Reinforcing and grouting method for large-scale high-pressure water-rich alteration structural belt

Abstract

The invention discloses a reinforcement grouting method for a large-scale high-pressure water-rich alteration tectonic zone. The invention aims to solve the technical problem that inrush is easily caused in a construction environment of a large-scale high-pressure water-rich alteration structural belt with poor self-stability. The anchoring capacity of the grout-stopping wall can be improved through the embedded steel bars embedded in the surrounding rock and the wall body, it is guaranteed that the grouting pressure can be resisted during high-pressure grouting, the grout-stopping wall is prevented from being extruded to retreat, and therefore the stability of the tunnel face is guaranteed. Besides, before reinforcing grouting of the unstable stratum, the grout stopping wall is reinforced in advance, so that a stress whole is formed between the grout stopping wall and surrounding rock in front of the grout stopping wall, and therefore the inrush prevention capacity of the grout stopping wall and the drawing resistance of the orifice pipe are improved. In addition, the orifice pipe is arranged before drilling grouting is started, and the orifice pipe can serve as a guide pipe and a grouting connector and can resist high-pressure grouting counter-acting force through large friction force generated after anchoring of the orifice pipe. And the grouting holes in different positions are selected for selection verification of the grout and the grouting mode, so that the stratum can be better reinforced, and the safety of subsequent excavation construction is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction, and in particular to a large-scale high-pressure, water-rich altered structural zone reinforcement grouting method. Background Art

[0002] The main mineral components of granite are feldspar, quartz, black and white mica, etc., and the quartz content is 10% to 50%. The feldspar content accounts for about 2 / 3 of the total, which is divided into orthoclase, plagioclase (alkali lime) and microcline (potash). The temperature of the contact zone between the intrusive rock and the surrounding rock is 300-1000℃, and the pressure is 100-300MPa. During the intrusion process, when the hydrothermal fluid acts on the rock, the two will inevitably tend to reach chemical equilibrium and exchange substances. Then the rock mass between the intrusive body and the parent rock is highly altered, forming a contact metamorphic zone. The rocks in the metamorphic zone are mostly clay-like, with obvious foliation, which is very easy to weather and becomes muddy when encountering water. The rock mass often slides along this surface. When there are large-scale and deep weak fracture zones or local fissure development zones in the rock mass, deep weathering troughs or weathering pockets are often formed in the later stage due to the alternating circulation of groundwater.

[0003] With the intrusion of magma, contact thermal metamorphism and contact metasomatic metamorphism, the intact granite develops joints and fissures, and the rock mass is mainly blocky and mosaic, and some of them have fragmented structures. As the alteration materials filling the rock joints and fissures erode for a long time, the mineral components are brought in and out of the rock mass to soften and form a fully weathered state, resulting in the rock mass structure being mainly dispersed. In a water-rich environment, the granite fracture zone has been eroded by fissure water and air for a long time, and the chemical composition has changed significantly. The highly hydrophilic clay minerals such as montmorillonite, chlorite and illite have increased, which increases the amount of water in the rock joints and fissures. After mixing with the alteration materials, it softens and lubricates, reduces the friction and stability between the rock blocks, and has very low strength. The weak structural surface of the rock mass is extremely developed, the overall structure of the rock mass is extremely broken, and the surrounding rock has poor self-stabilization ability. When excavating a tunnel, it will inevitably trigger unfavorable geological bodies and debris, causing them to flow into the tunnel to form a disaster with debris flow characteristics.

[0004] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0005] In view of at least one of the above technical problems, the present disclosure provides a large-scale high-pressure water-rich altered structural zone reinforcement grouting method; it aims to solve the technical problem that sudden surges are easily caused in the construction environment of a large-scale high-pressure water-rich altered structural zone with poor self-stability.

[0006] According to one aspect of the present disclosure, a large-scale high-pressure water-rich altered structural zone reinforcement grouting method is provided, which comprises the following steps: (1) Conduct geological exploration and determine the scope of reinforcement based on the geological conditions of the exploration holes; (2) constructing a stop wall of a certain thickness at the tunnel face, wherein the stop wall includes embedded reinforcement bars with one end disposed in the surrounding rock and the other end disposed in the stop wall; (3) Drilling a number of grouting holes along the tunnel excavation direction at a certain angle to the tunnel centerline from the tunnel face; and drilling corresponding grouting holes in the excavated tunnel to cover the grouting blind area within the corresponding reinforcement range of the grouting holes; (4) Select a number of grouting holes to reinforce the gap between the grouting wall and the surrounding rock by forward segmented grouting, and the grouting pressure is less than 6 MPa; (5) Select several grouting holes in the middle, upper, left and right areas of the corresponding tunnel face and use forward segmented grouting and backward grouting to inject different slurry types; (6) Drilling and coring at corresponding positions to determine the slurry diffusion radius and grouting effect corresponding to each slurry; (7) Full-section curtain grouting construction is carried out using the slurry and grouting method with the largest diffusion radius and the best grouting effect, and a grouting pressure of less than 15 MPa is selected according to the proven stratum conditions of the altered zone.

[0007] In some embodiments of the present disclosure, in step (2), the mortar-stopping wall further includes a steel mesh arranged in a section corresponding to the embedded reinforcement.

[0008] In some embodiments of the present disclosure, in the step (2), a lining is applied along the ring wall of the excavated tunnel to resist deformation of the tunnel.

[0009] In some embodiments of the present disclosure, in step (3), the drilling depth of the grouting holes matches the reinforcement range; the grouting holes correspond to an array along the contour of the tunnel face and correspond to an annular array with the center of the tunnel face as the reference point; In some embodiments of the present disclosure, in the step (4), a number of the grouting holes on the periphery are selected to serve as advance exploration holes, and the advance exploration holes are performed after a high-pressure anti-burst gate valve is installed at the hole mouth.

[0010] In some embodiments of the present disclosure, in step (4), an orifice pipe is provided at each of the grouting holes; and a grouting test is performed on the orifice pipe at twice the design pressure until the orifice pipe is stable and leak-free.

[0011] In some embodiments of the present disclosure, in step (5), the progressive segmented grouting includes the following sub-steps: (51) After the drilling rig drills along the grouting hole to the initial depth, grout is injected into the hole; (52) Drilling again along the grouting hole and increasing the drilling depth, and injecting grout into the hole; (53) Repeat step (52) until the hole is drilled to the designed depth.

[0012] In some embodiments of the present disclosure, in step (5), the slurry types include ultrafine sulphoaluminate cement slurry, sulphoaluminate cement slurry, ordinary silicate-water glass double liquid slurry, and ordinary silicate cement single liquid slurry; the grouting pressure and flow rate of each slurry type are consistent.

[0013] In some embodiments of the present disclosure, in the step (5), the backward grouting is performed by retreating from the hole bottom to the hole mouth in sections after the hole is directly drilled to the designed hole depth.

[0014] In some embodiments of the present disclosure, in step (7), when grouting the full-section curtain, the grouting is performed in a skip-hole manner from outside to inside and from top to bottom.

[0015] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: the anchoring capacity of the grouting wall can be improved by implanting reinforcement bars in the surrounding rock and the wall, ensuring that the grouting pressure can be resisted during high-pressure grouting, and the grouting wall is prevented from being squeezed back, thereby ensuring the stability of the face. In addition, before the reinforcement grouting of unstable strata, the grouting wall is reinforced first, so that a force-bearing whole is formed between the grouting wall and the surrounding rock in front of it, thereby improving the anti-surge capacity of the grouting wall and the tensile strength of the orifice pipe; in addition, the orifice pipe is installed before the drilling grouting begins. In addition to serving as a guide pipe and grouting interface, it can also resist the reaction force of high-pressure grouting through its larger friction after anchoring; and by selecting grouting holes in different positions to select and verify the slurry and grouting method, the stratum can be better reinforced to ensure the safety of subsequent excavation construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the distribution of grouting holes in one embodiment of the present application.

[0017] Figure 2 This is a schematic diagram of the longitudinal section of grouting in one embodiment of the present application.

[0018] In the above figures, 1 is the grouting hole, 2 is the tunnel outline, 3 is the stop wall, 4 is the grouting blind area, and 5 is the grouting hole. DETAILED DESCRIPTION

[0019] In order to better understand the technical solution of the present application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0020] This case takes a tunnel project as an example. According to two sudden surges and drilling analysis, the strata in this section are mainly granite structural influence zones, with severe rock fragmentation, alteration and clayification, and rich water and high pressure. According to geophysical prospecting and exploration drilling data, the current construction section has many secondary structures with compression and crushing zones, and the granite is breccia and gravel sand. Construction excavation revealed that the Cambrian strata are often distorted in bedding, the surrounding rock integrity is poor, and the granite strata are sandy, muddy and altered due to the transformation and degradation of geological structures, resulting in the destruction of the original rock structure. In addition, the tunnel bedrock fissure water is developed, the tunnel water level is high, and the generated water pressure is mainly borne by the broken and weathered rock mass. Because this layer is destroyed by excavation or water pressure, once the construction excavation reaches this layer, it is washed and transported by groundwater flow, and the cohesion and stability are reduced. The groundwater carries a large amount of mud and sand into the tunnel from the damaged area, causing collapse or water and mud bursts.

[0021] To this end, this example discloses a large-scale high-pressure water-rich altered structural zone reinforcement grouting method, which improves and reinforces the unstable strata in front before excavation to avoid collapse or sudden surge, and specifically includes the following steps: (1) Conduct geological exploration and determine the scope of reinforcement based on the geological conditions of the exploration holes.

[0022] In order to determine the scope of the unstable strata in front of the face and then determine the reinforcement grouting area, in this embodiment, a geological exploration hole is first constructed before reinforcement grouting, and the longitudinal reinforcement depth is adjusted according to the geological conditions of the exploration hole. In this embodiment, the longitudinal reinforcement depth is set to 15m (excluding the thickness of the stop wall), and the radial reinforcement range is set to 5m outside the excavation surface and excavation contour line.

[0023] (2) Construct a mortar stop wall of a certain thickness at the face of the work.

[0024] Considering that the surrounding rock in the construction area is broken and seriously altered, in order to avoid the slurry overflowing from the face after grouting and affecting the stability of the face, in this embodiment, a 3m thick grouting wall is constructed at the face. When constructing the grouting wall, a double layer of φ22mm threaded steel bars are first set along the tunnel excavation contour line. The length of the bars is 3m, of which 2m is embedded in the surrounding rock and the remaining 1m is embedded in the grouting wall, thereby ensuring the integrity of the grouting wall and the surrounding surrounding rock after pouring. In addition, in this example, a φ10mm steel mesh is laid in the steel mesh section to enhance the structure and force strength of the grouting wall. After the steel mesh and steel mesh are laid, C25 concrete is used for pouring, and the site is hardened as a grouting platform. In this example, the longitudinal length of the platform is not less than 15m, and a 1% slope is set away from the excavation face to achieve drainage.

[0025] In addition, since the slurry has a certain pressure during the reinforcement grouting operation, in order to prevent the rear support of the tunnel from being deformed due to being unable to withstand the slurry pressure of the high-pressure grouting, in this embodiment, a lining with a thickness of 50 cm is applied along the ring wall of the tunnel at the excavated tunnel as a sleeve lining, and vertical formwork casting is used to resist tunnel deformation.

[0026] (3) Drill a number of grouting holes along the tunnel excavation direction at a certain angle to the tunnel centerline; and drill corresponding grouting holes in the excavated tunnel to cover the grouting blind areas within the corresponding reinforcement range of the grouting holes.

[0027] After the grouting wall at the tunnel face is constructed, several grouting holes are drilled along the tunnel excavation direction at the grouting wall. The drilling depth of the grouting holes matches the reinforcement range determined by the exploration holes. In this embodiment, two sequences of holes with final hole lengths of 10m and 15m are arranged. Figure 1 , with the center of the tunnel face as the reference point, 6 circles of grouting holes are arranged in a circular array, and each circle of holes is arranged in an array corresponding to the contour shape along the tunnel face, with a total of 77 holes drilled. Among them, in order to achieve grouting reinforcement within the reinforcement depth range of 15m in the longitudinal direction and 5m in the radial direction, in this embodiment, each grouting hole is arranged in an umbrella shape with the central axis of the tunnel as the center, that is, the drilling direction of each grouting hole is set at an angle corresponding to the longitudinal central axis of the tunnel, thereby considering the diffusion radius of the slurry to ensure the flooding reinforcement of the slurry within the set reinforcement range; in this example, the slurry diffusion radius is set to 2m, and the hole bottom spacing is controlled to be no more than 2.8m, thereby achieving overlapping coverage.

[0028] See also Figure 2 Since the grouting holes are arranged in an umbrella shape and the cross-section of the reinforcement range is set to be rectangular, the grouting holes arranged in an umbrella shape cannot achieve full coverage within the reinforcement range. There is a certain range of triangular grouting blind areas at the corresponding positions on the upper and lower sides of the grouting wall. For this reason, in this embodiment, a ring of grouting holes is arranged at a position of 4m behind the excavated tunnel behind the heading face, with a total of 22 holes, and grouting reinforcement of the grouting blind areas is achieved through each grouting hole.

[0029] (4) Select a number of grouting holes and use forward segmented grouting to backfill and reinforce the gap between the grouting wall and the surrounding rock.

[0030] Since there is a surge body in front of the face, there are a lot of gaps in the surge body, and after the grouting wall is constructed, there is a gap between the surge body and the grouting wall, which makes the grouting wall at risk of backward movement under force. For this reason, in this embodiment, the gap between the grouting wall and the front surrounding rock is backfilled and reinforced, thereby ensuring that the grouting wall and the reinforced body are uniformly stressed. First, select the 6 grouting holes on the periphery, and then use forward segmented low pressure to backfill and reinforce the gaps between the grouting wall and the surge disturbance body, and control the grouting pressure to be less than 6MPa.

[0031] Specifically, in this embodiment, when the grouting wall reinforcement operation is performed, 6 grouting holes on the periphery are evenly selected, and a 3m long orifice pipe is installed at each grouting hole. The orifice pipe is used as a guide pipe to ensure that the borehole can be drilled in the designed direction and angle, and after the flange and grouting valve are installed at the end of the orifice pipe, it can be used as a grouting interface. After the orifice pipe is set, ordinary silicate cement single liquid slurry is injected into the hole to backfill and reinforce the grouting wall and the gap in front of the grouting wall and the loose stratum; when the grouting wall or structural surface leaks, ordinary cement-water glass double liquid slurry is used for intermittent grouting to reduce the leakage and seal it. In this example, the backfill reinforcement grouting pressure is less than 2MPa. Therefore, the front surrounding rock and the grouting wall can be closely combined through backfill reinforcement grouting to resist the high-pressure grouting pressure in the later stage. In addition, the orifice pipe can be anchored to the grouting wall and the surrounding rock to improve resistance and avoid the orifice pipe from being pulled out under high-pressure grouting.

[0032] In addition, after the orifice pipe and the grouting wall were reinforced, the orifice pipe was tested for grouting to ensure that the orifice pipe could withstand high pressure and would not be pulled out during high-pressure grouting. Specifically, the orifice pipe was tested for grouting at twice the design pressure until it was stable and not falling off and there was no leakage around the orifice pipe and nearby structures. If the orifice pipe fell off during high-pressure grouting, it was reopened, installed, and grouting anchored.

[0033] After the reinforcement in front of the stop wall is completed, in order to further identify the stratum in front and the drilling conditions, in this embodiment, 5 grouting holes on the periphery are selected as advance exploration holes, and high-pressure anti-burst gate valves are installed at the hole mouths to conduct advance exploration holes. Considering that the construction section is a water-rich altered rock mass, the material composition is more serious in clay, and it is a natural waterproof layer in the undisturbed state, which is in a dense and stable state. After the drilling disturbance, water infiltrates from the water-rich area, and the surrounding rock softens into mud and becomes plastic when it encounters water. The risk of sudden surge is extremely high. In order to prevent sudden surge and high-pressure slag spraying from injuring people, a high-pressure anti-burst gate valve is installed before the advance exploration hole is drilled. In addition, the one-time drilling depth, water volume, water pressure and returned slag color are recorded during drilling.

[0034] (5) Select several grouting holes in the middle, upper, left and right areas of the corresponding tunnel face and use forward segmented grouting and backward grouting to inject different slurry types.

[0035] In this embodiment, four grouting holes with the same drilling depth are selected in the middle, upper, left and right areas of the hole layout position, and four grouting materials are injected into the four grouting holes in each area, namely, ultrafine sulphoaluminate cement slurry with a water-cement ratio of (0.8-1.2):1, sulphoaluminate cement slurry with a water-cement ratio of (0.8-1.2):1, ordinary silicate-water glass double liquid slurry with a water-cement ratio of (0.8-1.2):1, and ordinary silicate cement single liquid slurry with a water-cement ratio of (0.8-1.2):1 and a volume ratio of 1:(1-0.3) water glass concentration of 30-35°Be, and the grouting pressure and grouting flow rate of each grouting material during grouting are the same.

[0036] In this example, the grouting is performed by using the forward segmented grouting process and the backward segmented grouting process respectively. Specifically, in this embodiment, the construction process of the forward segmented grouting includes the following sub-steps: (41) After the drilling rig drills the grouting hole to the initial depth, grouting is injected into the hole.

[0037] In this embodiment, a multifunctional crawler drill is used to drill a φ130mm grouting hole, and a φ108mm orifice pipe is installed at the orifice, and then a φ90mm drill bit is used to drill along the orifice pipe to an initial set depth, which in this example is 4.5m. After drilling to the set initial depth, a grouting pressure test operation is performed.

[0038] (42) Drill again along the grouting hole and increase the drilling depth, and inject grout into the hole.

[0039] Considering that the altered surrounding rock construction stratum is severely entrained and the single hole drilling distance is limited, a multifunctional crawler drilling rig is used to perform a hole-sweeping and hole-opening operation again along the grouting hole drilled and grouted in step (41), and the drilling depth is increased by 1m based on the initial set depth, and slurry is injected into the hole again after the drilling is completed.

[0040] (43) Repeat step (42), and increase the drilling depth by 1 m each time until the designed hole depth is reached. Thus, by means of progressive segmented grouting, drilling is first performed and then grouting is performed, and drilling is performed again after the slurry solidifies, and the second drilling length is slightly longer than the first drilling length, thereby gradually improving the formation.

[0041] In addition, in this embodiment, the backward grouting is to directly drill the hole to the designed hole depth, and then use grouting plugs to retreat from the bottom of the hole to the hole mouth in sections to perform grouting operations.

[0042] (6) Drill holes and take core samples at corresponding locations to determine the slurry diffusion radius and grouting effect corresponding to each slurry.

[0043] In this embodiment, two adjacent grouting holes are taken as one group, multiple groups are selected, and cores are drilled in the middle of the two adjacent holes to verify the grouting effect, and the diffusion radius of the slurry is determined accordingly. If the grouting is not full, additional grouting is performed in time.

[0044] In this case, the grouting pressure P and grouting speed Q recorded during the grouting construction are plotted into Pt and Qt curves, and the PQt curve is analyzed according to the geological characteristics, grouting mechanism, equipment performance, grouting parameters, etc., so as to judge the grouting effect. Ensure that the Pt curve shows an upward trend and the Qt curve shows a downward trend during the grouting construction. At the end of the grouting, the grouting pressure reaches the designed final pressure and the grouting speed reaches the designed speed. In addition, by counting the total grouting volume, according to Σ Q=Vnα ( 1+ β ) to calculate the grout filling rate, and evaluate the grouting effect according to the grout filling rate, where ΣQ is the total grouting volume (m 3 ), V is the volume of the reinforcement (m 3 ), n is the formation porosity or fracture degree, α is the slurry filling rate, and β is the slurry loss rate. When the slurry filling rate reaches more than 80%, the reinforcement grouting requirements are met. In addition, select weak parts for drilling inspection, and use in-hole camera equipment to record and observe the whole hole situation to ensure that there is no mud gushing or hole collapse in the inspection hole, the water output of the inspection hole is no more than 0.2L / min, and the number of inspection holes is not less than 5% of the number of grouting holes and no less than 3 holes.

[0045] (7) Full-section curtain grouting construction is carried out using the slurry and grouting method with the largest diffusion radius and the best grouting effect, and a grouting pressure of less than 15 MPa is selected according to the proven stratum conditions of the altered zone.

[0046] In this case, the slurry with the largest diffusion radius and the largest grouting volume is selected as the final grouting slurry, and the forward segmented grouting process that can solve the problem of drill bit wrapping caused by altered surrounding rock is selected for full-section curtain grouting construction. When grouting the full section curtain, the grouting is performed from the outside to the inside and from the top to the bottom, and the single hole grouting is performed in a constant pressure and variable quantity manner.

[0047] According to the exploration results of geological exploration holes and advance exploration holes, in this embodiment, the 0-6.5m section is an altered stratum with large clay particles, which is a relatively dense stratum. Considering the impact of high-pressure grouting on the safety of the stop wall, in order to avoid the stop wall from retreating during grouting, this section is grouted at a pressure of less than 4MPa in this example, so that the stop wall and the front sediment body are consolidated as a whole. The surrounding rock of the 6.5-15.5m section is in the form of loose gravel breccia and silty sand. The specific gravity of coarse particles in the stratum is relatively increased compared with the previous section, the sediment content is reduced, the water content reaches 35%, and the porosity and permeability coefficient are increased. According to the grouting effect of different slurries and grouting methods, this example selects ultra-fine sulphoaluminate cement, and grouting is carried out in a segmented forward grouting method, and the grouting pressure is increased from 4MPa to 15MPa. The stratum in the 15.5-18m section is heterogeneous, resulting in obvious differences in the physical coefficients of the soil, which easily forms slurry channels and causes slurry leakage. For this reason, in this example, a constant pressure but not a fixed quantity method is used for grouting, and the final grouting pressure is 15MPa to avoid phenomena such as the inability to advance the drill hole, collapsed holes, and drill bit wrapping after grouting.

[0048] Although some preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0049] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the inventive concept. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A large-scale high-pressure water-rich altered structural zone reinforcement grouting method, characterized in that: The steps include: (1) Conduct geological exploration and determine the scope of reinforcement based on the geological conditions of the exploration holes; (2) constructing a stop wall of a certain thickness at the tunnel face, wherein the stop wall includes embedded reinforcement bars with one end disposed in the surrounding rock and the other end disposed in the stop wall; (3) Drilling a number of grouting holes along the tunnel excavation direction at a certain angle to the tunnel centerline from the tunnel face; and drilling corresponding grouting holes in the excavated tunnel to cover the grouting blind area within the corresponding reinforcement range of the grouting holes; (4) Select a number of grouting holes to reinforce the gap between the grouting wall and the surrounding rock by forward segmented grouting, and the grouting pressure is less than 6 MPa; (5) Select several grouting holes in the middle, upper, left and right areas of the corresponding tunnel face and use forward segmented grouting and backward grouting to inject different slurry types; (6) Drilling and coring at corresponding positions to determine the slurry diffusion radius and grouting effect corresponding to each slurry; (7) Full-section curtain grouting construction is carried out using the slurry and grouting method with the largest diffusion radius and the best grouting effect, and a grouting pressure of less than 15 MPa is selected according to the proven stratum conditions of the altered zone.

2. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In the step (2), the mortar-stopping wall further comprises a steel mesh arranged in a section corresponding to the embedded reinforcement.

3. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In the step (2), a lining is applied along the ring wall of the excavated tunnel to resist deformation of the tunnel.

4. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In the step (3), the drilling depth of the grouting holes matches the reinforcement range; the grouting holes correspond to an array along the contour shape of the tunnel face and correspond to a ring array with the center of the tunnel face as the reference point.

5. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In the step (4), a number of the grouting holes on the periphery are selected to serve as advance exploration holes, and high-pressure anti-burst gate valves are installed at the hole mouths to perform advance exploration holes.

6. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In the step (4), an orifice pipe is provided at each of the grouting holes; and a grouting test is performed on the orifice pipe at twice the design pressure until the orifice pipe is stable and leak-free.

7. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In step (5), the progressive segmented grouting includes the following sub-steps: (51) After the drilling rig drills along the grouting hole to the initial depth, grout is injected into the hole; (52) Drilling again along the grouting hole and increasing the drilling depth, and injecting grout into the hole; (53) Repeat step (52) until the hole is drilled to the designed depth.

8. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In step (5), the slurry types include ultrafine sulphoaluminate cement slurry, sulphoaluminate cement slurry, ordinary silicate-water glass double liquid slurry, and ordinary silicate cement single liquid slurry; the grouting pressure and flow rate of each slurry type are consistent.

9. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In the step (5), after the hole is directly drilled to the designed hole depth, the backward grouting is performed in sections from the hole bottom to the hole mouth.

10. The large-scale high-pressure water-rich altered structural zone reinforcement grouting method according to claim 1 is characterized in that: In step (7), when grouting the full-section curtain, grouting is performed in a skip-hole manner from outside to inside and from top to bottom.

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