A vertical shaft three-rotation working face pre-grouting process

Abstract

The application discloses a vertical shaft three-rotation working face pre-grouting process and belongs to the vertical shaft construction field. It comprises the following steps: one, laying a water filtering layer, and then pouring a grout-stopping pad on the water filtering layer; two, selecting a grouting pressure and a slurry diffusion radius; three, arranging grouting borehole positions, and arranging three circles of grouting boreholes from outside to inside; four, drilling, grouting and hole-sweeping and re-grouting of the three circles of grouting boreholes from outside to inside in sequence. The application can be applied to deep wells with water-bearing rock bodies existing in the condition of slow fissure underdevelopment and steep fissure development, reduces the number of boreholes, improves the water plugging effect, and guarantees the safe construction of the shaft.

Description

Technical Field

[0001] This invention belongs to the field of vertical shaft construction, and more specifically, relates to a pre-grouting process for a three-rotation working face of a vertical shaft. Background Technology

[0002] Shaft construction refers to the general term for operations such as excavation, wall lining, and equipment installation of vertical shafts during underground mineral mining. In existing technologies, water control during shaft excavation and lining typically employs either the freezing method or the surface vertical shaft curtain grouting method. However, these two techniques are generally suitable for shallow wells with low aquifer temperatures. When used for deep wells with high aquifer temperatures, the construction costs of these techniques increase significantly.

[0003] For example, Chinese patent application number CN202111038205.5, published on January 11, 2022, discloses a design method for grouting and water-blocking curtains in fractured bedrock aquifers of vertical shafts under high stress conditions. It utilizes an indoor high-stress triaxial loading and unloading simulation system to simulate and analyze the excavation unloading failure range of the grouting curtain in fractured bedrock aquifers under high stress conditions; it uses a pressure water test system to determine the effective water-blocking curtain thickness under deep high water pressure conditions, and designs grouting and water-blocking curtains for kilometer-deep vertical shafts in bedrock aquifers. Physical model tests and numerical simulation tests are used to study the damage and deterioration range of the vertical shaft grouting curtain, determining the excavation unloading failure depth; an indoor 1:1 high-pressure water test is used to determine the effective water-blocking curtain thickness; finally, based on the principles of minimizing the effective water-blocking curtain thickness, the curtain excavation unloading failure depth, and the total grouting volume, a deep vertical shaft grouting curtain design is carried out, clarifying core process parameters such as the diameter of the pre-grouting holes on the ground, the hole spacing, and the grouting pressure. This method, known as the surface straight-cylinder curtain grouting method, is not suitable for pre-grouting construction in deep well working faces with high aquifer temperatures.

[0004] Currently, for pre-grouting construction at deep well working faces, a frustum-shaped curtain arrangement of grouting boreholes is generally adopted. On the cross section at the center of the well, the grouting boreholes are designed to be inclined downward and outward in a straight line, forming a frustum-shaped grouting curtain that is smaller at the top and larger at the bottom, sealing the hydraulic connection channels of the water-bearing rock strata and ensuring the safe excavation and lining construction of the well.

[0005] For example, Chinese patent application number CN201410791779.3, published on March 25, 2015, discloses a method for pre-grouting of a vertical shaft working face. This method includes the following steps: after the vertical shaft excavation face reaches the grout stop pad position, setting grouting hole orifice pipes and inspection hole orifice pipes, filter pipes, and laying a filter layer according to their positions and inclinations, followed by pouring concrete for the grout stop pad construction; injecting cement grout behind the supported shaft wall for wall grouting; after the aforementioned steps, drilling from the grouting hole orifice pipe until the water inflow exceeds a predetermined amount, stopping drilling and injecting grout, waiting for the grout to set, then sweeping the hole until the water inflow exceeds a predetermined amount, stopping drilling and injecting grout, until the water inflow is less than the predetermined amount, then continuing drilling, repeating this segmented downward drilling and grouting process to the full depth. This scheme is truncated cone curtain grouting. However, when the deep well water-bearing rock mass has no gently developed fractures but has developed steep fractures, the grout of the traditional working face truncated cone curtain pre-grouting sealing process is difficult to penetrate into each set of fractures due to the very small permeability coefficient between the interlayer fractures. The water blocking effect is poor, which makes it impossible to ensure the safe construction of the well. Summary of the Invention

[0006] 1. The problem to be solved

[0007] To address the problem that traditional frustum-shaped curtain pre-grouting sealing technology for deep wells with water-bearing rock masses exhibiting well-developed steep fractures but lacking gentle fractures, the present invention provides a vertical shaft three-rotation working face pre-grouting technology. By improving the working face pre-grouting technology, it can be applied to deep wells with water-bearing rock masses exhibiting well-developed steep fractures but lacking gentle fractures, reducing the number of holes, improving the water-blocking effect, and ensuring the safe construction of the well shaft.

[0008] 2. Technical Solution

[0009] To solve the above problems, the present invention adopts the following technical solution.

[0010] A pre-grouting process for a three-rotation working face in a vertical shaft includes the following steps:

[0011] 1. Lay a filter layer, and then pour a grout-stopping pad on the filter layer;

[0012] II. Selecting the grouting pressure and grout diffusion radius;

[0013] 3. Arrange the grouting borehole locations, with three rings of grouting boreholes arranged from the outside to the inside;

[0014] Fourth, proceed with drilling, grouting, and hole sweeping in three consecutive circles from the outside in.

[0015] As a further improvement to the technical solution, it is applicable to vertical shafts with a diameter of 5 to 6 m and an aquifer depth of 302 to 485 m.

[0016] As a further improvement to the technical solution, in step one, the thickness of the filter layer is 0.8–1.2 m, and the thickness of the grout stop pad is 3–4 m.

[0017] As a further improvement to the technical solution, in step two, the grouting pressure is selected according to the following formula: P A = (P0 + 1.3) MPa; P B = (P0 + 3.5) MPa; P C = (3.0±0.5)P0, set the maximum alarm pressure ≤17MPa, where P A As the initial pressure, P B For normal pressure, P C P0 is the final pressure, and P0 is the hydrostatic pressure at the grouting point.

[0018] As a further improvement to the technical solution, the slurry diffusion radius is (2.5±0.5)m.

[0019] As a further improvement to the technical solution, the specific arrangement of the grouting borehole locations in step three is as follows:

[0020] The first sequence of holes: that is, the outer ring of holes, with 12 holes, the opening diameter of the hole ring is 4.5-5m, and the final hole ring diameter is 11-11.5m;

[0021] The second sequence of holes: namely, the middle ring drilling, with 6 holes, an initial diameter of 2.8 to 3.2 m, and a final diameter of 7.2 to 7.6 m;

[0022] The third sequence of holes: that is, the inner ring drilling, with 6 holes, the opening diameter of the hole is 0.4 to 0.6 m, and the final hole diameter is 4.6 to 5 m.

[0023] As a further improvement to the technical solution, the first sequence of holes is a clockwise rotating hole, with a drilling apex angle of 3° to 3°35′ and a rotation angle of 40° to 50°; the second sequence of holes is a counterclockwise rotating hole, with a drilling apex angle of 2°40′ to 2°70′ and a rotation angle of 82° to 85°; the third sequence of holes consists of three counterclockwise rotating holes and three clockwise rotating holes, with a drilling apex angle of 1°30′ to 1°40′ and a rotation angle of 0° to 102°.

[0024] As a further improvement to the technical solution, in step four, the number of times the hole is cleaned and re-injected is no less than three times.

[0025] As a further improvement to the technical solution, in step four, the grouting material is a cement-water glass two-component grout, wherein the water-cement ratio of the cement grout is (1:1) to (0.8:1), and the modulus of the water glass is 2.4 to 3.1, the Baume degree is 41.2 to 45 Be', and the specific gravity is 1.4 to 1.45 t / m³. 3 The ratio of water glass to cement slurry is 1:1.

[0026] As a further improvement to the technical solution, in step four, the material for hole scanning and re-injection is MJ-I type modified urea-formaldehyde resin + oxalic acid + acrylamide, and the ratio of MJ-I type modified urea-formaldehyde resin, oxalic acid and acrylamide is 3:1:0.03.

[0027] 3. Beneficial effects

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The present invention provides a pre-grouting process for a three-rotation working face of a vertical shaft, which adopts static pressure infiltration and columnar diffusion grouting processes. It is suitable for pre-grouting of the working face of a vertical shaft under conditions where the hydraulic connection between fractures is weak. It solves the problem of unsatisfactory grouting effect in the pre-grouting of the working face of a vertical shaft with well-developed steep fractures and poorly developed gentle fractures. It can also be extended to the pre-grouting of the working face of horizontal tunnels and chambers.

[0030] (2) The present invention provides a pre-grouting process for a vertical shaft three-rotation working face. It comprehensively considers factors such as grouting depth, spatial position, hydrostatic pressure, water inflow, fracture orientation and fracture inclination angle to scientifically and rationally design various parameters of the overall process. Combined with the new technology of three-rotation expansion hole layout, it greatly improves the grouting and water plugging effect of pre-grouting of vertical shaft working face under complex working conditions.

[0031] (3) The present invention provides a pre-grouting process for a three-rotation working face of a vertical shaft, which uses differentiated grouting materials, with two-liquid grout as the main material, and "modified urea-formaldehyde resin + oxalic acid + acrylamide" to enhance the water-blocking effect, thus overcoming the problem of shrinkage, rebound and water seepage of the filling body of the two-liquid grout. Attached Figure Description

[0032] Figure 1 This is a longitudinal cross-sectional view of the grouting process of the present invention;

[0033] Figure 2 This is a layout diagram of the first sequence of boreholes;

[0034] Figure 3 This is a layout diagram of the second sequence of boreholes;

[0035] Figure 4 This is a layout diagram of the third sequence of boreholes;

[0036] Figure 5 This is a layout diagram of the overall drilling. Detailed Implementation

[0037] Exemplary embodiments of the present invention are described in detail below. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from its spirit and scope. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and does not limit the description of the features and characteristics of the invention, in order to suggest the best mode for carrying out the invention and to enable those skilled in the art to practice it. Therefore, the scope of the invention is defined only by the appended claims.

[0038] Example 1

[0039] A pre-grouting process for a three-rotation working face in vertical shafts is applicable to deep wells where gentle fractures are not developed but steep fractures are developed (the inclination angle of the layered steep fractures in the deep part of the wellbore is greater than 80°). It can reduce the number of holes, improve the water plugging effect, and ensure the safe construction of the wellbore.

[0040] like Figure 1 As shown, the process includes the following steps:

[0041] 1. Lay a filter layer, and then pour a grout-stopping pad on top of the filter layer. The filter layer should be 0.8–1.2 m thick, and the grout-stopping pad should be 3–4 m thick. A ring of anchor bolts should be installed at the bottom of the grout-stopping pad for reinforcement. Two symmetrical anchor bolts along the center of the shaft should be welded together with threaded steel to form a single-layer steel mesh structure. The orifice pipe should be welded and fixed to the steel mesh, effectively improving the strength of the grout-stopping pad and reducing the amount of excavation and masonry work.

[0042] II. Selection of grouting pressure and grout diffusion radius. Specifically, the grouting pressure is selected according to the following formula: P A = (P0 + 1.3) MPa; P B = (P0 + 3.5) MPa; P C = (3.0±0.5)P0, set the maximum alarm pressure ≤17MPa, where P A As the initial pressure, P B For normal pressure, P C P0 is the final pressure, and P0 is the hydrostatic pressure at the grouting point. The effective diffusion radius of the grout should be controlled within an empirical range of (2.5 ± 0.5) m.

[0043] III. Based on the on-site engineering geological and hydrogeological conditions, the locations of grouting boreholes should be arranged. The boreholes should penetrate as many steep fractures as possible and intersect with fracture joint surfaces. Three concentric rings of grouting boreholes should be arranged from the outside inwards, as shown in the specific layout below. Figures 2 to 5 As shown, it includes:

[0044] The first sequence of boreholes consists of the outer ring, with a water-blocking control range of 1.92–3.88 m outside the rough diameter of the vertical shaft. There are 12 boreholes in this sequence, with an initial borehole diameter of 4.5–5 m and a final borehole diameter of 11–11.5 m. This sequence involves clockwise rotation during drilling, with a borehole apex angle of 3°–3°35′ and a rotation angle of 40°–50°.

[0045] The second sequence of boreholes, also known as the middle circle boreholes, is mainly for sealing the bottom of the grouting section. The water shut-off control range is 1.68–2.48 m below the bottom of the well, with 6 boreholes. The opening diameter is 2.8–3.2 m, and the final diameter is 7.2–7.6 m. This sequence involves counterclockwise rotation for drilling, with a borehole apex angle of 2°40′–2°70′ and a rotation angle of 82°–85°.

[0046] The third sequence of boreholes, i.e., the inner ring boreholes, is mainly used to seal the confined water in the central lily-shaped steep fracture that is difficult to control with the first and second sequence grouting holes. There are six boreholes in this sequence, with an initial diameter of 0.4–0.6 m and a final diameter of 4.6–5 m. Three holes in this sequence are drilled counter-clockwise, and three are drilled clockwise. The borehole apex angle is 1°30′–1°40′, and the rotation angle is 0°–102°.

[0047] IV. Drilling, grouting, and hole sweeping re-grouting are carried out sequentially in three rings from the outside to the inside, using a top-down segmented grouting process, quantitative grouting, and gradually increasing grouting pressure. The single-hole water inflow during grouting should be ≥30m. 3 / h, is determined as the thickness of the rock strata injected in one operation; the single-hole water inflow in the swept section is ≥5m³ / h. 3 / h is used to determine the thickness of the rock strata for one reinjection. In this step, the number of borehole sweeping and reinjection cycles should not be less than 3.

[0048] The grouting material is a cement-water glass two-component grout, wherein the water-cement ratio of the cement grout is (1:1) to (0.8:1), and the modulus of the water glass is 2.4 to 3.1, the Baume degree is 41.2 to 45 Be', and the specific gravity is 1.4 to 1.45 t / m³. 3 The ratio of water glass to cement slurry is 1:1.

[0049] The material for hole scanning and re-injection is MJ-I type modified urea-formaldehyde resin + oxalic acid + acrylamide, with the ratio of MJ-I type modified urea-formaldehyde resin, oxalic acid and acrylamide being 3:1:0.03.

[0050] It should be noted that this grouting process is mainly suitable for vertical shafts with a diameter of 5 to 6 m and an aquifer depth of 302 to 485 m.

[0051] This grouting process employs static pressure infiltration and columnar diffusion grouting techniques, making it suitable for pre-grouting of shaft working faces under conditions where the hydraulic connection between fractures is weak. It solves the problem of unsatisfactory grouting effects in pre-grouting of shaft working faces with well-developed steep fractures and poorly developed gentle fractures. It can also be extended to pre-grouting of working faces in horizontal tunnels and chambers.

[0052] The design of this process comprehensively considers factors such as grouting depth, spatial location, hydrostatic pressure, water inflow, fracture orientation, and fracture inclination angle to scientifically and rationally design various parameters of the overall process. Combined with a new three-circle cyclic expansion perforation technique, it significantly improves the grouting and water-blocking effect of pre-grouting at the shaft working face under complex conditions. The quantitative grouting method ensures compliance with water control safety requirements while preventing excessive grouting, saving costs and improving efficiency.

[0053] Meanwhile, differentiated grouting materials are used, with two-component grout as the main component, and "modified urea-formaldehyde resin + oxalic acid + acrylamide" to enhance the water-blocking effect, thus overcoming the problem of shrinkage, rebound, and water seepage of the filling body in two-component grout.

[0054] The specific construction process is described below.

[0055] Taking the aquifer characteristics of a vertical shaft with a net diameter of 5.5m as an example: the aquifer lithology is secondary quartzite, with a depth of 302–485m and a platy structure. Pumping test results show a single-well yield Q = 7.65m³. 3 The water-conducting fractures have an influence radius of R = 96.12 meters and a permeability coefficient of K = 0.07989 meters / day. These fractures are tensile steep fractures with dip angles of 82–85°, a dip direction of ES46°, a strike direction of EN44°, a development rate of 3–5 fractures / meter, a fracture width of 2–20 mm, a porosity of 4.2–11.1%, and a hydrostatic pressure consistent with the depth of occurrence (3.02–4.85 MPa). The water temperature is 28–30°C.

[0056] (1) 1 meter filter layer, 3.5 meters grout stop pad, C30 concrete. One ring of anchor rods is installed at the lower end of the grout stop pad for reinforcement. There are 8 anchor rods with specifications of Φ36*2800. Two symmetrical anchor rods along the center of the well are welded with Φ25 threaded steel to form a single-layer steel mesh structure, and the orifice pipe is welded and fixed to the steel mesh.

[0057] (2) The height of the grouting treatment section is set at 60m, the height of the filter layer is 1m, the height of the grout stop pad is 3.5m, and the total height is 64.5m.

[0058] (3) The borehole opening diameter is Φ130mm and the depth is 7.0m; the normal section borehole diameter is Φ90mm and the depth is 64.5m.

[0059] (4) Grouting pressure and grout diffusion radius:

[0060] Grouting pressure is selected based on empirical values: initial pressure PA = (P0 + 1.3) MPa, normal pressure P B = (P0 + 3.5) MPa, final pressure P C = (3.0±0.5)P0, set the maximum alarm pressure ≤17MPa. Where: P0—static water pressure at the grouting point (MPa).

[0061] The effective diffusion radius of the slurry should be controlled within an empirical range of (2.5 ± 0.5) m.

[0062] (5) Pre-grouting borehole design: Based on the on-site engineering geology and hydrogeology conditions, the boreholes are designed to penetrate as many steep fractures as possible and intersect with the fracture joint surfaces. Based on the simulated working conditions of 0.25m fracture spacing and 85° inclination angle, a total of 24 grouting boreholes are designed, with a total drilling depth of approximately 1560m.

[0063] The first sequence is the outer ring, which controls water shut-off within 1.92 to 3.88 meters outside the rough diameter of the vertical shaft. There are 12 holes, with an opening diameter of Φ4.8 meters and a final hole diameter of Φ11.2 meters. The borehole apex angle is 3°17′40″ and the tangential clockwise rotation angle is 46°.

[0064] The second sequence, namely the middle circle, mainly consists of the bottom of the well for sealing the grouting section. The water shut-off control range is 1.68 to 2.48 meters below the bottom of the well, with 6 holes, an opening diameter of Φ3.0m, and a final hole diameter of Φ7.4m; the borehole apex angle is 2°54′58″, and the tangential counterclockwise rotation angle is 84°.

[0065] The third sequence, i.e. the inner ring, is mainly used to seal the confined water in the central lily-shaped steep fissure that is difficult to control in the grouting holes of the first and second sequences. There are 6 holes, with 3 sets of forward and reverse rotations. The diameter of the opening ring is Φ0.5m, and the diameter of the final hole ring is Φ4.89m. The borehole apex angle is 1°39′27″~2°10′4″, and the rotation angle is 0~102°.

[0066] (6) Construction sequence: carried out in sections from the outside to the inside and from top to bottom. Grouting depth per hole with a water inflow ≥ 30m³. 3 / h, is determined as the thickness of the rock strata injected in one operation; the single-hole water inflow in the swept section is ≥5m³ / h. 3 / h is determined as the thickness of the rock layer in a single injection.

[0067] like Figure 2 As shown, the first step is to construct the first sequence of holes, followed by drilling, grouting, and cleaning and re-grouting of holes 1-2, 1-8, 1-1, 1-9, 1-3, 1-7, 1-4, 1-6, 1-12, 1-5, 1-10, and 1-11 in sequence.

[0068] like Figure 3 As shown, the second step involves constructing the second sequence of holes, which are then drilled, grouted, and cleaned and re-grouted in sequence: 2-1, 2-5, 2-2, 2-4, 2-3, and 2-6.

[0069] like Figure 4 As shown, the third step involves constructing the third sequence of holes, which are drilled, grouted, and then cleaned and re-grouted in sequence: 3-1, 3-6, 3-3, 3-5, 3-2, and 3-4.

[0070] (7) Hole cleaning and re-injection: The design average number of cleaning and re-injection cycles is 3, and the total hole cleaning advance is about 4680m.

[0071] (8) Grouting method: from top to bottom, in sections, quantitative grouting, and gradually increasing grouting pressure.

[0072] (9) Grouting material: Combined grouting material is used.

[0073] When newly exposed steep fissures are exposed to confined water, priority should be given to injecting "cement-water glass double-liquid grout" to seal larger tensile fissures. Material ratio: P.O42.5 cement grout water-cement ratio = 1:1 to 0.8:1, water glass modulus 2.4 to 3.1, Baume degree 41.2 to 45 Be', specific gravity approximately 1.42 t / m³. 3 Water glass / cement grout = 1:1.

[0074] If a small amount of water comes out during the pore cleaning process, re-inject "MJ-I type modified urea-formaldehyde resin + oxalic acid + acrylamide" to seal the microcracks and pores. Material ratio: urea-formaldehyde resin / oxalic acid / acrylamide = 3:1:0.03.

[0075] Based on an average porosity of 7.65%, the material consumption requires 207 tons of P.O42.5 cement and 153 cubic meters of water glass. 3 MJ-I type modified urea-formaldehyde resin 46m 3 oxalic acid 15m 3 Acrylamide 0.46m 3 .

[0076] (10) Planned construction period: The total construction period is 90 days, including 5 days for the construction and maintenance of the filter layer and grout stop pad, 55 days for drilling, cleaning and grouting, and 30 days for excavation and masonry.

[0077] (11) Acceptance criteria: Water inflow of each section of the wellbore ≤ 20m³ 3 / h, the residual water inflow volume of the whole wellbore is ≤6m 3 / h.

[0078] The examples described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

Claims

1. A pre-grouting process for a three-rotation working face in a vertical shaft, characterized in that: Includes the following steps:

1. Lay a filter layer, and then pour a grout-stopping pad on the filter layer; II. Selecting the grouting pressure and grout diffusion radius; 3. Arrange the grouting borehole locations, with three rings of grouting boreholes arranged from the outside to the inside; In step three, the specific arrangement of the grouting borehole locations is as follows: The first sequence of holes: that is, the outer ring of holes, with 12 holes, the opening diameter of the hole ring is 4.5-5m, and the final hole ring diameter is 11-11.5m; The second sequence of holes: namely, the middle circle drilling, with 6 holes, the initial diameter of the hole circle is 2.8 to 3.2 m, and the final diameter of the hole circle is 7.2 to 7.6 m; The third sequence of holes: namely, the inner ring drilling, with 6 holes, an initial hole diameter of 0.4 to 0.6 m, and a final hole diameter of 4.6 to 5 m; The first sequence of holes is drilled by clockwise rotation, with a drill apex angle of 3° to 3°35′ and a rotation angle of 40° to 50°; the second sequence of holes is drilled by counterclockwise rotation, with a drill apex angle of 2°40′ to 2°70′ and a rotation angle of 82° to 85°; the third sequence of holes consists of three holes drilled by counterclockwise rotation and three holes drilled by clockwise rotation, with a drill apex angle of 1°30′ to 1°40′ and a rotation angle of 0° to 102°. IV. Drilling, grouting, and hole sweeping and re-grouting are carried out in three rings from the outside to the inside. In step four, the grouting material is a cement-water glass two-component grout, wherein the water-cement ratio of the cement grout is (1:1) to (0.8:1). In step four, the material for hole scanning and re-injection is MJ-I type modified urea-formaldehyde resin + oxalic acid + acrylamide, and the ratio of MJ-I type modified urea-formaldehyde resin, oxalic acid and acrylamide is 3:1:0.

03.

2. The pre-grouting process for a three-rotation working face of a vertical shaft according to claim 1, characterized in that: It is suitable for vertical shafts with a diameter of 5 to 6 m and an aquifer depth of 302 to 485 m.

3. The pre-grouting process for a three-rotation working face of a vertical shaft according to claim 2, characterized in that: In step one, the thickness of the filter layer is 0.8–1.2 m, and the thickness of the grout stop pad is 3–4 m.

4. The pre-grouting process for a three-rotation working face of a vertical shaft according to claim 2, characterized in that: In step two, the grouting pressure is selected according to the following formula: ; The maximum alarm pressure is set to ≤17MPa, where, As the initial pressure, Normal pressure, For the ultimate pressure, This refers to the hydrostatic pressure at the grouting point.

5. The pre-grouting process for a three-rotation working face of a vertical shaft according to claim 2, characterized in that: The diffusion radius of the slurry is (2.5±0.5)m.

6. The pre-grouting process for a three-rotation working face of a vertical shaft according to claim 2, characterized in that: In step four, the number of times the hole is cleaned and re-injected is no less than three.

7. A pre-grouting process for a three-rotation working face of a vertical shaft according to any one of claims 1-6, characterized in that: Water glass has a modulus of 2.4–3.1, a Baumé degree of 41.2–45 Be', and a specific gravity of 1.4–1.45 t / m³. 3 The ratio of water glass to cement slurry is 1:1.

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