel excavation section line", minimizing the overexcavation distance (d) "actual lattice support installation" space-time line” is an invention.

The NATM method can make the most of the bearing capacity of the ground and can be managed by on-site measurement, so the NATM method is applied to almost all blast tunnel excavations today. The NATM method expects the effects of visible “artificial supports” such as rock bolts, shotcrete, and “steel supports” and at the same time fully utilizes the strength of the bedrock itself, that is, the load-bearing capacity, to provide optimal economic feasibility and high-quality tunnels. It is a technique that pursues

Despite these advantages, the NATM method as a blast tunnel excavation is virtually impossible to predict the excavation cross section due to blasting, and especially when overcharged to increase excavation efficiency, the prediction is even more difficult.

Since it is impossible to predict the excavation section, grid support is generally designed based on the “design construction line”. It is considered that the lattice beam is installed on the "design construction line" and the factory manufacture of the lattice beam is performed.

The “actual tunnel excavation section line” by blasting is overexcavated deeper than the “design construction line”.

This is why the overexcavation distance (d) between the “design construction line” and the “actual tunnel excavation section line” is unavoidable. Here, the “design construction line” is the construction line on the design drawing.

Shotcrete (S) is filled in the overexcavation distance (d) between the lattice support installed on the “design construction line” and the “actual tunnel excavation section line”.

The lattice support is installed immediately after tunnel excavation and before shotcrete (S) is poured, and functions as a structural material that supports the ground load until the shotcrete (S) is hardened. After the shotcrete (S) is hardened, the shotcrete (S) and the lattice support function as a composite member (shell) to support the tunnel ground load.

Needless to say, the greater the overexcavation distance (d), the greater the filling amount of shotcrete (S), resulting in a non-horn. This is because the amount of shotcrete filling is proportional to the overexcavation distance (d). In addition, as the overexcavation distance (d) increases, the curing speed of the shotcrete (S) is slow, so that the function as a composite member (shell) is not quickly achieved, so there is a problem in that the unstable state of the tunnel ground support structure is prolonged.

According to the tunnel specification standards of the Ministry of Land, Infrastructure and Transport, the thickness of one shotcrete is regulated and managed within 10 cm.

For example, if the overexcavation distance (d) is 50 cm, the shotcrete should be divided into 5 times and poured. The total time required by adding 5 casting times and 5 curing times is 60 hours when excavating 2 sections per day. As a result, there is a serious problem in the structural stability of the tunnel because the tunnel face is in a non-reinforced state for 60 hours.

In addition, when 50 cm is poured at once, the shotcrete placed near the top of the arch tunnel is in an uncured, uncured state, so the adhesive cohesion of the shotcrete does not overcome its weight and is conducted (falls) downward. The reason why the thickness of one shotcrete is regulated within 10 cm is to prevent such conduction.

As the overexcavation distance (d) is minimized, the number of shotcrete placements is minimized, so the curing speed is so fast that the minimum strength (more than 10Mpa) of the lattice support and synthesized shotcrete is quickly exhibited. It is made evenly so that the structural stability of the tunnel is secured.

Therefore, if the installation position of the factory-manufactured lattice beam can be moved from the “design construction line” to the “actual tunnel excavation section line” based on the “design construction line,” the overexcavation distance (d) is reduced by that much, and the shotcrete (S) As the amount of filling and the number of times of pouring shotcrete are reduced, there are advantages in terms of construction. This is because as the overexcavation distance (d) is minimized, the structural stability of the tunnel and the efficiency and economic feasibility of construction are maximized.

In this way, factory-manufactured lattice supports along the “design construction line” have no distance adjustment function for the overextension distance (d), and are installed only on the “design construction line” regardless of the length and length of the overexcursion distance (d). There is a problem in that the construction is unreasonable (inefficient and uneconomical) because the amount of shotcrete cannot be estimated.

As such, blasting excavation inevitably results in a “tunnel excavation cross section” of unpredictable sudden and irregular overexcavation, and as a result, the problem of inefficient and uneconomical construction as well as the problem of unstable structure in an unreinforced state and deterioration of the quality of the poured shotcrete is blasting type excavation. It is an inherent problem with excavation.

Next, look at the characteristics according to the type of 'steel support' as follows.

Representative examples of the 'steel support' include the lattice support 30 and the H-beam support 20.

7 is a comparison table comparing the cross-sectional shape and cross-sectional performance (sectional area, cross-sectional moment of inertia (I)) of the lattice support and the H-beam support.

If the cross-sectional performance is compared based on the grid support by the comparison table, first, the cross-sectional area of the H-beam support is 64% larger than the cross-sectional area of the grid support. A larger cross section by 64% means that the weight of the steel is also heavier, and the price is also expensive. Since the H-beam support is that heavy, it has a disadvantage in that it is not easy to handle according to installation compared to the lattice support. On the contrary, the advantage of the grid support is that it is light in weight and easy to handle.

Next, the structure of the normal standard lattice support is as shown in FIG.

As shown in Figure 1, the lattice support is composed of three steel bars and is constructed so that the upper steel bar (A) with a large diameter comes to the inner wall of the tunnel. The diameter of the lower steel bar (B) is smaller than the upper steel bar (A). The lattice support is formed in a triangular shape by the upper and lower steel bars A and B, and a spider (C), which is a stiffener, is connected and welded therebetween.

The spider (C) interconnects the upper steel bar (A) and the lower steel bar (B), and is welded by bending the steel wire into a triangular truss shape in the longitudinal direction, that is, in the form of a three-dimensional closed polygon.

The spider (C) is a connecting material that interconnects the upper steel bar (A) and the lower steel bar (B) in the shape of a longitudinal triangular truss, that is, a connecting material bent in the form of a three-dimensional closed polygon.

The spider (C) serves to improve structural stability by maintaining a constant distance between the upper and lower steel bars (A) (B) and at the same time increasing the bending strength of the lattice support against the tunnel load (see Fig. 1).

The installation of lattice beams is generally symmetrical with respect to the vertical line of gravity of the crown apex point (J), and the upper and lower parts (SA) (SB) centered on the upper and lower connection points (E), as shown in FIG. 3 for the convenience of construction. It is built by dividing The vertical fastening plates 350B contacted on both sides of the lattice support at the crown apex point J and the upper and lower connection points E are connected to each other by fastening bolts 360 (see FIG. 2). According to Figure 2, a fixed plate (350A) welded and fixed to the upper steel bar (A) and the lower steel bar (B) on both sides of the lattice support, and a flange vertical fastening plate ( 350B) is a fastening structure. By facing the vertical fastening plate 350B and fastening with the fastening bolt 360, both lattice supports are connected and fastened as one.

In this way, the present invention applies the variable expandable connector 400 to the lattice support that is light in weight, easy to handle, and has good rigidity to solve the problem that H-beams have good rigidity but are too heavy to handle and difficult to install. .

(a) In the present invention, in installing the lattice support, the arched tunnel section is divided into left and right symmetrical half sections with respect to the vertical line of gravity of the crown apex point (J) of the arched tunnel section, and the half section is based on the vertical connection point (E) It is divided into an upper half section (SA) and a lower half section (SB), and lattice supports are installed on both symmetrical sides of the upper and lower half sections (SA) (SB), but the crown apex point (J) and the upper and lower connection points where the lattice supports are assembled and connected ( E) by inserting a variable expandable ceiling connector (400A) and a variable expandable upper and lower connector (400B) into each of the gaps and connecting them with the lattice supports on both sides, the horizontal direction by the variable expandable ceiling connector (400A) at the top point of the crown (J). The height expansion in the vertical direction is made by the length expansion of the vertical connection point (E) and the height expansion in the vertical direction by the variable expansion type vertical connector (400B) of the vertical connection point (E), and the "design construction line" where the factory-manufactured lattice support is installed is the "tunnel excavation section line" The purpose is to make the "actual grid support installation construction line" with the minimized overexcavation distance (d) by moving as close as possible to the side,

⒝ The “actual installation construction line” of the factory-manufactured lattice support is “tunnel excavation section line” by the variable expandable top connector 400A at the top point of the crown (J) and the variable expandable top and bottom connector 400B at the top and bottom connection point E. As the overexcavation distance (d) is minimized by moving closely to the side as much as possible, the amount of filling and the number of castings of shotcrete are minimized, and the safe composite strength (10Mpa) of shotcrete and lattice beam is quickly reached, securing structural stability of ground bearing capacity. On the other hand, the structure of the variable expandable ceiling connector (400A) and the variable expandable top and bottom connector (400B) is simple, so it is easy to adhere to the "actual grid support installation line", and it is an efficient and economical support structure. Another purpose is to secure stability.

The configuration of the variable expandable connection structure of the tunnel grid support of the present invention will be described as follows.

Install factory-manufactured lattice beams on the “design construction line” for the arched tunnel blasting excavation cross-section line (G), where overexcavation is unavoidable, but make the arched tunnel cross-section symmetric It is divided into half sections, and the half sections are divided into upper and lower half sections (SA) (SB) based on the upper and lower connecting points (E), and the upper and lower connecting points of the crown apex (J) and the upper and lower half sections (SA) (SB) ( In the connection structure in which the vertical fastening plates 350B for the fixed plates 350A installed on each of the grid supports on both sides located at E) are butted with each other and the grid supports are fastened by the fastening bolts 360

A variable expandable connecting member 400 inserted between the lattice supports on both sides of the crown apex point (J) and the upper and lower connection points (E) of the upper and lower half sections (SA) (SB);

The variable expandable connector 400 differs only in the insertion position and has the same structure as the variable expandable ceiling connector 400A and the variable expandable upper and lower connector 400B;

The variable expandable ceiling connector 400A and the variable expandable upper and lower connector 400B are a triangular columnar concrete block 410 body, a tension member 420 in which the buried tension member 420A and the exposed tension member 420B of the body are integrated into one. And, it is formed at both ends of the concrete block 410, and the flange fastening part 430A and the central part 430B are formed as a parallelogram flange fastening plate 430 in one body. Variable expansion type connector of tunnel lattice beam, characterized in that It is a structure.

here,

By inserting the variable expandable connector 400 between the lattice supports on both sides of the upper and lower connection points (E) of the crown apex (J) and the upper and lower half sections (SA) (SB), respectively, the vertical fastening plates (350B) of the lattice supports on both sides The protruding flange fastening parts 430A of the variable expandable connector 400 are butted to each other and connected and fastened by fastening bolts 360, but the variable expandable connector 400 is a triangular columnar concrete block 410 and the tension member 420. ) and a parallelogram flange fastening plate 430, and the tension member 420 is a tension member 420 in which the buried tension member 420A and the exposed tension member 420B are one, and the buried tension member 420A is attached to the concrete block 410. It is buried, and the exposed tension member 420B is exposed to both ends of the concrete block 410, and the parallelogram flange fastening plate 430 through which the exposed tension member 420B penetrates is the flange fastening portion 430A with respect to the concrete block 410. protrudes beyond both ends of the concrete block 410, and while forming a vertical plane, the parallelogram flange fastening plate 430 is fixed while being positioned at both ends of the concrete block 410, and at this time, the fixing is the exposed tension member 420B ) and the exposed tension member through hole 432B are fixed by welding, and the extended protruding flange fastening part 430A is vertically fastened with the flange fastening part 430A in the same shape and size as the vertical fastening plate 350B of the lattice support. The plate 350B is connected and fastened by the fastening bolt 360 in a state of complete contact, and the variable expandable connector 400 and the lattice support are fastened. At this time, the both exposed tension member 420B is the first spider 330 ) It is a variable expansion type connection structure of tunnel grid support, characterized in that it is installed extended to.

Not only that,

The exposed tension member through hole 432B is a variable expansion type connecting member structure of the tunnel grid support, characterized in that it is formed at the center of the central portion 430B of the parallelogram flange fastening plate 430.

also,

The buried tension member 420A and the exposed tension member 420B are deformed reinforcing bars, and the end of the exposed tension member 420B is a variable expansion type connecting member structure of the tunnel lattice support, characterized in that it has a hook 420C shape.

A) Regarding the production of lattice beams and the filling of the overexcavation distance (d)

Grid supports are factory-manufactured according to the “design construction line”. The place where the grid support is usually installed is also the “design construction line”. Blasting-type “tunnel excavation section line” excavates larger than “design construction line”, so overexcavation is unavoidable. Since the lattice beams manufactured at the factory according to the “design construction line” are installed on the “design construction line”, an overexcavation distance (d) is inevitable between the “design construction line” and the actual “tunnel excavation section line”. By filling the overexcavation distance (d) with shotcrete, a composite cross-section support structure with lattice beams is formed.

For example, in general, when overexcavation occurs by 50 cm, when the overexcavated volume of 50 cm is filled with shotcrete, about 3 to 4 m of steel fiber shotcrete is used per set of support materials, which is uneconomical because it costs as much as 2 sets of lattice supports.

B) Regarding the movement of the location of the grid support installation “design construction line”

The arched tunnel “design construction line” is divided into an upper half section (SA) and a lower half section (SB) symmetrically with respect to the vertical line of gravity at the apex point (J) of the crown, and the upper and lower connection point (E) is the upper and lower half section (SA). ) (SB). Since the lattice supports are installed along the upper and lower half sections (SA) (SB) of the “design construction line”, the shape of the factory-made lattice beams is the same as the shape of the upper and lower half sections (SA) (SB). In this way, it is common for lattice beams to be factory-manufactured by the "design construction line" and for factory-manufactured lattice beams to be installed on the "design construction line". However, here, the present application inserts the variable expandable ceiling connector (400A) and the variable expandable upper and lower connector (EC) at the crown apex point (J) and the upper and lower connection point (E) of the lattice beam, respectively, and connects them with the lattice beams on both sides to ensure a horizontal level. Length expansion in the direction, and height expansion in the vertical direction, so that the “design construction line” where the factory-made lattice beams will be installed is moved to the “tunnel excavation section line” as much as possible, so that the overexcavation distance (d) is It becomes the minimized 「actual grid support installation construction line」.

C) Regarding the advantage of 「actual grid support installation construction line」with minimized overexcavation distance (d)

When the grid support is installed on the "actual grid support installation construction line" where the overexcavation distance (d) is minimized, the filling amount of shotcrete (S) is minimized and the number of shotcrete (S) placement is also minimized. As a result, There is an advantage in that the ground bearing capacity and its structural stability are quickly achieved because the composite strength is quickly made and the unsupported state is minimized.

D) Structure of the variable expandable ceiling connector (400A) and the variable expandable top and bottom connector (400B)

① The variable expandable top connector 400A and the variable expandable upper and lower connector 400B are variable expandable connectors 400 having the same structure. However, for convenience of explanation, only the insertion position is distinguished.

② The concrete block 410 of the variable expandable connector 400 is in the shape of a triangular column and has the same shape as the triangular cross section of the lattice support. In the tension member 420, the buried tension member 420A and the exposed tension member 420B are one tension member. Is the buried tension member (420A) buried in the concrete block (410)? It is a tension member, and the exposed tension member 420B is an exposed tension member 420A in which the buried tension member 420A protrudes to both ends of the concrete block 410. The tension member is preferably a deformed reinforcing bar for attachment with the shotcrete (S).

③ The exposed tension member 420B of the variable expandable connector 400 is extended and installed to the first spider 330 of the grid support on both sides. Since the shotcrete (S) is poured in the extended installed state, the variable expansion type connector 400 and the grid supports on both sides form a composite cross section. The end of the exposed tension member 420B has a hook 420C shape. This is to improve the pulling force with shotcrete (S).

④ At both ends of the concrete block 410, the parallelogram flange fastening plate 430, in which the triangular central portion 430B and the parallelogram flange fastening portion 430A are integrated, has a structure in close contact. The exposed tension member 420B passes through the through hole 432B of the triangular central portion 430B. The parallelogram flange fastening plate 430 is fixed to both ends of the concrete block 410 by welding the contact surfaces of the exposed tension member 420B and the through hole 432B. The parallelogram flange fastening part 430A is a protrusion at both ends of the concrete block 410 and is a contact surface corresponding to the vertical fastening plate 350B of the grid support. Since the parallelogram flange fastening part 430A and the vertical fastening plate 350B of the lattice support are fastening parts fastened by fastening bolts, both have the same shape and the same area.

⑤ In a state where the parallelogram flange fastening part 430A and the vertical fastening plate 350B of the lattice beam are completely in contact with each other, both lattice beams are integrally fastened via the variable expandable connector 400 via the fastening bolts.

⑥ After the variable expandable connector 400 and the grid support on both sides are installed on the "actual grid support installation construction line", shotcrete (S) is cast to make the grid support and composite cross section.

E) In the connection between the crown apex point (J) and the upper and lower connection points (E), the shear force performance according to the connection cross-sectional area of the conventional lattice beams alone and the connection sectional area of the lattice beams by inserting the variable expandable connector 400 of the present invention about

As shown in FIG. 2, the existing connection of the lattice supports at the crown apex point (J) and the upper and lower connection points (E) is performed by abutting the vertical fastening plates (350B) (350B) of the lattice beams and fastening bolts 360 (M20 bolts) on both sides. As two of them are fastened one by one, the cross-sectional area of the connection part is small and the shear force is weak. As shown in FIG. It can be seen that by being extended toward the grid support by the cross-sectional area, the shear force performance of the connection part of the grid support, that is, the increase rate of the connection cross-section area, is improved by 32 to 71% compared to the previous one (see Table 1 below).

Connection between existing lattice supports Connection between the present invention variable expandable connector and lattice support fastening method fastening bolt Fastening bolts and deformed bars number of bolts 2 M20 2 M20 Arrangement Deformed Rebar doesn't exist. 1 deformed rebar 16~24mm total cross-sectional area 628.3㎟ 829.3~1080.7㎟ Connection cross-sectional area increase rate 100% 132-171%

(a) In the present invention, in installing the lattice support, the arched tunnel section is divided into left and right symmetrical half sections with respect to the vertical line of gravity of the crown apex point (J) of the arched tunnel section, and the half section is based on the vertical connection point (E) It is divided into an upper half section (SA) and a lower half section (SB), and lattice supports are installed on both symmetrical sides of the upper and lower half sections (SA) (SB), but the crown apex point (J) and the upper and lower connection points where the lattice supports are assembled and connected ( E) by inserting a variable expandable ceiling connector (400A) and a variable expandable upper and lower connector (400B) into each of the gaps and connecting them with the lattice supports on both sides, the horizontal direction by the variable expandable ceiling connector (400A) at the top point of the crown (J). The height expansion in the vertical direction is made by the length expansion of the vertical connection point (E) and the height expansion in the vertical direction by the variable expansion type vertical connector (400B) of the vertical connection point (E), and the "design construction line" where the factory-manufactured lattice support is installed is the "tunnel excavation section line" It is effective in becoming a "real grid support installation construction line" with a minimized overexcavation distance (d) by moving as close as possible to the side.

⒝ The “actual installation construction line” of the factory-manufactured lattice support is “tunnel excavation section line” by the variable expandable top connector 400A at the top point of the crown (J) and the variable expandable top and bottom connector 400B at the top and bottom connection point E. As the overexcavation distance (d) is minimized by moving closely to the side as much as possible, the amount of filling and the number of castings of shotcrete are minimized, and the safe composite strength (10Mpa) of shotcrete and lattice beam is quickly reached, securing structural stability of ground bearing capacity. On the other hand, the structure of the variable expandable ceiling connector (400A) and the variable expandable top and bottom connector (400B) is simple, so it is easy to adhere to the "actual grid support installation line", and it is an efficient and economical support structure. It is a useful invention having the effect of ensuring stability.

[Figure 1] Structure of standard lattice support
[Figure 2] A combined state diagram showing the connection of lattice supports at the crown apex point (J) and the top and bottom connection points (E)
[Figure 3] An arched tunnel cross-sectional view showing the insertion position of the variable expandable connector (EC) at the crown apex point (J) of the lattice beam of the present invention and the upper and lower connection points (E) of the upper and lower half sections (SA) (SB)
[Figure 4] An exploded state diagram in which the lattice supports of the crown apex point (J) and the upper and lower connection points (E) are spread apart to insert and fasten the variable expandable connector (EC)
[Figure 5a] a perspective view of a variable expandable connector (EC)
[Fig. 5b] Sectional view in the longitudinal direction of Fig. 5a
[Fig. 5c] a perspective view of a parallelogram flange fastening plate of a variable expandable connector (EC)
[Fig. 5d] CC cross-sectional view of Fig. 5a
[Figure 6a] A cross-sectional view showing a state in which the variable expandable connector (EC) of the present invention is inserted and connected to the crown apex point (J) and the upper and lower connection point (E) of the lattice beam
[Fig. 6b] AA cross section of Fig. 6a
[Fig. 6c] BB sectional view of Fig. 6a
[Figure 7] Comparison table of section performance [section area, moment of inertia (Ⅰ)] of lattice support and H-beam support

The configuration of the tunnel lattice support installation system according to the minimization of the over-bending distance using the variable expandable connector structure of the present invention will be described as follows.

Install factory-manufactured lattice beams on the “design construction line” for the arched tunnel blasting excavation cross-section line (G), where overexcavation is unavoidable, but make the arched tunnel cross-section symmetric It is divided into half sections, and it is divided into upper half sections (SA) and lower half sections (SB) based on the upper and lower connection points (E), and lattice supports are installed on both sides of the upper and lower half sections (SA) (SB) symmetrically, but the crown cloth The “design of the lattice beams in which the vertical fastening plates 350B for the fixed plates 350A installed on each of the lattice beams on both sides located at the point J and the upper and lower connection points E are butted with each other and fastened and connected by the fastening bolts 360. In the construction line "installation system

A variable expansion type consisting of a concrete block 410 in the shape of a triangular column, a tension member 420, and a parallelogram flange fastening plate 430 between the crown apex point (J) and the lattice beams on both sides of the upper and lower half connection points (E). Insert the ceiling connector (400A) and the variable expandable vertical connector (400B), respectively, but fasten both protruding flanges of the variable expandable ceiling connector (400A) and the variable expandable upper and lower connector (400B) with respect to the vertical fastening plates (350B) of the lattice beams on both sides. By connecting and fastening the vertical fastening plate 350B and the flange fastening part 430A by connecting the vertical fastening plate 350B and the flange fastening part 430A by butting the parts 430A against each other, the variable expansion type ceiling connecting member 400A at the apex point J of the crown makes the horizontal horizontal fastening. The length expansion in the direction and the height expansion in the vertical direction are made by the variable expandable top and bottom connectors (400B) at the top and bottom connection points (E), so that the “design construction line” where the factory-manufactured lattice support will be installed is the “tunnel excavation cross-section.” It is a tunnel lattice support installation system according to the minimization of the overextension distance using a variable expansion type connecting material structure, characterized in that it becomes a "real grid support installation construction line" with a minimized overextension distance (d) by being moved as close as possible to the "line".

here,

The position of the “design construction line” of the factory-made lattice beam is moved as close as possible to the “tunnel excavation section line” and the shotcrete (S) is placed in a state where the overexcavation distance (d) is minimized. Tunnel according to minimization of overexcavation distance using variable expandable connector structure, characterized in that safe composite strength with lattice beams including variable expandable upper and lower connectors (400B) is achieved quickly, while minimizing the amount of shotcrete (S) casting and the number of castings It is a grid support installation system.

also,

The buried tension member (420A) and the exposed tension member (420B) are deformed reinforcing bars, and the end of the exposed tension member (420B) is a hook (420C) shape. It is a tunnel grid support installation system according to the minimization of the overbending distance using a variable expansion type connector structure .

In this way, by inserting a variable expansion type ceiling connection member (400A) and a variable expansion type top and bottom connection member (400B) between the crown apex point (J) and the upper and lower connection point (E), respectively, where the lattice support is assembled and connected, and connecting them with the lattice support on both sides of the crown, the crown Length expansion in the horizontal direction by the variable expandable top connector 400A at the top point J, and height expansion in the vertical direction by the variable expandable top and bottom connector 400B at the top and bottom connection points E The “design construction line” on which the grid support will be installed is moved as close as possible to the “tunnel excavation section line” to become the “actual grid support installation construction line” with the minimized overexcavation distance (d).

As the overexcavation distance (d) is minimized, the amount of filling of shotcrete is minimized and the number of times of casting is minimized, quickly reaching a safe composite strength (10Mpa) between shotcrete and lattice beams, and securing structural stability of ground bearing capacity is also useful. It is an invention.

SA; upper half section (SA), SB; Bottom Half Section (SB)
100A; Upper half-section lattice supports (100A), 200B; Lower half section lattice beam,
J; crown apex (J), E; lower junction point (E), G; Tunnel excavation section line (G), F; design construction line (F), S; shotcrete (S), W; welding (W),
300; Lattice support (100A) (200B) structure (300), 310; Upper steel bar (310), 320; Lower steel bar (320), 330; Spiders 330, 340; welds 340 and 350; Connection fastening part 350, 350A; fixing plates 350A, 350B; Vertical fastening plate (350B), 360; fastening bolts (360), 370; bolt hole
400; Variable expandable connector 400, 400A; Variable expandable ceiling connectors (400A), 400B; Variable expandable upper and lower connectors (400B), 410; concrete blocks 410, 420; Tension member 420, 420A; Buried tension member (420A), 420B; exposed tension member (420B), 420C; hook (420C), 430; Parallelogram flange fastening plate 430, 430A; Flange fastening part (430A), 432A; fastening bolt holes 432A, 430B; central portions 430B, 432B; Exposed tension member through hole (432B),

Claims (7)

Install factory-manufactured lattice beams on the “design construction line” for the arched tunnel blasting excavation cross-section line (G), where overexcavation is unavoidable, but make the arched tunnel cross-section symmetric It is divided into half sections, and the half sections are divided into upper and lower half sections (SA) (SB) based on the upper and lower connecting points (E), and the upper and lower connecting points of the crown apex (J) and the upper and lower half sections (SA) (SB) ( In the connection structure in which the vertical fastening plates 350B for the fixed plates 350A installed on each of the grid supports on both sides located at E) are butted with each other and the grid supports are fastened by the fastening bolts 360
A variable expandable connecting member 400 inserted between the lattice supports on both sides of the crown apex point (J) and the upper and lower connection points (E) of the upper and lower half sections (SA) (SB);
The variable expandable connector 400 differs only in the insertion position and has the same structure as the variable expandable ceiling connector 400A and the variable expandable upper and lower connector 400B;
The variable expandable ceiling connector 400A and the variable expandable upper and lower connector 400B are a triangular columnar concrete block 410 body, a tension member 420 in which the buried tension member 420A and the exposed tension member 420B of the body are integrated into one. And, it is formed at both ends of the concrete block 410, and the flange fastening part 430A and the central part 430B are formed as a parallelogram flange fastening plate 430 in one body. Variable expansion type connector of tunnel lattice beam, characterized in that structure According to claim 1
By inserting the variable expandable connector 400 between the lattice supports on both sides of the upper and lower connection points (E) of the crown apex (J) and the upper and lower half sections (SA) (SB), respectively, the vertical fastening plates (350B) of the lattice supports on both sides The protruding flange fastening parts 430A of the variable expandable connector 400 are butted to each other and connected and fastened by fastening bolts 360, but the variable expandable connector 400 is a triangular columnar concrete block 410 and the tension member 420. ) and a parallelogram flange fastening plate 430, and the tension member 420 is a tension member 420 in which the buried tension member 420A and the exposed tension member 420B are one, and the buried tension member 420A is attached to the concrete block 410. It is buried, and the exposed tension member 420B is exposed to both ends of the concrete block 410, and the parallelogram flange fastening plate 430 through which the exposed tension member 420B penetrates is the flange fastening portion 430A with respect to the concrete block 410. protrudes beyond both ends of the concrete block 410, and while forming a vertical plane, the parallelogram flange fastening plate 430 is fixed while being located at both ends of the concrete block 410, and at this time, the fixing is the exposed tension member 420B ) and the exposed tension member through hole 432B are fixed by welding, and the extended protruding flange fastening part 430A is vertically fastened with the flange fastening part 430A in the same shape and size as the vertical fastening plate 350B of the lattice support. The plate 350B is connected and fastened by the fastening bolt 360 in a state in which it is completely in contact with the variable expandable connector 400 and the lattice support, and at this time, the exposed tension member 420B on both sides is the first spider 330 ) Variable expansion type connection reconstruction structure of tunnel grid support, characterized in that it is installed extended to According to claim 1
The exposed tension member through-hole (432B) is a variable expansion type connecting member structure of the tunnel lattice support, characterized in that it is formed at the center of the central portion (430B) of the parallelogram flange fastening plate (430) According to claim 1
The buried tension member (420A) and the exposed tension member (420B) are deformed reinforcing bars, and the end of the exposed tension member (420B) has a hook (420C) shape. delete delete Install factory-manufactured lattice beams on the “design construction line” for the arched tunnel blasting excavation cross-section line (G), where overexcavation is unavoidable, but make the arched tunnel cross-section symmetric It is divided into half sections, and it is divided into upper half sections (SA) and lower half sections (SB) based on the upper and lower connection points (E), and lattice supports are installed on both sides of the upper and lower half sections (SA) (SB) symmetrically, but the crown cloth The “design of the lattice beams in which the vertical fastening plates 350B for the fixed plates 350A installed on each of the lattice beams on both sides located at the point J and the upper and lower connection points E are butted with each other and fastened and connected by the fastening bolts 360. In the "construction line" installation system, between the lattice supports on both sides of the crown apex point (J) and the upper and lower half upper and lower connection points (E), a concrete block 410 in the shape of a triangular column, a tension member 420 and a parallelogram flange fastening plate The variable expandable ceiling connector 400A and the variable expandable top and bottom connector 400B made of 430 are inserted, respectively, but the variable extendable ceiling connector 400A and the variable expandable top and bottom connector 400B are inserted with respect to the vertical fastening plates 350B of the lattice beams on both sides. The variable expandable top of the crown peak point (J) by connecting the flange fastening parts 430A on both sides of the protruding side to each other and connecting the vertical fastening plate 350B and the flange fastening part 430A by the fastening bolt 360. The length expansion in the horizontal direction by the connecting material (400A) and the height expansion in the vertical direction by the variable expandable vertical connecting material (400B) at the top and bottom connection point (E) are made, so that the factory-manufactured lattice support will be installed. The "line" is moved to the "tunnel excavation section line" as much as possible to make it an "actual grid support installation construction line" with a minimized over-excavation distance (d), and the buried tension member (420A) and the exposed tension member (420B) are deformed reinforcing bars , Tunnel lattice support installation system according to the minimization of the overextension distance using a variable expandable connector structure, characterized in that the end of the exposed tension member (420B) is in the shape of a hook (420C)

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