A method for controlling stability of surrounding rock of a large-section railway tunnel

Abstract

The application discloses a large-section railway tunnel surrounding rock stability control method, comprising the following steps: step S1, using a soil strength device to detect the strength in the tunnel; step S2, dividing out the broken area with soil strength lower than a predetermined threshold and marking it as a low-strength area, and dividing out the area with soil strength higher than the predetermined threshold and marking it as a high-strength area; step S3, according to the different strength parameters of each low-strength area, calculating the amount of grouting material needed to be injected into each low-strength area to achieve the same strength, and injecting the corresponding amount of grouting material into each low-strength area; step S4, covering the surface of the low-strength area with a glass fiber cloth; and step S5, coating a layer of concrete. According to the application, targeted grouting is carried out according to the different strengths of different broken areas, so that the broken areas with different strengths can achieve relatively consistent strength after reinforcement treatment, and the purpose of uniformly strengthening the tunnel is finally achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tunnel surrounding rock stability control. More particularly, the present application relates to a large-section railway tunnel surrounding rock stability control method. BACKGROUND

[0002] With the rapid development of China's railways, it has spread throughout the country's large and small cities. As of the end of 2021, the total length of the national railway was 150,000 kilometers, of which the length of the high-speed railway was 40,000 kilometers. When the railway passes through the mountainous area, it needs to excavate the tunnel. After the excavation of the large-section tunnel, the rock mass at the top of the cavern often produces a large settlement, and the broken rock mass may even collapse and cave in. Especially the rock mass around the shallow-buried and strongly weathered underground tunnel is in a state of dense joints and very broken, resulting in low efficiency of subway construction and weakening of the surrounding rock support effect. The current tunnel surrounding rock reinforcement method is usually to directly inject grouting material into the surrounding rock. This treatment method is simple and practical, but the broken condition is different in different areas. If the same method is used for grouting regardless of the situation, it will inevitably lead to different strengths in different areas, and over time, it will inevitably cause further cracking problems. SUMMARY

[0003] In order to achieve these objects and other advantages of the present application, a large-section railway tunnel surrounding rock stability control method is provided, comprising the following steps:

[0004] Step S1, investigate the geological conditions of the railway tunnel surrounding rock, determine the properties of the tunnel soil, and detect the strength in the tunnel using soil strength equipment;

[0005] Step S2, divide and mark the broken area with soil strength lower than the predetermined threshold as a low-strength area, and mark the area with soil strength higher than the predetermined threshold as a high-strength area according to the strength parameters of each low-strength area from high to low in order;

[0006] Step S3, according to the different strength parameters of each low-strength area, calculate the amount of grouting material needed to be injected into each low-strength area to achieve the same strength, and inject the corresponding amount of grouting material into each low-strength area;

[0007] Step S4, after the grouting material hardens to a first predetermined strength, cover the low-strength area with glass fiber cloth, and use anchor nails to fix the glass fiber cloth. For each low-strength area, the glass fiber cloth not only covers the low-strength area, but also partially covers the high-strength area adjacent to the low-strength area;

[0008] Step S5, after the grouting material is completely hardened, coat a layer of concrete on the surface of all low-strength areas and high-strength areas.

[0009] Preferably, in the process of injecting the grouting material into the low-intensity area, a drilling device is used to drill a plurality of grouting holes in each low-intensity area, and the grouting material is injected through the grouting holes.

[0010] Preferably, when the intensity parameter of a certain low-intensity area is lower than a preset value, a thin layer of concrete is first sprayed on the surface of the low-intensity area before the drilling device is used to drill a grouting hole in the low-intensity area.

[0011] Preferably, the higher the intensity parameter of a low-intensity area, the more grouting holes that need to be drilled in the low-intensity area.

[0012] Preferably, in the step S3, when the amount of the grouting material injected into a certain low-intensity area is higher than a set threshold, an anchor rod is inserted into the low-intensity area during the injection process.

[0013] Preferably, after the step S3, after the grouting material is injected into each low-intensity area in a corresponding amount, when the grouting material hardens to a second preset threshold, the intensity of each low-intensity area is detected by using a soil strength device, and if the intensity of a certain low-intensity area is lower than the average value and exceeds a preset range, the injection of the grouting material is continued, and when the grouting material hardens to the second preset threshold, the intensity of the low-intensity area is detected by using the soil strength device, and the above operation is repeated until the intensity of each low-intensity area is within the average value range.

[0014] Preferably, in the step S5, the process of coating a layer of concrete on the surface of all low-intensity areas and high-intensity areas specifically includes the following operations:

[0015] A first layer of concrete is coated on the surface of all low-intensity areas and high-intensity areas, and then a plurality of steel wire meshes are laid on the surface of the first layer of concrete before it hardens, and adjacent two steel wire meshes are partially stacked, and the stacked part is connected by using a rigid spring.

[0016] Preferably, the second preset threshold is smaller than the first preset threshold.

[0017] Preferably, in the step S4, a plurality of glass fiber cloths are laid, and adjacent two glass fiber cloths are partially stacked, and the stacked part is connected by using a flexible spring.

[0018] Preferably, the thickness of the glass fiber cloth is 3-5 mm.

[0019] The present application at least includes the following beneficial effects: the present application can achieve consistent intensity of different intensity broken areas after reinforcement treatment, and ultimately achieve the purpose of uniform strengthening of the tunnel.

[0020] Other advantages, objects, and features of the application will be apparent to those skilled in the art from the following specification. DETAILED DESCRIPTION

[0021] The application will be further described with reference to the drawings, in which embodiments of the application will be explained.

[0022] The following description is presented to enable any person skilled in the art to practice the application as claimed. Preferred embodiments are provided in the following description only as examples and modifications will be readily apparent to those skilled in the art with the benefit of this disclosure. The general principles defined herein can be applied to other embodiments and modifications without departing from the scope of the application as defined by the appended claims.

[0023] It is to be understood that the term "a" or "an" shall not be construed as limiting the number of items to a single item, but rather "one or more". That is, the terms "a" or "an" shall be read to mean "at least one" or "one or more" to include one or more of the elements, features, structures, items, components, etc.

[0024] In actual construction, the broken conditions of different areas of the tunnel surrounding rock are often different, and the conventional reinforcing means is to directly inject grouting material without distinction, and to simply and roughly reinforce, but this reinforcing method has a big problem, that is, the broken conditions of different areas are different, which inevitably leads to different strengths, and if the same method is used for grouting without distinction, the strengths of different areas will inevitably be different, and over time, further cracking problem will inevitably occur, in order to solve this technical problem, a preferred embodiment of the application provides a large-section railway tunnel surrounding rock stability control method, comprising the following steps:

[0025] Step S1, investigating the geological conditions of the railway tunnel surrounding rock, determining the properties of the tunnel soil, and detecting the strength in the tunnel by using a soil strength device;

[0026] Step S2, dividing and marking the broken areas with soil strength lower than a predetermined threshold value as low-strength areas, and marking each low-strength area in order from high to low according to the strength parameters, and dividing and marking the areas with soil strength higher than the predetermined threshold value as high-strength areas;

[0027] Step S3, according to the different strength parameters of each low-strength area, calculating the amount of grouting material needed to be injected into each low-strength area to achieve the same strength, and injecting the corresponding amount of grouting material into each low-strength area;

[0028] Step S4, after the grouting material hardens to a first preset strength, a glass fiber cloth is covered on the surface of the low-strength area, and the glass fiber cloth is fixed by using anchor nails, and for each low-strength area, the glass fiber cloth covers the low-strength area and also partially covers the high-strength area adjacent to the low-strength area; the thickness of the glass fiber cloth is 3-5 mm.

[0029] Step S5, after the grouting material is completely hardened, a layer of concrete is coated on the surface of all low-strength areas and high-strength areas.

[0030] In the above embodiment, the traditional method of strengthening the tunnel surrounding rock without distinguishing the broken area and directly grouting all the broken areas is abandoned, and targeted grouting is performed according to the different strengths of different broken areas, so that the broken areas with different strengths can reach a relatively consistent strength after reinforcement treatment. Specifically, the low-strength area with relatively lower strength is grouted with more grouting material to improve its strength, and the low-strength area with relatively higher strength is grouted with relatively less grouting material, so as to finally achieve the purpose of uniformly strengthening the tunnel.

[0031] The grouting material refers to a fluid material injected into the cracks, holes of the stratum, rock or structure under pressure to increase the bearing capacity, prevent leakage and improve the overall performance of the structure, which can be solidified. The type of grouting material is not limited here, and the conventional building grouting material available on the market can be used.

[0032] Among them, the strength of the low-strength area does not meet the standard and needs subsequent reinforcement treatment, and the strength of the high-strength area meets the standard and does not need subsequent reinforcement treatment. This threshold value can be set according to the actual situation, which is not limited here.

[0033] Among them, after the grouting material hardens to a first preset strength, a glass fiber cloth is covered on the surface of the low-strength area, and the glass fiber cloth is fixed by using anchor nails, and the toughness of the glass fiber cloth is used to increase the toughness of the area. After the grouting material hardens, the glass fiber cloth can deform to some extent to offset the stress, thereby reducing or avoiding the deformation caused by stress, and for each low-strength area, the glass fiber cloth covers the low-strength area and also partially covers the high-strength area adjacent to the low-strength area. The glass fiber cloth simultaneously connects the high-strength area and the low-strength area, so that the low-strength area can also use the high strength of the high-strength area.

[0034] In a preferred embodiment of the present application, during the process of injecting grouting material into the low-strength area, a drilling device is used to drill a plurality of grouting holes in each low-strength area, and then the grouting material is injected through the grouting holes.

[0035] In the above embodiment, it is noted that during the drilling process, the speed must be kept uniform and slow, and too fast speed will cause collapse.

[0036] In view of the high degree of fragmentation of the low-intensity area, if direct drilling is performed, collapse can easily occur everywhere. In order to avoid this problem, a preferred embodiment of the present application provides the following solution: when the intensity parameter of a certain low-intensity area is lower than a preset value, before drilling a grouting hole in the low-intensity area using a drilling device, a thin layer of concrete is first sprayed on the surface of the low-intensity area. After the thin layer of concrete hardens to a certain hardness, the drilling device is used to perform drilling operation. The certain hardness refers to the fact that the thin layer of concrete at this position can provide a certain support, but it can be cut and drilled by the drilling machine under a small drilling force. In this way, drilling can be performed without causing collapse.

[0037] In a preferred embodiment of the present application, the higher the intensity parameter of the low-intensity area, the lower the intensity, and the more grouting holes that need to be drilled.

[0038] In a preferred embodiment of the present application, in the step S3, and when the amount of grouting material injected into a certain low-intensity area is higher than a set threshold, an anchor rod is inserted into the low-intensity area during the injection process, which is also for reinforcement performance.

[0039] In a preferred embodiment of the present application, after the step S3, after a corresponding amount of grouting material is injected into each low-intensity area, when the grouting material hardens to a second preset threshold, the intensity of each low-intensity area is detected using a soil strength device. If the intensity of a certain low-intensity area is lower than the average value and exceeds a preset range, the injection of grouting material is continued. When the grouting material hardens to the second preset threshold, the intensity of the low-intensity area is detected using the soil strength device. The above operation is repeated until the intensity of each low-intensity area is within the average value range. The second preset threshold is smaller than the first preset threshold.

[0040] In a preferred embodiment of the present application, the step S5 of coating a layer of concrete on the surfaces of all low-intensity areas and high-intensity areas specifically includes the following operations:

[0041] A first layer of concrete is coated on the surfaces of all low-intensity areas and high-intensity areas. After the first layer of concrete hardens, a plurality of steel wire meshes are laid on the surface of the first layer of concrete, and the adjacent two steel wire meshes are partially stacked. The two stacked parts are connected by a rigid spring.

[0042] In the concrete, embed steel wire mesh, in the process of thermal expansion and cold shrinkage in the concrete, the steel wire mesh has a little deformation force to offset part of the stress, and when the stress is larger, the strong deformation force of the rigid spring can offset the stress generated by the thermal expansion and cold shrinkage in the concrete, and the partial stacking between the two adjacent steel wire meshes can also offset the stress generated by the thermal expansion and cold shrinkage in the concrete, avoiding the deformation stress to cause the concrete to crack.

[0043] In a preferred embodiment of the application, in the step S4, a plurality of glass fiber cloths are laid, and the two adjacent glass fiber cloths are partially stacked, and the two are connected by using flexible springs at the stacking positions.

[0044] Although the embodiments of the present application have been disclosed as above, they are not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and other modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to specific details and the embodiments shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A method for controlling the stability of surrounding rock in a large cross-section railway tunnel, characterized by, The method comprises the following steps: Step S1, investigating the geological conditions of the surrounding rock of the railway tunnel, determining the properties of the tunnel soil, and detecting the strength in the tunnel by using a soil strength device; Step S2, dividing and marking the broken area with soil strength lower than a predetermined threshold as a low-strength area, and marking the area with soil strength higher than the predetermined threshold as a high-strength area according to the strength parameters of each low-strength area from high to low in order; Step S3, calculating the amount of grouting material needed to be injected into each low-strength area to achieve the same strength according to the different strength parameters of each low-strength area, and injecting the corresponding amount of grouting material into each low-strength area; Step S4, covering the surface of the low-strength area with a glass fiber cloth after the grouting material hardens to a first predetermined strength, and fixing the glass fiber cloth by using anchor nails, and for each low-strength area, the glass fiber cloth covers the low-strength area and also partially covers the high-strength area adjacent to the low-strength area; Step S5, coating a layer of concrete on the surface of all low-strength areas and high-strength areas after the grouting material is completely hardened.

2. The large cross-section railway tunnel surrounding rock stability control method according to claim 1, characterized by, During the process of injecting grouting material into the low-strength area, a drilling device is used to drill multiple grouting holes in each low-strength area, and then the grouting material is injected through the grouting holes.

3. The large cross-section railway tunnel surrounding rock stability control method according to claim 2, characterized by, When the strength parameter of a certain low-strength area is lower than the preset value, a thin layer of concrete is first sprayed on the surface of the low-strength area before drilling grouting holes in the low-strength area using a drilling device.

4. The large cross-section railway tunnel surrounding rock stability control method according to claim 1, characterized by, The higher the strength parameter of the low-strength area, the more grouting holes need to be drilled.

5. The large cross-section railway tunnel surrounding rock stability control method according to claim 1, characterized by, In step S3, when the amount of grouting material injected into a certain low-strength area is higher than the set threshold, an anchor rod is inserted into the low-strength area during the injection process.

6. The large cross-section railway tunnel surrounding rock stability control method according to claim 1, characterized by, After injecting the corresponding amount of grouting material into each low-strength area in step S3, the strength of each low-strength area is detected by using a soil strength device when the grouting material hardens to a second predetermined threshold. If the strength of a certain low-strength area is lower than the average value and exceeds the preset range, the grouting material is continuously injected. When the grouting material hardens to the second predetermined threshold, the strength of the low-strength area is detected by using the soil strength device. The above operation is repeated until the strength of each low-strength area is within the average range.

7. The large cross-section railway tunnel surrounding rock stability control method according to claim 2, characterized by, In step S5, coating a layer of concrete on the surface of all low-strength areas and high-strength areas, specifically comprising the following operations: A first layer of concrete is coated on the surface of all low-strength areas and high-strength areas, and then a plurality of steel wire meshes are laid on the surface of the first layer of concrete before it hardens, and the adjacent two steel wire meshes are partially stacked, and the stacked part is connected by a rigid spring.

8. The large cross-section railway tunnel surrounding rock stability control method according to claim 6, characterized by, The second predetermined threshold is less than the first predetermined threshold.

9. The large cross-section railway tunnel surrounding rock stability control method according to claim 2, characterized by, In step S4, a plurality of glass fiber cloths are laid, and the adjacent two glass fiber cloths are partially stacked, and the stacked part is connected by a flexible spring.

10. The large cross-section railway tunnel surrounding rock stability control method according to claim 9, characterized by, The thickness of the glass fiber cloth is 3-5 mm.