Soft stratum hyperbolic curve arch-shaped hole-entering first-supporting-and-then-breaking underground excavation structure and construction method

Abstract

The invention discloses a soft stratum hyperbolic curve arch-shaped hole-entering first-supporting-and-then-breaking underground excavation structure and a construction method, and aims to solve the related problem of main body construction of underground excavation of a transverse channel of a station in urban subway construction. A main body tunnel is excavated by adopting a hyperbolic curve arch-shaped hole-entering first-supporting and then-breaking underground excavation mode at a connection section of a construction transverse channel and the main body tunnel, and the arch crown of the excavation construction transverse channel and the connection section of the main body tunnel is kept consistent with an upward convex radian curve of the arch crown of the main body tunnel in the longitudinal direction; a tunnel portal opening grating steel frame and a tunnel portal opening profile steel frame are arranged at the arch-shaped tunnel entrance of the main body tunnel, and a main body tunnel grating steel frame and a main body tunnel profile steel frame are erected at the position of a tunnel portal for structural pouring. According to the subsurface excavation construction method suitable for the soft stratum hyperbolic curve arch-shaped hole entering, the construction steps are effectively reduced, the construction efficiency is improved, the construction risk is reduced, and compared with a traditional construction method, the safety, the construction efficiency and the like of a transverse channel entering main body hidden project can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel engineering, and particularly relates to a support-before-break dark excavation structure in a soft stratum hyperbolic arch-shaped tunnel and a construction method thereof. Background Art

[0002] With the construction of urban subways, underground tunnel stations are increasingly being used in urban rail transit. Among them, the construction of the main body of the transverse channel is an essential part of the construction of the underground tunnel station. The transverse channel entering the main body is generally divided into two methods: gantry-type flat-top entry and arched entry. Both methods are widely used in construction projects such as subways, railway tunnels, and highway tunnels. Since the method of entering the main body of the transverse channel is a concealed project, in actual construction, there are many factors that affect its construction quality, and the construction quality is difficult to control. In addition, due to problems such as the conversion of the force system, there is a high possibility of safety problems occurring here, and it is easy to cause monitoring data to exceed the standard, roof collapse, support frame deformation, and limit violation. In order to solve the above problems, a new method of entering the main body of the transverse channel into the arched hole is proposed. Summary of the Invention

[0003] In response to the deficiencies in the prior art, the present invention provides a soft stratum hyperbolic arch tunneling structure with support first and then breaking and a construction method, which can improve the stability of the tunnel during construction, reduce surface settlement, and ensure construction safety.

[0004] The present invention achieves this object through the following technical solutions:

[0005] The present invention provides a method for underground excavation in a soft stratum by supporting first and breaking later with a hyperbolic arched tunnel, comprising the following steps:

[0006] Step S1, constructing the advanced support, support and channel structure of the standard section of the cross channel;

[0007] Step S2: excavating the soil above the connecting section between the construction transverse passage and the main tunnel. The construction transverse passage arch of the connecting section presents an upward convex arc curve of the main tunnel arch in the longitudinal direction, forming a hyperbolic arch structure in both the transverse and longitudinal directions.

[0008] Step S3: constructing advance support for the connecting section between the cross passage and the main tunnel, including double rows of small guide tubes at the top and side wall anchors;

[0009] Step S4: The support profile of the connection section between the construction cross passage and the main tunnel adopts a straight side wall design of the arch near the main tunnel side. The construction cross passage grid steel frame supporting the connection section between the construction cross passage and the main tunnel is arranged along the arch. On the excavation side of the main tunnel, the outermost first steel pad of the support-before-break steel portal frame is welded to the main reinforcement of the arch construction cross passage grid steel frame adjacent to the side wall. The connection section between the construction cross passage and the main tunnel is supported by sprayed concrete.

[0010] Step S5: After the support shotcrete of the connection section between the construction cross passage and the main tunnel reaches a certain strength, the construction cross passage locking anchor rods are installed at the position of the construction cross passage grid steel frame in the connection section between the construction cross passage and the main tunnel along the contour line of the main tunnel entrance excavation surface, and then the main tunnel advance middle pipe shed is installed above the contour line of the main tunnel entrance excavation surface;

[0011] Step S6: welding the main structure of the steel portal frame to the first steel plate in the support of the connecting section between the cross passage and the main tunnel near the main tunnel side;

[0012] Step S7: dismantle the supporting structure of the construction cross passage and the main tunnel connection section and the side wall anchors within the main tunnel construction range on the main tunnel side, and weld the exposed construction cross passage grid steel frame to the construction cross passage locking anchors;

[0013] Step S8: excavate the upper soil of the main tunnel, set up the main tunnel grid steel frame at the main tunnel entrance, and spray concrete for pouring;

[0014] Step S9, erecting the main tunnel steel frame inside the cast main tunnel grid steel frame and spraying concrete for casting;

[0015] Step S10, erecting a gate grille steel frame at a position corresponding to the projection of the main tunnel grille steel frame inside the first-support-then-break steel door frame, and erecting a gate steel frame at a position corresponding to the projection of the main tunnel steel frame inside the gate grille steel frame;

[0016] Step S11, continue to excavate the upper soil of the main tunnel forward, continue to erect the main tunnel grid steel frame along the main tunnel steel frame sprayed concrete structure and spray concrete for pouring;

[0017] Step S12, excavating the soil below the connecting section between the cross passage and the main tunnel and the soil below the main tunnel;

[0018] Step S13: construct the main tunnel structure and the secondary lining structure of the transverse passage;

[0019] Step S14: construct the structural mid-plate and other internal structures.

[0020] Furthermore, the overall structure of the supported-before-broken steel gantry is as follows: a second steel plate is arranged inside the first steel plate, a first steel plate is welded between the first and second steel plates, a third and fourth steel plates are arranged inside the second steel plate, a second steel plate is welded between the third and fourth steel plates, and the second and third steel plates are connected by bolts.

[0021] Furthermore, the first and second steel sections are double-pieced Ⅰ25a steel sections, with the first steel section facing the longitudinal direction of the main tunnel and evenly arranged circumferentially between the first steel plate and the second steel plate; the second steel section is facing perpendicular to the longitudinal direction of the main tunnel and is circumferentially welded to the third steel plate and the fourth steel plate along the contour of the support-first-break-later steel frame.

[0022] Furthermore, the double rows of small conduits in the construction of the cross channel are used The length of the advance small duct shall be no less than 4.5m. The external insertion angle of the two rows of small ducts shall be adjusted according to the curvature of the arch, and the overlap length shall be no less than 2m.

[0023] Furthermore, the locking anchor rods for the construction cross channel are made by driving two hollow anchor rods into each construction cross channel grid steel frame, and the length of the anchor rods shall not be less than 6m.

[0024] Furthermore, the main tunnel advance pipe shed adopts For pipe roof, the external insertion angle is 1 to 3 degrees.

[0025] Furthermore, after the main tunnel soil is excavated in step S8, 3 to 4 main tunnel grid steel frames are erected at the tunnel excavation entrance.

[0026] Furthermore, steel plates are respectively provided on the interface between the portal grille steel frame and the portal section steel frame, and between the main tunnel grille steel frame and the main tunnel section steel frame, and the two interface steel plates are connected by bolts.

[0027] Furthermore, steel bars are used to connect the portal grille steel frame and the main tunnel grille steel frame, as well as the portal steel frame and the main tunnel steel frame, longitudinally, and the inner and outer sides of the steel bars should be staggered.

[0028] The present invention also provides a soft stratum hyperbolic arch-shaped tunneling structure with support first and then breaking, which is constructed according to any of the above methods.

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

[0030] The technical solution proposed in the present invention can solve the related problems of the construction of underground excavation station cross passages into the main body during urban subway construction. Compared with traditional construction methods, it can effectively improve the safety and construction efficiency of the hidden engineering of the cross passages into the main body. The present invention adopts a underground excavation construction method of supporting first and then breaking the hyperbolic arch into the soft stratum, which effectively reduces the construction steps, improves construction efficiency and reduces construction risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The construction steps of the embodiment of the present invention are as follows Figure 1 ;

[0032] Figure 2The construction steps of the embodiment of the present invention are as follows Figure 2 ;

[0033] Figure 3 The construction steps of the embodiment of the present invention are as follows Figure 3 ;

[0034] Figure 4 The construction steps of the embodiment of the present invention are as follows Figure 4 ;

[0035] Figure 5 The construction steps of the embodiment of the present invention are as follows Figure 5 ;

[0036] Figure 6 The construction steps of the embodiment of the present invention are as follows Figure 6 ;

[0037] Figure 7 The construction steps of the embodiment of the present invention are as follows Figure 7 ;

[0038] Figure 8 The construction steps of the embodiment of the present invention are as follows Figure 8 ;

[0039] Figure 9 The construction steps of the embodiment of the present invention are as follows Figure 9 ;

[0040] Figure 10 The construction steps of the embodiment of the present invention are as follows Figure 10 ;

[0041] Figure 11 The construction steps of the embodiment of the present invention are as follows Figure 10 one;

[0042] Figure 12 The construction steps of the embodiment of the present invention are as follows Figure 10 two;

[0043] Figure 13 This is a schematic diagram of the overall structure of the main tunnel direction of an embodiment of the present invention;

[0044] Figure 14 for Figure 9 A partial enlarged view of the middle A;

[0045] Figure 15 This is a schematic diagram of the structure of the steel portal frame that is supported first and then broken in an embodiment of the present invention.

[0046] Reference numerals in the figure: 1-double row of small ducts, 2-side wall anchor rods, 3-construction cross channel grid steel frame, 4-construction cross channel locking foot anchor rods, 5-main tunnel advance middle pipe shed, 6-support first and then break steel door frame, 7-opening door grid steel frame, 8-opening door steel frame, 9-main tunnel grid steel frame, 10-main tunnel steel frame, 11-construction cross channel second lining structure, 12-main tunnel structure, 13-structural middle plate, 601-first steel pad, 602-first steel, 603-second steel pad, 604-third steel pad, 605-second steel, 606-fourth steel pad. DETAILED DESCRIPTION

[0047] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present invention and the features within the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0048] The present invention provides an embodiment of a construction method for a double-curved arched tunnel in a soft stratum, wherein support is first provided and then broken. Figure 1-15 , the construction method comprises the following steps:

[0049] Step S1, constructing the advance support, support and channel structure of the standard section of the transverse channel.

[0050] Step S2: excavate the upper soil of the connecting section between the construction transverse passage and the main tunnel. The construction transverse passage arch of the connecting section presents an upward convex arc curve of the main tunnel arch in the longitudinal direction, forming a hyperbolic arch structure in both the horizontal and vertical directions.

[0051] Step S3: construct the advance support of the connecting section between the cross passage and the main tunnel, including the double rows of small guide tubes 1 and side wall anchor rods 2 at the top.

[0052] As a preferred method, the double-row small conduits 1 in the construction of the horizontal channel are used The length of the leading small duct is not less than 4.5m. The external insertion angle of the two rows of small ducts 1 is adjusted according to the curvature of the hyperbolic plate, and the overlap length is not less than 2m.

[0053] Step S4, the support contour of the connection section between the construction cross channel and the main tunnel adopts the arch straight side wall design close to the main tunnel side, and the construction cross channel grid steel frame 3 supporting the connection section between the construction cross channel and the main tunnel is arranged along the arch. On the excavation side of the main tunnel, the outermost first steel pad 601 of the support-before-break steel door frame 6 is welded to the main reinforcement of the arch construction cross channel grid steel frame 3 adjacent to the side wall, and the connection section between the construction cross channel and the main tunnel is supported by sprayed concrete.

[0054] Close to the main tunnel side, the support of the connecting section between the construction cross passage and the main tunnel is expanded outward to reserve space for erecting a first-support-then-break-door type steel frame 6.

[0055] Step S5, after the support shotcrete of the connection section between the construction cross channel and the main tunnel reaches the strength, the construction cross channel locking anchor rod 4 is installed at the position of the construction cross channel grid steel frame 3 in the support of the connection section between the construction cross channel and the main tunnel along the contour line of the main tunnel entrance excavation surface, and then the main tunnel advance middle pipe shed 5 is installed above the contour line of the main tunnel entrance excavation surface.

[0056] Preferably, the construction cross channel locking anchor rods 4 are provided with two hollow anchor rods per construction cross channel grid steel frame 3, and the length of the anchor rods is not less than 6m.

[0057] As a preferred option, the main tunnel advance pipe shed 5 adopts For pipe roof, the external insertion angle is 1 to 3 degrees.

[0058] Step S6, welding the main structure of the first-support-then-break steel portal frame 6 to the first steel pad 601 inside the support of the connecting section between the cross passage and the main tunnel near the main tunnel side.

[0059] like Figure 15 As shown, the overall structure of the supported-before-broken steel gantry 6 is as follows: a second steel plate 603 is arranged inside the first steel plate 601, a first steel section 602 is welded between the first steel plate 601 and the second steel plate 603, a third steel plate 604 and a fourth steel plate 606 are arranged inside the second steel plate 603, a second steel section 605 is welded between the third steel plate 604 and the fourth steel plate 606, the second steel plate 603 and the third steel plate 604 are connected by bolts, and the outline of the fourth steel plate 606 is consistent with the outline of the main tunnel entrance excavation surface. Figure 15 (a) and Figure 15 (b) is a schematic diagram of the structure of the first-support-then-broken steel portal frame 6 from different angles.

[0060] Preferably, the first steel section 602 and the second steel section 605 are double-pieced Ⅰ25a steel sections, with the first steel section 602 facing the longitudinal direction of the main tunnel and being evenly arranged circumferentially between the first steel plate 601 and the second steel plate 603; the second steel section 605 faces perpendicular to the longitudinal direction of the main tunnel and is circumferentially welded to the third steel plate 604 and the fourth steel plate 606 along the contour of the support-before-break steel gantry 6.

[0061] Preferably, the size of the first steel plate 601 in the supported-before-broken steel door frame 6 is not less than 450mm (length) × 350mm (width) × 10mm (height), and the size of the second steel plate 603, the third steel plate 604, and the fourth steel plate 606 is not less than 300mm (length) × 350mm (width) × 10mm (height).

[0062] Preferably, the height and inclination angle of the first section steel 602 in the first-support-then-break section steel door frame 6 should be adjusted according to the actual situation on site.

[0063] Preferably, the second steel plate 603 and the third steel plate 604 in the first-support-then-break steel door frame 6 are connected by M27 bolts with a bolt length of 70 mm and a steel plate opening of 30 mm.

[0064] Step S7, dismantle the construction cross channel and the main tunnel connection section support structure and the side wall anchor rods 2 within the main tunnel construction range on the main tunnel side, and weld the cut construction cross channel grid steel frame 3 and the construction cross channel locking foot anchor rods 4.

[0065] A connecting steel plate can be reserved at the cutoff position of the construction cross channel grid steel frame 3, an anchor rod connecting hole can be reserved on the connecting steel plate, and then the construction cross channel locking foot anchor rod 4 can be welded to the connecting steel plate.

[0066] Step S8: excavate the upper soil of the main tunnel, set up the main tunnel grid steel frame 9 at the main tunnel entrance, and spray concrete for pouring.

[0067] Preferably, the number of main tunnel grid steel frames 9 connected at the tunnel excavation entrance is 3 to 4.

[0068] Step S9: erecting the main tunnel section steel frame 10 inside the cast main tunnel grid steel frame 9 and spraying concrete for casting.

[0069] Preferably, steel plates are provided on the interface between the main tunnel grid steel frame 9 and the main tunnel section steel frame 10, and the two interface steel plates are connected by bolts.

[0070] Step S10, erecting the opening door grille steel frame 7 at the corresponding position of the main tunnel grille steel frame 9 inside the first support and then break steel door frame 6, and erecting the opening door steel frame 8 at the corresponding position of the main tunnel steel frame 10 inside the opening door grille steel frame 7.

[0071] Preferably, the portal grille steel frame 7 and the main tunnel grille steel frame 9, and the portal section steel frame 8 and the main tunnel section steel frame 10 are connected longitudinally with steel bars, and the inner and outer sides of the steel bars should be staggered.

[0072] Preferably, steel plates are provided on the interface between the opening door grille steel frame 7 and the opening door section steel frame 8, and the two interface steel plates are connected by bolts.

[0073] Step S11, continue to excavate the upper soil of the main tunnel forward, continue to erect the main tunnel grid steel frame 9 along the main tunnel steel frame 10 sprayed concrete structure and spray concrete for pouring.

[0074] Step S12: excavate the soil below the connecting section between the cross passage and the main tunnel and the soil below the main tunnel.

[0075] Step S13: construct the main tunnel structure 12 and the secondary lining structure 11 of the transverse passage.

[0076] Step S14: construct the structural middle plate 13 and other internal structures.

[0077] The final structure of the connection section between the construction cross passage and the main tunnel is as follows: Figure 12 、 Figure 13 shown.

[0078] The arch foot of the main tunnel support (including the main tunnel grid steel frame and shotcrete structure and the main tunnel steel frame and shotcrete structure) and the first-support-then-break steel door frame, portal grid steel frame, and portal steel frame are all erected on the rock surface after the upper soil of the main tunnel is hollowed out. During tunnel construction, special attention should be paid to the protection of the rock surface at the bottom of the main tunnel support arch foot and the rock mass below. If necessary, pre-splitting blasting technology can be used to reduce disturbance and damage to the rock surface at the bottom of the main tunnel support arch foot and the surrounding rock.

[0079] The present invention has been described in detail above through the embodiments, but the contents described are only exemplary embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. The scope of protection of the present invention is defined by the claims. Any use of the technical solution described in the present invention, or any person skilled in the art who, inspired by the technical solution of the present invention, designs a similar technical solution within the essence and scope of protection of the present invention to achieve the above-mentioned technical effects, or any equivalent changes and improvements made to the scope of application, shall still fall within the scope of protection covered by the patent of the present invention. It should be noted that for the sake of clarity, the description of some components and processes that have no direct and obvious connection with the scope of protection of the present invention but are known to those skilled in the art are omitted in the description of the present invention.

Claims

1. A method for underground excavation in a soft stratum with a hyperbolic arched tunnel, first supporting and then breaking, characterized in that: The following steps are involved: Step S1, constructing the advanced support, support and channel structure of the standard section of the cross channel; Step S2: excavating the soil above the connecting section between the construction transverse passage and the main tunnel. The construction transverse passage arch of the connecting section presents an upward convex arc curve of the main tunnel arch in the longitudinal direction, forming a hyperbolic arch structure in both the transverse and longitudinal directions. Step S3: constructing advance support for the connecting section between the cross passage and the main tunnel, including double rows of small guide tubes at the top and side wall anchors; Step S4: The support profile of the connection section between the construction cross passage and the main tunnel adopts a straight side wall design of the arch near the main tunnel side. The construction cross passage grid steel frame supporting the connection section between the construction cross passage and the main tunnel is arranged along the arch. On the excavation side of the main tunnel, the outermost first steel pad of the support-before-break steel portal frame is welded to the main reinforcement of the arch construction cross passage grid steel frame adjacent to the side wall. The connection section between the construction cross passage and the main tunnel is supported by sprayed concrete. Step S5: After the support shotcrete of the connection section between the construction cross passage and the main tunnel reaches a certain strength, the construction cross passage locking anchor rods are installed at the position of the construction cross passage grid steel frame in the connection section between the construction cross passage and the main tunnel along the contour line of the main tunnel entrance excavation surface, and then the main tunnel advance middle pipe shed is installed above the contour line of the main tunnel entrance excavation surface; Step S6: welding the main structure of the steel portal frame to the first steel plate in the support of the connecting section between the cross passage and the main tunnel near the main tunnel side; Step S7: dismantle the supporting structure of the construction cross passage and the main tunnel connection section and the side wall anchors within the main tunnel construction range on the main tunnel side, and weld the exposed construction cross passage grid steel frame to the construction cross passage locking anchors; Step S8: excavate the upper soil of the main tunnel, set up the main tunnel grid steel frame at the main tunnel entrance, and spray concrete for pouring; Step S9, erecting the main tunnel steel frame inside the cast main tunnel grid steel frame and spraying concrete for casting; Step S10, erecting a gate grille steel frame at a position corresponding to the projection of the main tunnel grille steel frame inside the first-support-then-break steel door frame, and erecting a gate steel frame at a position corresponding to the projection of the main tunnel steel frame inside the gate grille steel frame; Step S11, continue to excavate the upper soil of the main tunnel forward, continue to erect the main tunnel grid steel frame along the main tunnel steel frame sprayed concrete structure and spray concrete for pouring; Step S12, excavating the soil below the connecting section between the cross passage and the main tunnel and the soil below the main tunnel; Step S13: construct the main tunnel structure and the secondary lining structure of the transverse passage; Step S14: construct the structural mid-plate and other internal structures.

2. The method according to claim 1, characterized in that The overall structure of the support-before-break steel gantry is as follows: the second steel plate is arranged inside the first steel plate, the first steel plate is welded between the first and second steel plates, the third and fourth steel plates are arranged inside the second steel plate, the second steel plate is welded between the third and fourth steel plates, and the second and third steel plates are connected by bolts.

3. The method according to claim 2, characterized in that The first and second steel sections are double-pieced Ⅰ25a steel sections. The first steel section faces the longitudinal direction of the main tunnel and is evenly arranged circumferentially between the first steel plate and the second steel plate. The second steel section faces perpendicular to the longitudinal direction of the main tunnel and is circumferentially welded to the third steel plate and the fourth steel plate along the outline of the support-before-break steel gantry.

4. The method according to claim 1, wherein Double rows of small conduits are used in the construction of horizontal channels The length of the advance small duct shall be no less than 4.5m. The external insertion angle of the two rows of small ducts shall be adjusted according to the curvature of the arch, and the overlap length shall be no less than 2m.

5. The method according to claim 1, characterized in that The locking anchor rods for the construction cross channel are made by driving two hollow anchor rods into each construction cross channel grid steel frame, and the length of the anchor rods shall not be less than 6m.

6. The method according to claim 1, characterized in that The main tunnel advance pipe shed adopts For pipe roof, the external insertion angle is 1 to 3 degrees.

7. The method according to claim 1, characterized in that After the main tunnel soil is excavated in step S8, 3 to 4 main tunnel grid steel frames are erected at the tunnel excavation entrance.

8. The method according to claim 1, characterized in that Steel plates are respectively provided on the interface between the portal grille steel frame and the portal section steel frame, and between the main tunnel grille steel frame and the main tunnel section steel frame, and the two interface steel plates are connected by bolts.

9. The construction method according to claim 1, characterized in that: Steel bars are used to connect the portal grille steel frame and the main tunnel grille steel frame, as well as the portal steel frame and the main tunnel steel frame, longitudinally. The inside and outside of the steel bars should be staggered.

10. A double-curved arched tunneling structure in soft strata, characterized by: The structure is constructed according to the method described in any one of claims 1 to 9.

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