Station tunnel space stand column tunneling construction method

Abstract

The invention provides a station tunnel space stand column tunneling construction method which comprises the following steps that S1, a construction channel is excavated to the top end of a proposed tunnel, and transverse expanding excavation is conducted to the full width of the top end of the tunnel; s2, pilot tunnels on the left side and the right side of the top end of the proposed tunnel are excavated to the full length of the tunnel, the middle area of the top end of the tunnel is cut through at intervals so that multiple sections of supporting rock pillars can be formed in the full-length space of the tunnel, the full-length space of the tunnel is divided into a plurality of small caverns with the limited length through the multiple sections of supporting rock pillars, and the purposes that the whole tunnel space is changed into large and small and the whole is broken into parts are achieved; the space effect of the surrounding rock is fully exerted to enhance the stability of the tunnel; s3, at least one cavern is selected and downwards excavated to the whole section of the tunnel in an expanded mode; s4, the supporting rock pillar located on one side of the selected cavern is broken so as to be communicated with the next adjacent cavern, and then the broken area of the supporting rock pillar is downwards expanded and excavated to the whole section of the tunnel; and S5, the next adjacent cavern is selected, and the steps S3-S4 are repeated, so that the tunnel is tunneled hole by hole until the whole line of the proposed tunnel is through.

Description

Technical Field

[0001] The invention relates to the field of underground engineering construction, and in particular to a station tunnel space column excavation method. Background Art

[0002] The construction method of the traditional dark excavation station large-section tunnel is generally to first dig a construction channel to connect with the proposed station tunnel, and then gradually excavate along the longitudinal direction of the station tunnel at the connection position to the full length of the station tunnel. Among them, the proposed tunnel is generally constructed using the double-side wall pilot tunnel method, and the construction organization is carried out from the longitudinal direction along the heading face. The number of construction working surfaces is limited and the construction efficiency is low. In addition, the double-side wall pilot tunnel method construction method has many temporary supports, the construction steps are cumbersome, and the project investment increases significantly. Summary of the invention

[0003] In view of the defects in the prior art, the station tunnel space column excavation method provided by the present invention at least solves the technical problem of low efficiency of the existing construction method of subway stations.

[0004] In order to achieve the above object, the present invention is implemented by the following technical solutions: A station tunnel space column excavation method comprises the following steps: S1. Excavate the construction channel to the top of the proposed tunnel, and expand the tunnel horizontally to the full width of the top of the tunnel to obtain the initial excavation chamber; S2. In the initial excavation chamber, guide tunnels are excavated on the left and right sides of the top of the proposed tunnel along the extension direction of the proposed tunnel to the full length of the tunnel, and the middle area of ​​the top of the proposed tunnel is excavated at intervals to connect the guide tunnels on both sides, so as to form multiple sections of supporting rock pillars in the full length of the tunnel, and the multiple sections of the supporting rock pillars divide the full length of the tunnel into multiple small caverns of limited length; S3. Select at least one cavern and dig downward to the full section of the tunnel in the selected cavern, and construct the secondary lining structure of the selected cavern in sections; S4, when the secondary lining structure of the selected cavern approaches the tunnel face, the supporting rock pillar on one side of the selected cavern is broken to connect with the next adjacent cavern, and then the tunnel is expanded downward to the full section of the tunnel in the area where the supporting rock pillar is broken; S5, selecting the next adjacent cavern and repeating steps S3-S4, so as to excavate the proposed tunnel hole by hole until the proposed tunnel is fully connected.

[0005] Optionally, step S3 further includes the following sub-steps: S31. Dig down to the designed depth on the left or right side of the selected cavern, and provide temporary protection for the unexcavated area in the middle of the selected cavern based on the slope support technology; S32, continue to dig down to the tunnel base on the left or right side of the selected cavern, and after the left and right sides of the selected cavern are respectively dug down to the tunnel base, excavate the unexcavated area in the middle of the selected cavern to the tunnel base.

[0006] Optionally, the selected cavern is divided into a plurality of sections along the extension direction of the proposed tunnel, and each section is separately excavated downward to the full cross-section of the tunnel.

[0007] Optionally, in step S3, selecting at least one cavern and digging downward in the selected cavern to the full cross-section of the tunnel includes at least simultaneously selecting two caverns to carry out excavation operations in opposite, opposite or same directions.

[0008] Optionally, in step S4, the following steps are also included: The guide holes on the left and right sides of the top of the proposed tunnel will be used as platforms for placing demolition equipment to complete the demolition of supporting rock pillars.

[0009] It can be seen from the above technical solution that the beneficial effects of the present invention are: The invention provides a method for excavating space pillars in a station tunnel, comprising the following steps: S1, excavating a construction channel to the top of a planned tunnel, and laterally expanding the excavation along the planned tunnel to the full width of the top of the tunnel to obtain an initial excavation chamber; S2, excavating guide tunnels on the left and right sides of the top of the tunnel along the extension direction of the planned tunnel in the initial excavation chamber to the full length of the tunnel, and excavating the middle area of ​​the top of the tunnel at intervals to allow the guide tunnels on both sides to penetrate to form multiple sections of supporting rock pillars, and at the same time dividing the full length of the tunnel into multiple small chambers of limited length; S3, at least one chamber is selected to be excavated downward to the full section of the tunnel; S4, the supporting rock pillar located on one side of the selected chamber is broken to penetrate with the next adjacent chamber, and then the supporting rock pillar is excavated downward to the full section of the tunnel in the broken area; S5, the next adjacent chamber is selected and steps S3-S4 are repeated to excavate the tunnel hole by hole in the planned tunnel until the tunnel is fully penetrated. This construction method achieves the goal of "reducing the size of the whole tunnel into small pieces and breaking the whole into parts" by constructing several sections of supporting rock pillars within the full-length space of the station, and the rock pillars divide the full-length space of the station into multiple small caverns of limited length, giving full play to the spatial effect of the surrounding rock to enhance the stability of the tunnel. Each small cavern is a separate working area, which increases the construction surface of the tunnel, improves construction efficiency, and realizes safe, economical and efficient construction of multiple working surfaces of the entire station. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0011] Figure 1 This is a cross-sectional view of the connection between the construction channel and the station tunnel described in this excavation method; Figure 2 This is a schematic diagram of the downward excavation steps of the selected cavern described in this excavation method; Figure 3 The cross-sectional view of the tunnel when the selected cavern is excavated downward to the full cross-section of the tunnel as described in this excavation method; Figure 4 This is the layout of the station tunnel pilot tunnel in this excavation method; Figure 5 It is a tunnel section sequence diagram when two caverns are selected to carry out excavation operations facing each other; Figure 6 It is a tunnel cross-section sequence diagram when two caverns are selected to carry out excavation operations in opposite directions; Figure 7 The tunnel section sequence diagram for the case where two caverns are selected to carry out excavation work in the same direction; Reference numerals: 1- Construction channel, 2- Station tunnel, 3- Support rock pillar. DETAILED DESCRIPTION

[0012] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0013] See also Figure 1-5 The present invention provides a station tunnel space column excavation method, which is suitable for rock areas with relatively stable surrounding rock (generally surrounding rock grades are Ⅰ, Ⅱ, Ⅲ), and includes the following steps: S1. Excavate a construction passage to the top of the proposed tunnel, and expand the excavation along the proposed tunnel to the full width of the tunnel top to obtain the initial excavation chamber; the construction passage can be connected to any position in the length direction of the proposed tunnel, that is, the initial excavation chamber can be set at any longitudinal position of the station tunnel; S2. In the initial excavation chamber, guide tunnels are excavated on both sides of the top of the proposed tunnel along the extension direction of the proposed tunnel to the full length of the tunnel, and the middle area of ​​the top of the proposed tunnel is excavated at intervals to connect the guide tunnels on both sides, so as to form multiple sections of supporting rock pillars in the full length of the tunnel, and the multiple sections of the supporting rock pillars divide the full length of the tunnel into multiple small caverns of limited length; wherein the unexcavated areas between adjacent caverns form the supporting rock pillars, and the distance between adjacent supporting rock pillars must meet the design requirements and be within a safe distance to avoid tunnel instability; S3. At least one cavern shall be selected and excavated downward to the full section of the tunnel in the selected cavern. When the length of the selected cavern is relatively long, the selected cavern shall be divided into multiple sections along the extension direction of the proposed tunnel. Each section shall be excavated downward to the full section of the tunnel separately, and the secondary lining structure of the selected cavern shall be constructed in sections. Obviously, in order to shorten the construction period, two caverns may be selected at the same time to carry out excavation operations facing, facing away or in the same direction. For details, please refer to Figure 5-7 ; S4. When the selected cavern secondary lining structure approaches the tunnel face, the supporting rock pillar on one side of the selected cavern is broken to connect with the next adjacent cavern. At this time, the rock pillar of the adjacent cavern in front and the secondary lining of the previous cavern in the back play a supporting role on the surrounding rock, and the length of the cavern is controlled within a limited length range to ensure the stability of the cavern. After that, the tunnel is expanded downward to the full section of the tunnel in the area where the supporting rock pillar is broken. Obviously, the supporting rock pillar and the area where it is located can also be broken in sections and excavated step by step to ensure that the distance between the secondary lining and the rock pillar of the adjacent cavern in front meets the design requirements, that is, the safety distance is dynamically adjusted; S5, selecting the next adjacent cavern and repeating steps S3-S4, so as to excavate the proposed tunnel hole by hole until the proposed tunnel is fully connected.

[0014] As a further improvement to the above solution, step S3 further includes the following sub-steps: S31. Dig down to the designed depth on the left or right side of the selected cavern, and apply temporary protection to the unexcavated area in the middle of the selected cavern based on the slope support technology; under the strong support of the supporting rock pillars on both sides, the unexcavated area in the middle of the selected cavern no longer bears the upper load of the tunnel, and its support strength can be optimized, that is, only anchor spraying support is required to prevent it from landslide, collapse, etc.; For traditional construction methods, please refer to CN112031807A. The core parts of the middle and lower steps of the traditional construction method need to be supported horizontally and vertically, and installation and removal are time-consuming and labor-intensive; S32, continue to dig down to the tunnel base on the left or right side of the selected cavern, and after the left and right sides of the selected cavern are respectively dug down to the tunnel base, excavate the unexcavated area in the middle of the selected cavern to the tunnel base.

[0015] As a further improvement to the above solution, in step S4, the following steps are also included: The guide holes on the left and right sides of the top of the proposed tunnel are used as platforms for placing demolition equipment to complete the demolition of supporting rock pillars. The tunnel section is generally excavated in three steps. The upper step always exists before the entire tunnel is completed. Therefore, during the construction of removing the rock pillars on the upper step, there is always a construction path for slag discharge and material feeding on the upper step. The demolition equipment for the rock pillar can be directly placed in the guide holes on the left and right sides of the top of the tunnel, avoiding the traditional construction organization of removing the rock pillar by padding slag and lifting the construction platform after the tunnel falls to the bottom, which is more convenient for the upper step construction and rock pillar excavation.

[0016] See also Figure 4 Based on the three-step method, this construction method divides the cross-section of the station tunnel into upper steps, middle steps and lower steps. The upper steps include the upper left guide tunnel ①, the upper core step ⑦ and the upper right guide tunnel ②, the middle steps include the left middle guide tunnel ③, the middle core step ⑧ and the right middle guide tunnel ④, and the lower steps include the lower left guide tunnel ⑤, the lower core step ⑨ and the lower right guide tunnel ⑥.

[0017] The following is a sequence of excavation steps based on the section where the initial excavation chamber is located. Figure 1-3 First, excavate the construction channel 1 to connect with the upper left pilot tunnel ①, then expand the upper core step ⑦ and the upper right pilot tunnel ② along the tunnel transversely to the full width of the tunnel top to obtain the initial excavation chamber, and simultaneously construct the primary support; in the initial excavation chamber, continue to excavate the upper left pilot tunnel ① and the upper right pilot tunnel ② along the extension direction of the proposed tunnel to the full length of the tunnel, and excavate the upper core step ⑦ at intervals to connect the pilot tunnels on both sides, so as to form multiple sections of supporting rock pillars (i.e., the upper core step ⑦ that has not been excavated yet) in the full length of the tunnel, and primary supports are also required on both sides of the supporting rock pillars; then, on the left side of the initial excavation chamber, The left middle guide hole ③ is excavated downward from the position of the upper guide hole ①, and anchor rods are driven toward the middle core step ⑧ to form a slope support; then the right middle guide hole ④ is excavated downward from the position of the right upper guide hole ② of the initial excavation chamber, and anchor rods are driven toward the middle core step ⑧ to form a slope support; then the left lower guide hole ⑤ and the right lower guide hole ⑥ are further excavated downward, and anchor rods are driven toward the lower core step ⑨ to form a slope support at the same time; after the construction of the left middle guide hole ③, the right middle guide hole ④, the left lower guide hole ⑤ and the right lower guide hole ⑥ are completed, the middle core step ⑧ and the lower core step ⑨ can be excavated step by step from top to bottom. Obviously, in the above excavation sequence, the left lower guide hole ⑤ can be directly excavated downward after the left middle guide hole ③ is completed, and the right lower guide hole ⑥ can be directly excavated downward after the right middle guide hole ④ is completed.

[0018] This method divides the large underground space into multiple miniaturized underground spaces by setting up multiple rock pillars, giving full play to the supporting role of rock pillars and the beneficial role of miniaturized caverns in stabilizing the surrounding rock. Each miniaturized cavern is also an independent construction organization unit, which increases the construction action surface of the tunnel and improves the construction efficiency. The tunnel section is generally excavated in three steps. The upper step always exists before the entire tunnel is completed. Therefore, during the construction of removing the rock pillars on the upper step, there is always a construction path for slag discharge and material feeding on the upper step, which avoids the traditional construction organization of removing the rock pillars by padding the construction platform after the tunnel falls to the bottom, making it more convenient for the upper step construction and rock pillar excavation. At the same time, the method only sets up temporary steel frame initial support on the upper step, while the middle and lower steps adopt spray anchor design, which optimizes the construction sequence and reduces the construction difficulty, further improves the construction efficiency and saves the project investment.

[0019] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A station tunnel space column excavation method, characterized in that: The steps include: S1. Excavate the construction channel to the top of the proposed tunnel, and expand the tunnel horizontally to the full width of the top of the tunnel to obtain the initial excavation chamber; S2. In the initial excavation chamber, guide tunnels are excavated on the left and right sides of the top of the proposed tunnel along the extension direction of the proposed tunnel to the full length of the tunnel, and the middle area of ​​the top of the proposed tunnel is excavated at intervals to connect the guide tunnels on both sides, so as to form multiple sections of supporting rock pillars in the full length of the tunnel, and the multiple sections of the supporting rock pillars divide the full length of the tunnel into multiple small caverns of limited length; S3. Select at least one cavern and dig downward to the full section of the tunnel in the selected cavern, and construct the secondary lining structure of the selected cavern in sections; S4, when the secondary lining structure of the selected cavern approaches the tunnel face, the supporting rock pillar on one side of the selected cavern is broken to connect with the next adjacent cavern, and then the tunnel is expanded downward to the full section of the tunnel in the area where the supporting rock pillar is broken; S5, selecting the next adjacent cavern and repeating steps S3-S4, so as to excavate the proposed tunnel hole by hole until the proposed tunnel is fully connected.

2. The station tunnel space column excavation method according to claim 1 is characterized in that: Step S3 also includes the following sub-steps: S31. Dig down to the designed depth on the left or right side of the selected cavern, and provide temporary protection for the unexcavated area in the middle of the selected cavern based on the slope support technology; S32, continue to dig down to the tunnel base on the left or right side of the selected cavern, and after the left and right sides of the selected cavern are respectively dug down to the tunnel base, excavate the unexcavated area in the middle of the selected cavern to the tunnel base.

3. The station tunnel space column excavation method according to claim 2 or 3, characterized in that: The selected cavern is divided into multiple sections along the extension direction of the proposed tunnel, and each section is excavated downward separately to the full section of the tunnel.

4. The station tunnel space column excavation method according to claim 1 is characterized in that: In step S3, at least one cavern is selected and excavated downward in the selected cavern to the full cross-section of the tunnel, which at least includes simultaneously selecting two caverns to carry out excavation operations in opposite, opposite or same directions.

5. The station tunnel space column excavation method according to claim 1 is characterized in that: In step S4, the following steps are also included: The guide holes on the left and right sides of the top of the proposed tunnel will be used as platforms for placing demolition equipment to complete the demolition of supporting rock pillars.

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