Pre-protection structure for ground pre-grouting in excavation process of large-gradient long inclined shaft

Abstract

The utility model relates to the technical field of ground pre-grouting of a large-gradient long inclined shaft, in particular to a pre-protection structure for ground pre-grouting in the excavation process of the large-gradient long inclined shaft, which comprises a plugging body, the plugging body comprises a grouting stopping wall and a rock plug, the rock plug is arranged between a pressurization starting point of the ground pre-grouting and a tunnel face, and the grouting stopping wall is connected with the rock plug. The grouting stopping wall is arranged on the side, away from the rock plug, of the tunnel face, the rock plug is used for sharing the grouting pressure of ground pre-grouting, and the grouting stopping wall is used for assisting construction of the rock plug and sharing the grouting pressure of ground pre-grouting. Before the unfavorable geological section is excavated, the plugging body is arranged between the excavated section and the unfavorable geological section, and the pressurization starting point of ground pre-grouting is separated from the excavated section, so that the excavated section and the pressurization starting point of ground pre-grouting meet the safety distance requirement, and the existing supporting structure of the excavated section is protected.

Description

Technical Field

[0001] The utility model relates to the technical field of ground pre-grouting for a steep long inclined shaft, in particular to a pre-protection structure for ground pre-grouting during the excavation of a steep long inclined shaft. Background Art

[0002] Grouting treatment is a commonly used technology for inclined shafts crossing poor geological sections. Combined with the application of modern construction equipment, grouting schemes can be divided into two categories: in-tunnel advance grouting and ground pre-grouting.

[0003] The solution for in-tunnel advance grouting is relatively flexible. The arrangement of grouting holes and grouting technology can be adjusted in real time according to the rock mass conditions in the tunnel revealed by excavation section by section to ensure smooth construction. However, the main disadvantage is that in-tunnel advance grouting directly occupies the linear construction period of the face. At the same time, in-tunnel advance grouting of the surrounding rock in front of the face carries construction safety risks such as mud and water gushing, landslides, and deformation. In particular, in long inclined shafts with large slopes, as the excavation footage increases, the buried depth of the inclined shaft gradually increases, and the groundwater pressure at the face becomes greater and greater. The construction safety risks faced by in-tunnel advance grouting and excavation support are also increasing. At the same time, the construction space for in-tunnel advance grouting at the face of long inclined shafts with large slopes is small, the working environment is poor, and the use of large equipment is relatively difficult, resulting in low construction efficiency.

[0004] Ground pre-grouting is the use of directional drilling technology to drill holes and inject grouting into the ground, thereby pre-treating the surrounding rock of the inclined shaft. Due to the high pressure of ground pre-grouting (up to 30MPa) and the large impact range (up to tens or even hundreds of meters), in order to avoid damage to the existing support structure of the excavated tunnel section, ground pre-grouting treatment is usually carried out before the excavation of the inclined shaft. It does not occupy the linear construction period of the inclined shaft construction and has a great advantage in improving the construction period guarantee rate. However, in some projects, ground pre-grouting measures are required to treat the subsequent unexcavated sections during the excavation process, but ground pre-grouting has a greater impact on the existing support structure of the excavated tunnel section. Utility Model Content

[0005] The purpose of this utility model is to address the defects of the existing technology and provide a pre-protection structure for ground pre-grouting during the excavation of a long inclined shaft with a large slope. Before excavation reaches the poor geological section, a sealing body is set between the excavated section and the poor geological section to separate the pressurization starting point of the ground pre-grouting from the excavated section, so that the excavated section and the ground pre-grouting pressurization starting point meet the safety distance requirements, thereby protecting the existing support structure of the excavated section.

[0006] In order to solve the above technical problems, the utility model provides a pre-protection structure for ground pre-grouting during the excavation of a long inclined shaft with a large slope, including a sealing body, the sealing body including a grouting wall and a rock plug, the rock plug being arranged between the pressurization starting point of the ground pre-grouting and the tunnel face, the grouting wall being arranged on the side of the tunnel face away from the rock plug, the rock plug being used to share the grouting pressure of the ground pre-grouting, and the grouting wall being used to assist the construction of the rock plug and share the grouting pressure of the ground pre-grouting.

[0007] Furthermore, the rock plug includes parent rock and slurry, and the slurry is used to reinforce the parent rock to form the rock plug.

[0008] Furthermore, the cross-sectional area of ​​the rock plug is not less than the cross-sectional area of ​​the long inclined well.

[0009] Furthermore, the mortar-stopping wall includes a reinforced concrete wall.

[0010] Furthermore, a plurality of advance grouting holes are provided on the grout-stopping wall, and the advance grouting holes are used to inject the slurry into the original rock.

[0011] Furthermore, the plurality of advance grouting holes are evenly arranged on the grouting wall, and the plurality of advance grouting holes are used for full-section drilling and grouting in front of the tunnel face to form a rock plug.

[0012] Furthermore, it includes a construction platform, which is arranged on the side of the mortar stop wall away from the rock plug, the bottom of the construction platform is fixed to the bottom surface of the inclined long shaft, and the top of the construction platform is arranged horizontally.

[0013] Furthermore, the construction platform is integrated with the slurry stop wall.

[0014] Furthermore, a reinforcement anchor rod is provided in the rock plug.

[0015] Furthermore, the reinforcement anchor rod comprises a glass fiber anchor rod.

[0016] The beneficial effects of the utility model are:

[0017] 1. The utility model sets a blocking body before the pressurization starting point of ground pre-grouting, so that the blocking body can share the grouting pressure of ground pre-grouting, thereby avoiding damage to the existing support structure of the excavated hole section during the ground pre-grouting process.

[0018] 2. The plugging body of the present invention includes a grouting wall and a rock plug. The grouting wall can not only share the grouting pressure of the ground pre-grouting, but also assist in the construction of the rock plug.

[0019] 3. The cross-sectional area of ​​the rock plug of the present invention is not less than the cross-sectional area of ​​the long inclined shaft, which can ensure the protective effect of the rock plug on the existing support structure.

[0020] 4. The utility model can further improve the strength and anti-slip ability of the rock plug by arranging reinforcement anchor rods in the rock plug.

[0021] 5. The utility model sets a construction platform so that the construction machinery is in a horizontal state in a steep inclined shaft, which is convenient for construction. The construction platform can also further enhance the anti-slip ability of the mortar stop wall and the rock plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a three-dimensional diagram of the present utility model;

[0023] Figure 2 It is a cross-sectional view of the utility model;

[0024] Figure 3 This is a cross-sectional view of the reserved protection section of the utility model.

[0025] Reference numerals: excavated section 1; reserved protection section 2; grouting wall 21; rock plug 22; ground pre-grouting treatment section 3; normal excavation section in the tunnel 4; ground pre-grouting drilling track 5; reinforcement anchor rod 6; construction platform 7. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0027] like Figure 1 As shown, the geological conditions of the excavated section 1 and the normal excavation section 4 in the tunnel are good and can be directly excavated (such as drilling and blasting method), while there is a bad geological section between the excavated section 1 and the normal excavation section 4 in the tunnel (i.e. Figure 1 In the case of the ground pre-grouting treatment section 3), as excavation progresses, the depth of the inclined shaft gradually increases, and the groundwater pressure at the face also increases. When encountering unfavorable geological sections, adopting a construction plan of in-tunnel grouting and excavation support will face significant construction safety risks. In this case, ground pre-grouting can be used to treat the subsequent unexcavated sections, effectively reducing construction risks within the tunnel and improving construction efficiency. However, the high pressure of ground pre-grouting affects a wide range, making it very likely to damage the existing support structure in the excavated section 1.

[0028] To avoid damage to the existing support structure of the excavated section 1, a reserved protection section 2 is required. The utility model proposes a pre-protection structure for ground pre-grouting during the excavation of a long, steeply inclined shaft. Before excavation reaches the unfavorable geological section, a sealing body is provided between the excavated section 1 and the unfavorable geological section, separating the pressurization starting point of the ground pre-grouting from the excavated section 1. This ensures that the excavated section 1 and the ground pre-grouting pressurization starting point meet the safety distance requirements, thereby protecting the existing support structure of the excavated section 1.

[0029] The pre-grouting protection structure on the ground during the excavation of the long inclined shaft with a large slope includes a plugging body (i.e. Figure 1 The reserved protection section 2) in the sealing body includes a grouting wall 21 and a rock plug 22. The rock plug 22 is arranged between the pressurization starting point of the ground pre-grouting and the tunnel face. The grouting wall 21 is arranged on the side of the tunnel face away from the rock plug 22. The grouting wall 21 and the rock plug 22 are connected as a whole. The rock plug 22 is used to share the grouting pressure of the ground pre-grouting. The grouting wall 21 is used to assist the construction of the rock plug 22 and share the grouting pressure of the ground pre-grouting.

[0030] It should be noted that, due to the limitations of ground topography, traffic and other conditions, the layout of the ground pre-grouting drilling site is relatively limited. When drilling at the proposed drilling site, considering the limitations of directional drilling and deflection drill tools, the target front distance and deflection inclination requirements of directional drilling technology, the starting point of the ground pre-grouting drilling trajectory 5 that can enter the inclined well grouting range the fastest is not necessarily the starting point of the unfavorable geological section. Therefore, the rock plug 22 can only be arranged between the pressurization starting point of the ground pre-grouting (that is, entering the inclined well grouting range) and the heading face.

[0031] The rock plug 22 includes original rock and slurry. The slurry is used to reinforce the original rock to form the rock plug 22. The slurry is injected into the original rock by means of advance grouting in the cave.

[0032] In order to ensure the protective effect of the rock plug 22, the cross-sectional area of ​​the rock plug 22 is not less than the cross-sectional area of ​​the long inclined well, that is, the cross-sectional area of ​​the slurry reinforcement range is not less than the cross-sectional area of ​​the long inclined well.

[0033] like Figure 2 As shown, a reinforcement anchor rod 6 is provided in the rock plug 22 to further improve the integrity of the rock plug 22. The reinforcement anchor rod 6 can be a glass fiber anchor rod.

[0034] like Figure 3 As shown, the stop wall 21 comprises a reinforced concrete wall. Multiple pre-grouting holes are provided on the stop wall 21 for injecting grout into the original rock. These holes are evenly distributed throughout the stop wall 21 and are used for full-section drilling and grouting in front of the tunnel face, thereby forming a rock plug 22. The travel range of the rock plug 22 can be controlled by varying the number and inclination of the pre-grouting holes.

[0035] It should be noted that if the surrounding rock grade corresponding to the rock plug 22 is higher, grouting can be directly performed through the tunnel face to form the rock plug 22, and then the grouting wall 21 can be constructed.

[0036] like Figure 3 As shown, the pre-grouting protection structure for ground pre-grouting during the excavation of a steeply inclined long shaft also includes a construction platform 7. Construction platform 7 is located on the side of the grouting wall 21 away from the rock plug 22. The bottom of construction platform 7 is fixed to the bottom surface of the inclined long shaft, and the top of construction platform 7 is arranged horizontally, allowing construction machinery to be placed horizontally on construction platform 7 for ease of construction. Construction platform 7 is constructed of reinforced concrete, with the steel bars of construction platform 7 overlapping the grouting wall 21, making the construction platform 7 and grouting wall 21 integrally connected.

[0037] It should be noted that the purpose of arranging the reserved protection section 2 (i.e., the plugging body) is to ensure that the excavated section 1 and the starting point of the ground pre-grouting pressurization meet the safety distance requirements. The safety distance is determined by the calculated plugging body thickness. The plugging body thickness should meet the following anti-slip stability requirements under the action of ground grouting pressure transmission:

[0038] (1)K·S≤R,

[0039] (2) S = ∑P,

[0040] (3) R = f'∑W + c'∑λ i A i ,

[0041] Where K is the anti-sliding stability safety factor calculated based on the shear strength, S is the design value of the load effect (KN), ∑P is the maximum tangential fraction of the total load effect borne by the plugging body on the sliding surface (KN), R is the design value of the bearing capacity of the plugging body (KN), f' is the shear friction coefficient between the plugging body and the surrounding rock or concrete, ΣW is the normal fraction of the total load effect borne by the plugging body on the sliding surface (KN), c' is the shear cohesion between the plugging body and the surrounding rock or concrete (kPa), and λ i A is the effective area coefficient of the contact surface between the sealing body and the surrounding rock or concrete, i is the contact area between the sealing body and the surrounding rock or concrete (m 2 ).

[0042] The sealing body consists of a rock plug 22 and a grouting wall 21. The rock plug 22 is the rock mass between the starting point of ground pre-grouting and pressurization and the face of the excavated section 1; the grouting wall 21 is a cast-in-place concrete wall that meets the thickness of the sealing body, and its thickness is equal to the calculated sealing body thickness minus the thickness of the rock plug 22.

[0043] The following is an example of a project: The total length of the inclined shaft A in a certain project is 1246m (pile number is K0+000~K1+246), the longitudinal slope is 24.71°, and the cross-sectional dimensions are 6.5mx6.0m (width×height). From the pile number K0+325, it enters the fault zone and is basically in the fault zone until the pile number K1+100. The rock types are mainly fault breccia and crushed powder rock. When the construction in the tunnel reached the pile number K0+526m, water gushed out from the face and a local protrusion appeared. The amount of water and mud gushing out reached 1000m 3 . For long inclined shafts with large slopes, as the excavation footage increases, the buried depth of the inclined shaft increases significantly, the water output from the face becomes larger and larger, the water pressure becomes higher and higher, and the safety risk of continued excavation and construction becomes higher and higher. After repeated demonstrations, ground pre-grouting measures are adopted to pre-treat the subsequent large pile number poor geological sections. Due to the limitations of ground terrain, traffic and other conditions, the layout of the ground pre-grouting drilling site is relatively limited. Drilling at the proposed drilling site location, considering the limitations of directional drilling and deflection drilling tools, the target front distance of directional drilling technology and the requirements of deflection inclination, the ground pre-grouting drilling trajectory 5 can enter the starting pile number of the A inclined shaft grouting section the fastest at K0+610.

[0044] According to the calculation results of the sealing body thickness calculation formula, the sealing body thickness of 52m can meet the requirements of resisting the grouting pressure of ground pre-grouting, that is, the reserved protection section 2 to be arranged should include the tunnel section between pile number K0+610 and pile number K0+558.

[0045] During the ground pre-grouting preparation phase, pre-treatment measures such as backfill grouting and full-section advanced consolidation grouting were implemented in sections within the tunnel. Excavation continued to pile number K0+566, and secondary lining was completed to pile number K0+560. Therefore, a concrete stop wall 21 was constructed from pile numbers K0+558 to K0+566. Pre-grouting was then performed at this stop wall 21 in the unexcavated tunnel section beyond pile number K0+566 to form a rock plug 22. The stop wall 21 and rock plug 22 in the section from pile numbers K0+558 to K0+610 together comprise the reserved protection section 2.

[0046] According to the geological data of Inclined Shaft A, the entire tunnel section from stakes K0+610 to K1+100 lies within the lime kiln fault zone, so surface pre-grouting was performed in this section. The tunnel section from stakes K1+100 to K1+195, affected by the fault, remains relatively fragmented, with significant issues of high external water pressure and surrounding rock stability. Furthermore, due to the complexity and uncertainty of stratigraphic boundaries, surface pre-grouting is still necessary in this section. The basalt strata in the tunnel section beyond K1+195 are uniform, and geological conditions gradually improve. Therefore, surface pre-grouting terminates at stake K1+195. Therefore, stakes K0+610 to K1+195 are designated as surface pre-grouting section 3.

[0047] By arranging ground pre-grouting holes at appropriate locations in the ground drilling site, selecting appropriate grouting materials, and performing ground pre-grouting in accordance with the designed drilling and grouting process, the section achieves both water blocking and reinforcement. Once the ground pre-grouting treatment is complete, the working environment within the tunnel is improved, ensuring construction safety. Excavation, support, and secondary lining can be carried out within the tunnel according to normal procedures for the ground pre-grouting treatment section 3, improving construction efficiency.

[0048] The basalt stratum in the tunnel section after pile number K1+195 is uniform, and the geological conditions gradually improve. Advance treatment and excavation and support operations can be carried out in the tunnel according to normal construction procedures. The tunnel section from pile number K1+195 to K1+246 is the normal excavation section 4 in the tunnel.

[0049] Based on the actual completion of advance grouting in the A Inclined Shaft and other construction experience, ground pre-grouting and in-tunnel reinforcement grouting averaged 0.6 days of linear construction time per meter of tunnel section, with a total grouting period of 11 months. Using the traditional in-tunnel advance grouting scheme, the average linear construction time per meter of tunnel section was 4 to 7 days, with a total grouting period of 78 to 137 months. Compared with the in-tunnel grouting scheme, the ground pre-grouting scheme for the tunnel section from pile numbers K0+610 to K1+195 can shorten the linear construction period by 67 to 126 months. Since the A Inclined Shaft is located on a critical construction route for the entire project, the use of a ground pre-grouting arrangement for ground pre-grouting will help reduce the difficulty of in-tunnel treatment and shorten the linear construction period, thereby facilitating the early commissioning of the project.

[0050] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A pre-grouting protection structure for the ground during the excavation of a long and steep inclined shaft, characterized by: The invention comprises a blocking body, wherein the blocking body comprises a grouting wall (21) and a rock plug (22); the rock plug (22) is arranged between the pressurization starting point of the ground pre-grouting and the tunnel face; the grouting wall (21) is arranged on the side of the tunnel face away from the rock plug (22); the rock plug (22) is used to share the grouting pressure of the ground pre-grouting; the grouting wall (21) is used to assist the construction of the rock plug (22) and share the grouting pressure of the ground pre-grouting.

2. The pre-grouting protection structure for the ground during the excavation of a steep and long inclined shaft according to claim 1 is characterized by: The rock plug (22) comprises original rock and slurry, and the slurry is used to reinforce the original rock to form the rock plug (22).

3. The pre-grouting protection structure for the ground during the excavation of a steep and long inclined shaft according to claim 1 is characterized by: The cross-sectional area of ​​the rock plug (22) is not less than the cross-sectional area of ​​the long inclined well.

4. The pre-grouting protection structure for ground during excavation of a steep and long inclined shaft according to any one of claims 1 to 3, characterized in that: The mortar-stopping wall (21) comprises a reinforced concrete wall.

5. The pre-grouting protection structure for the ground during the excavation of a steep and long inclined shaft according to claim 2 is characterized by: A plurality of advance grouting holes are provided on the grout-stopping wall (21), and the advance grouting holes are used to inject the grout into the original rock.

6. The pre-grouting protection structure for ground during excavation of a steep and long inclined shaft according to claim 5 is characterized by: The plurality of advance grouting holes are evenly arranged on the grouting wall (21), and the plurality of advance grouting holes are used for full-section drilling and grouting in front of the tunnel face to form a rock plug (22).

7. The pre-protection structure for ground pre-grouting during excavation of a steep and long inclined shaft according to any one of claims 1 to 3, characterized in that: The invention comprises a construction platform (7), wherein the construction platform (7) is arranged on a side of a slurry stop wall (21) away from a rock plug (22), the bottom of the construction platform (7) is fixed on the bottom surface of the inclined long shaft, and the top of the construction platform (7) is arranged horizontally.

8. The pre-grouting protection structure for the ground during the excavation of a steep and long inclined shaft according to claim 7 is characterized by: The construction platform (7) is integrated with the mortar-stopping wall (21).

9. The pre-protection structure for ground pre-grouting during excavation of a steep and long inclined shaft according to any one of claims 1 to 3, characterized in that: A reinforcement anchor rod (6) is arranged in the rock plug (22).

10. The pre-protection structure for ground pre-grouting during the excavation of a steep and long inclined shaft according to claim 9, characterized in that: The reinforcement anchor rod (6) comprises a glass fiber anchor rod.

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