Extra-large-span tunnel dynamic supporting system and construction method

Abstract

The invention relates to the technical field of tunnel engineering, and discloses an extra-large-span tunnel dynamic supporting system and a construction method, a first primary supporting layer is directly connected to surrounding rock, and a plurality of strain sensors are connected to the first primary supporting layer; the secondary lining layer comprises a first secondary lining layer and a second secondary lining layer, and when the load detected by the strain sensor is larger than a set threshold value, and / or the load of the temporary support is larger than the set threshold value, or the monitored deformation of the first primary support layer is not converged, the second primary support layer is constructed on the basis of the first primary support layer; the first secondary lining layer is constructed on the second primary support layer; and when the monitoring deformation of the first primary support layer converges and the load detected by the strain sensor is smaller than or equal to a set threshold value, the second secondary lining layer is applied to the first primary support layer. The method has the beneficial effects that whether the second primary support layer is constructed or not is dynamically judged based on the real-time monitoring data, production materials are saved, and the construction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering, and in particular to a dynamic support system and a construction method for a super-large span tunnel. Background Art

[0002] In traditional large-span tunnel construction, the initial support mostly adopts a single-layer or double-layer structure. The single-layer initial support is suitable for tunnels with good geological conditions and strong surrounding rock self-stabilization ability. The design of two-layer initial support is usually used in tunnel projects with complex geological conditions, poor surrounding rock stability, and high-stress areas, such as in weak and broken surrounding rocks, large-span tunnels, crossing fault zones or high-stress compression strata.

[0003] At present, the support structure to be adopted is determined based on the geological conditions and surrounding rock stability data obtained in the early stage of construction. However, the geological conditions and surrounding rock stability in actual construction are different from the survey data, resulting in the following problems: the support system lacks a dynamic adjustment mechanism, and double-layer support is still mandatory when the formation conditions are good, resulting in material waste. The secondary lining and initial support are designed independently, and a coordinated force system is not formed. The construction process is rigid, and the support strategy cannot be adjusted in real time according to the deformation of the surrounding rock, resulting in material waste and low construction efficiency. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the current construction process is rigidified and the support strategy cannot be adjusted in real time according to the deformation of the surrounding rock, resulting in material waste and low construction efficiency. The purpose is to provide a dynamic support system and construction method for extra-large span tunnels, so as to realize dynamic judgment based on real-time monitoring data on whether to construct a second initial support layer, save production materials, and improve construction efficiency.

[0005] The present invention is achieved through the following technical solutions: A dynamic support system for a very large-span tunnel comprises a first initial support layer and a secondary lining layer, wherein the first initial support layer is directly connected to the surrounding rock, and a plurality of strain sensors are connected to the first initial support layer; the secondary lining layer comprises a first secondary lining layer and a second secondary lining layer, and when the load detected by the strain sensor is greater than a set threshold, and / or the load of the temporary support is greater than the set threshold, or the monitored deformation of the first initial support layer does not converge, a second initial support layer is constructed on the basis of the first initial support layer, and the first secondary lining layer is applied on the second initial support layer; when the monitored deformation of the first initial support layer converges and the load detected by the strain sensor is less than or equal to the set threshold, the second secondary lining layer is applied on the first initial support layer.

[0006] The beneficial effects of the present invention are as follows. Several strain sensors are connected to the first primary support layer. By means of the strain sensors, the real-time load of the first primary support layer is obtained, which facilitates changing the support plan to construct a second primary support layer on the basis of the first primary support layer and applying a first secondary lining layer on the second primary support layer to meet the support for the surrounding rock when the load of the first primary support layer is greater than the set threshold, or the load of the temporary support is greater than the set threshold, or the loads of both are greater than the set threshold, or the monitored deformation of the first primary support layer does not converge. When the monitored deformation of the first primary support layer converges and the support load detected by the strain sensors is less than or equal to the set threshold, the second secondary lining layer is applied on the first primary support layer, realizing dynamic judgment of whether to construct the second primary support layer based on real-time monitoring data (whether it converges and real-time load), saving production materials and improving construction efficiency.

[0007] In some embodiments, several temporary supports are provided, and strain sensors are provided on each of the several temporary supports. By installing strain sensors on the temporary supports as well, the load of the temporary supports can be obtained in real time, further improving the accuracy of determining whether to construct the second primary support layer and realizing the overall stability evaluation of the support system.

[0008] In some embodiments, several data processors are further included. Each data processor is electrically connected to a corresponding strain sensor, and each data processor is connected to the first primary support layer or the temporary support and is adjacent to the corresponding strain sensor.

[0009] In some embodiments, a light-emitting data converter is provided on the data processor. The light-emitting data converter can be displayed in green, blue, orange, and red. In the working state, when the load detected by the strain sensor is 0-30% of the design load, the light-emitting data converter is displayed in green; when the load detected by the strain sensor is 30%-60% of the design load, the light-emitting data converter is displayed in blue; when the load detected by the strain sensor is 60%-90% of the design load, the light-emitting data converter is displayed in orange; when the load detected by the strain sensor is more than 90% of the design load, the light-emitting data converter is displayed in red. By providing a light-emitting data converter on the data processor, it is convenient to convert the data signal into an optical signal and display the corresponding color when the strain load is different data, so that the on-site workers can intuitively understand the load situation of the support structure, so that the workers can make corresponding treatment measures according to the color displayed by the converter, and it can also be used as a safety warning light.

[0010] In some embodiments, the sum of the thicknesses of the first secondary lining layer and the second primary support layer is equal to the thickness of the second secondary lining layer. When the deformation rate of the first layer of support is stable and the load borne by the temporary support is small, the originally designed thickness (h2) of the second layer of support is incorporated into the secondary lining to form a composite reinforced lining layer (h2 + h3), which can not only meet the design requirements but also save the materials and processes for constructing the second support layer.

[0011] In some embodiments, steel frames are provided in both the first primary support layer and the second primary support layer, and the steel frames are I-beams. By providing steel frames in both the first primary support layer and the second primary support layer, the problem of large deformation of the surrounding rock tunnel can be prevented, the construction quality can be improved, and the construction safety risk can be reduced.

[0012] In some embodiments, the first primary support layer sequentially includes a shotcrete layer, a steel frame, and a wire mesh from the inside to the outside, and the second primary support layer sequentially includes a shotcrete layer and a steel frame from the inside to the outside. By including a shotcrete layer, a steel frame, and a wire mesh in the first primary support layer and a shotcrete layer and a steel frame in the second primary support layer, a strength gradient of "rigid outside and flexible inside" is formed, and the first layer of primary support is preferentially used to bear the load, reducing the amount of inner layer materials.

[0013] A construction method for dynamic support of an extra-large-span tunnel, implemented based on the above extra-large-span tunnel dynamic support system, includes the following steps: S1. While excavating, construct the first primary support layer and the temporary support structure according to the setting steps, and install several strain sensors and several data processors on both the first primary support layer and the temporary support structure. S2. Monitor whether the deformations of the temporary support and the first primary support layer converge. If the deformations converge and all the loads detected by the strain sensors are less than or equal to the set threshold, construct the first secondary lining layer on the first primary support layer; if the deformations do not converge or any one of the loads detected by the strain sensors is greater than the set threshold, construct the second primary support layer on the first primary support layer and construct the second secondary lining layer on the second primary support layer. It realizes the overall stability evaluation of the support system based on real-time monitoring data (whether it converges, the real-time loads of the first primary support layer and the temporary support layer), and then dynamically judges whether to construct the second primary support layer, saving production materials and improving construction efficiency.

[0014] In some embodiments, if the deformation rate of the first primary support layer and the temporary support structure is less than or equal to 0.2 mm / d, it is determined that the deformation converges; if the deformation rate of the first primary support layer and the temporary support structure is greater than 0.2 mm / d, it is determined that the deformation does not converge.

[0015] In some embodiments, the set threshold is 60% of the design load.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Realize the overall stability evaluation of the support system based on real-time monitoring data (whether it converges, the real-time loads of the first primary support layer and the temporary support layer), and then dynamically determine whether to construct the second primary support layer, saving production materials and improving construction efficiency.

[0017] 2. The structure of the first primary support layer adopts (shotcrete + steel frame + steel mesh), and the structure of the second primary support layer adopts (shotcrete + small-section steel), forming a strength gradient of "rigid outside and flexible inside", giving priority to using the first primary support for bearing and reducing the amount of inner-layer materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings: Figure 1 is the logic schematic diagram of the present invention; Figure 2 is the elevation view of the construction process of the double-side drift method for the type II lining of the present invention; Figure 3 is the elevation view of the construction process of the double-side drift method for the type I lining of the present invention; Figure 4 is the partial cross-sectional view in the longitudinal direction of the type II lining of the present invention; Figure 5 is the partial cross-sectional view in the longitudinal direction of the type I lining of the present invention; Figure 6 is the elevation view of the type II lining of the present invention; Figure 7 is the elevation view of the type I lining of the present invention.

[0019] Marks in the drawings and corresponding component names: Advance Pilot Tunnel Advanced Support 1. Upper part of the advance pilot tunnel 2. Support for the upper part of the advance pilot tunnel 3. Strain sensor 4. Data processor 5. Lower part of the advance pilot tunnel 6. Support for the lower part of the advance pilot tunnel 7. Advanced support for the rear pilot tunnel 8. Upper part of the rear pilot tunnel 9. Support for the upper part of the rear pilot tunnel 10. Lower part of the rear pilot tunnel 11. Support for the lower part of the rear pilot tunnel 12. Advanced support for the arch part of the middle wall 13. Upper part of the middle wall 14. Initial support for the upper part of the middle wall 15. Lower part of the middle wall 16. Initial support for the lower part of the middle wall 17. Inverted arch secondary lining 19. Steel frame 21. First initial support layer 30. Second initial support layer 31. First secondary lining layer 32. Second secondary lining layer 321. Temporary support 33. Detailed Implementation Manner

[0020] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments and drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0021] Throughout the specification, the reference to "one embodiment", "embodiment", "one example" or "example" means that a specific feature, structure or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment", "embodiment", "one example" or "example" that appear in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, specific features, structures or characteristics can be combined in any appropriate combination and / or sub-combination in one or more embodiments or examples. In addition, those of ordinary skill in the art should understand that the drawings provided herein are for illustrative purposes only and the drawings are not necessarily drawn to scale. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0022] In the description of the present invention, the orientation or positional relationships indicated by the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the protection scope of the present invention.

[0023] The terms "first", "second", etc. used in the present invention are only used to distinguish the corresponding components clearly and are not intended to limit any order or emphasize importance, etc. In addition, the term "connection" used herein, without special explanation, can be directly connected or indirectly connected via other components.

[0024] Embodiment 1 See Figures 1-7 , Embodiment 1 of the present invention provides a dynamic support system for an extra-large-span tunnel, including a first primary support layer 30 and a secondary lining layer. The first primary support layer 30 is directly connected to the surrounding rock, and several strain sensors 4 are connected to the first primary support layer 30. The secondary lining layer includes a first secondary lining layer 32 and a second secondary lining layer 321. When the load detected by the strain sensors 4 is greater than the set threshold, and / or the load of the temporary support 33 is greater than the set threshold, or the monitored deformation of the first primary support layer 30 does not converge, a second primary support layer 31 is constructed on the basis of the first primary support layer 30, and the first secondary lining layer 32 is constructed on the second primary support layer 31 (Type II lining). When the monitored deformation of the first primary support layer 30 converges and the load detected by the strain sensors 4 is less than or equal to the set threshold, the second secondary lining layer 321 is constructed on the first primary support layer 30 (Type I lining). It realizes dynamic judgment of whether to construct the second primary support layer 31 based on real-time monitoring data (whether it converges and real-time load), saves production materials, and improves construction efficiency.

[0025] See Figure 2 and Figure 3 , several temporary supports 33 are provided, and strain sensors 4 are provided on each of the several temporary supports 33. By installing strain sensors 4 on the temporary supports 33 as well, the load of the temporary supports 33 can be obtained in real time, further improving the accuracy of determining whether to construct the second primary support layer 31 and realizing the overall stability assessment of the support system.

[0026] See Figure 2 and Figure 3 , it further includes several data processors 5. Each data processor 5 is electrically connected to a corresponding strain sensor 4, and each data processor 5 is connected to the first primary support layer 30 or the temporary support 33 and is adjacent to the corresponding strain sensor 4.

[0027] See Figure 2 and Figure 3, a light-emitting data converter is provided on the data processor 5. The light-emitting data converter can be displayed in green, blue, orange, and red. In the working state, when the load detected by the strain sensor 4 is 0-30% of the design load, the light-emitting data converter is displayed in green; when the load detected by the strain sensor 4 is 30%-60% of the design load, the light-emitting data converter is displayed in blue; when the load detected by the strain sensor 4 is 60%-90% of the design load, the light-emitting data converter is displayed in orange; when the load detected by the strain sensor 4 is more than 90% of the design load, the light-emitting data converter is displayed in red. By providing a light-emitting data converter on the data processor 5, it is convenient to convert data signals into optical signals and display corresponding colors when the strain loads are different data, so that on-site workers can intuitively understand the load conditions of the support structure, so that workers can make corresponding treatment decisions according to the colors displayed by the converter, and it can also be used as a safety warning light. Specifically, batteries are installed in both the strain sensor 4, the data processor 5, and the light-emitting data converter.

[0028] See Figures 4-7 , the sum of the thicknesses of the first secondary lining layer 32 and the second primary support layer 31 is equal to the thickness of the second secondary lining layer 321. When the deformation rate of the first layer of support is stable and the load borne by the temporary support is small, the originally designed thickness (h2) of the second layer of support is combined with the secondary lining to form a composite reinforced lining layer (h2 + h3), which can not only meet the design requirements but also save the materials and processes of the second support layer during construction.

[0029] See Figures 4-7 , steel frames 21 are provided in both the first primary support layer 30 and the second primary support layer 31, and the steel frames 21 are I-beams. By providing steel frames 21 in both the first primary support layer 30 and the second primary support layer 31, the problem of large deformation of the surrounding rock tunnel can be prevented, the construction quality can be improved, and the construction safety risk can be reduced.

[0030] See Figures 4-7 , the first primary support layer 30 sequentially includes a shotcrete layer, a steel frame 21, and a steel mesh from the inside to the outside, and the second primary support layer 31 sequentially includes a shotcrete layer and a steel frame 21 from the inside to the outside. By including a shotcrete layer, a steel frame 21, and a steel mesh in the first primary support layer 30, and a shotcrete layer and a steel frame 21 in the second primary support layer 31, a strength gradient of "rigid outside and flexible inside" is formed, and the first layer of primary support is preferentially used to bear the load, reducing the amount of inner layer materials.

[0031] Embodiment 2 See Figures 1-7, Embodiment 2 of the present invention provides a construction method for dynamic support of extra-large-span tunnels, which is implemented based on the above-mentioned dynamic support system for extra-large-span tunnels, and includes the following steps: S1. While excavating, construct the first primary support layer 30 and the temporary support structure according to the setting steps, and install several strain sensors 4 and several data processors 5 on both the first primary support layer 30 and the temporary support structure; S2. Monitor whether the deformations of the temporary support and the first primary support layer 30 converge. If the deformations converge and all the loads detected by the strain sensors 4 are less than or equal to the set threshold, then construct the first secondary lining layer 32 on the first primary support layer 30; if the deformations do not converge or any of the loads detected by the strain sensors 4 is greater than the set threshold, then construct the second primary support layer 31 on the first primary support layer 30, and construct the second secondary lining layer 321 on the second primary support layer 31. It realizes the overall stability evaluation of the support system based on real-time monitoring data (whether it converges, the real-time loads of the first primary support layer 30 and the temporary support 33 layer), and then dynamically judges whether to construct the second primary support layer 31, saving production materials and improving construction efficiency.

[0032] See Figure 1 , if the deformation rate of the first primary support layer 30 and the temporary support structure is less than or equal to 0.2 mm / d, it is determined that the deformation converges; if the deformation rate of the first primary support layer 30 and the temporary support structure is greater than 0.2 mm / d, it is determined that the deformation does not converge.

[0033] See Figure 1 , the set threshold is 60% of the design load.

[0034] See Figure 1 , specifically, the construction process is as follows: Pre-design: Double-layer primary support for the arch wall + single-layer cast-in-place concrete Construct the advanced support 1 of the pilot drift, the upper part 2 of the pilot drift, the upper part support 3 of the pilot drift (including the first primary support layer 30 of the main tunnel and the temporary support 33 on the leading side. Strain sensors 4 and data processors 5 are installed on the steel frames 21 of the first primary support layer 30 and the temporary support 33. Different axial force detection data can be converted into different colors for display in combination with the light-emitting data converter, and different colors correspond to different loads. Green (design load 0 - 30%), blue (design load 30% - 60%), orange (design load 60% - 90%), red (above 90% of the design load)), excavate the lower part 6 of the pilot drift, construct the lower part support 7 of the pilot drift (including the primary support of the main tunnel and the temporary support 33 on the leading side), construct the advanced support 8 of the rear drift, excavate the upper part 9 of the rear drift, construct the upper part support 10 of the rear drift (including the primary support of the main tunnel and install strain sensors 4 and data processors 5 on the temporary support 33 on the rear side), excavate the lower part 11 of the rear drift, construct the lower part support 12 of the rear drift (including the primary support of the main tunnel and the temporary support 33 on the rear side, install strain sensors 4 and data processors 5), construct the advanced support 13 of the middle wall arch, excavate the upper part 14 of the middle wall, construct the upper part primary support 15 of the middle wall and close it with the upper part support 3 of the pilot drift and the upper part support 10 of the rear drift, excavate the lower part 16 of the middle wall, construct the lower part primary support 17 of the middle wall and close it with the lower part support 7 of the pilot drift and the lower part support 12 of the rear drift, continuously detect the first primary support layer 30 and the temporary support, and establish the response relationship between the monitoring data and the number of support layers.

[0035] a; When the deformation rate ≤ 0.2 mm / d and the load ≤ 60% of the design value, trigger the mode switch to form the type I lining (single-layer support + thickened cast-in-place lining, i.e., the second secondary lining layer 321).

[0036] b: If the load of the first layer of primary support or temporary support > 60% of the design value, continue to select the pre-designed type II lining (double-layer support + standard cast-in-place lining, i.e., the first secondary lining layer 32).

[0037] For the subsequent construction sequence of the type I lining: Construct the inverted arch secondary lining 19 (first remove the temporary support 33).

[0038] Construct the thickened arch wall secondary lining 32.

[0039] For the subsequent construction sequence of the type II lining: Install the second layer of primary support structure integrally.

[0040] Construct the inverted arch secondary lining 19 (first remove the temporary support 33).

[0041] Construct the arch wall secondary lining.

[0042] "60% design load" in the present invention is a commonly used term in the engineering field, which means that the load (i.e., external force) borne by a structure or component is 60% of its design load. The meaning of other proportional design loads is the same. The design load is the target load value artificially set by engineers when designing structures (such as buildings, bridges, tunnels, etc.) according to specifications, usage requirements and expected environmental conditions.

[0043] The extra-long-span tunnel in the present invention refers to: a single-tunnel four-lane tunnel or a single-tunnel with an excavation span greater than 20 meters.

[0044] The specific embodiments described above further elaborate on the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dynamic support system for extra-long-span tunnels, characterized in that, Including: A first primary support layer directly connected to the surrounding rock, and several strain sensors are connected to the first primary support layer; A secondary lining layer, which includes a first secondary lining layer and a second secondary lining layer. When the load detected by the strain sensors is greater than the set threshold, and / or the load of the temporary support is greater than the set threshold, or the monitored deformation of the first primary support layer does not converge, a second primary support layer is constructed on the basis of the first primary support layer, and the first secondary lining layer is constructed on the second primary support layer; when the monitored deformation of the first primary support layer converges and the load detected by the strain sensors is less than or equal to the set threshold, the second secondary lining layer is constructed on the first primary support layer.

2. The extra-large-span tunnel dynamic support system according to claim 1, wherein Several temporary supports are provided, and strain sensors are provided on each of the several temporary supports.

3. The extra-large-span tunnel dynamic support system according to claim 1 or 2, characterized in that, It further includes several data processors, each of which is electrically connected to a corresponding strain sensor, and each of the data processors is connected to the first primary support layer or the temporary support and is adjacent to the corresponding strain sensor.

4. The extra-large-span tunnel dynamic support system according to claim 3, wherein, A light-emitting data converter is provided on the data processor. The light-emitting data converter can be displayed in green, blue, orange, and red. In the working state, when the load detected by the strain sensor is 0-30% of the design load, the light-emitting data converter is displayed in green; when the load detected by the strain sensor is 30%-60% of the design load, the light-emitting data converter is displayed in blue; when the load detected by the strain sensor is 60%-90% of the design load, the light-emitting data converter is displayed in orange; when the load detected by the strain sensor is more than 90% of the design load, the light-emitting data converter is displayed in red.

5. The extra-large-span tunnel dynamic support system according to claim 1, characterized in that, The sum of the thicknesses of the first secondary lining layer and the second primary support layer is equal to the thickness of the second secondary lining layer.

6. The extra-large-span tunnel dynamic support system according to claim 1, characterized in that, Steel frames are provided inside both the first primary support layer and the second primary support layer, and the steel frames are I-beams.

7. The extra-large-span tunnel dynamic support system according to claim 1, characterized in that The first primary support layer sequentially includes a shotcrete layer, a steel frame, and a steel mesh from the inside to the outside, and the second primary support layer sequentially includes a shotcrete layer and a steel frame from the inside to the outside.

8. A construction method for dynamic support of extra-long-span tunnels, characterized in that, Implementing the dynamic support system for extra-large-span tunnels according to any one of claims 1-7, including the following steps: S1. While excavating, construct the first primary support layer and the temporary support structure according to the setting steps, and install several strain sensors and several data processors on both the first primary support layer and the temporary support structure; S2. Monitor whether the deformations of the temporary support and the first primary support layer converge. If the deformations converge and all the loads detected by the strain sensors are less than or equal to the set threshold, construct the first secondary lining layer on the first primary support layer; if the deformations do not converge or any of the loads detected by the strain sensors is greater than the set threshold, construct the second primary support layer on the first primary support layer and construct the second secondary lining layer on the second primary support layer.

9. The extra-large-span tunnel dynamic support system according to claim 8, characterized in that, If the deformation rate of the first primary support layer and the temporary support structure is less than or equal to 0.2 mm / d, it is determined that the deformation converges; if the deformation rate of the first primary support layer and the temporary support structure is greater than 0.2 mm / d, it is determined that the deformation does not converge.

10. The extra-large-span tunnel dynamic support system according to claim 8, characterized in that, The set threshold is 60% of the design load.

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