Large cross section chamber layered excavation construction method

Abstract

The application discloses a large-section chamber layer-by-layer excavation construction method and belongs to the chamber construction method field. A slope with a proper slope is arranged as a measure lane, the construction surface is lifted to the layer-by-layer position on the large section of the chamber, the upper layer is preferentially excavated during construction, and then the middle and lower layers are sequentially constructed after the construction of the upper layer is completed, so that the construction safety problems of the large exposed area of the roof and the long exposed time during the construction of the middle and lower layers are avoided, the construction mode of the top layer of the chamber is set as a small pilot chamber excavation and temporary support, the small pilot chamber is expanded and brushed and temporarily supported, and the smooth blasting and anchor net spray support, after the small pilot chamber is expanded and brushed, a compensation space is formed in the middle, the thickness of the distance from the planned section is only one meter, the smooth blasting layer is reserved, the section edge is better ensured to be smooth, then the middle and lower chambers are constructed, and the smooth blasting and anchor net spray support of the side edges of the chamber are carried out, so that the construction is safer and the chamber section edge is ensured to be smooth.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction methods, and specifically relates to a method for layered tunneling construction of large-section tunnels. Background Technology

[0002] A tunnel is a horizontal tunnel with a large cross-section and a short length that does not lead directly to the surface. Its function is to install various equipment and machinery, store materials and tools, or use it for other special purposes, such as machine repair rooms, explosives depots, and rest rooms. In the current technology for tunnel construction, because the cross-section of large tunnels is too high and the arm length of rock drilling equipment is insufficient, the tunnel cross-section is often divided into upper and lower layers. After the lower layer is constructed, the bottom slab is raised with crushed stone to create conditions for the upper layer to be constructed. During the construction process, the exposed area of ​​the roof slab of the lower layer is too large and the exposure time is too long, which poses safety hazards such as roof collapse and sidewall spalling. In addition, when using the existing technology, the original smooth blasting design detonates the peripheral holes and auxiliary holes at the same time, resulting in poor blasting effect and irregular cross-section edges. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To overcome the shortcomings of existing technologies, a layered excavation construction method for large-section chambers is proposed. This method addresses the problem that existing technologies often involve dividing the chamber cross-section into upper and lower layers, with the lower layer constructed first, and then using crushed stone to raise the bottom slab to create conditions for the upper layer construction. However, during the construction process, the exposed area and exposure time of the lower layer's roof slab are too large, posing safety hazards such as roof falls and sidewall collapses.

[0005] Secondly, to address the issue that existing technologies, when used in the original smooth-surface blasting design, involve the simultaneous detonation of peripheral and auxiliary holes, resulting in poor blasting effects and irregular cross-sectional edges.

[0006] (II) Technical Solution

[0007] This invention is achieved through the following technical solution: This invention proposes a method for layered tunneling construction of large-section chambers, the structure of which includes a construction roadway;

[0008] First, the location of the chamber is planned. The chamber consists of a top floor and a bottom floor. The top of the chamber is an arched vault, that is, the top of the top floor is an arched vault.

[0009] Second, according to the planned location of the chamber, a ramp is first excavated in the construction roadway towards the chamber as a measure roadway. The measure roadway is controlled within 10°, that is, the slope is within 17.6%. After being raised to the top floor of the chamber, it is leveled. A reserved groove is opened at the connection between the measure roadway and the top floor.

[0010] Third, a smooth blasting layer is planned on the top and both sides of the top layer. The thickness of the smooth blasting layer is 1m. After the measure tunnel is leveled, a small guide tunnel is first constructed at the top layer. The top of the small guide tunnel is connected to the smooth blasting layer. The width of the small guide tunnel is 1 / 2 to 1 / 3 of the width of the top layer after removing the smooth blasting layers on both sides. The bottom of the small guide tunnel is flush with the bottom of the top layer. The constructed part of the small guide tunnel is temporarily supported by plain shotcrete in a timely manner. The tunneling and support are carried out in cycles.

[0011] Fourth, after the small pilot tunnel is completed, the top layer is expanded to the smooth blasting layer by brushing the side. During the expansion of the top layer, the completed part is also temporarily supported by plain spraying in a timely manner, and the tunneling and support are carried out in a cycle.

[0012] Fifth, plan the location of the smooth blasting parallel hole at the smooth blasting layer, and drill the smooth blasting parallel hole from the reserved slot into the smooth blasting layer using the mechanical arm of the rock drilling rig.

[0013] Sixth, the smooth blasting layer is blasted through the smooth blasting parallel holes. After the smooth blasting layer is removed by blasting, the top layer is promptly supported by anchor spray mesh. Blasting and support are carried out in cycles.

[0014] Seventh, after the top layer construction is completed, the bottom layer construction begins at the measure tunnel. During the bottom layer construction, normal smooth blasting is used on both sides. After each single excavation of the bottom layer is completed, anchor spraying mesh support is used in a timely manner. Excavation and support are carried out in cycles until the entire chamber construction is completed.

[0015] Furthermore, at its lowest height, the bottom of the top layer should be parallel to the arching line of the vault at the top of the chamber.

[0016] Furthermore, the maximum height of both the top and bottom layers is 3-4.5 meters. When the top layer exceeds 3-4.5 meters, it can be divided into an upper layer and one or more middle layers. The construction method of the middle layer is the same as that of the bottom layer, and the construction method of the upper layer is the same as that of the top layer.

[0017] Furthermore, the spacing between the smooth blasting parallel holes is 10 to 20 times the diameter of the smooth blasting parallel holes.

[0018] Furthermore, the spacing between the smooth blasting parallel holes should be smaller relative to the diameter of the smooth blasting parallel holes in rocks with well-developed joints and fissures, and larger in rocks with good integrity.

[0019] Furthermore, the thickness of the smooth blasting layer or the distance between the peripheral eye and the adjacent auxiliary eye is the minimum resistance line. The minimum resistance line should be greater than or equal to the spacing between the smooth blasting parallel holes. If the distance from the smooth blasting parallel hole to the free surface is ≤1.0 meter, no auxiliary eye is added. If the distance from the smooth blasting parallel hole to the free surface is >1.0 meter, an auxiliary eye needs to be added.

[0020] Furthermore, the temporary support for the plain sprayed concrete is 7cm thick.

[0021] Furthermore, during the construction of the upper layer and one or more middle layers, the upper layer is constructed first. After the upper layer is completed, one or more middle layers are constructed sequentially from top to bottom, and finally the bottom layer is constructed.

[0022] (III) Beneficial Effects

[0023] One of the above technical solutions has the following advantages or beneficial effects:

[0024] 1) To address the issue that existing technologies often result in large chambers with excessively high cross-sections but insufficient drilling equipment arm length, leading to the common practice of dividing the chamber cross-section into upper and lower layers, and then using crushed stone to raise the bottom slab after the lower layer is completed to create conditions for the upper layer construction, which can cause excessively large exposed areas and prolonged exposure time of the lower layer's roof slab during construction, posing safety hazards such as roof falls and wall collapses, a sloped roadway with a suitable gradient is used as a measure roadway to raise the construction face to the layering point on the large cross-section of the chamber. During construction, the upper layer is excavated first, and the middle and lower layers are constructed sequentially after the upper layer is fully completed. This avoids the construction safety problems of excessively large exposed areas and prolonged exposure time of the roof slab during the middle and lower layer construction.

[0025] 2) To address the issue that existing smooth blasting designs, which involve simultaneous detonation of peripheral and auxiliary holes, resulting in poor blasting effects and irregular cross-section edges, a new construction method is adopted for the top layer of the chamber. This method involves: small pilot tunnel excavation and temporary support (excavation-support cycle) → widening and temporary support (excavation-support cycle) → smooth blasting and anchor-mesh-sprayed support (excavation-support cycle). After the small pilot tunnel is widened, a compensation space is formed in the middle, with a thickness of only one meter around the planned cross-section. By reserving such a smooth blasting layer, sufficient free surface can be provided during blasting, reducing clamping forces and better ensuring the smoothness of the cross-section edges. Then, the middle and lower chambers are constructed, and smooth blasting and anchor-mesh-sprayed support are applied to the sides of the chambers, making construction safer and better ensuring the smoothness of the chamber cross-section edges. Attached Figure Description

[0026] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 This is a schematic diagram of the overall construction steps of the side structure when the chamber of the present invention has a middle layer;

[0028] Figure 2 This is a schematic diagram of the overall construction steps of the side walls when the chamber of this invention only has a top and bottom floor.

[0029] Figure 3This is a schematic diagram illustrating the side construction steps after the upper layer is completed when the chamber of this invention has a middle layer;

[0030] Figure 4 This is a schematic diagram illustrating the side construction steps after the top layer is completed when the chamber of this invention has a middle layer;

[0031] Figure 5 This is a side view of the chamber after construction of the present invention is completed;

[0032] Figure 6 This is a schematic diagram of the overall construction steps of the cross-section of the chamber of the present invention when it has a middle layer;

[0033] Figure 7 This is a schematic diagram of the upper construction steps on the cross-sectional side of the chamber of the present invention when the middle layer is present;

[0034] Figure 8 This is a schematic diagram of the construction steps of the middle layer on the cross-section side when the chamber of the present invention has a middle layer;

[0035] Figure 9 This is a schematic diagram of the construction steps of the bottom layer on the cross-sectional side when the chamber of the present invention has a middle layer;

[0036] Figure 10 This is a schematic diagram showing the cross-sectional side of the chamber of the present invention after the middle layer has been constructed.

[0037] Figure 11 This is a schematic diagram of the upper smooth surface blasting parallel holes on the cross-sectional side of the chamber of the present invention when the middle layer is present;

[0038] In the diagram: Construction tunnel-1, Measures tunnel-2, Reserved trench-3, Top layer-4, Bottom layer-5, Chamber-6, Upper layer-4a, Middle layer-4b, Small guide tunnel-4c, Anchor spraying mesh support-4d, Smooth blasting layer-4e, Smooth blasting parallel hole-4e1. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0040] This invention provides a method for layered tunneling construction of large-section chambers: its structure includes a construction roadway 1;

[0041] First, the location of chamber 6 is planned. Chamber 6 consists of a top layer 4 and a bottom layer 5. The top of chamber 6 is an arched dome, that is, the top of the top layer 4 is an arched dome.

[0042] Second, according to the planned location of the chamber 6, a ramp is first excavated in the direction of the chamber 6 at the construction roadway 1 as a measure roadway 2. The measure roadway 2 is controlled within 10°, that is, the slope is within 17.6%. It is raised to the top floor 4 of the chamber 6 and then leveled. A reserved groove 3 is opened at the connection between the measure roadway 2 and the top floor 4.

[0043] Third, a smooth blasting layer 4e is planned on the top and both sides of the top layer 4. The thickness of the smooth blasting layer 4e is 1m. After the measure tunnel 2 is leveled, a small guide tunnel 4c is constructed at the top layer 4. The top of the small guide tunnel 4c is connected to the smooth blasting layer 4e. The width of the small guide tunnel 4c is 1 / 2 to 1 / 3 of the width of the top layer 4 after removing the smooth blasting layers 4e on both sides. The bottom of the small guide tunnel 4c is flush with the bottom of the top layer 4. The constructed part of the small guide tunnel 4c is temporarily supported by plain shotcrete in a timely manner. The tunneling and support are carried out in cycles.

[0044] Fourth, after the small guide tunnel 4c is completed, the interior of the top layer 4 is expanded to the smooth blasting layer 4e by brushing. When the top layer 4 is expanded, the completed part is also temporarily supported by plain spraying in a timely manner, and the tunneling and support are carried out in a cycle.

[0045] Fifth, plan the position of the smooth blasting parallel hole 4e1 at the smooth blasting layer 4e, and drill the smooth blasting parallel hole 4e1 from the reserved slot 3 into the smooth blasting layer 4e using the mechanical arm of the rock drilling rig.

[0046] Sixth, the smooth blasting layer 4e is blasted through the smooth blasting parallel hole 4e1. After the smooth blasting layer 4e is removed by blasting, the top layer 4 is promptly supported by anchor spray mesh 4d. Blasting and support are carried out in a cycle.

[0047] Seventh, after the top layer 4 is completed, the construction of the bottom layer 5 will begin at the measure tunnel 2. During the construction of the bottom layer 5, normal smooth blasting on both sides will be used. After the single excavation of the bottom layer 5 is completed, anchor spraying mesh support will be used for 4 days. The excavation and support will be carried out in cycles until the entire chamber 6 is completed.

[0048] Wherein, the bottom of the top layer 4 at its lowest height should be parallel to the arching line of the top arch of the chamber 6.

[0049] The top layer 4 and the bottom layer 5 have a maximum height of 3-4.5 meters. When the top layer 4 exceeds 3-4.5 meters, it is divided into an upper layer 4a and one or more middle layers 4b. The construction method of the middle layer 4b is the same as that of the bottom layer 5, and the construction method of the upper layer 4a is the same as that of the top layer 4.

[0050] The spacing between the smooth blasting parallel holes 4e1 is 10 to 20 times the diameter of the smooth blasting parallel holes 4e1.

[0051] The spacing between the smooth blasting parallel holes 4e1 should be smaller relative to the diameter of the smooth blasting parallel holes 4e1 in rocks with well-developed joints and fissures, and larger in rocks with good integrity.

[0052] The thickness of the smooth blasting layer 4e or the distance between the peripheral holes and the adjacent auxiliary holes is the minimum resistance line. The minimum resistance line should be greater than or equal to the spacing between the smooth blasting parallel holes 4e1. If the distance from the smooth blasting parallel hole 4e1 to the free face is ≤1.0 meter, no auxiliary holes are added. If the distance from the smooth blasting parallel hole 4e1 to the free face is >1.0 meter, auxiliary holes are added to avoid under-excavation during construction.

[0053] The temporary support for the plain sprayed concrete is 7cm thick.

[0054] When constructing the upper layer 4a and one or more middle layers 4b, the upper layer 4a is constructed first. After the upper layer 4a is constructed, one or more middle layers 4b are constructed sequentially from top to bottom, and finally the bottom layer 5 is constructed.

[0055] Implementation Plan: When constructing chamber 6, which is 11.06 meters high, 10.6 meters wide, and 29.3 meters long, since the height of chamber 6 (11.06 meters) is greater than twice but less than three times the length of 4.5 meters, the plan is to construct chamber 6 in three layers: upper, middle, and lower. Based on the height of chamber 6, a 10° (slope within 17.6%) ramp is planned as the secondary access roadway 2. The top of secondary access roadway 2 is adjacent to the top of chamber 6. The calculated length of secondary access roadway 2 is 36.9 meters. One end of secondary access roadway 2 connects to construction roadway 1. After secondary access roadway 2 is completed, a chamber 4.5 meters high, 10.6 meters wide, and 29.3 meters long can be constructed first, maximizing the initial construction. In the upper layer 4a of chamber 6, during construction, based on the width requirement, 2 meters (8.6 meters) were deducted from the original 10.6 meters, representing 1 / 3 to 1 / 2 of the total width, plus a reserved smooth blasting layer 4e at the top. First, a small pilot tunnel 4c, 3.5 meters high, 4.3 meters wide, and 29.3 meters long, was constructed. The bottom of the small pilot tunnel 4c was flush with the bottom of the upper layer 4a. The completed sections of the small pilot tunnel 4c were immediately temporarily supported with shotcrete. Excavation and support were carried out in a cyclical manner. After the small pilot tunnel 4c was completed, the interior of the upper layer 4a was expanded to the smooth blasting layer 4e using a brushing method. During the expansion of the upper layer 4a, the completed sections were also immediately temporarily supported with shotcrete. Excavation and support were carried out in a cyclical manner. After the expansion was completed, if under-excavation occurred... If the distance from the smooth blasting parallel hole 4e1 to the free face is greater than 1.0 meter due to the situation, an auxiliary hole is added for smooth blasting. If the distance from the smooth blasting parallel hole 4e1 to the free face is ≤1.0 meter due to the situation or over-excavation, no auxiliary hole is added. A reserved groove 3 is constructed by utilizing the height difference between the top of the measure tunnel 2 and the top of the upper layer 4a, and a smooth blasting parallel hole 4e1 is drilled from the reserved groove 3 into the smooth blasting layer 4e. The smooth blasting layer 4e is blasted through the smooth blasting parallel hole 4e1. After the smooth blasting layer 4e is removed by blasting, the upper layer 4a is promptly supported by anchor spray mesh 4d. Blasting and support are carried out in cycles. After the construction of the upper layer 4a is completed, the blasting begins from the upper layer 4e in measure tunnel 2. The construction of the middle layer 4b and the bottom layer 5 is carried out sequentially. During the construction of the middle layer 4b and the bottom layer 5, normal smooth blasting is used on both sides. After each excavation, anchor spraying mesh support is used in time for 4d. Excavation and support are carried out in cycles until the entire chamber 6 is completed. This can avoid the construction safety problems of excessive exposed area and excessive exposure time of the top plate during the construction of the middle and lower layers. By using the method of pre-reserving a smooth blasting layer by expanding the small guide tunnel, sufficient free surface can be provided during blasting, reducing the clamping force and better ensuring the flatness of the cross-section edge. Then the middle and lower chambers are constructed, and smooth blasting and anchor spraying mesh support are used on the sides of the chambers, making the construction safer and better ensuring the flatness of the chamber cross-section edge.

[0056] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for layered excavation of large-section chambers, the structure of which includes a construction roadway (1); Its features are: First, the location of the chamber (6) is planned. The chamber (6) consists of a top floor (4) and a bottom floor (5). The top of the chamber (6) is an arched dome, that is, the top of the top floor (4) is an arched dome. Second, according to the planned location of the chamber (6), a ramp is first excavated in the direction of the chamber (6) at the construction roadway (1) as a measure roadway (2). The measure roadway (2) is controlled within 10°, that is, the slope is within 17.6%. It is raised to the top floor (4) of the chamber (6) and then leveled. A reserved groove (3) is opened at the connection between the measure roadway (2) and the top floor (4). Third, a smooth blasting layer (4e) is planned on the top and both sides of the top layer (4). The thickness of the smooth blasting layer (4e) is 1m. After the measure tunnel (2) is leveled, a small guide tunnel (4c) is constructed at the top layer (4). The top of the small guide tunnel (4c) is connected to the smooth blasting layer (4e). The width of the small guide tunnel (4c) is 1 / 2 to 1 / 3 of the width of the top layer (4) after removing the smooth blasting layers (4e) on both sides. The bottom of the small guide tunnel (4c) is flush with the bottom of the top layer (4). The part of the small guide tunnel (4c) that has been constructed is temporarily supported by plain spraying in time. The tunneling and support are carried out in a cycle. Fourth, after the small guide tunnel (4c) is completed, the top layer (4) is expanded to the smooth blasting layer (4e) by brushing the side. When the top layer (4) is expanded, the completed part is also temporarily supported by plain spraying in a timely manner. The tunneling and support are carried out in a cycle. Fifth, plan the position of the smooth blasting parallel hole (4e1) at the smooth blasting layer (4e), and drill the smooth blasting parallel hole (4e1) from the reserved slot (3) into the smooth blasting layer (4e) using the mechanical arm of the rock drilling rig. Sixth, the smooth blasting layer (4e) is blasted through the smooth blasting parallel hole (4e1). The top layer (4) after the smooth blasting layer (4e) is removed by blasting is promptly supported by anchor spray net (4d). Blasting and support are carried out in a cycle. Seventh, after the top layer (4) is completed, the bottom layer (5) is constructed at the measure tunnel (2). During the construction of the bottom layer (5), normal smooth blasting is used on both sides. After the single excavation of the bottom layer (5) is completed, anchor spray net support (4d) is used in time. The excavation and support are carried out in a cycle until the entire chamber (6) is completed.

2. The method for layered tunneling construction of large-section chambers according to claim 1, characterized in that: When the top layer (4) is at its lowest height, the bottom should be parallel to the arching line of the top arch of the chamber (6).

3. The method for layered tunneling construction of large-section chambers according to claim 1, characterized in that: The maximum height of the top layer (4) and the bottom layer (5) is 3-4.5 meters. When the top layer (4) exceeds 3-4.5 meters, it can be divided into an upper layer (4a) and one or more middle layers (4b). The construction method of the middle layer (4b) is the same as that of the bottom layer (5), and the construction method of the upper layer (4a) is the same as that of the top layer (4).

4. The method for layered tunneling construction of large-section chambers according to claim 1, characterized in that: The spacing between the smooth blasting parallel holes (4e1) is 10 to 20 times the diameter of the smooth blasting parallel holes (4e1).

5. The method for layered tunneling construction of large-section chambers according to claim 4, characterized in that: The spacing between the smooth blasting parallel holes (4e1) should be smaller relative to the diameter of the smooth blasting parallel holes (4e1) in rocks with well-developed joints and fissures, and larger in rocks with good integrity.

6. The method for layered tunneling construction of large-section chambers according to claim 1, characterized in that: The thickness of the smooth blasting layer (4e) or the distance between the peripheral eye and the adjacent auxiliary eye is the minimum resistance line. The minimum resistance line should be greater than or equal to the spacing between the smooth blasting parallel holes (4e1). If the distance from the smooth blasting parallel hole (4e1) to the free surface is ≤1.0 meter, no auxiliary eye is added. If the distance from the smooth blasting parallel hole (4e1) to the free surface is >1.0 meter, an auxiliary eye is added.

7. The method for layered tunneling construction of large-section chambers according to claim 1, characterized in that: The temporary support for the plain sprayed concrete is 7cm thick.

8. The method for layered tunneling construction of large-section chambers according to claim 3, characterized in that: When constructing the upper layer (4a) and one or more middle layers (4b), the upper layer (4a) shall be constructed first, then one or more middle layers (4b) shall be constructed sequentially from top to bottom, and finally the bottom layer (5) shall be constructed.

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