CN216305957U - Construction structure for restraining subsidence of initial support of tunnel based on excavation by step method - Google Patents

Abstract

The utility model discloses a construction structure for inhibiting sinking of a primary support of a tunnel based on step-by-step excavation, which comprises a first support body, a second support body and a third support body, wherein the first support body, the second support body and the third support body have the same structure, and each of the first support body, the second support body and the third support body comprises a plurality of groups of positioning steel arches arranged on the inner side surface of the tunnel, a reinforcing layer structure arranged at the bottom of each positioning steel arch and reinforcing blocks arranged on the outer side of each positioning steel arch; the reinforcing block and the positioning steel arch are connected through a foot locking anchor rod; a reinforcing layer supporting structure is arranged in the reinforcing layer structure. The outer side surface of the steel arch frame is reinforced by arranging the reinforcing blocks; the bottom of the steel arch is reinforced by the reinforcing layer structure, vertical settlement and convergence of primary support of the tunnel are restrained, the scale of the surrounding rock loosening ring is controlled, surrounding rock load borne by the lining structure is reduced, and engineering construction cost is reduced.

Description

Construction structure for restraining subsidence of initial support of tunnel based on excavation by step method

technical field

The utility model belongs to the technical field of tunnel and underground engineering support, in particular to a construction structure for suppressing the subsidence of initial support of a tunnel based on excavation by a step method.

Background technique

With the continuous expansion of the number and scale of tunnel projects in my country, the excavated tunnels mostly pass through the soil with poor foundation bearing capacity, weak surrounding rocks and fault fracture zones. Usually, the inverted arch fills the bulge on the top surface, resulting in longitudinal cracks, longitudinal cracks in the lining structure and other diseases, and even major safety accidents such as instability of the inverted slope at the entrance of the cave. The reasons are all caused by the excessive vertical settlement of the initial support. Therefore, the research and development of the stability of the arch foot and the wall foot and the subsidence control measures have gradually attracted people's attention.

In order to solve this problem, it is one of the effective measures to control the vertical settlement to set the lock foot anchor pipe at the arch foot or the wall foot. However, due to the difference in the construction level on site, the angle of application of the locking foot anchor pipe and the reliability of the connection with the profiled steel arch foot cannot be guaranteed. In addition, by welding the steel arch frame and the foot-locking anchor pipe with the direct connecting rib, due to the small contact area between the connecting rib and the foot-locking anchor pipe and the thin wall of the foot-locking anchor pipe, it is easy to penetrate the steel pipe during welding, and it is When the force is applied, the weld between the connecting rib and the locking foot anchor pipe is prone to fracture, resulting in the failure of the anchor pipe. Therefore, a construction structure that can effectively restrain the initial support subsidence of the tunnel is proposed.

Utility model content

The technical problem to be solved by the present utility model is to provide a construction structure based on the excavation of the step method to suppress the subsidence of the initial support of the tunnel, in view of the deficiencies in the prior art. The outer side of the tunnel is reinforced; the bottom of the steel arch is reinforced by the reinforcement layer structure, which inhibits the vertical settlement and convergence of the initial support of the tunnel, thereby controlling the scale of the loose circle of surrounding rock and reducing the burden on the lining structure. The surrounding rock load can be reduced, and the construction cost of the project can be reduced.

In order to solve the above-mentioned technical problems, the technical scheme adopted by the present utility model is: a construction structure for suppressing the subsidence of the initial support of the tunnel excavated based on the step method, and the tunnel is excavated and supported by the step method. The tunnel is constructed from the back to the front in the longitudinal extension direction, and the transverse passage of the tunnel includes an upper step, a middle step arranged under the upper step, and a middle step arranged at the bottom of the tunnel and arranged below the middle step When excavating the transverse passage of the tunnel, first excavate and support the upper steps, then excavate and support the middle steps, and finally excavate and support the lower steps; It is characterized by:

It includes a first support body that supports the upper steps, a second support body that is arranged below the first support body and supports the steps in the middle, and a second support body that is arranged below the second support body and supports all the steps. The third support body of the lower step support, the first support body, the second support body and the third support body have the same structure, the first support body, the Both the second support body and the third support body include a plurality of sets of positioning steel arches arranged on the inner side of the tunnel, a reinforcement layer structure arranged at the bottom of the positioning steel arches, and a plurality of sets of positioning steel arches arranged at the bottom of the positioning steel arches. Reinforcing blocks on the outside of the frame; the reinforcing blocks and the positioning steel arches are connected by locking foot anchors; multiple groups of positioning steel arches are evenly arranged along the longitudinal extension direction of the tunnel;

The positioning steel arch frame includes a steel arch frame erected on the inner side of the step and two sets of directional duct tube groups arranged obliquely at the bottom of the steel arch frame, the steel arch frame and two sets of the directional duct tube sets. One-piece molding; the shape of the longitudinal section of the steel arch is adapted to the shape of the longitudinal section of the step; the steel arch of the upper step is an arched structure, and the steel arch of the middle step and the lower step is an arch shelf segment;

The reinforcement layer structure is provided with a reinforcement layer support structure, and the reinforcement layer support structure includes a longitudinal steel bar group arranged at the bottom of the steel arch and arranged in the reinforcement cavity, and a ring set on the longitudinal reinforcement group. The longitudinal reinforcement group and the circumferential reinforcement group are integrally formed.

The above-mentioned construction structure based on excavation of the step method to restrain the subsidence of the initial support of the tunnel is characterized in that: the directional duct pipe group comprises two directional ducts symmetrically arranged on the same side of the steel arch, and the two The directional ducts are arranged obliquely on the front and rear sides of the bottom of the steel arch, the directional ducts are fixed on the steel arch by a plurality of limit bars, the directional ducts are hollow structures, and the directional ducts run along the The direction away from the central axis of the tunnel gradually slopes downward.

The above-mentioned construction structure for restraining the initial support subsidence of tunnel excavation based on the step method is characterized in that: a locking anchor rod is inserted into the directional guide pipe, and the locking anchor rod extends into the directional guide pipe. The end extends into the surrounding rock after passing through the directional conduit, and the other end of the locking foot bolt extends to the inner side of the step.

The above-mentioned construction structure based on the excavation of the step method to restrain the subsidence of the initial support of the tunnel is characterized in that: the end of the directional guide pipe extending into the surrounding rock is flush with the bottom of the step; the directional guide pipe is flush with the bottom of the step; The inner diameter is larger than the outer diameter of the locking foot anchor rod.

The above-mentioned construction structure based on the excavation of the step method for restraining the subsidence of the initial support of the tunnel is characterized in that: the number of the limit steel bars is two, and the two directional guide pipes are sleeved on the limit steel bars. Inside, one of the limit bars is arranged inside the tunnel and is fixed at the connection between the directional conduit and the steel arch; the other limit bar is arranged on the steel arch away from the tunnel and it is fixed at the junction of the directional conduit and the steel arch.

The above-mentioned construction structure based on the excavation of the step method for suppressing the subsidence of the initial support of the tunnel is characterized in that: the longitudinal steel bar group includes a plurality of reinforcement layer longitudinal steel bars all arranged along the longitudinal extension direction of the tunnel, and a plurality of The longitudinal reinforcement bars of the reinforcement layer are evenly arranged on the inner and outer sides of the steel arch;

The hoop reinforcement group includes a plurality of reinforcement layer hoop reinforcements sleeved on the longitudinal reinforcement group, and a plurality of the reinforcement layer hoop reinforcement bars are arranged along the extension direction of the reinforcement layer longitudinal reinforcement; the reinforcement layer hoop reinforcement The reinforcing bars are of right-angled trapezoidal structure, and the longitudinal reinforcing bars of the reinforcing layer are arranged at four top corners of the circumferential reinforcing bars of the reinforcing layer.

The above-mentioned construction structure for restraining the subsidence of initial tunnel support based on excavation by the step method is characterized in that: the bottom of the steel arch frame is horizontally provided with a connection pad, and the connection pad is arranged on the reinforcement layer structure. Inside, the cross-sectional area of the connecting backing plate is larger than the cross-sectional area of the steel arch, and the connecting backing plate is fixed on the bottom of the reinforcement cavity by a plurality of fixing parts.

The above-mentioned construction structure based on the excavation of the step method for suppressing the subsidence of the initial support of the tunnel is characterized in that: the outer side of the connecting pad is sleeved with a protective cover, and the connecting pad and the protective cover are enclosed in a closed manner. the cuboid area.

Compared with the prior art, the utility model has the following advantages:

1. The utility model reinforces the outer side of the steel arch by setting reinforcement blocks; the bottom of the steel arch is reinforced by using the reinforcement layer structure, which suppresses the vertical settlement and convergence of the initial support of the tunnel, Then, the scale of the surrounding rock loose circle is controlled, the surrounding rock load borne by the lining structure is reduced, and the engineering construction cost is reduced.

2. In the present invention, a reinforcement layer structure is formed at the bottom of the steel arch frame, and the reinforcement layer structure can be used as a reinforced bottom longitudinal beam to effectively connect the upper and lower step arch frames to improve the longitudinal stiffness of the initial support and the Integrity, improve the bearing capacity of the upper lining structure.

To sum up, the utility model reinforces the outer side of the steel arch by setting the reinforcement block; uses the reinforcement layer structure to reinforce the bottom of the steel arch, which restrains the vertical settlement of the initial support of the tunnel and convergence, thereby controlling the scale of the surrounding rock loose circle, reducing the surrounding rock load borne by the lining structure, and reducing the construction cost.

The technical solutions of the present utility model will be described in further detail below through the accompanying drawings and embodiments.

Description of drawings

Figure 1 is a schematic structural diagram of the utility model.

FIG. 2 is a schematic diagram of the connection relationship between the reinforcement layer support structure and the positioning steel arch of the present invention.

Figure 3 is a state diagram of the utility model in use.

Explanation of reference numbers:

1-up step; 2-middle step; 3-down step;

4—steel arch; 5—reinforcing block;

6—Locking anchor rod; 9—Direction guide pipe; 10—Limiting steel bar;

11—connecting backing plate; 12—reinforcing side plate; 13—fixing part;

14—reinforcing the bottom plate; 15—the longitudinal reinforcement of the reinforcement layer; 16—the circumferential reinforcement of the reinforcement layer;

17—protective cover; 18—reinforcing rod; 20—surrounding rock;

21—Reinforcement layer structure.

Detailed ways

As shown in Figure 1, Figure 2 and Figure 3, the utility model adopts the step method to excavate and support the tunnel, and the tunnel is constructed from the back to the front along the longitudinal extension direction of the tunnel. The horizontal passage includes an upper step 1, a middle step 2 arranged below the upper step 1, and a lower step 3 arranged at the bottom of the tunnel and below the middle step 2; open the horizontal passage of the tunnel. When excavating, first excavate and support the upper step 1, then excavate and support the middle step 2, and finally excavate and support the lower step 3;

It includes a first support body supporting the upper step 1, a second support body disposed below the first support body and supporting the middle step 2, and a second support body disposed below the second support body and For the third support body supported by the lower step 3, the structures of the first support body, the second support body and the third support body are all the same, and the first support body , Both the second support body and the third support body include a plurality of sets of positioning steel arches arranged on the inner side of the tunnel, a reinforcement layer structure 21 arranged at the bottom of the positioning steel arch, and The reinforcing block 5 on the outer side of the positioning steel arch frame; the reinforcing block 5 and the positioning steel arch frame are connected by locking foot anchors 6; multiple groups of positioning steel arch frames are evenly arranged along the longitudinal extension direction of the tunnel;

The positioning steel arch includes a steel arch 4 erected on the inner side of the step and two sets of directional conduit tubes arranged at the bottom of the steel arch 4 obliquely. The conduit tube assembly is integrally formed; the longitudinal section shape of the steel arch frame 4 is adapted to the longitudinal section shape of the step; the steel arch frame 4 of the upper step 1 is an arched structure, the middle step 2 and the lower step The steel arch 4 of the step 3 is an arch section;

The reinforcement layer structure 21 is provided with a reinforcement layer support structure, and the reinforcement layer support structure includes a longitudinal reinforcement group arranged at the bottom of the steel arch 4 and arranged in the reinforcement cavity, and a longitudinal reinforcement group sleeved on the longitudinal reinforcement group. The circumferential steel bar group is integrally formed with the longitudinal steel bar group and the circumferential steel bar group.

In actual use, the outer side of the steel arch 4 is reinforced by setting the reinforcement block 5; the bottom of the steel arch 4 is reinforced by the reinforcement layer structure 21, which suppresses the vertical settlement of the initial support of the tunnel and convergence, thereby controlling the scale of the loose circle of surrounding rock 20, reducing the surrounding rock load borne by the lining structure, and reducing the construction cost.

Among them, a reinforcement layer structure 21 is formed at the bottom of the steel arch 4, and the reinforcement layer structure 21 can be used as a reinforced bottom longitudinal beam to effectively connect the upper and lower step arches to improve the longitudinal stiffness of the initial support and the overall improve the bearing capacity of the upper lining structure.

It should be noted that, the reinforcement layer structure 21 needs to manually excavate a reinforcement cavity at the bottom of the construction step. The longitudinal section of the reinforcement cavity is a right-angled trapezoid, and the reinforcement cavity is along the longitudinal extension direction of the tunnel. Arrangement; the bottom of the steel arch 4 is arranged in the reinforcement cavity, and the bottom surface of the reinforcement cavity and the bottom surface of the steel arch 4 in the step are arranged in the same horizontal plane; as shown in Fig. 3, Fig. The area enclosed by the dashed line and the reinforced side plate 12 is the area of the reinforced cavity.

As shown in FIG. 1 , in this embodiment, the directional duct tube group includes two directional ducts 9 symmetrically arranged on the same side of the steel arch 4 , and the two directional ducts 9 are obliquely arranged on the steel arch 4 . On the front and rear sides of the bottom of the arch 4, the directional guide 9 is fixed on the steel arch 4 through a plurality of limit steel bars 10, the directional guide 9 is a hollow structure, and the directional guide 9 is far away from the central axis of the tunnel. direction gradually slopes downward.

In actual use, the directional guide 9 is for the subsequent installation of the locking foot anchor 6, and the directional guide 9 is fixedly connected with the steel arch 4 as a whole, which is equivalent to determining the installation position of the locking foot anchor 6 in advance. , to avoid the displacement of the foot-locking bolt 6 during construction, to ensure the operating angle of the foot-locking bolt 6, to better play the role of the foot-locking bolt 6, and to better suppress the vertical settlement of the tunnel. effect.

As shown in FIG. 1 and FIG. 3 , in this embodiment, a locking foot anchor 6 is inserted into the directional conduit 9 , and the end of the locking foot anchor 6 extending into the directional conduit 9 passes through the The directional conduit 9 is then extended into the surrounding rock 20, and the other end of the locking foot anchor rod 6 is extended to the inner side of the step.

In actual use, a grouting mechanism is installed on the end of the locking foot bolt 6 located on the inside of the tunnel, and the grouting mechanism is used to pour grouting into the locking foot bolt 6 . The end of the inner locking foot anchor rod 6 forms a reinforcement block 5 .

As shown in FIGS. 1 and 3 , in this embodiment, the end of the directional conduit 9 extending into the surrounding rock 20 is flush with the bottom of the step; the inner diameter of the directional conduit 9 is larger than the locking foot The outer diameter of the anchor rod 6.

In particular, the inner diameter of the directional catheter 9 is larger than the outer diameter of the locking foot anchor rod 6 , and the inner diameter of the directional catheter 9 only needs to allow the locking foot anchor rod 6 to be inserted. The installation position of the foot-locking anchor rod 6 is determined in advance according to the directional guide tube 9 , so as to ensure the operating angle of the foot-locking anchor rod 6 and better play the role of the foot-locking anchor rod 6 . The outer side surface of the steel arch 4 is reinforced by using the locking foot bolt 6 to reinforce the block 5 in the surrounding rock 20 .

As shown in FIG. 2 and FIG. 3 , in this embodiment, the number of the limit bars 10 is two, two of the directional guide tubes 9 are sleeved in the limit bars 10, and one of the limit bars 10 is provided. Reinforcing bars 10 are arranged inside the tunnel and are fixed at the connection between the directional conduit 9 and the steel arch 4 ; another limit bar 10 is arranged at a part of the steel arch 4 away from the tunnel. side and it is fixed at the junction of the directional duct 9 and the steel arch 4 .

In actual use, the limiting steel bar 10 fixes the two directional conduits 9 on the front and rear sides of the steel arch 4; The arch frame 4 is processed as a whole. In addition, the directional conduit 9 and the steel arch 4 are pre-welded in advance in the steel bar processing plant through the limit steel bar 10, the quality is controllable, the construction and installation are simple and convenient, and the on-site construction time in the tunnel hole is shortened.

As shown in FIG. 2 and FIG. 3 , in this embodiment, the longitudinal steel bar group includes a plurality of reinforcement layer longitudinal reinforcement bars 15 arranged along the longitudinal extension direction of the tunnel, and the plurality of reinforcement layer longitudinal reinforcement bars 15 are evenly arranged On the inner and outer sides of the steel arch 4;

The hoop reinforcement group includes a plurality of reinforcement layer hoop reinforcement bars 16 sleeved on the longitudinal reinforcement group, and the plurality of reinforcement layer hoop reinforcement bars 16 are arranged along the extension direction of the reinforcement layer longitudinal reinforcement bars 15; the reinforcement layer The layer hoop reinforcement bars 16 are of right-angled trapezoid structure, and the reinforcement layer longitudinal reinforcement bars 15 are arranged at four top corners of the reinforcement layer hoop reinforcement bars 16 .

In actual use, the longitudinal reinforcement group and the circumferential reinforcement group play the role of support and reinforcement, and are arranged in the concrete forming cavity to ensure the overall stability of the reinforcement layer structure 21 formed by pouring in the later stage.

As shown in FIG. 2 and FIG. 3 , in this embodiment, the bottom of the steel arch 4 is provided with a connection pad 11 horizontally, and the connection pad 11 is arranged in the reinforcement layer structure 21 . The cross-sectional area of the plate 11 is larger than the cross-sectional area of the steel arch 4 , and the connection backing plate 11 is fixed to the bottom of the reinforcement cavity by a plurality of fixing pieces 13 .

In actual use, the early settlement can be controlled by using the connecting backing plate 11 installed at the bottom of the steel arch 4, and the connecting backing plate 11 can be reused; The installation position is convenient for the connection and fixation of the steel arch 4 in the upper and lower steps.

As shown in FIG. 2 and FIG. 3 , in this embodiment, a protective cover 17 is sleeved on the outer side of the connection pad 11 , and the connection pad 11 and the protective cover 17 enclose a closed cuboid area.

In actual use, in order to prevent the connecting backing plate 11 from being poured into concrete when the reinforcement cavity is poured into concrete, the connecting backing plate 11 needs to be protected. The connection pad 11 is used for protection.

When the utility model is used, the positioning steel arch is installed in the excavated steps, and then the locking anchor rod 6 is inserted into the directional guide pipe 9, and the locking anchor rod 6 located on the inside of the tunnel. A grouting mechanism is installed on the end, and the grouting mechanism is used to grouting into the locking foot bolt 6, and a reinforcement block 5 is formed at the end of the locking foot bolt 6 located in the surrounding rock 20; grouting; After completion, the grouting assembly is removed; as shown in Figure 3, then artificially excavate the outside of the bottom of the step, and form a reinforcement cavity with a right-angled trapezoid at the bottom of the step, and inside the reinforcement cavity After installing the reinforcement layer support structure, after installation, a reinforcement side plate 12 is installed vertically on the outside of the reinforcement cavity, and a reinforcement bottom plate 14 is installed at the bottom of the reinforcement cavity. The reinforcement bottom plate 14, the reinforcement side plate 12, and The inner wall of the tunnel encloses a concrete forming cavity whose longitudinal section is a right-angled trapezoid; in order to ensure the stability of the reinforced side plate 12, a plurality of Reinforcement rods 18, a plurality of said reinforcement rods 18 are evenly arranged along the longitudinal extension direction of the tunnel; then concrete is poured in the concrete forming cavity to form a reinforcement layer structure 21, and the reinforcement side plates 12 and reinforcement are removed after the concrete is solidified The bottom plate 14 is sufficient.

The above are only preferred embodiments of the present utility model, and do not limit the present utility model. Any simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the present utility model still belong to the scope of the present utility model. within the protection scope of the technical solution of the present invention.

Claims (8)

1. The construction structure for inhibiting the sinking amount of the primary support of the tunnel based on the step method is characterized in that the step method is adopted to excavate and support the tunnel, the tunnel is constructed from back to front along the longitudinal extension direction of the tunnel, and a transverse channel of the tunnel comprises an upper step (1), a middle step (2) arranged below the upper step (1) and a lower step (3) arranged at the bottom of the tunnel and arranged below the middle step (2); when the transverse channel of the tunnel is excavated, firstly excavating and supporting the upper step (1), then excavating and supporting the middle step (2), and finally excavating and supporting the lower step (3); the method is characterized in that:

the tunnel supporting device comprises a first supporting body supporting an upper step (1), a second supporting body arranged below the first supporting body and supporting a middle step (2), and a third supporting body arranged below the second supporting body and supporting a lower step (3), wherein the first supporting body, the second supporting body and the third supporting body are identical in structure, and each of the first supporting body, the second supporting body and the third supporting body comprises a plurality of groups of positioning steel arches arranged on the inner side surface of a tunnel, a reinforcing layer structure (21) arranged at the bottoms of the positioning steel arches, and reinforcing blocks (5) arranged on the outer sides of the positioning steel arches; the reinforcing block (5) is connected with the positioning steel arch frame through a foot locking anchor rod (6); a plurality of groups of positioning steel arches are uniformly distributed along the longitudinal extension direction of the tunnel;

the positioning steel arch comprises a steel arch (4) erected on the inner side surface of the step and two groups of directional pipe tube groups obliquely arranged at the bottom of the steel arch (4), and the steel arch (4) and the two groups of directional pipe tube groups are integrally formed; the longitudinal section shape of the steel arch (4) is adapted to the longitudinal section shape of the step; the steel arch (4) of the upper step (1) is of an arch structure, and the steel arches (4) of the middle step (2) and the lower step (3) are arch sections;

the reinforced layer structure (21) is internally provided with a reinforced layer supporting structure, the reinforced layer supporting structure comprises a longitudinal steel bar group and a circumferential steel bar group, the longitudinal steel bar group is arranged at the bottom of the steel arch frame (4) and is arranged in a reinforcing cavity, the circumferential steel bar group is sleeved on the longitudinal steel bar group, and the longitudinal steel bar group and the circumferential steel bar group are integrally formed.

2. The construction structure for restraining the sinking amount of the preliminary tunnel support excavated according to the bench method as claimed in claim 1, wherein: the directional pipe nest of tubes includes that two symmetries set up directional pipe (9) with one side of steel bow member (4), two directional pipe (9) slant is laid both sides around steel bow member (4) bottom, directional pipe (9) are fixed through a plurality of spacing reinforcing bars (10) on steel bow member (4), directional pipe (9) are hollow structure, directional pipe (9) are along the orientation downward sloping gradually of keeping away from the tunnel axis.

3. The construction structure for restraining the sinking amount of the preliminary tunnel support excavated by the bench method according to claim 2, wherein: and a foot locking anchor rod (6) is inserted in the directional guide pipe (9), the end part of the foot locking anchor rod (6) extending into the directional guide pipe (9) penetrates through the directional guide pipe (9) and then extends into the surrounding rock (20), and the other end of the foot locking anchor rod (6) extends to the inner side of the step.

4. The construction structure for restraining sinking amount of preliminary tunnel support excavated according to the bench method as claimed in claim 3, wherein: the end of the directional conduit (9) extending into the surrounding rock (20) is flush with the bottom of the step; the inner diameter of the directional guide pipe (9) is larger than the outer diameter of the locking pin anchor rod (6).

5. The construction structure for restraining the sinking amount of the preliminary tunnel support excavated by the bench method according to claim 2, wherein: the number of the limiting steel bars (10) is two, the two directional guide pipes (9) are sleeved in the limiting steel bars (10), and one limiting steel bar (10) is arranged on the inner side of the tunnel and fixed at the connecting position of the directional guide pipes (9) and the steel arch frame (4); and the other limiting steel bar (10) is arranged on one side of the steel arch (4) far away from the tunnel and is fixed at the joint of the directional guide pipe (9) and the steel arch (4).

6. The construction structure for restraining the sinking amount of the preliminary tunnel support excavated according to the bench method as claimed in claim 1, wherein: the longitudinal reinforcing steel bar group comprises a plurality of reinforcing layer longitudinal reinforcing steel bars (15) which are arranged along the longitudinal extension direction of the tunnel, and the plurality of reinforcing layer longitudinal reinforcing steel bars (15) are uniformly distributed on the inner side and the outer side of the steel arch frame (4);

the circumferential reinforcing steel bar group comprises a plurality of reinforcing layer circumferential reinforcing steel bars (16) sleeved on the longitudinal reinforcing steel bar group, and the plurality of reinforcing layer circumferential reinforcing steel bars (16) are distributed along the extending direction of the reinforcing layer longitudinal reinforcing steel bars (15); the reinforcing layer hoop reinforcing steel bars (16) are of a right-angle trapezoidal structure, and the reinforcing layer longitudinal reinforcing steel bars (15) are arranged at four top corners of the reinforcing layer hoop reinforcing steel bars (16).

7. The construction structure for restraining the sinking amount of the preliminary tunnel support excavated according to the bench method as claimed in claim 1, wherein: the bottom level of steel bow member (4) is provided with connecting backing plate (11), connecting backing plate (11) are laid in reinforcing layer structure (21), the cross-sectional area of connecting backing plate (11) is greater than the cross sectional area of steel bow member (4), connecting backing plate (11) are fixed through a plurality of mounting (13) the bottom in reinforcement chamber.

8. The construction structure for restraining the sinking amount of the preliminary tunnel support excavated according to the bench method as claimed in claim 7, wherein: the outside cover of connecting backing plate (11) is equipped with safety cover (17), connecting backing plate (11) with safety cover (17) enclose into the confined cuboid region.

Images