Roadway thin spraying composite supporting structure

Abstract

The invention discloses a roadway thin spraying composite supporting structure which comprises a composite spraying layer and an anchoring assembly, the composite spraying layer comprises a first spraying layer and a second spraying layer which are sequentially and alternately arranged, the first spraying layer is a base material layer of the composite spraying layer, and the second spraying layer is a reinforcing layer of the composite spraying layer. The outer side spraying layers, close to and away from the surrounding rock, of the composite spraying layer are first spraying layers, the anchoring assembly comprises a plurality of anchor rods, the anchor rods are evenly arranged on the surrounding rock sprayed with the composite spraying layer, the anchor rods penetrate through the composite spraying layer and are inserted into the surrounding rock, and steel bar beams are arranged between the anchor rods. According to the roadway thin spraying composite supporting structure, the superfine organic fibers are added when the thin spraying material is sprayed, and compared with a thin spraying layer which does not contain a superfine fiber interlayer and is of the same thickness, the composite spraying layer containing the superfine fiber interlayer is high in tensile strength and low in cost, higher supporting rigidity is provided, generation of surrounding rock cracks is restrained, and the bearing capacity of surrounding rock is enhanced; and the long-term control effect of the supporting structure is improved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a tunnel thin-spray composite support structure. Background Art

[0002] With the rapid development of underground engineering construction, tunnel excavation technology has been continuously improved, and the requirements for tunnel support materials have become higher and higher. Traditional tunnel support methods such as metal mesh or plastic mesh have certain limitations, such as complex installation, slow construction speed, and high cost.

[0003] To this end, a spray support technology has been proposed in the relevant technology. This technology uses a special spray gun and pumping equipment to spray the spray material evenly onto the tunnel surface to form a hard protective layer.

[0004] Spraying support materials have the advantages of inhibiting the expansion of shallow surrounding rock cracks, reducing the weathering of surrounding rock strength by water vapor in the tunnel, and extending the tunnel empty wall time, which effectively improves the mechanization degree and excavation speed of tunnel excavation. However, the high cost of spraying support materials limits its large-scale promotion and application in engineering.

[0005] In addition, in rock burst tunnels, frequent impact energy events lead to large deformation of the surrounding rock and loss of anchor preload. Although spray support can control the damage of impact energy specimens to the surrounding rock and reduce the loss of anchor preload in the initial stage, as time goes by, the spray layer is prone to tearing, the deformation of the surrounding rock increases, and the loss of anchor preload increases, resulting in serious damage to the spray layer.

[0006] For example, in the soft rock tunnels of kilometer-deep wells, affected by high ground stress, spray support can control the initial deformation of the surrounding rock. However, as the surrounding rock expands and deforms more, the spray layer is prone to tearing, its integrity is destroyed, and the support effect decreases, causing the surrounding rock damage to develop deeper and the surrounding rock deformation to increase sharply. Summary of the invention

[0007] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0008] To this end, an embodiment of the present invention proposes a tunnel thin-spray composite support structure with cost-effectiveness and excellent support performance.

[0009] The tunnel thin shotcrete composite support structure of the embodiment of the present invention comprises:

[0010] A composite spray layer, which is used for spraying on the surface of the surrounding rock of the tunnel, and comprises a first spray layer and a second spray layer which are alternately arranged in sequence, wherein the first spray layer is a base material layer of the composite spray layer, the second spray layer is a reinforcement layer of the composite spray layer, and the outer spray layers of the composite spray layer close to and away from the surrounding rock are both the first spray layers;

[0011] An anchoring assembly, the anchoring assembly includes a plurality of anchor rods, the plurality of anchor rods are evenly arranged on the surrounding rock on which the composite sprayed layer is sprayed, the anchor rods penetrate the composite sprayed layer and are inserted into the surrounding rock, and steel beams are arranged between the anchor rods.

[0012] The tunnel thin-spray composite support structure of the embodiment of the present invention adds ultrafine organic fibers when spraying the thin-spray material. The fibers have the advantages of high tensile strength, good adhesion to the thin-spray material and low price. Compared with the thin-spray layer of the same thickness without the ultrafine fiber interlayer, the composite spray layer containing the ultrafine fiber interlayer has high tensile strength and low cost, provides higher support stiffness, inhibits the generation of surrounding rock cracks, enhances the bearing capacity of the surrounding rock, and improves the long-term control effect of the support structure.

[0013] In some embodiments, the thickness of the composite spray layer is H, and 5mm≤H≤8mm.

[0014] In some embodiments, the thicknesses of the multiple layers of the first sprayed layers are all equal.

[0015] In some embodiments, the second spray layer has multiple layers, and the thicknesses of the multiple layers of the second spray layer are equal.

[0016] In some embodiments, the thickness of the multiple layers of the first sprayed layers decreases sequentially from close to the surrounding rock to far away from the surrounding rock.

[0017] In some embodiments, the second sprayed layer has multiple layers, and the thickness of the multiple layers of the second sprayed layer decreases in sequence from close to the surrounding rock to far away from the surrounding rock.

[0018] In some embodiments, the second sprayed layer has multiple layers, the thickness of the first sprayed layer located on the outside of the composite sprayed layer close to and far from the surrounding rock is equal, the thickness of the second sprayed layer adjacent to the first sprayed layer located on the outside is equal, and the thickness of the first sprayed layer between two adjacent second sprayed layers is less than the thickness of the first sprayed layer located on the outside.

[0019] In some embodiments, the first sprayed layer between two adjacent second sprayed layers has multiple layers, and the thicknesses of the multiple layers of the first sprayed layers are all equal, and the thicknesses of the multiple layers of the second sprayed layers are all equal.

[0020] In some embodiments, the first spray layer between two adjacent second spray layers has multiple layers, and the thickness of the multiple layers of the first spray layer increases sequentially from the inside to the outside of the composite spray layer, and the thickness of the multiple layers of the second spray layer increases sequentially from the inside to the outside of the composite spray layer.

[0021] In some embodiments, the bonding force between the first sprayed layer of the composite sprayed layer located on the outside close to the surrounding rock and the surrounding rock is greater than or equal to 1.8 MPa, and the bonding force between the first sprayed layer and the second sprayed layer is greater than or equal to the tensile strength of the first sprayed layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a plan view of a tunnel thin-spray composite support structure according to an embodiment of the present invention.

[0023] Figure 2 It is a cross-sectional schematic diagram of a tunnel thin-spray composite support structure according to an embodiment of the present invention.

[0024] Figure 3 It is a partial schematic diagram of the structural form of the composite spray layer in one embodiment of the present invention.

[0025] Figure 4 It is a partial schematic diagram of the structural form of the composite spray layer in one embodiment of the present invention.

[0026] Figure 5 It is a partial schematic diagram of the structural form of the composite spray layer of another embodiment of the present invention.

[0027] Figure 6 It is a partial schematic diagram of the structural form of the composite spray layer of another embodiment of the present invention.

[0028] Figure 7 It is a partial schematic diagram of the structural form of the composite spray layer in another embodiment of the present invention.

[0029] Figure 8 It is a partial schematic diagram of the structural form of the composite spray layer in another embodiment of the present invention.

[0030] Fig. 9 It is a partial schematic diagram of the structural form of the composite spray layer in another embodiment of the present invention.

[0031] Reference numerals:

[0032] 1-composite spraying layer, 11-first spraying layer, 12-second spraying layer, 2-anchoring assembly, 21-anchor rod, 22-reinforced beam, 3-surrounding rock. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0034] The tunnel thin shotcrete composite support structure according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0035] like Figures 1 to 9 As shown, the tunnel thin-spray composite support structure of the embodiment of the present invention includes: a composite spray layer 1 and an anchoring assembly 2.

[0036] The composite spray layer 1 is used for spraying on the surface of the tunnel surrounding rock 3. The composite spray layer 1 includes a first spray layer 11 and a second spray layer 12 which are alternately arranged in sequence. The first spray layer 11 is the base material layer of the composite spray layer 1, and the second spray layer 12 is the reinforcement layer of the composite spray layer 1. The outer spray layers of the composite spray layer 1 close to and away from the surrounding rock 3 are both the first spray layer 11.

[0037] It can be understood that the first spray layer 11 is sprayed with a thin spray material, and the second spray layer 12 is sprayed with an ultrafine fiber material. In other words, the ultrafine fiber material is added when the thin spray material is sprayed, thereby forming a composite spray layer 1. When the composite spray layer 1 is constructed, the thin spray material and the ultrafine fiber material are sprayed multiple times, and gradually stacked in the order of a first spray layer 11 and a second spray layer 12, so that the thickness of the composite spray layer 1 reaches the designed thickness.

[0038] For example, the spraying material of the first spray layer 11 is a mixture of organic materials of components A and B, wherein component A is aromatic isocyanate, and component B is composed of terminal amino polyether and terminal amino chain extender. During the spraying process of this material, components A and B are mixed in the spray gun, react immediately after mixing and solidify on the surface of the surrounding rock 3, and the solidification time does not exceed 20 seconds, so that the spray layer can be uniform during the spraying process without sagging, forming a tough and durable coating.

[0039] Since it is used in the tunnel and is not exposed to ultraviolet rays, aromatic isocyanates such as toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) can be selected, which have high reactivity, good mechanical properties and cost-effectiveness.

[0040] The ultrafine fibers of the second spray layer 12 are used as reinforcing materials, and polypropylene fibers, glass fibers and steel fibers can be selected. The ultrafine fibers have super tensile strength and strong bonding properties with the thin spray material, so that the ultrafine fibers and the thin spray material form an integral composite spray layer 1. The addition of ultrafine fibers significantly enhances the mechanical properties of the composite spray layer 1, making it perform better when subjected to stress.

[0041] Furthermore, the first spray layer 11 close to the surrounding rock 3 penetrates into the surface of the surrounding rock 3, and the bonding force with the surrounding rock 3 is not less than 1.8 MPa, and the bonding force between the first spray layer 11 and the second spray layer 12 is not less than the tensile strength of the first spray layer 11. During the construction process, before the first spray layer 11 contacts the surrounding rock 3 and has not yet completely solidified, the ultrafine fibers of the second spray layer 12 are spread on the surface of the first spray layer 11 by high-pressure wind, so that the ultrafine fibers can be effectively integrated with the front and rear two layers of thin spray materials to prevent the front and rear two layers of spray layers from delaminating.

[0042] After the composite spray layer 1 is completely solidified, the anchor assembly 2 is constructed. The anchor assembly 2 includes a plurality of anchor rods 21, which are evenly arranged on the surrounding rock 3 on which the composite spray layer 1 has been sprayed, the anchor rods 21 penetrate the composite spray layer 1 and are inserted into the surrounding rock 3, and steel beams 22 are arranged between the anchor rods 21.

[0043] Optionally, the thickness of the composite spray layer 1 is not less than 5 mm and not more than 8 mm. The thickness design of the composite spray layer 1 is determined according to the physical and mechanical properties of the surrounding rock 3, such as the hardness, strength, and degree of crack development of the rock, to ensure the support effect while meeting the low cost requirement.

[0044] In summary, in the tunnel thin-spray composite support structure of the embodiment of the present invention, ultrafine organic fibers are added when spraying the thin-spray material. The fibers have the advantages of high tensile strength, good adhesion to the thin-spray material and low price.

[0045] Therefore, compared with the thin sprayed layer of the same thickness without ultra-fine fiber interlayer, the tensile strength of the composite sprayed layer 1 containing ultra-fine fiber interlayer is increased by 10%, and the elongation after fracture is not reduced, which provides higher support stiffness, inhibits the generation of cracks in the surrounding rock 3, enhances the bearing capacity of the surrounding rock 3, and improves the long-term control effect of the support structure.

[0046] Furthermore, by mixing ultra-fine fibers, the amount of spray material used can be reduced, and the spacing between the anchor rods 21 can be increased, thereby reducing the amount of anchor rods 21 used and reducing the cost by 15%.

[0047] like Figures 2 to 9 As shown, in the tunnel thin shotcrete composite support structure of the embodiment of the present invention, the composite shotcrete layer 1 has various structural forms to adapt to the physical and mechanical properties of different surrounding rocks 3 and realize the optimal support structure.

[0048] Alternatively, if Figure 3 As shown, the arrangement of the composite spray layer 1 is that the first spray layer 11 has two layers, a second spray layer 12 is sandwiched between the two first spray layers 11, and the thickness of the two first spray layers 11 is equal. Figure 4 As shown, the first sprayed layer 11 is provided with more than two layers, and the second sprayed layer 12 has at least two layers, and the thicknesses of the multiple second sprayed layers 12 are also equal.

[0049] Alternatively, if Figure 5 As shown, the arrangement of the composite spray layer 1 is also that the first spray layer 11 has two layers, and a second spray layer 12 is sandwiched between the two first spray layers 11, but the thickness of the two first spray layers 11 decreases in sequence from close to the surrounding rock 3 to far away from the surrounding rock 3. Figure 6As shown, if the first spray layer 11 is provided with more than two layers, the second spray layer 12 has at least two layers, and the thickness of the multiple second spray layers 12 also decreases in sequence from close to the surrounding rock 3 to far away from the surrounding rock 3.

[0050] Alternatively, if Figure 7 As shown, the arrangement of the composite spray layer 1 is that the first spray layer 11 has more than two layers, and the second spray layer 12 has at least two layers. The thickness of the first spray layer 11 located on the outside close to and far from the surrounding rock 3 of the composite spray layer 1 is equal, and the thickness of the second spray layer 12 adjacent to the first spray layer 11 located on the outside is also equal. The thickness of the first spray layer 11 between two adjacent second spray layers 12 is less than the thickness of the first spray layer 11 located on the outside.

[0051] In other words, the thickness of the spray layer located on the outside of the composite spray layer 1 is greater than the thickness of the spray layer located on the inside. The composite spray layer 1 of this arrangement also includes the following two situations.

[0052] First, if Figure 8 As shown, there are multiple layers of the first sprayed layer 11 between two adjacent second sprayed layers 12. The thickness of the first sprayed layers 11 sandwiched between the second sprayed layers 12 is equal, and the thickness of all the second sprayed layers 12 is also equal.

[0053] Second, if Fig. 9 As shown, similarly, the first spray layer 11 between two adjacent second spray layers 12 has multiple layers. However, the thickness of the multiple first spray layers 11 increases from the inside to the outside of the composite spray layer 1, and the thickness of the multiple second spray layers 12 also increases from the inside to the outside of the composite spray layer 1.

[0054] In summary, the thickness design of the first spray layer 11 and the second spray layer 12 needs to be determined according to specific engineering requirements and environmental conditions.

[0055] For example, when spraying with a spray gun, spraying layers of the same thickness can simplify the construction process and improve construction efficiency. In addition, when the thickness of the spray layer is consistent, it is easier to monitor and evaluate the spray layer status.

[0056] Different thicknesses of shotcrete can be adjusted according to the different stress distribution of the surrounding rock 3 to better disperse and bear the stress. In areas where the surrounding rock 3 conditions vary greatly, more effective support can be achieved by adjusting the thickness of the shotcrete. Increasing the thickness of the shotcrete only in areas that need to be strengthened can avoid unnecessary material waste.

[0057] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0058] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0059] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0061] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0062] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A tunnel thin shotcrete composite support structure, characterized in that: include: A composite spray layer, which is used for spraying on the surface of the surrounding rock of the tunnel, and comprises a first spray layer and a second spray layer which are alternately arranged in sequence, wherein the first spray layer is a base material layer of the composite spray layer, the second spray layer is a reinforcement layer of the composite spray layer, and the outer spray layers of the composite spray layer close to and away from the surrounding rock are both the first spray layers; An anchoring assembly, the anchoring assembly includes a plurality of anchor rods, the plurality of anchor rods are evenly arranged on the surrounding rock on which the composite sprayed layer is sprayed, the anchor rods penetrate the composite sprayed layer and are inserted into the surrounding rock, and steel beams are arranged between the anchor rods.

2. The tunnel thin shotcrete composite support structure according to claim 1 is characterized in that: The thickness of the composite spray layer is H, and 5mm≤H≤8mm.

3. The tunnel thin shotcrete composite support structure according to claim 2 is characterized in that: The thicknesses of the multiple layers of the first sprayed layers are all equal.

4. The tunnel thin shotcrete composite support structure according to claim 3 is characterized in that: The second sprayed layer has multiple layers, and the thicknesses of the multiple layers of the second sprayed layer are equal.

5. The tunnel thin shotcrete composite support structure according to claim 2 is characterized in that: The thickness of the multiple layers of the first sprayed layers decreases in sequence from close to the surrounding rock to far away from the surrounding rock.

6. The tunnel thin shotcrete composite support structure according to claim 5 is characterized in that: The second sprayed layer has multiple layers, and the thickness of the multiple layers of the second sprayed layer decreases in sequence from close to the surrounding rock to far away from the surrounding rock.

7. The tunnel thin shotcrete composite support structure according to claim 2 is characterized in that: The second sprayed layer has multiple layers, the thickness of the first sprayed layer located on the outside close to and far from the surrounding rock of the composite sprayed layer is equal, the thickness of the second sprayed layer adjacent to the first sprayed layer located on the outside is equal, and the thickness of the first sprayed layer between two adjacent layers of the second sprayed layer is less than the thickness of the first sprayed layer located on the outside.

8. The tunnel thin shotcrete composite support structure according to claim 7 is characterized in that: The first sprayed layer between two adjacent second sprayed layers has multiple layers, and the thicknesses of the multiple layers of the first sprayed layers are all equal, and the thicknesses of the multiple layers of the second sprayed layers are all equal.

9. The tunnel thin shotcrete composite support structure according to claim 7 is characterized in that: The first spray layer between two adjacent second spray layers has multiple layers, and the thickness of the multiple first spray layers increases from the inside to the outside of the composite spray layer, and the thickness of the multiple second spray layers increases from the inside to the outside of the composite spray layer.

10. The tunnel thin shotcrete composite support structure according to any one of claims 1 to 9, characterized in that: The bonding force between the first sprayed layer of the composite sprayed layer located on the outside close to the surrounding rock and the surrounding rock is greater than or equal to 1.8 MPa, and the bonding force between the first sprayed layer and the second sprayed layer is greater than or equal to the tensile strength of the first sprayed layer.

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