A simplified construction structure and construction method for connecting upper and lower arch frames in tunnel sectional excavation.

Abstract

This invention discloses a simplified construction structure and method for connecting upper and lower arch frames in tunnel sectional excavation. After the arch frames and longitudinal connecting bars are installed, and before shotcreting, high-strength foam is applied above the connecting steel plates, with the foam height exceeding twice the bolt length. During shotcreting, the foam is sprayed directly upwards from the top plane of the high-strength foam. Because the shotcrete solidifies very quickly, the weight of the shotcrete acting on the high-strength foam does not increase significantly. After the upper part is completed, the high-strength foam is removed during the lower part construction, providing ample space for inserting nuts and tightening bolts. The high-strength foam used has sufficient strength and is easy to remove, with a deformation rate not exceeding 20% ​​under the spraying pressure of the shotcrete. During the lower part shotcreting, the removed high-strength foam space is filled with shotcrete, ensuring that the connecting plates and bolts are completely encased in concrete.

Description

Technical Field

[0001] This invention relates to the field of tunnel initial support sub-construction, specifically to a simple connection construction structure and method for the upper and lower arch frames during tunnel sub-excavation, which makes the initial support connection during tunnel sub-construction simple, fast, labor-intensive, and of high quality. Background Technology

[0002] During the initial support construction of tunnels, the connection points at these sections are often constructed using either direct shotcreting followed by chiseling, or by piling up loose slag, spraying, and then chiseling to create space for connecting bolts. Both methods require significant labor to remove the shotcrete, as each arch frame's foot area needs to be chiseled away. This results in a large workload, high labor intensity, and wasted shotcrete. Furthermore, incomplete chiseling often leads to poor bolt connections and inadequate bonding between the old and new shotcrete. This project fundamentally solves the problems of chiseling, limited operating space, and insufficient shotcreting density at the connection points, achieving high quality and efficiency in the initial support construction of tunnels. Summary of the Invention

[0003] Therefore, to solve the above problems and improve the existing issues of difficult quality control, low efficiency, and high labor intensity at the connection points of tunnel initial support sub-section construction, this invention adopts a simplified connection construction structure and method for upper and lower arch frames during tunnel sub-section excavation. First, after erecting the upper arch frame and installing the anchor bolts, high-strength foam is installed above the connecting plate, completely covering the bottom connecting plate and connecting bolts of the arch frame. Next, concrete is sprayed above the top of the high-strength foam. After the lower section is excavated, the high-strength foam is removed using simple tools, the lower arch frame is erected, the connecting bolts are installed, and finally, the lower section is sealed with sprayed concrete, forming a good initial support system. This invention is easy to implement and the process is simple. This invention is implemented by innovating the construction connection process and implementation method. The method is characterized by: reserving a simple method for chiseling and connecting the upper part for the lower part during construction. High-strength foam is used to first occupy the position of the connecting steel plate and part of the sprayed concrete, which is easy to chisel away during the lower part construction. At the same time, it is easy to chisel away cleanly, leaving enough operating space for the lower part construction. At the same time, it can ensure good contact between the subsequent sprayed concrete and the previous sprayed concrete, achieving the goals of convenient construction and high quality.

[0004] This invention is implemented as follows: a simple construction structure for connecting upper and lower arch frames in tunnel sectional excavation is provided, characterized in that: the structure has a steel arch frame and a lower arch frame, with anchor bolts driven between the steel arch frame and the rock strata; the steel arch frame and the lower arch frame are connected by connecting steel plates and connecting bolts, and shotcrete is applied at the steel arch frame and the lower arch frame respectively.

[0005] A simplified construction method for connecting the upper and lower arch frames in tunnel sectional excavation is characterized by the following: This method involves adding high-strength foam, removing the foam and connecting bolts at the lower construction stage, and then spraying it to ensure a good connection between the sequential construction parts of the tunnel sectional excavation, guaranteeing quality. The specific process of this construction method is as follows:

[0006] Step 1: Level the concrete blocks according to the design elevation, then place the steel arch frame on the concrete blocks and install the anchor bolts.

[0007] Step 2: After the steel arch frame is installed, apply high-strength foam to the arch frame connecting plate to completely seal the connecting plate position. The high-strength foam fully covers the bottom connecting plate and connecting bolts of the arch frame, so as not to contaminate the connecting steel plate and bolt holes by the subsequent construction concrete; then spray concrete on the top surface of the high-strength foam.

[0008] Step 3: After the lower excavation is completed, remove the concrete pad blocks, then chisel away the high-strength foam to expose the uncontaminated connecting plates and bolt holes. Position the lower arch frame in place, install connecting bolts at the locations where the high-strength foam was removed, and seal the lower part with shotcrete after secure installation. The removed high-strength foam leaves ample space for the construction of connecting plates and bolts, facilitating bolt installation and quality control. Pass the high-strength bolts through the bolt holes and tighten the nuts. Seal the lower steel arch frame and the areas where the high-strength foam was removed with shotcrete.

[0009] The overall construction process is simple and convenient, enabling rapid, efficient, and high-quality construction of tunnel sectional excavation, connection of upper and lower arch frames, and shotcreting.

[0010] Therefore, this invention discloses a simplified construction structure and method for connecting upper and lower arch frames in tunnel sectional excavation. After the arch frames and longitudinal connecting bars are installed, before shotcreting, high-strength foam is applied above the connecting steel plates, with the foam height exceeding twice the bolt length. During shotcreting, the foam is sprayed directly upwards from the top plane of the high-strength foam. Because the shotcrete solidifies very quickly, the weight of the shotcrete acting on the high-strength foam does not increase significantly. After the upper part is completed, the high-strength foam is removed during the lower part construction, providing ample space for inserting nuts and tightening bolts. The high-strength foam used has sufficient strength and is easy to remove, with a deformation rate not exceeding 20% ​​under the spraying pressure of the shotcrete. During the lower part shotcreting, the removed high-strength foam is filled with shotcrete, ensuring that the connecting plates and bolts are completely encased in concrete. In conventional tunnel initial support construction, the connection points at the sections are often constructed using either direct shotcreting followed by chiseling to remove the connection, or by piling up loose slag, shotcreting, and then chiseling to leave space for connecting bolts. Both methods require significant labor to remove the shotcrete, as each arch frame's foot needs to be chiseled away. This is labor-intensive, wasteful of shotcrete, and often results in incomplete removal, leading to poor bolt connections and poor bonding between the old and new shotcrete. The method disclosed in this invention fundamentally solves the problems of connection technology between upper and lower arch frames and shotcrete connection quality during tunnel section excavation.

[0011] The present invention has the following advantages: a simplified construction method for connecting the upper and lower arch frames during tunnel sectional excavation. First, after erecting the upper arch frame and installing the anchor bolts, high-strength foam is installed above the connecting plate, fully covering the bottom connecting plate and connecting bolts of the arch frame. Then, concrete is sprayed above the top of the high-strength foam. After the lower part is excavated, the high-strength foam is removed using simple tools, the lower arch frame is erected, the connecting bolts are installed, and then the lower part is sealed with sprayed concrete, forming a good initial support system.

[0012] Secondly, the construction method provided by this invention has the following advantages: Firstly, the method includes a simple method for reserving space for chiseling and connecting the upper part of the construction and the lower part of the construction. High-strength foam is used to first occupy the position of the connecting steel plate and part of the sprayed concrete, which is easy to chisel away during the lower part of the construction. At the same time, it is easy to chisel away cleanly, leaving enough operating space for the lower part of the construction. It also enables the subsequent sprayed concrete to have good contact with the previous sprayed concrete, thus achieving the goals of convenient construction and high quality.

[0013] Furthermore, this method reduces the workload and quantity of initial support connections during sectional construction, while ensuring tight connections at the steel plate joints, facilitating bolt installation, and improving the bonding and contact between sequentially applied shotcrete sections. This enhances the construction quality of the initial tunnel support. Attached Figure Description

[0014] Figure 1 This is a diagram showing the completion of the installation of the upper steel arch frame and the completion of the anchor bolt installation for the tunnel section excavation;

[0015] Figure 2 This is a schematic diagram of the high-strength foam being applied to the bottom of the upper steel arch frame during the tunnel excavation section.

[0016] Figure 3 This is a schematic diagram showing the completion of the tunnel section excavation, including the upper steel arch frame, anchor bolts, high-strength foam, and shotcrete.

[0017] Figure 4 This is a schematic diagram showing the completion of the lower excavation of the tunnel section and the removal of the high-strength foam.

[0018] Figure 5 This is a schematic diagram showing the secure connection between the lower and upper steel arch frames during the tunnel excavation section.

[0019] Figure 6 This is a schematic diagram of the integrated support system formed by the lower steel arch frame and shotcrete of the tunnel section excavation and the upper steel arch frame and shotcrete.

[0020] The components include: 1. Concrete pad block; 2. Steel arch frame; 3. Anchor bolt; 4. High-strength foam; 5. Shotcrete; 6. Lower arch frame; 7. Connecting bolts; 8. Lower shotcrete. Detailed Implementation

[0021] The following will be combined with the appendix Figure 1 - Figure 6 This invention will be described in detail, and the technical solutions in the embodiments of this invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] This invention provides a simple connection construction structure for upper and lower arch frames in tunnel sectional excavation. The structure has a steel arch frame 2 and a lower arch frame 6. Anchor bolts 3 are installed between the steel arch frame 2 and the rock strata. The steel arch frame 2 and the lower arch frame 6 are connected by connecting steel plates and connecting bolts 7. Shotcrete 5 and shotcrete 8 are sprayed at the steel arch frame 2 and the lower arch frame 6, respectively.

[0023] This invention provides a simplified construction method for connecting the upper and lower arch frames during sectional excavation of a tunnel. The operation involves the following steps: 1. Concrete pads; 2. Steel arch frames; 3. Anchor bolts; 4. High-strength foam; 5. Shotcrete; 6. Lower arch frames; 7. Connecting bolts; 8. Lower shotcrete. By sequentially constructing 1, 2, 3, 4, and 5; then removing 1, chiseling away 4, 6, and 7, and finally 8, the construction space for the connecting bolts 7 is effectively created, while simultaneously reducing labor intensity and meeting design requirements.

[0024] The implementation steps of this invention are as follows:

[0025] Step 1: After the steel arch frame 2 is installed, apply high-strength foam 4 to the arch frame connecting plate to completely seal the connecting plate position, preventing subsequent concrete construction from contaminating and sealing the connecting steel plate and bolt holes. Then spray high-strength foam 4 or higher with shotcrete 5.

[0026] Step 2: After the lower excavation is completed, use simple tools to easily remove the high-strength foam 4, exposing the uncontaminated connecting plate and bolt holes. After the lower arch frame is installed in place, the removed high-strength foam 4 leaves a large space for the construction of the connecting plate and bolts, facilitating bolt construction and quality control. The high-strength bolts pass through the bolt holes, and the nuts are tightened. Shotcrete is then used to seal the lower steel arch frame and the removed high-strength foam area.

[0027] The simplified construction method for connecting the upper and lower arch frames during tunnel sectional excavation creatively incorporates high-strength foam. After removing the foam and connecting bolts during the lower construction phase, the foam is sprayed onto the arch frame, ensuring a good connection between the sequential construction sections during tunnel sectional excavation and guaranteeing quality. First, concrete blocks 1 are leveled according to the design elevation. Then, the steel arch frame 2 is placed on the concrete blocks 1, and anchor bolts 3 are installed. High-strength foam 4 is applied at the arch frame connection plate to completely seal the connection plate position. Shotcrete 5 is then applied above the high-strength foam as designed. After the lower excavation, the concrete blocks 1 are removed, and the high-strength foam 4 is removed using simple tools. The lower arch frame 6 is then positioned correctly, and connecting bolts 7 are installed at the removed high-strength foam area. After secure installation, the lower shotcrete 8 is used to seal the connection. The overall construction process is simple, convenient, and enables rapid, efficient, and high-quality connection of the upper and lower arch frames during tunnel sectional excavation.

[0028] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A simplified construction method for connecting the upper and lower arch frames in sectional excavation of a tunnel, characterized in that: This construction method involves adding high-strength foam, removing the foam and connecting bolts before spraying it compacted during the lower construction phases, ensuring good connection between the sequential construction parts of the tunnel excavation and guaranteeing quality; the specific process of this construction method is as follows: Step 1: Level the concrete pad (1) according to the design elevation, then place the steel arch frame (2) on the concrete pad (1) and install the anchor rod (3). Step 2: After the steel arch frame (2) is installed, high-strength foam is used to occupy the position of the connecting steel plate and part of the sprayed concrete. High-strength foam (4) is first applied at the arch frame connecting plate to completely seal the position of the connecting plate. The high-strength foam fully covers the bottom connecting plate and connecting bolts of the arch frame, so as not to contaminate the connecting steel plate and bolt holes of the subsequent construction concrete; then spray concrete above the top surface of the sprayed high-strength foam (4). Step 3: After the lower excavation is completed, remove the concrete pad block (1), then chisel off the high-strength foam (4) to expose the uncontaminated connecting plate and bolt holes. Position the lower arch frame (6) in place, and install connecting bolts (7) at the location where the high-strength foam has been removed. After the installation is secure, the lower part is sealed with shotcrete. The removed high-strength foam (4) leaves a large space for the construction of the connecting plate and bolts, which facilitates bolt construction and quality control. The high-strength bolts pass through the bolt holes and the nuts are tightened. The lower steel arch frame and the area where the high-strength foam has been removed are sealed with shotcrete. The high-strength foam used has a certain strength and is easy to remove. Under the spraying pressure of the shotcrete, the deformation rate is not greater than 20%.

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