A construction method for a supporting structure of a multi-arch tunnel without a central pilot tunnel

Abstract

The invention discloses a construction method for a supporting structure of a multi-arch tunnel without a central pilot tunnel. The left chamber is a chamber with a relatively deep burial depth, and the right chamber is a chamber with a relatively shallow burial depth. The left chamber is excavated first, and then the right chamber is excavated. The left pilot tunnel is excavated with a three-step circular excavation method to reserve core soil. When the excavation reaches the lower step of the right tunnel, a trench is excavated at the arch foot position at the lower right side of the left pilot tunnel, close to the side of the rear tunnel, and EVA foam shock-absorbing material is laid close to the side of the right chamber. The initial support The I-beams for protection are extended into the trench and backfilled with concrete; small conduit grouting is used at the expanded position of the arch foot trench to strengthen the foundation strength; the initial support and connecting plates at the arch waist of the leading tunnel arch area are thickened to reduce the impact on the secondary lining of the leading tunnel during the construction of the rear tunnel; the three-step circular excavation method for reserving core soil is adopted for the right rear tunnel; the initial support steel arch frame of the right rear tunnel is overlapped on the initial support steel arch frame of the leading tunnel; the advanced support adopts advanced small conduits to reinforce the strata.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a construction method of a multi-arch tunnel support structure without a central pilot tunnel. Background Art

[0002] Arch tunnels are often used in areas where route selection is difficult, especially in areas where bridges and tunnels are connected. They have the advantages of reducing project investment and saving floor space. The composite curved wall arch tunnel is currently the most commonly used arch tunnel structure, but it has low construction efficiency and complex structural stress state conversion. The arch tunnel without a central guide inherits all the advantages of the traditional arch tunnel, and at the same time has the advantages of less land occupation, protection of the natural environment, and smooth linearity, which better overcomes some of the shortcomings of the traditional arch tunnel. In addition, the arch tunnel without a central guide has simple procedures, short construction period, and low cost, and is widely used in tunnel design and construction. The traditional construction method of the arch tunnel without a central guide is to simply overlap the initial support steel arch frame. Such a design usually easily causes the arch tunnel to be subjected to terrain bias, and the arch tunnel in operation and under construction has lining cracking and other diseases, especially a large number of longitudinal and oblique cracks in the secondary lining of the pilot tunnel. Summary of the invention

[0003] To this end, the present invention provides a construction method for a multi-arch tunnel support structure without a central pilot tunnel to solve the above-mentioned problems in the prior art.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] According to a first aspect of the present invention, a construction method of a multi-arch tunnel support structure without a central pilot tunnel comprises the following steps:

[0006] Step S100, the multi-arch tunnel is divided into two left and right chambers, the left chamber is a chamber with a deeper burial depth, and the right chamber is a chamber with a shallower burial depth. The excavation method is to first excavate the left chamber and then excavate the right chamber. The left chamber is a left leading tunnel, and the right chamber is a right trailing tunnel.

[0007] Step S200: The left pilot tunnel adopts a three-step circular excavation method to reserve core soil;

[0008] Step S300: When the excavation reaches the lower step of the right tunnel, a trench is excavated at the arch foot position at the lower right side of the left leading tunnel, close to the side of the trailing tunnel, and EVA foam shock-absorbing material is laid close to the side of the right cavern. The I-beam of the initial support is extended into the trench and backfilled with concrete.

[0009] Step S400: Use a small pipe to grout the expanded position of the arch foot groove to strengthen the foundation strength;

[0010] Step S500, thickening the initial support and connection plate at the arch waist of the leading tunnel joint arch area to reduce the impact on the secondary lining of the leading tunnel during the construction of the subsequent tunnel;

[0011] Step S600: The right rear tunnel adopts a three-step circular excavation method to reserve core soil;

[0012] Step S700, the initial support steel arch frame of the right rear tunnel is overlapped on the initial support steel arch frame of the leading tunnel, and connected by a connecting plate;

[0013] In step S800, the advance support adopts the advance small guide tube to reinforce the stratum to solve the problems of poor surrounding rock and serious bias of earth pressure.

[0014] Furthermore, step S200 specifically includes:

[0015] Step S201, excavation of an arc-shaped pilot pit on the upper step on the left side of the right tunnel, and initial support of the upper step on the right side of the right tunnel;

[0016] Step S202, excavation of the core soil of the upper step of the right hole;

[0017] Step S203, excavation of steps in the right tunnel and initial support of steps in the right tunnel;

[0018] Step S204, excavation of the lower step of the right tunnel, and initial support of the lower step and invert arch of the right tunnel;

[0019] Step S205, pouring the secondary lining and filling of the left tunnel invert;

[0020] Step S206: laying a waterproof layer and pouring the secondary lining of the left arch wall.

[0021] Furthermore, the groove in step S300 has a depth of 100 cm and a width of 50 cm-80 cm.

[0022] Furthermore, the thickness of the EVA foam shock-absorbing material in step S300 is 10 cm.

[0023] Furthermore, the I-beam used for initial support in step S300 extends to 100 cm into the trench.

[0024] Furthermore, the type of concrete in step S300 is C50 concrete.

[0025] Furthermore, the specification of the small conduits in step S400 is Φ42×4; the length is 3 meters, and the distribution spacing is 80 cm×80 cm.

[0026] Furthermore, step S600 specifically includes:

[0027] Step S601, excavation of arc-shaped pilot pit on the upper step of the right tunnel, and initial support of the upper step of the right tunnel;

[0028] Step S602: excavation of the core soil of the upper step of the right hole, and temporary invert of the upper step of the right hole;

[0029] Step S603: excavation of steps in the right tunnel and initial support of steps in the right tunnel;

[0030] Step S604, excavation of the lower step of the right tunnel, and initial support of the lower step and invert arch of the right tunnel;

[0031] Step S605, dismantle the temporary invert of the left tunnel in sections, and cast the secondary lining and invert filling of the left tunnel invert;

[0032] Step S606: laying a waterproof layer and pouring the secondary lining of the left arch wall.

[0033] Furthermore, the length of the leading small catheter in step S800 is L=3.5m or 2.5m, and the distribution spacing is 100cm×60cm.

[0034] The invention has the following advantages: the method can effectively solve the problems of cracking and water seepage of the secondary lining of the preliminary tunnel after the tunnel construction is completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0036] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0037] Figure 1 A structural diagram of a multi-arch tunnel without a central pilot tunnel according to a construction method of a multi-arch tunnel support structure without a central pilot tunnel provided in some embodiments of the present invention.

[0038] Figure 2 A diagram of the initial support and excavation of the left pilot tunnel of a construction method of a multi-arch tunnel support structure without a central pilot tunnel provided in some embodiments of the present invention.

[0039] Figure 3A diagram of the initial support steel arch frame of the left pilot tunnel of a construction method of a multi-arch tunnel support structure without a central pilot tunnel provided in some embodiments of the present invention.

[0040] Figure 4 A construction drawing of initial support and excavation of a rear tunnel for a construction method of a multi-arch tunnel support structure without a central pilot tunnel provided in some embodiments of the present invention.

[0041] Figure 5 A diagram of erecting a steel arch frame for initial support of a rear tunnel according to a construction method of a multi-arch tunnel support structure without a central pilot tunnel provided in some embodiments of the present invention.

[0042] Figure 6 A schematic diagram of step S300 of a construction method of a multi-arch tunnel support structure without a central pilot tunnel provided in some embodiments of the present invention.

[0043] Figure 7 A schematic diagram of initial support for a pilot tunnel in a construction method of a multi-arch tunnel support structure without a central pilot tunnel provided in some embodiments of the present invention. DETAILED DESCRIPTION

[0044] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] like Figures 1 to 7 As shown, a construction method of a multi-arch tunnel support structure without a central pilot tunnel in an embodiment of the first aspect of the present invention comprises the following steps:

[0046] Step S100, the multi-arch tunnel is divided into two left and right chambers, the left chamber is a chamber with a deeper burial depth, and the right chamber is a chamber with a shallower burial depth. The excavation method is to first excavate the left chamber and then excavate the right chamber. The left chamber is a left leading tunnel, and the right chamber is a right trailing tunnel.

[0047] Step S200: The left pilot tunnel adopts a three-step circular excavation method to reserve core soil;

[0048] Step S300: When the excavation reaches the lower step of the right tunnel, a trench is excavated at the arch foot position at the lower right side of the left leading tunnel, close to the side of the trailing tunnel, and EVA foam shock-absorbing material is laid close to the side of the right cavern. The I-beam of the initial support is extended into the trench and backfilled with concrete.

[0049] Step S400: Use a small pipe to grout the expanded position of the arch foot groove to strengthen the foundation strength;

[0050] Step S500, thickening the initial support and connection plate at the arch waist of the leading tunnel joint arch area to reduce the impact on the secondary lining of the leading tunnel during the construction of the subsequent tunnel;

[0051] Step S600: The right rear tunnel adopts a three-step circular excavation method to reserve core soil;

[0052] Step S700, the initial support steel arch frame of the right rear tunnel is overlapped on the initial support steel arch frame of the leading tunnel, and connected by a connecting plate;

[0053] In step S800, the advance support adopts the advance small guide tube to reinforce the stratum to solve the problems of poor surrounding rock and serious bias of earth pressure.

[0054] The technical effect achieved by the above embodiment is: the use of this method can effectively solve the problems of cracking and water seepage in the secondary lining of the preliminary tunnel after the tunnel construction is completed.

[0055] Specifically, it includes the following steps:

[0056] Step S100, the arch tunnel is generally a shallow buried dark excavation tunnel, and the tunnel is subject to great terrain bias pressure; the arch tunnel is divided into two left and right chambers, the left chamber is a chamber with a deeper burial depth, and the right chamber is a chamber with a shallower burial depth; the excavation method is to first excavate the left chamber and then the right chamber; see Figure 1 .

[0057] Step S200: The left pilot tunnel adopts the three-step circular excavation method to reserve the core soil. The specific method is as follows: Figure 2 : In the figure, the Greek letters (Ⅰ, Ⅱ, Ⅲ, etc.) represent the excavation order, and the Arabic numerals (1, 2, 3, etc.) represent the lining support order; when constructing a tunnel, the one with poor geology and shallower burial depth should be constructed first; the right tunnel with shallower burial depth should be constructed first; "B" in the figure is the tunnel excavation span.

[0058] Construction steps:

[0059] Ⅰ. Excavation of arc-shaped guide pit on the upper step on the left side of the right tunnel; 1. Initial support of the upper step on the right side of the right tunnel.

[0060] Ⅱ. Excavation of core soil on the upper step of the right tunnel.

[0061] III. Excavation of steps in the right tunnel; 2. Initial support of steps in the right tunnel.

[0062] IV. Excavation of steps under the right tunnel; 3. Initial support of steps and invert arch under the right tunnel.

[0063] 4. Cast the secondary lining and arch filling of the left tunnel.

[0064] 5. Lay the waterproof layer and pour the secondary lining of the left arch wall.

[0065] Step S300, the left pilot tunnel adopts the three-step circular excavation method to reserve the core soil. When the excavation reaches the lower step of the right tunnel in step IV, a trench with a depth of 100cm and a width of 50cm-80cm is excavated at the arch foot position at the lower right of the left pilot tunnel, close to the side of the rear tunnel; a 10cm thick EVA foam shock-absorbing material is laid close to the side of the right chamber; the initial support I-beam is extended 100cm into the trench and backfilled with C50 concrete; the initial support of the pilot tunnel plays a supporting role in the middle, and the pressure on the side of the pilot tunnel is transmitted to the bottom of the tunnel. Figure 3 .

[0066] Step S400: Use Φ42×4 small pipes for grouting at the expanded position of the arch foot groove. The length of the small pipes is 3 meters and the spacing is 80cm×80cm to strengthen the foundation strength. Figure 4 .

[0067] Step S500, thickening the initial support and connection plate at the waist of the leading tunnel in the arch area to reduce the impact on the secondary lining of the leading tunnel during the construction of the subsequent tunnel.

[0068] Step S600: The right rear tunnel adopts a three-step circular excavation method to reserve the core soil. The method is as follows: Figure 4 :

[0069] Ⅴ. Excavation of arc-shaped guide pit on the upper step of the right tunnel; 6. Initial support of the upper step of the right tunnel.

[0070] VI. Excavation of core soil for the upper step of the right tunnel; 7. Temporary invert arch for the upper step of the right tunnel.

[0071] Ⅶ. Excavation of steps in the right tunnel; 8. Initial support of steps in the right tunnel.

[0072] VIII. Excavation of steps under the right tunnel; 9. Initial support of steps and invert arch under the right tunnel.

[0073] 10. Dismantle the temporary invert of the left tunnel in sections, and pour the secondary lining and invert filling of the left tunnel.

[0074] 11. Lay the waterproof layer and pour the secondary lining of the left arch wall.

[0075] Step S700: The initial support steel arch frame of the right rear tunnel is overlapped on the initial support steel arch frame of the leading tunnel, and is connected by a connecting plate. The connection method is shown in step S400. Figure 5 .

[0076] In step S800, advance support uses Φ42 small advance guide tubes L=3.5m, 2.5m, and a spacing of 100cm×60cm to reinforce the stratum and solve the problems of poor surrounding rock and severe earth pressure bias.

[0077] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

[0078] The terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and are not intended to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as within the scope of implementation of the present invention without substantially changing the technical content.

Claims

1. A construction method for a multi-arch tunnel support structure without a central pilot tunnel, characterized in that: The following steps are involved: Step S100, the multi-arch tunnel is divided into two left and right chambers, the left chamber is a chamber with a deeper burial depth, and the right chamber is a chamber with a shallower burial depth. The excavation method is to first excavate the left chamber and then excavate the right chamber. The left chamber is a left leading tunnel, and the right chamber is a right trailing tunnel. Step S200: The left pilot tunnel adopts a three-step circular excavation method to reserve core soil; Step S300: When the excavation reaches the lower step of the right tunnel, a trench is excavated at the arch foot position at the lower right side of the left leading tunnel, close to the side of the trailing tunnel, and EVA foam shock-absorbing material is laid close to the side of the right cavern. The I-beam of the initial support is extended into the trench and backfilled with concrete. Step S400: Use a small pipe to grout the expanded position of the arch foot groove to strengthen the foundation strength; Step S500, thickening the initial support and connection plate at the waist of the leading tunnel in the arch area to reduce the impact on the secondary lining of the leading tunnel during the construction of the subsequent tunnel; Step S600: The right rear tunnel adopts a three-step circular excavation method to reserve core soil; Step S700, the initial support steel arch frame of the right rear tunnel is overlapped on the initial support steel arch frame of the leading tunnel, and connected by a connecting plate; Step S800 and advance support both use advance small pipes to reinforce the stratum to solve the problems of poor surrounding rock and severe bias of earth pressure; Step S200 specifically includes: Step S201, excavation of an arc-shaped pilot pit on the upper step on the left side of the right tunnel, and initial support of the upper step on the right side of the right tunnel; Step S202, excavation of the core soil of the upper step of the right hole; Step S203, excavation of steps in the right tunnel and initial support of steps in the right tunnel; Step S204, excavation of the lower step of the right tunnel, and initial support of the lower step and invert arch of the right tunnel; Step S205, pouring the secondary lining and filling of the left tunnel invert; Step S206, laying a waterproof layer and pouring the secondary lining of the left arch wall; The groove depth in step S300 is 100 cm and the width is 50 cm-80 cm; The thickness of the EVA foam shock-absorbing material in step S300 is 10 cm; In step S300, the I-beam used for initial support extends to 100 cm into the trench.

2. The construction method of a multi-arch tunnel support structure without a central pilot tunnel according to claim 1, characterized in that: The type of concrete in step S300 is C50 concrete.

3. The construction method of a multi-arch tunnel support structure without a central pilot tunnel according to claim 1, characterized in that: The specification of the small conduit in step S400 is Φ42×4; the length is 3 meters, and the distribution spacing is 80 cm×80 cm.

4. The construction method of a multi-arch tunnel support structure without a central pilot tunnel according to claim 1, characterized in that: Step S600 specifically includes: Step S601, excavation of arc-shaped pilot pit on the upper step of the right tunnel, and initial support of the upper step of the right tunnel; Step S602: excavation of the core soil of the upper step of the right hole, and temporary invert of the upper step of the right hole; Step S603: excavation of steps in the right tunnel and initial support of steps in the right tunnel; Step S604, excavation of the lower step of the right tunnel, and initial support of the lower step and invert arch of the right tunnel; Step S605, dismantle the temporary invert of the left tunnel in sections, and cast the secondary lining and invert filling of the left tunnel invert; Step S606: laying a waterproof layer and pouring the secondary lining of the left arch wall.

5. The construction method of a multi-arch tunnel support structure without a central pilot tunnel according to claim 1, characterized in that: The length of the leading small catheter in step S800 is L=3.5m or 2.5m, and the distribution spacing is 100cm×60cm.

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