Layered gradient grouting method for deep underground space and integrated structure of reinforcement, sealing and protection

Abstract

This invention belongs to the field of deep underground engineering surrounding rock control technology, and particularly relates to a layered gradient grouting method and integrated reinforcement and sealing structure for deep underground spaces. The structure comprises: a deep permeable grouting layer, a middle high-strength reinforcement layer, and a surface high-toughness sealing layer arranged radially from the inside to the outside along the surrounding rock. The three layers meet preset relationships in terms of permeability coefficient, strength, and elastic modulus, with the permeability coefficient decreasing layer by layer, and the middle layer exhibiting the highest strength and elastic modulus. A continuous transition zone is provided between adjacent layers, resulting in a continuous transition in material properties. This structure is integrated through staged grouting from deep to shallow, radially decreasing grouting pressure, and dynamic control of grouting parameters via fiber optic monitoring. This invention achieves synergy between grouting, reinforcement, and sealing functions, forming a load-bearing and seepage-proof coupled composite surrounding rock structure that can adapt to changes in stress gradient in deep surrounding rock, eliminate weak interfaces between layers, and ensure the long-term stability and safety of deep underground spaces.

Description

Technical Field

[0001] This invention belongs to the field of deep underground engineering surrounding rock control technology, and particularly relates to a layered gradient grouting method for deep underground spaces and an integrated reinforcement and sealing structure. Background Technology

[0002] As energy resource development, transportation infrastructure construction, and underground space utilization expand to deeper areas, the surrounding rock of deep underground engineering projects is situated in a complex geological environment characterized by high ground stress and high permeability pressure. This leads to frequent engineering disasters such as large rock deformation and sudden water inrush, seriously threatening construction safety and long-term operational stability. Currently, the main techniques for controlling the surrounding rock in deep underground spaces include anchor bolt support, shotcrete, and grouting reinforcement. These technologies have achieved good application results under shallow or general geological conditions.

[0003] However, existing technologies exhibit significant shortcomings when dealing with deep and complex surrounding rock. First, grouting, reinforcement, and waterproofing are typically implemented as independent processes, lacking integrated design between functional layers. This easily leads to weak interfaces between structures, resulting in insufficient overall load-bearing capacity and waterproofing performance. Second, grouting parameter design is often crude, failing to fully consider the differences in damage states and permeability characteristics of different depth layers of the surrounding rock. The use of uniform grouting parameters often results in over-grouting in shallow layers and insufficient grouting in deep layers, or significant grout loss, making it difficult to form an effective load-bearing and waterproofing layer. Third, a single structure cannot adapt to the gradient change in stress transmission from the outside to the inside of deep surrounding rock. Deformation incoordination easily occurs between the surrounding rock and the support structure, leading to premature structural failure. Summary of the Invention

[0004] The purpose of this invention is to provide a layered gradient grouting method for deep underground spaces and an integrated reinforcement and sealing structure to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following solution: The steps of the layered gradient grouting method for deep underground spaces are as follows: Information on the loosened zone, plastic zone, and elastic zone of the surrounding rock after excavation is obtained, as well as information on the degree of damage, fracture development characteristics, and permeability coefficient distribution of the surrounding rock. Based on the acquired surrounding rock information, the grouting-affected zone of the surrounding rock is sequentially divided into a deep permeability zone, a middle reinforcement zone, and a surface sealing zone, and construction parameter information is determined based on construction requirements. Among them, the surface protection zone is close to the excavation face; Based on the construction parameter information, in order from deep to shallow, grout is first injected into the deep penetration zone to form a deep penetration grouting layer for sealing water-conducting cracks, then grout is injected into the middle reinforcement zone to form a middle high-strength reinforcement layer for supporting the arch, and finally grout is injected into the surface sealing zone to form a surface high-toughness sealing layer for deformation coordination and boundary sealing. Among them, the permeability coefficients of the deep-penetrating grouting layer, the middle high-strength reinforcement layer, and the surface high-toughness protective layer decrease in that order. The elastic modulus and strength of the middle high-strength reinforcement layer are both greater than those of the deep-penetrating grouting layer and the surface high-toughness protective layer.

[0006] In the deep underground space layered gradient grouting method of the present invention, when grouting into the deep permeable zone, a deep hole grouting process is adopted, and the grouting material includes chemical grout or ultrafine cement grout.

[0007] In the deep underground space layered gradient grouting method of the present invention, when grouting the middle layer reinforcement zone, a segmented retreat grouting process is adopted, and the grouting material includes high-strength micro-expansion cement-based grout.

[0008] In the deep underground space layered gradient grouting method of the present invention, when grouting the surface protection zone, a process combining high-pressure fracturing grouting and high-pressure spraying is adopted, and the grouting material includes a high-toughness crack-resistant material mixed with fiber-reinforced components.

[0009] In the deep underground space layered gradient grouting method of the present invention, when grouting into the middle layer reinforcement zone, the surrounding rock strain and grouting pressure are monitored in real time. The monitoring methods include monitoring through fiber optic grating sensors or distributed fiber optic sensors.

[0010] In the deep underground space layered gradient grouting method of the present invention, the high toughness crack-resistant material includes polymer modified cement-based material with added expansion agent and water-reducing agent, with a water-cement ratio of 0.3-0.4, and the fiber reinforcement component includes polypropylene fiber or basalt fiber, with a fiber reinforcement component mixing amount of 0.5%-1.5%.

[0011] In the deep underground space layered gradient grouting method of the present invention, the permeability coefficient of the deep permeable grouting layer is 1 / 10-1 / 100 of the original rock, and the grouting diffusion radius is ≥2.0m.

[0012] In the deep underground space layered gradient grouting method of the present invention, the uniaxial compressive strength of the middle high-strength reinforcement layer is ≥40MPa, the elastic modulus is 25GPa-35GPa, and the permeability coefficient is ≤10. -6 cm / s, with a thickness of 1.5m-3.0m.

[0013] In the deep underground space layered gradient grouting method of the present invention, the permeability coefficient of the surface high-toughness protective layer is ≤10. -8 cm / s, impermeability grade ≥ P12, 28-day compressive strength ≥ 8MPa, elastic modulus ≤ 20GPa, thickness 0.5m-1.5m.

[0014] An integrated reinforcement and sealing structure is obtained by a layered gradient grouting method for deep underground space construction.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention achieves a strength gradient match and a decreasing permeability gradient in the surrounding rock from the inside out by setting up a deep-penetrating grouting layer, a middle-layer high-strength reinforcement layer, and a surface high-toughness sealing layer, ensuring that these three layers meet preset relationships in terms of permeability coefficient, strength, and elastic modulus. The deep-penetrating grouting layer seals long-distance water-conducting fractures, the middle-layer high-strength reinforcement layer forms the main load-bearing arch, and the surface high-toughness sealing layer isolates external water head and adapts to surrounding rock deformation. The three layers are connected by a continuous transition zone to achieve continuous stress and seepage transmission. The grouting sequence, from deep to shallow and with decreasing pressure, ensures that the grout layers overlap and interlock tightly, with no weak points between layers. This forms an integrated reinforcement and sealing structure that can adapt to the stress gradient changes in deep surrounding rock, avoid structural damage caused by deformation incoordination, and significantly improve long-term impermeability, solving the problems of functional separation, unclear gradients, and insufficient sealing in existing technologies. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort: Figure 1 This is a schematic diagram of the integrated reinforcement and sealing structure in this invention; Detailed Implementation The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] This invention discloses a layered gradient grouting method for deep underground spaces, the steps of which are as follows: Information on the loosened zone, plastic zone, and elastic zone of the surrounding rock after excavation is obtained, as well as information on the degree of damage, fracture development characteristics, and permeability coefficient distribution of the surrounding rock. Based on the acquired surrounding rock information, the grouting-affected zone of the surrounding rock is sequentially divided into a deep permeability zone, a middle reinforcement zone, and a surface sealing zone, and construction parameter information is determined based on construction requirements. Among them, the surface protection zone is close to the excavation face; Based on the construction parameter information, in order from deep to shallow, grout is first injected into the deep penetration zone to form a deep penetration grouting layer for sealing water-conducting cracks, then grout is injected into the middle reinforcement zone to form a middle high-strength reinforcement layer for supporting the arch, and finally grout is injected into the surface sealing zone to form a surface high-toughness sealing layer for deformation coordination and boundary sealing. Among them, the permeability coefficients of the deep-penetrating grouting layer, the middle high-strength reinforcement layer, and the surface high-toughness protective layer decrease in that order. The elastic modulus and strength of the middle high-strength reinforcement layer are both greater than those of the deep-penetrating grouting layer and the surface high-toughness protective layer.

[0019] The permeability coefficient, elastic modulus, and strength of the deep permeable grouting layer, the intermediate high-strength reinforcement layer, and the surface high-toughness sealing layer exhibit continuous functional variations or piecewise linear variations along the radial direction of the surrounding rock.

[0020] The ratio of the permeability coefficient of the deep-penetrating grouting layer to the surface high-toughness protective layer is ≥10².

[0021] A continuous transition zone is set between the deep-penetrating grouting layer and the intermediate high-strength reinforcement layer, and between the intermediate high-strength reinforcement layer and the surface high-toughness protective layer. The thickness of the continuous transition zone is not less than 0.2m. Moreover, the material properties of the continuous transition zone change continuously between adjacent layers to achieve continuous stress and seepage transfer.

[0022] First, the loosened zone, plastic zone, and elastic zone of the surrounding rock after deep underground space excavation are determined, along with the degree of rock damage, fracture development characteristics, and permeability coefficient distribution. Based on this information, the grouting-affected area is divided from the inside out into a deep permeability zone, a middle reinforcement zone, and a surface sealing zone, and construction parameters for each zone are determined according to construction requirements. Then, following a sequence from deep to shallow, grout is injected first into the deep permeability zone to form a deep permeability grouting layer for sealing water-conducting fractures; then, grout is injected into the middle reinforcement zone to form a middle high-strength reinforcement layer for supporting the arch; and finally, grout is injected into the surface sealing zone to form a surface high-toughness sealing layer for deformation coordination and boundary sealing. The permeability coefficients of the three layers decrease sequentially, with the middle layer having a higher elastic modulus and strength than the other two layers. This invention, through zonal detection, gradient design, and sequential construction, matches the grouting layer with the surrounding rock damage zones, forming a composite structure that coordinates load-bearing and seepage prevention, solving the problems of functional separation, coarse parameters, and deformation incoordination in existing technologies.

[0023] In one alternative approach, when grouting into the deep permeation zone, a deep-hole grouting process is employed, and the grouting material includes chemical grout or ultrafine cement grout.

[0024] When grouting into deep permeable zones, deep-hole grouting technology is employed, using chemical grout or ultrafine cement grout as the grouting material. Deep-hole grouting can deliver the grout deep into the surrounding rock. Chemical grout or ultrafine cement grout has the characteristics of low viscosity and high permeability, which can effectively fill long-distance water-conducting fractures, reduce the deep permeability of the surrounding rock, and provide stable foundation conditions for subsequent intermediate and surface grouting.

[0025] In one alternative approach, a segmented retreating grouting process is used when grouting the intermediate reinforcement zone, and the grouting material includes high-strength micro-expansion cement-based grout.

[0026] When grouting the intermediate reinforcement zone, a segmented retreating grouting process is adopted, and high-strength micro-expansion cement-based grout is selected as the grouting material. The segmented retreating grouting process can control the diffusion range of the grout segment by segment, avoiding impact damage to the already formed deep permeable layer; after the high-strength micro-expansion cement-based grout hardens, it will generate micro-expansion, tightly interlock with the surrounding rock, form a high-strength load-bearing arch, improve the overall stiffness of the surrounding rock, and at the same time, the micro-expansion characteristics can compensate for shrinkage and reduce the interlayer gaps.

[0027] In one alternative approach, when grouting the surface sealing zone, a process combining high-pressure fracturing grouting and high-pressure spraying is employed, and the grouting material includes a high-toughness, crack-resistant material mixed with fiber-reinforced components.

[0028] When grouting the surface sealing zone, a combination of high-pressure fracturing grouting and high-pressure spraying is used. The grouting material is a high-toughness, crack-resistant material mixed with fiber-reinforced components. High-pressure fracturing grouting allows the grout to penetrate into the surface micro-fractures, while high-pressure spraying forms a continuous and dense surface film. The combination of the two ensures full-section sealing of the surface layer. The fiber-reinforced components improve the crack resistance and deformation capacity of the material, enabling the surface layer to adapt to minor deformations of the surrounding rock in the later stages without cracking, forming a long-term effective low-permeability sealing boundary.

[0029] In one alternative approach, during grouting of the intermediate reinforcement zone, the surrounding rock strain and grouting pressure are monitored in real time, using methods such as fiber optic grating sensors or distributed fiber optic sensors.

[0030] During grouting into the intermediate reinforcement zone, the surrounding rock strain and grouting pressure are monitored in real time using fiber optic grating sensors or distributed fiber optic sensors. The monitoring data can be dynamically fed back to the grouting control system, allowing operators to adjust parameters such as grouting pressure and flow rate accordingly. This prevents excessively high grouting pressure from damaging the already formed deep permeable layer, or from being too low, resulting in insufficient compaction of the intermediate reinforcement layer, thus achieving precise control of the grouting process and interlayer synergy.

[0031] In one alternative, the high-toughness crack-resistant material includes a polymer-modified cementitious material with added expansion agent and water-reducing agent, with a water-cement ratio of 0.3-0.4, and the fiber reinforcement component includes polypropylene fiber or basalt fiber, with a fiber reinforcement component mixing amount of 0.5%-1.5%.

[0032] The specific composition of the high-toughness crack-resistant surface material is as follows: polymer-modified cementitious material, with added expansive agent and water-reducing agent, water-cement ratio of 0.3-0.4, and fiber reinforcement component mixed at 0.5%-1.5%. Polymer modification improves adhesion and flexibility, the expansive agent compensates for shrinkage, the water-reducing agent lowers the water-cement ratio and increases density, and the fiber reinforcement component inhibits the propagation of microcracks. This material formulation gives the surface layer low permeability, high impermeability, appropriate strength, and low elastic modulus, enabling it to both seal water head and adapt to deformation.

[0033] In one alternative scheme, the permeability coefficient of the deep-penetrating grouting layer is 1 / 10 to 1 / 100 of that of the original rock, and the grouting diffusion radius is ≥2.0m.

[0034] The permeability coefficient of the deep grouting layer is reduced to 1 / 10 to 1 / 100 of that of the original rock, and the grouting diffusion radius is ≥2.0m. This indicator ensures that deep grouting can seal water-conducting fractures over a large area, significantly reduce the permeability of the surrounding rock foundation, provide the preconditions for gradient seepage reduction in the middle and surface layers, and prevent the upward transmission of deep water pressure, thus controlling the groundwater seepage field from the source.

[0035] In one alternative design, the uniaxial compressive strength of the intermediate high-strength reinforcement layer is ≥40MPa, the elastic modulus is 25GPa-35GPa, and the permeability coefficient is ≤10. -6 cm / s, with a thickness of 1.5m-3.0m.

[0036] The uniaxial compressive strength of the intermediate high-strength reinforcement layer is ≥40MPa, the elastic modulus is 25GPa-35GPa, and the permeability coefficient is ≤10⁻. 6 The layer has a permeability of cm / s and a thickness of 1.5m-3.0m. This layer has the highest strength and modulus of elasticity, forming the main load-bearing arch structure, which can resist high ground stress; at the same time, the permeability coefficient is controlled at a low level, which also has a certain seepage prevention function; the thickness is moderate, ensuring a balance between load-bearing capacity and construction economy.

[0037] In one alternative approach, the permeability coefficient of the high-toughness surface sealing layer is ≤10. -8 cm / s, impermeability grade ≥ P12, 28-day compressive strength ≥ 8MPa, elastic modulus ≤ 20GPa, thickness 0.5m-1.5m.

[0038] The permeability coefficient of the high-toughness protective layer is ≤10⁻ 8The permeability coefficient is ≥ cm / s, the impermeability grade is ≥P12, the 28-day compressive strength is ≥8MPa, the elastic modulus is ≤20GPa, and the thickness is 0.5m-1.5m. This layer has the lowest permeability coefficient and the highest impermeability grade, serving as the final waterproof barrier to isolate external water head; its low elastic modulus and high toughness allow it to deform in coordination with the surrounding rock, avoiding cracks caused by excessive stiffness; the appropriate thickness ensures both sealing effect and control of material usage.

[0039] Reference Figure 1 A reinforced and sealed integrated structure is obtained by a layered gradient grouting method for deep underground space construction.

[0040] A three-layer gradient composite structure is formed in the rock surrounding the excavation outline of the underground space: a deep permeable grouting layer to seal water-conducting fissures, a middle high-strength reinforcement layer to bear stress, and a surface high-toughness protective layer to isolate water head and adapt to deformation. The permeability coefficients of the three layers decrease sequentially, with the middle layer having the highest strength and modulus. Furthermore, the sequential grouting from deep to shallow achieves continuous transition and integrated molding between layers, avoiding the weak interfaces formed by the separate construction of functional layers in traditional methods. This achieves coupled synergy between load-bearing and seepage prevention, significantly improving the long-term stability of the deep surrounding rock.

[0041] One specific example: Step 1: Using sonic testing, digital borehole photography, and water pressure testing, the loose zone, plastic zone, and elastic zone of the surrounding rock after excavation are detected to obtain the degree of damage, fracture development characteristics, and permeability coefficient distribution of the surrounding rock. Based on the information obtained about the surrounding rock, the grouting-affected zone is divided into a deep permeability zone, a middle reinforcement zone, and a surface sealing zone, and the thickness of each layer and the performance indicators of the grouting material are determined.

[0042] Step 2: Utilize deep-hole grouting technology to perform deep grouting at a distance of 1-2 times the tunnel diameter behind the excavation face. Use low-viscosity, high-permeability chemical grout or ultrafine cement grout with adjustable gel time. The grouting pressure is 1.5-3.0 times the hydrostatic pressure, and the designed diffusion radius is not less than 2.0m, forming a deep-penetrating grouting layer to seal long-distance water-conducting fractures and initially improve the integrity of the surrounding rock.

[0043] Step 3: After the deep permeation grouting layer reaches a certain strength, a segmented retreating grouting process is adopted to inject high-strength micro-expansion cement-based grout into the middle layer reinforcement zone. The grouting pressure is 2.0-4.0 MPa. The grouting pressure in the middle layer high-strength reinforcement stage is higher than that in the deep layer. The grout diffusion radius is controlled within the range of 1.5m-2.5m to form a high-strength reinforcement layer, which together with the deep permeation grouting layer and the surrounding rock forms a load-bearing arch. Fiber optic grating sensors or distributed optical fibers are used to monitor the surrounding rock strain and grouting pressure in real time, and the grouting parameters are dynamically adjusted to prevent damage to the formed deep permeation grouting layer. At the same time, the grouting pressure range can be adjusted according to the burial depth of the surrounding rock, the ground stress, and the groundwater pressure conditions.

[0044] Step 4: After the intermediate reinforcement layer is constructed, a combination of high-pressure fracturing grouting and high-pressure spraying is used to inject high-toughness crack-resistant material and fiber reinforcement components into the surface 0.5m-1.5m range. This forms a dense surface sealing layer with a certain degree of deformation adaptability. The grouting pressure range can be adjusted according to the surrounding rock depth, ground stress, and groundwater pressure conditions. The surface high-toughness sealing layer material is a polymer-modified cement-based material, incorporating polypropylene fiber or basalt fiber at a volume fraction of 0.5%-1.5% and a water-cement ratio of 0.3-0.4. Expansion agents and water-reducing agents are also added.

[0045] The grouting sequence strictly follows the principle of "from deep to shallow, sealing layer by layer, and decreasing pressure gradient" to ensure that the grout layers overlap and interlock tightly, with no weak surfaces between layers, forming an integrated composite structure with gradient changes in strength, stiffness, and permeability and synergistic functions.

[0046] The overall grouting pressure decreases radially along the surrounding rock to control the grout diffusion range and the quality of interlayer overlap.

[0047] By controlling the construction time interval between adjacent layers and the grouting parameters, a continuous composite structure without obvious weak interfaces is formed between the layers.

[0048] Step 5: After grouting is completed, core sampling, acoustic testing, water pressure testing and borehole inspection are used to check whether the thickness, strength and permeability of each layer meet the design requirements. Supplementary grouting is carried out in areas that do not meet the standards.

[0049] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0050] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A layered gradient grouting method for deep underground spaces, characterized in that, The steps are as follows: Information on the loosened zone, plastic zone, and elastic zone of the surrounding rock after excavation is obtained, as well as information on the degree of damage, fracture development characteristics, and permeability coefficient distribution of the surrounding rock. Based on the acquired surrounding rock information, the grouting-affected zone of the surrounding rock is sequentially divided into a deep permeability zone, a middle reinforcement zone, and a surface sealing zone, and construction parameter information is determined based on construction requirements. Among them, the surface protection zone is close to the excavation face; Based on the construction parameter information, in order from deep to shallow, grout is first injected into the deep penetration zone to form a deep penetration grouting layer for sealing water-conducting cracks, then grout is injected into the middle reinforcement zone to form a middle high-strength reinforcement layer for supporting the arch, and finally grout is injected into the surface sealing zone to form a surface high-toughness sealing layer for deformation coordination and boundary sealing. Among them, the permeability coefficients of the deep-penetrating grouting layer, the middle high-strength reinforcement layer, and the surface high-toughness protective layer decrease in that order. The elastic modulus and strength of the middle high-strength reinforcement layer are both greater than those of the deep-penetrating grouting layer and the surface high-toughness protective layer.

2. The layered gradient grouting method for deep underground spaces according to claim 1, characterized in that: When grouting into deep penetration zones, deep hole grouting technology is used, and the grouting materials include chemical grout or ultrafine cement grout.

3. The layered gradient grouting method for deep underground spaces according to claim 1, characterized in that: When grouting the intermediate reinforcement zone, a segmented retreat grouting process is adopted, and the grouting material includes high-strength micro-expansion cement-based grout.

4. The layered gradient grouting method for deep underground spaces according to claim 1, characterized in that: When grouting the surface protection zone, a process combining high-pressure fracturing grouting and high-pressure spraying is adopted. The grouting material includes a high-toughness crack-resistant material mixed with fiber-reinforced components.

5. The layered gradient grouting method for deep underground spaces according to claim 1, characterized in that: When grouting into the intermediate reinforcement zone, the surrounding rock strain and grouting pressure are monitored in real time. The monitoring methods include monitoring through fiber optic grating sensors or distributed fiber optic sensors.

6. The layered gradient grouting method for deep underground spaces according to claim 4, characterized in that: High-toughness crack-resistant materials include polymer-modified cementitious materials with added expansion agents and water-reducing agents, with a water-cement ratio of 0.3-0.4, and fiber reinforcement components including polypropylene fibers or basalt fibers, with a fiber reinforcement component mixing amount of 0.5%-1.5%.

7. The layered gradient grouting method for deep underground spaces according to claim 1, characterized in that: The permeability coefficient of the deep-penetrating grouting layer is 1 / 10 to 1 / 100 of that of the original rock, and the grouting diffusion radius is ≥2.0m.

8. The layered gradient grouting method for deep underground spaces according to claim 1, characterized in that: The uniaxial compressive strength of the intermediate high-strength reinforcement layer is ≥40MPa, the elastic modulus is 25GPa-35GPa, and the permeability coefficient is ≤10. -6 cm / s, with a thickness of 1.5m-3.0m.

9. The layered gradient grouting method for deep underground spaces according to claim 1, characterized in that: The permeability coefficient of the high-toughness protective layer is ≤10. -8 cm / s, impermeability grade ≥ P12, 28-day compressive strength ≥ 8MPa, elastic modulus ≤ 20GPa, thickness 0.5m-1.5m.

10. An integrated reinforced and protected structure, characterized in that, Obtained by the deep underground space layered gradient grouting method according to any one of claims 1-9.

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