Temporary support node, protective tunnel and air duct synchronous excavation method

Abstract

The invention relates to a synchronous excavation method for a temporary support node, a protective tunnel and an air duct. The synchronous excavation method comprises the following steps: S1, calculating a main body enclosure structure rough hole anchoring and shotcreting support parameter, a secondary lining parameter and a rough hole anchoring and shotcreting support parameter of the air duct; s2, determining the position of a pre-buried air pipe and an excavation outer contour line of a corresponding underground excavation air duct; s3, the positions of temporary support nodes are drawn up, and all parameters of the temporary support nodes are calculated; s4, synchronous excavation is conducted on the main body enclosure structure and the rough hole section of the air duct, and a supporting base plate is pre-buried in surrounding rock at the intersection; anchor-shotcrete supporting is carried out in time; s5, vertical profile steel supports are erected according to the set spacing requirement and welded to the supporting base plates; s6, longitudinal connecting ribs are arranged according to the prepared spacing requirement; s7, embedding an air pipe; and S8, the temporary supporting joints are dismantled according to needs, and secondary lining is conducted. The air duct can be synchronously excavated on the outer side of the side wall of the protective tunnel, the excavation and backfill work amount is reduced, and therefore the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of underground engineering construction, and particularly relates to a temporary support node, a synchronous excavation method for a protective tunnel and an air duct. Background Art

[0002] The tunnel structure is a structural form often adopted in national defense and civil air defense projects, and has the characteristics of strong protection ability, small load acting on the main retaining structure of the tunnel project, and large shelter capacity inside the project. From the perspective of protection, as long as the functional requirements of the project can be met and the engineering geological conditions permit, tunnel projects should be constructed as much as possible. When designing tunnel projects, ventilation ducts will be arranged at different positions according to different protection areas. Among them, at the entrance and exit, considering the protection requirements, the ventilation ducts are generally buried outside the retaining structure of the entrance and exit, and are protected by wrapping a certain thickness of concrete.

[0003] Generally, the buried ventilation duct is a circular steel plate air duct with a diameter generally not exceeding 2 meters. For the pre-burial of the air duct, it is necessary to pre-excavate a civil air duct with a matching size. There are generally two schemes for the construction of this pre-excavated air duct: 1. First, excavate and support according to the cross-sectional size of the primary hole of the main retaining structure, and then separately excavate and support the pre-excavated air duct outside the retaining structure according to the process requirements; 2. Synchronously excavate and support according to the cross-sectional size of the large envelope of the main retaining structure and the pre-excavated air duct. In the above two schemes, in Scheme 1, there are problems such as local secondary excavation and secondary support of the surrounding rock on the outside of the side wall, and the need to locally break the initial support of the main retaining structure first before the air duct excavation can be carried out; in Scheme 2, there are problems such as large excavation and backfilling quantities, the need to strengthen the initial support parameters, and an increase in safety hazards caused by the increase in the excavation span when excavating and supporting according to the cross-sectional size of the large envelope, and all of these will cause an increase in the project cost.

[0004] Therefore, it is necessary to provide a temporary support node, a synchronous excavation method for a protective tunnel and an air duct, to synchronously excavate the air duct outside the side wall of the protective tunnel, and reduce the excavation and backfilling quantities, thereby reducing the cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a temporary support node, a synchronous excavation method for a protective tunnel and an air duct, to synchronously excavate the air duct outside the side wall of the protective tunnel, and reduce the excavation and backfilling quantities, thereby reducing the cost.

[0006] In order to solve the problems existing in the prior art, the present invention provides a temporary support node, which is located at the intersection of the pre-excavated air duct and the main retaining structure of the protective tunnel. The temporary support node includes: a plurality of vertical steel supports, a plurality of support pads, a plurality of longitudinal connecting sleeves, and a plurality of longitudinal connecting bars;

[0007] The supporting pad includes a top pad and a bottom pad corresponding to each other, the top pad and the bottom pad are respectively located in the top surrounding rock and the bottom surrounding rock at the intersection of the dark excavation air duct and the main enclosure structure of the protective tunnel, and the top pad and the corresponding bottom pad are located in the same vertical plane;

[0008] The vertical steel support is arranged along the vertical direction, and the horizontal cross section of the vertical steel support is in the shape of an "I" character. The two parallel surfaces in the vertical steel support are called parallel plates, and the vertical surface connecting the two parallel plates is called a web. The top and bottom ends of the vertical steel support are welded to the top pad and the bottom pad, respectively.

[0009] The longitudinal connecting sleeve is welded to the web, the longitudinal connecting rib is inserted into the longitudinal connecting sleeve, and the longitudinal connecting rib is arranged along the horizontal direction.

[0010] Optionally, in the temporary support node, there is a spacing between each vertical steel support, and there is a spacing between each longitudinal connecting rib.

[0011] Optionally, in the temporary support node, the top pad is in close contact with the top surrounding rock, and the bottom pad is in close contact with the bottom surrounding rock.

[0012] Optionally, in the temporary support node, the temporary support node is a removable structure.

[0013] The present invention also provides a method for synchronous excavation of a protective tunnel and a wind tunnel, using the temporary support node, and the synchronous excavation method comprises the following steps:

[0014] S1: Calculate the anchor-spray support parameters and secondary lining parameters of the rough hole of the main retaining structure of the protective tunnel according to the rough hole cross-sectional dimensions, engineering geological conditions and hydrogeological conditions, and also calculate the rough hole anchor-spray support parameters of the dark excavated air duct outside the side wall of the main retaining structure;

[0015] S2: Determine the location of the pre-buried air duct and the outer contour of the corresponding dark excavated air duct according to the diameter of the pre-buried air duct, the thickness of the concrete covering the air duct, and the thickness of the shotcrete layer;

[0016] S3: Determine the required support height of the vertical steel support according to the proposed excavation outer contour line, and plan to set the temporary support node at the intersection of the dark excavation air duct and the main enclosure structure, and calculate the parameters of the temporary support node in combination with the engineering geological conditions;

[0017] S4: Synchronously excavate the primary enclosure structure and the blind-drift air duct according to the excavation outline of the primary enclosure structure and the blind-drift air duct, and embed the top and bottom pads of the support pad in the surrounding rock at the intersection, so that the top and bottom pads correspond one by one, and the top pad and the corresponding bottom pad are located in the same vertical plane; after embedding the support pad, promptly carry out the construction of shotcrete support.

[0018] S5: Erect vertical steel supports according to the longitudinal layout spacing requirements of the proposed vertical steel supports, and weld them to the top and bottom pads.

[0019] S6: Weld longitudinal connecting sleeves to the webs of the vertical steel supports according to the longitudinal connecting bar layout spacing requirements of the proposal. After welding, insert longitudinal connecting bars, and fix them by spot welding between the longitudinal connecting bars and the sleeves.

[0020] S7: After the temporary support nodes are completed, embed the air duct according to the proposed air duct position, and pour the concrete for the outer concrete wall of the air duct.

[0021] S8: After the concrete reaches the design strength, demolish the temporary support nodes as required, arrange the secondary lining steel bars, and pour the secondary lining.

[0022] Optionally, in the synchronous excavation method of the protective tunnel and the air duct, the parameters of the temporary support nodes include:

[0023] The thickness, length and width of the support pad;

[0024] The spacing between each vertical steel support, the thickness of the web, the width of the two parallel plates, and the distance between the outer sides of the two parallel plates;

[0025] The spacing between each longitudinal connecting bar and the diameter of the longitudinal connecting bar.

[0026] Optionally, in the synchronous excavation method of the protective tunnel and the air duct, the thickness range of the concrete for the outer wall of the air duct is 200 mm.

[0027] Optionally, in the synchronous excavation method of the protective tunnel and the air duct, when embedding the top and bottom pads of the support pad, remove the loose slag at the contact part to ensure that the top of the vertical steel support is in close contact with the top surrounding rock, and the bottom of the vertical steel support is in close contact with the bottom surrounding rock.

[0028] Optionally, in the synchronous excavation method of the protective tunnel and the air duct, before embedding the air duct, carry out anti-corrosion measures and fire prevention measures.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) Synchronously excavate the air duct outside the side wall of the protective tunnel, and reduce the excavation and backfilling work volume, thereby reducing the cost.

[0031] (2) It solves the safety hazard problem caused by the increase in the excavation span during synchronous excavation construction.

[0032] (3) By building temporary support nodes, it avoids the problem of increasing the initial support parameters due to the increase in the excavation span. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the synchronous excavation section provided by an embodiment of the present invention;

[0034] Figure 2 It is a schematic plan view of the temporary support node provided by an embodiment of the present invention;

[0035] Figure 3 It is a schematic connection diagram of the vertical steel support and the support backing plate provided by an embodiment of the present invention;

[0036] Figure 4 It is a schematic installation diagram of the longitudinal connecting bars provided by an embodiment of the present invention;

[0037] Figure 5 It is a horizontal sectional view when the vertical steel support is vertically installed provided by an embodiment of the present invention;

[0038] Figure 6 It is a schematic diagram of the sectional view of the concrete outer casing of the air duct provided by an embodiment of the present invention.

[0039] 1 - Support backing plate; 2 - Vertical steel support; 3 - Longitudinal connecting sleeve; 4 - Longitudinal connecting bar; 5 - Excavation outline; 6 - Shotcrete layer; 7 - Anchor bolt; 8 - Air duct; 9 - Main retaining structure; 10 - Subsurface excavation air duct; 11 - Secondary lining steel bars; 12 - Outer casing concrete. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following will describe the specific embodiments of the present invention in more detail with reference to the schematic diagrams. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are all in a very simplified form and use non-precise scales, only for the purpose of conveniently and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0041] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0042] Both of the two solutions in the prior art will cause an increase in the project cost.

[0043] To solve the problems existing in the prior art, the present invention provides a temporary support node, and the temporary support node is located at the intersection of the mined tunnel 10 and the main retaining structure 9 of the protective tunnel. As Figures 1-6 described, the temporary support node includes: a plurality of vertical steel supports 2, a plurality of support pads 1, a plurality of longitudinal connecting sleeves 3, and a plurality of longitudinal connecting bars 4;

[0044] The support pad 1 includes a corresponding top pad and bottom pad, and the top pad and bottom pad are respectively located in the top surrounding rock and bottom surrounding rock at the intersection of the mined tunnel 10 and the main retaining structure 9 of the protective tunnel. Referring to Figure 1 , the top end of the vertical steel support 2 is in close contact with the top surrounding rock, the bottom end of the vertical steel support 2 is in close contact with the bottom surrounding rock, and the top pad and the corresponding bottom pad are located in the same vertical plane;

[0045] The vertical steel support 2 is arranged in the vertical direction, and the horizontal cross-section of the vertical steel support 2 is in the shape of "I". The two parallel surfaces in the vertical steel support 2 are called parallel plates, and the vertical surface connecting the two parallel plates is called the web. The top end and the bottom end of the vertical steel support 2 are respectively welded to the top pad and the bottom pad (as Figure 3 shown);

[0046] The longitudinal connecting sleeve 3 is welded to the web, the longitudinal connecting bar 4 is inserted into the longitudinal connecting sleeve 3, and the longitudinal connecting bar 4 is arranged in the horizontal direction. In one embodiment, as Figure 4 shown, the webs of adjacent vertical steel supports 2 are parallel, and the end of the longitudinal connecting bar 4 is bent and inserted into the longitudinal connecting sleeve 3. In this case, the longitudinal connecting sleeve 3 is perpendicular to the longitudinal connecting bar 4.

[0047] Preferably, as Figure 2 shown, there is a spacing S between the vertical steel supports 2, and there is a spacing D (not shown in the figure) between the longitudinal connecting bars 4.

[0048] Preferably, the temporary support node is a removable structure.

[0049] The present invention also provides a method for synchronous excavation of a protective tunnel and a wind tunnel, using the temporary support node, referring to Figures 1-6 , the synchronous excavation method comprises the following steps:

[0050] S1: Calculate the anchor and spray support parameters of the rough hole of the main enclosure structure 9 and the secondary lining parameters according to the rough hole cross-sectional dimensions of the main enclosure structure 9 of the protective tunnel, the engineering geological conditions and the hydrogeological conditions, and also calculate the rough hole anchor and spray support parameters of the dark excavated air duct 10 outside the side wall of the main enclosure structure 9, the thickness of the outer concrete 12 of the air duct 8 and the thickness of the sprayed concrete layer 6, etc.;

[0051] S2: According to the diameter of the air duct 8 to be buried ( Figure 1 DN), the thickness of the concrete 12 (usually 200 mm) wrapped around the air duct 8, and the thickness of the shotcrete layer 6, determine the position of the pre-buried air duct 8 and the corresponding excavation outer contour line 5 of the dark excavated air duct 10; the air duct 8 is generally laid close to the bottom plate ground, and the distance from the center of the air duct 8 to the bottom plate excavation outer contour line 5 and the dark excavated air duct 10 excavation outer contour line 5 is ≥ DN / 2+200mm (the position is shown in the figure below). Figure 1 Anchor rods 7 are arranged around the outer contour line 5 for supporting purposes.

[0052] S3: Determine the required support height of the vertical steel support 2 according to the proposed excavation outer contour line 5 (such as Figure 1 H), and it is proposed to set the temporary support node at the intersection of the dark excavation air duct 10 and the main enclosure structure 9, and calculate the parameters of the temporary support node in combination with the engineering geological conditions; the parameters of the temporary support node include: the thickness (e.g. 15 mm), length (e.g. 200 mm) and width (e.g. 200 mm) of the support pad 1; the spacing S between the vertical steel supports 2, the thickness of the web ( Figure 5 Medium w ), the width of the two parallel plates ( Figure 5 In the figure, the distance between the outer edges of the two parallel plates ( Figure 5 The distance D between the longitudinal connecting ribs 4 and the diameter of the longitudinal connecting ribs 4 are represented by h, for example 180 mm);

[0053] S4: Synchronously excavate the main body enclosure structure 9 and the blind-drift air duct 10 according to the excavation outline line 5 of the main body enclosure structure 9 and the air duct, and embed the top and bottom pads of the support pad 1 in the surrounding rock at the intersection, so that the top and bottom pads correspond one by one, and the top pad and the corresponding bottom pad are located in the same vertical plane. When embedding the top and bottom pads of the support pad 1, remove the loose slag at the contact part to ensure that the top of the vertical steel support 2 is in close contact with the top surrounding rock and the bottom of the vertical steel support 2 is in close contact with the bottom surrounding rock. After embedding the support pad 1, promptly carry out the shotcrete support construction.

[0054] S5: According to the requirement of the longitudinal layout spacing S of the planned vertical steel support 2, erect the vertical steel support 2 and weld it to the top and bottom pads, and the welding quality shall meet the requirements of relevant specifications.

[0055] S6: According to the requirement of the layout spacing D of the planned longitudinal connecting bars 4, weld the longitudinal connecting sleeves 3 to the webs of the vertical steel supports 2. After welding, insert the longitudinal connecting bars 4, and fix the longitudinal connecting bars 4 and the sleeves by spot welding, and the welding quality shall meet the requirements of relevant specifications.

[0056] S7: Refer to Figure 6 , after the temporary support nodes are completed, embed the air duct 8 according to the planned position of the air duct 8, and then pour the concrete 12 wall outside the air duct 8 with concrete not less than C20 grade to ensure that the thickness of the concrete 12 outside the air duct 8 meets the previously planned requirements. Among them, before embedding the air duct 8, carry out anti-corrosion measures and fire prevention measures.

[0057] S8: After the concrete reaches the design strength, demolish the temporary support nodes as required, arrange the secondary lining steel bars 11, and pour the secondary lining.

[0058] In summary, compared with the prior art, the present invention has the following advantages:

[0059] (1) Synchronously excavate the air duct outside the side wall of the protective tunnel, and reduce the excavation and backfilling workload, thereby reducing the cost.

[0060] (2) Solve the safety hazard problem caused by the increase in excavation span during synchronous excavation construction.

[0061] (3) By building temporary support nodes, avoid the problem of increasing the initial support parameters due to the increase in excavation span.

[0062] The above are only the preferred embodiments of the present invention and do not impose any restrictive effect on the present invention. Any person skilled in the art, within the scope of the technical solution of the present invention, makes any form of equivalent substitution or modification and other changes to the technical solution and technical content disclosed by the present invention, which are all within the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. A temporary support node, characterized in that: The temporary support node is located at the intersection of the dark excavation air duct and the main enclosure structure of the protective tunnel, and the temporary support node includes: a plurality of vertical steel supports, a plurality of support pads, a plurality of longitudinal connecting sleeves and a plurality of longitudinal connecting ribs; The supporting pad includes a top pad and a bottom pad corresponding to each other, the top pad and the bottom pad are respectively located in the top surrounding rock and the bottom surrounding rock at the intersection of the dark excavation air duct and the main enclosure structure of the protective tunnel, and the top pad and the corresponding bottom pad are located in the same vertical plane; The vertical steel support is arranged along the vertical direction, and the horizontal cross section of the vertical steel support is in the shape of an "I" character. The two parallel surfaces in the vertical steel support are called parallel plates, and the vertical surface connecting the two parallel plates is called a web. The top and bottom ends of the vertical steel support are welded to the top pad and the bottom pad, respectively. The longitudinal connecting sleeve is welded to the web, the longitudinal connecting rib is inserted into the longitudinal connecting sleeve, and the longitudinal connecting rib is arranged along the horizontal direction.

2. The temporary support node according to claim 1, characterized in that: There is a spacing between each vertical steel support and a spacing between each longitudinal connecting reinforcement.

3. The temporary support node according to claim 1, characterized in that: The top pad is in close contact with the top surrounding rock, and the bottom pad is in close contact with the bottom surrounding rock.

4. The temporary support node according to claim 1, characterized in that: The temporary support node is a removable structure.

5. A method for synchronous excavation of a protective tunnel and an air duct, characterized in that: Using the temporary support node according to any one of claims 1 to 4, the synchronous excavation method comprises the following steps: S1: Calculate the anchor-spray support parameters and secondary lining parameters of the rough hole of the main retaining structure of the protective tunnel according to the rough hole cross-sectional dimensions, engineering geological conditions and hydrogeological conditions, and also calculate the rough hole anchor-spray support parameters of the dark excavated air duct outside the side wall of the main retaining structure; S2: Determine the location of the pre-buried air duct and the outer contour of the corresponding dark excavated air duct according to the diameter of the pre-buried air duct, the thickness of the concrete covering the air duct, and the thickness of the shotcrete layer; S3: Determine the required support height of the vertical steel support according to the proposed excavation outer contour line, and plan to set the temporary support node at the intersection of the dark excavation air duct and the main enclosure structure, and calculate the parameters of the temporary support node in combination with the engineering geological conditions; S4: According to the excavation outer contours of the main enclosure structure and the dark excavated air duct, the rough hole sections of the main enclosure structure and the air duct are excavated synchronously, and the top pad and the bottom pad of the support pad are pre-buried in the surrounding rock at the intersection, so that the top pad and the bottom pad correspond to each other one by one, and the top pad and the corresponding bottom pad are located in the same vertical plane; after the support pad is pre-buried, the anchor spraying support is carried out in time; S5: According to the proposed longitudinal arrangement spacing requirements of the vertical steel supports, erect the vertical steel supports and weld them with the top pad and the bottom pad; S6: According to the proposed longitudinal connecting rib arrangement spacing requirements, the longitudinal connecting sleeve is welded to the web of the vertical steel support, and after welding, the longitudinal connecting rib is inserted, and the longitudinal connecting rib and the sleeve are fixed by spot welding; S7: After the temporary support node is completed, bury the air duct according to the planned air duct position, and cast the air duct with concrete to cover the concrete wall; S8: After the concrete reaches the design strength, remove the temporary support nodes as needed, arrange the secondary lining reinforcement, and pour the secondary lining.

6. The method for synchronous excavation of a protective tunnel and an air duct according to claim 5, characterized in that: The parameters of temporary support nodes include: Thickness, length and width of the support pad; The spacing between each vertical steel support, the thickness of the web, the width of the two parallel plates, and the distance between the outer edges of the two parallel plates; The spacing between each longitudinal connecting rib and the diameter of the longitudinal connecting rib.

7. The method for synchronous excavation of a protective tunnel and an air duct according to claim 5, characterized in that: The thickness of the concrete covering the air duct is in the range of 200 mm.

8. The method for synchronous excavation of a protective tunnel and an air duct according to claim 5, characterized in that: When the top and bottom pads of the support pad are embedded, remove the loose slag at the contact parts to ensure that the top of the vertical steel support is in close contact with the top surrounding rock, and the bottom of the vertical steel support is in close contact with the bottom surrounding rock.

9. The method for synchronous excavation of a protective tunnel and an air duct according to claim 5, characterized in that: Before burying the air duct, take anti-corrosion and fire prevention measures.

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