Supporting structure for deep engineering block-shaped surrounding rock cavern and construction method of supporting structure

Abstract

The invention discloses a supporting structure for a deep engineering blocky surrounding rock cavern and a construction method of the supporting structure, and belongs to the technical field of design and construction of hydropower engineering structures. The supporting structure for the deep engineering blocky surrounding rock cavern and the construction method of the supporting structure are suitable for deep engineering cavern construction, and the supporting effect is remarkably improved. The supporting structure comprises an excavated deep engineering cavern and further comprises three-dimensional reinforcing systems and a drainage system, and the three-dimensional reinforcing systems are arranged on the surface of the excavated deep engineering cavern and in adjacent blocky surrounding rock. Underground water in the rock mass above the bottom plane of the excavated deep engineering cavern is drained out of the excavated deep engineering cavern through a drainage system; in the operation process, the block-shaped surrounding rock around the excavated deep engineering cavern is kept stable through the three-dimensional reinforcing system.

Description

Technical Field

[0001] The present invention relates to a support structure, in particular to a support structure for a deep engineering block surrounding rock cavern, belonging to the technical field of hydropower engineering structure design and construction. The present invention also relates to a construction method for the deep engineering block surrounding rock cavern support structure. Background Art

[0002] Terminology explanation:

[0003] Deep engineering: In the field of hydropower engineering, underground engineering with a depth of more than 600m is considered to be in the deep engineering field, which generally has a geological environment with high ground stress and high osmotic pressure, and the stability of the surrounding rock is prominent;

[0004] Blocky surrounding rock: After the underground project is excavated, the surrounding rock mass is cut into blocky surrounding rock by joints and fissures;

[0005] Stability control: Through engineering treatment measures, deformation or instability of the surrounding rock mass caused by development disturbance, such as deformation and falling blocks, can be prevented.

[0006] Different from shallow underground projects, deep underground projects will face a certain degree of blindness, inefficiency and uncertainty due to the complexity of the deep geological environment and the limitations of the detection technology level, and the fact that the rock mechanics theory and deep earth science laws in the deep environment are still unclear. After the excavation of deep underground caverns is completed, the surrounding rock is affected by high ground stress and high osmotic pressure, and the stress state changes due to the excavation. Under the combination of unloading, ground stress and unfavorable cracks, there are prominent problems of blocky surrounding rock stability, and there are also problems of water inrush in areas with abundant groundwater. For shallow underground projects, surrounding rock support can be divided into two categories according to the support mechanism: one is active support, and the other is improved surrounding rock state support. This type of support method needs to be carried out in conjunction with active support. At present, the main active support measures include anchor rods, anchor cables and surrounding rock surface lining, and this technology is relatively mature. On the other hand, in order to make the surrounding rock support play a positive role in regulating and controlling the deformation of the surrounding rock, the support is often arranged before the surrounding rock is loosened and damaged, so that the support can bear the load together with the surrounding rock while the surrounding rock still maintains its self-bearing capacity; at the same time, grouting can also be carried out in the cracks of the surrounding rock to enhance the stability of the surrounding rock itself and strengthen the support effect. Although the current support methods for the surrounding rock of underground projects are relatively mature and diverse, their support mechanisms are similar, that is, anchoring force is applied through anchor rods or anchor cables, surrounding rock deformation or grouting is controlled, and a bearing support system is formed with the surrounding rock surface lining. In addition, when facing the block rock mass of deep engineering, the support range of active support is limited, and the surrounding rock grouting is difficult to cover the entire surrounding rock range, resulting in insufficient grouting. After excavation and support, some rock blocks have problems such as local instability and block falling under unfavorable structural surface combinations.

[0007] As mentioned above, the existing surrounding rock supports are all one-way and one-dimensional, and they all maintain the stability of the rock mass by actively or passively applying support forces through the axis of the anchor rod / anchor cable, without fully utilizing the stability of the surrounding rock itself and the characteristics of the significant increase in rock mass strength under the confining pressure. The existing technology has two main defects: ① The support effect is poor. For block rock mass, the block is stable when anchor rods and other support parts are applied, but the surrounding rock without the application may be unstable under unfavorable structural surface combinations. In addition, the surrounding rock is squeezed by the applied anchoring force, and the unapplied part is prone to be squeezed in the empty direction, further aggravating the instability; ② The grouting efficiency is low. For deep projects, under the action of high ground stress, the joints and fissures are in a closed state. When grouting is used to reinforce the surrounding rock, the grouting efficiency is limited. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a support structure for deep engineering block-shaped surrounding rock caverns which is suitable for deep engineering cavern construction and has significantly improved support effect, and a construction method for the support structure for deep engineering block-shaped surrounding rock caverns.

[0009] The technical solution adopted to solve the above technical problems is: a support structure for deep engineering block rock caverns, including an excavated deep engineering cavern, the support structure also includes a three-dimensional reinforcement system and a drainage system, the three-dimensional reinforcement system is arranged on the surface of the excavated deep engineering cavern and in the adjacent block rock, the groundwater in the rock mass above the bottom plane of the excavated deep engineering cavern is discharged to the outside of the excavated deep engineering cavern through the drainage system; during operation, the block rock around the excavated deep engineering cavern is kept stable by the three-dimensional reinforcement system.

[0010] Furthermore, the drainage system includes drainage holes and drainage ditches. Drainage holes are drilled in the side wall rock mass and the arc-shaped top wall rock mass of the excavated deep engineering cavern along the circumferential direction. The drainage ditch is arranged on the bottom plane of the excavated deep engineering cavern. The water outlet end of each drainage hole is connected to the drainage ditch. The collected water in the excavated deep engineering cavern is discharged to the outside of the excavated deep engineering cavern through the drainage ditch.

[0011] The preferred embodiment of the above scheme is that the three-dimensional reinforcement system includes a radial reinforcement structure, a shaft-ring composite reinforcement structure and a surface consolidation reinforcement structure. The shaft-ring composite reinforcement structure is inserted into the block surrounding rock of the side wall and the curved top wall of the excavated deep engineering cavern at intervals from each other along the circumferential and axial directions through the radial reinforcement structure embedded in the shaft-ring composite reinforcement structure, and consolidation stress is applied to the block surrounding rock along the radial, circumferential and axial directions; the outer end of the radial reinforcement structure is fixed on the wall of the excavated deep engineering cavern through the surface consolidation reinforcement structure and wall pressure is applied.

[0012] Furthermore, installation holes are drilled in the block surrounding rocks of the side walls and the curved top wall of the excavated deep engineering cavern, and the shaft-ring composite reinforcement structure is arranged in the block surrounding rocks of the side walls and the curved top wall of the excavated deep engineering cavern through the installation holes with the cooperation of the radial reinforcement structure.

[0013] The preferred embodiment of the above scheme is that the installation holes are anchor holes or anchor cable holes drilled in the blocky surrounding rock of the side walls and curved top walls of the excavated deep engineering cavern, and the radial reinforcement structure is a prestressed anchor rod or prestressed anchor cable arranged in the anchor hole or anchor cable hole.

[0014] Furthermore, the shaft-ring composite reinforcement structure is the corresponding expansive concrete filled in each anchor hole or anchor cable hole, and the corresponding prestressed anchor rod or prestressed anchor cable is embedded in the expansive concrete.

[0015] The preferred embodiment of the above scheme is that the surface consolidation reinforcement structure includes an anchor head, a consolidation nut, a prefabricated primary lining module and a secondary lining cast-in-place layer. A connecting thread is respectively provided at the free end of each prestressed anchor rod or prestressed anchor cable. The anchor head is respectively arranged on each prestressed anchor rod or prestressed anchor cable through the consolidation nut in cooperation with the connecting thread. The prefabricated primary lining module is padded between the anchor head and the side walls and arc-shaped top walls corresponding to the excavated deep engineering cavern, and the secondary lining cast-in-place layer is covered on the prefabricated primary lining module.

[0016] Furthermore, the surface consolidation reinforcement structure also includes a gasket-type stress gauge and a pea gravel filling layer. The gasket-type stress gauge is padded between the consolidation nut and the anchor head, and the pea gravel filling layer is coated on the blocky surrounding rock of the side wall and the arc-shaped top wall of the excavated deep engineering cavern.

[0017] A construction method for a support structure for a deep engineering block-shaped surrounding rock cavern, the construction method sequentially comprises the steps of excavating the deep engineering cavern in sections, drilling drainage holes and anchor holes or anchor cable holes, laying anchors or anchor cables, pouring expansive concrete, installing prefabricated primary lining modules and filling a pea gravel filling layer between the prefabricated primary lining modules and the surrounding rock free surface, applying prestress to the anchors or anchor cables and applying wall pressure consolidation through the anchor head in cooperation with the consolidation nut and the gasket-type stress gauge, and finally performing several steps of pouring a secondary cast-in-place layer, repeating the above steps to carry out the construction of the next section of the deep engineering cavern until the construction of all the deep engineering caverns is completed.

[0018] Furthermore, after drilling the drainage holes and anchor holes or anchor cable holes, the holes need to be cleaned first, and then the anchor rods or anchor cables are laid. During the process of laying the anchor rods or anchor cables, they are fixed by simple brackets and then poured with expansive concrete. After the expansive concrete reaches the specified strength, the prefabricated primary lining module is installed. After the overall support is completed, the corresponding anchor rods or anchor cables are reinforced by consolidation nuts when the anchor rods or anchor cables with reduced stress are monitored by gasket-type stress gauges.

[0019] The beneficial effects of the present invention are as follows: the technical solution provided by the present application is based on the excavation of deep engineering caverns, and the support structure of the present application is formed by adding a three-dimensional reinforcement system and a drainage system, and the three-dimensional reinforcement system is arranged on the surface of the excavated deep engineering cavern and in the adjacent blocky surrounding rock, and then the groundwater in the rock mass above the bottom plane of the excavated deep engineering cavern is discharged to the outside of the excavated deep engineering cavern through the drainage system; thereby achieving the function of maintaining stability of the blocky surrounding rock around the excavated deep engineering cavern through the three-dimensional reinforcement system during operation. In this way, since the blocky surrounding rock around the blocky surrounding rock cavern of the present application is supported in three dimensions, many defects of the one-dimensional support in the prior art are changed, and the blocky surrounding rock cavern of the present application can be made suitable for the construction of deep engineering caverns, achieving the purpose of significantly improving the support effect. That is, the technical solution provided by this application solves the technical problem that traditional support fails or has poor effect due to the influence of high ground stress and high-pressure seepage water for deep engineering. It makes full use of the strength of the surrounding rock itself and the mechanical properties of the rock mass to carry out coordinated support, such as applying radial and circumferential forces to the surrounding rock, and improving the uniaxial stress state after excavation unloading to a triaxial stress state with a certain confining pressure. The strength of the rock mass under confining pressure is significantly higher than the strength under uniaxial without confining pressure, and its own stability can also be fully utilized. The deep engineering surrounding rock stability control of this application adopts the support + surrounding rock synergistic mode, which makes full use of the strength of the surrounding rock of the cavern and improves the stability, which is of great significance to improving the support effect and saving investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the stress of the deep engineering surrounding rock before excavation involved in the supporting structure of the deep engineering block surrounding rock cavern of the present invention;

[0021] Figure 2 It is a schematic diagram of the stress of the deep engineering surrounding rock after excavation involved in the supporting structure of the deep engineering block surrounding rock cavern of the present invention;

[0022] Figure 3 The state diagram of the massive surrounding rock under stress after the deep engineering surrounding rock is excavated, which is involved in the supporting structure of the deep engineering massive surrounding rock cavern of the present invention;

[0023] Figure 4 The diagram of the stress state of the surrounding rock after the synergistic effect of the excavated surrounding rock and the support involved in the support structure of the deep engineering block surrounding rock cavern of the present invention;

[0024] Figure 5 It is a schematic diagram of the stable state of the block under the existing support conditions;

[0025] Figure 6It is a stress state diagram of the supporting structure of the blocky surrounding rock cavern in deep engineering under supporting conditions according to the present invention;

[0026] Figure 7 It is a structural schematic diagram of the support structure of the present invention for a massive surrounding rock cavern in a deep engineering;

[0027] Figure 8 It is a partial detailed diagram of the support structure of the present invention for a deep engineering block surrounding rock cavern;

[0028] Fig. 9 It is a structural relationship diagram of the anchor rods, pea gravel layers, primary lining baffles and secondary lining involved in the supporting structure of the blocky surrounding rock cavern in deep engineering according to the present invention;

[0029] Fig.10 for Fig. 9 A-direction view.

[0030] Marked in the figure are: excavated deep engineering cavern 1, massive surrounding rock 2, drainage hole 3, prestressed anchor rod or prestressed anchor cable 4, expansive concrete 5, anchor head 6, consolidation nut 7, prefabricated primary lining module 8, secondary lining cast-in-place layer 9, gasket-type stress gauge 10, and pea gravel filling layer 11.

[0031] right Figure 4 Notes on the stresses in the figure: After the excavation of deep engineering caverns, the surrounding rock is exposed to the air and the radial force is 0, that is, the minimum principal stress σ3 is 0 and the maximum principal stress is σ1, which does not meet the Coulomb criterion and may be unstable. When the surrounding rock-support synergistic effect is applied, certain radial and circumferential forces are applied to the surrounding rock, so that the minimum principal stress σ3>0 and is within the range of the Coulomb criterion, meeting the stability requirements. DETAILED DESCRIPTION

[0032] like Figures 1 to 10The present invention provides a support structure for deep engineering caverns with blocky surrounding rock, which is suitable for deep engineering cavern construction and has significantly improved support effects, and a construction method for the support structure for deep engineering caverns with blocky surrounding rock. The support structure includes an excavated deep engineering cavern 1, and the support structure also includes a three-dimensional reinforcement system and a drainage system. The three-dimensional reinforcement system is arranged on the surface of the excavated deep engineering cavern and in the adjacent blocky surrounding rock 2. The groundwater in the rock mass above the bottom plane of the excavated deep engineering cavern is discharged to the outside of the excavated deep engineering cavern 1 through the drainage system; during operation, the blocky surrounding rock 2 around the excavated deep engineering cavern 1 is kept stable by the three-dimensional reinforcement system. The technical solution provided by the present application is based on the excavation of deep engineering caverns. The support structure of the present application is formed by adding a three-dimensional reinforcement system and a drainage system. The three-dimensional reinforcement system is arranged on the surface of the excavated deep engineering cavern and in the adjacent blocky surrounding rock. Then, the groundwater in the rock mass above the bottom plane of the excavated deep engineering cavern is discharged to the outside of the excavated deep engineering cavern through the drainage system; thereby, the blocky surrounding rock around the excavated deep engineering cavern is kept stable by the three-dimensional reinforcement system during operation. In this way, since the blocky surrounding rock around the blocky surrounding rock cavern of the present application is supported in three dimensions, many defects of the one-dimensional support in the prior art are changed, and the blocky surrounding rock cavern of the present application can be made suitable for the construction of deep engineering caverns, achieving the purpose of significantly improving the support effect. That is, the technical solution provided by this application solves the technical problem that traditional support fails or has poor effect due to the influence of high ground stress and high-pressure seepage water for deep engineering. It makes full use of the strength of the surrounding rock itself and the mechanical properties of the rock mass to carry out coordinated support, such as applying radial and circumferential forces to the surrounding rock, and improving the uniaxial stress state after excavation unloading to a triaxial stress state with a certain confining pressure. The strength of the rock mass under confining pressure is significantly higher than the strength under uniaxial without confining pressure, and its own stability can also be fully utilized. The deep engineering surrounding rock stability control of this application adopts the support + surrounding rock synergistic mode, which makes full use of the strength of the surrounding rock of the cavern and improves the stability, which is of great significance to improving the support effect and saving investment. With reference to the prior art, the drainage system of the present application includes drainage holes 3 and drainage ditches. Drainage holes 3 are drilled circumferentially in the side wall rock mass and the arc-shaped top wall rock mass of the excavated deep engineering cavern. The drainage ditch is arranged on the bottom plane of the excavated deep engineering cavern. The water outlet end of each drainage hole 3 is connected to the drainage ditch. The collected water in the excavated deep engineering cavern 1 is discharged to the outside of the excavated deep engineering cavern 1 through the drainage ditch.

[0033] Correspondingly, as the key structure improved by the present application, in order to maximize the support effect, the three-dimensional reinforcement system described in the present application includes a radial reinforcement structure, a shaft ring composite reinforcement structure and a surface consolidation reinforcement structure. The shaft ring composite reinforcement structure is inserted into the block surrounding rock 2 of the side wall and the arc-shaped top wall of the excavated deep engineering cavern in the circumferential and axial directions through the radial reinforcement structure embedded in the shaft ring composite reinforcement structure, and applies consolidation stress to the block surrounding rock 2 in the radial, circumferential and axial directions; the outer end of the radial reinforcement structure is fixed on the wall surface of the excavated deep engineering cavern 1 through the surface consolidation reinforcement structure and applies wall pressure. At the same time, in order to facilitate the arrangement, the present application also drills installation holes in the block surrounding rock 2 of the side wall and the arc-shaped top wall of the excavated deep engineering cavern, and the shaft ring composite reinforcement structure is arranged in the block surrounding rock 2 of the side wall and the arc-shaped top wall of the excavated deep engineering cavern through the installation holes in cooperation with the radial reinforcement structure. More specifically, the mounting holes described in the present application are anchor holes or anchor cable holes drilled in the blocky surrounding rock of the side walls and arc-shaped top walls of the excavated deep engineering cavern, and the radial reinforcement structure is a prestressed anchor rod or prestressed anchor cable 4 arranged in the anchor hole or anchor cable hole. The shaft ring composite reinforcement structure is the corresponding expansive concrete 5 filled in each anchor hole or anchor cable hole, and the corresponding prestressed anchor rod or prestressed anchor cable 4 is embedded in the expansive concrete 5. The surface consolidation reinforcement structure includes an anchor head 6, a consolidation nut 7, a prefabricated primary lining module 8 and a secondary lining cast-in-place layer 9. A connecting thread is provided at the free end of each prestressed anchor rod or prestressed anchor cable 4. The anchor head 6 is arranged on each prestressed anchor rod or prestressed anchor cable 4 respectively and in cooperation with the connecting thread through the consolidation nut 7. The prefabricated primary lining module 8 is padded between the anchor head 6 and the side wall and arc-shaped top wall corresponding to the excavated deep engineering cavern. The prefabricated primary lining module 8 is covered with a secondary lining cast-in-place layer 9. At the same time, the surface consolidation reinforcement structure described in the present application also includes a gasket-type stress gauge 10 and a bean gravel filling layer 11. The gasket-type stress gauge 10 is padded between the consolidation nut 7 and the anchor head 6. The bean gravel filling layer 11 is coated on the blocky surrounding rock 2 of the side wall and arc-shaped top wall of the excavated deep engineering cavern.

[0034] In this way, the support structure of the present application can be constructed according to the following construction method, which includes, in sequence, excavating deep engineering caverns in sections, drilling drainage holes and anchor holes or anchor cable holes, laying anchor rods or anchor cables, pouring expansive concrete, installing prefabricated primary lining modules and filling a pea gravel filling layer between the prefabricated primary lining modules and the surrounding rock free surface, applying prestress to the anchor rods or anchor cables and applying wall pressure consolidation through the anchor head in cooperation with the consolidation nut and the gasket-type stress gauge, and finally performing several steps of pouring a secondary cast-in-place layer, repeating the above steps to carry out the construction of the next section of the deep engineering cavern until the construction of all the deep engineering caverns is completed.

[0035] Furthermore, after drilling the drainage holes and anchor holes or anchor cable holes, the present application needs to clean the holes first, and then lay the anchor rods or anchor cables. During the process of laying the anchor rods or anchor cables, they are fixed by simple brackets and then poured with expansive concrete. After the expansive concrete reaches the specified strength, the prefabricated primary lining module is installed. After the overall support is completed, the corresponding anchor rods or anchor cables are reinforced by consolidation nuts when the anchor rods or anchor cables with reduced stress are monitored by gasket-type stress gauges.

[0036] In summary, the technical solution of the present application applies force in the circumferential range of the cavern through expansion concrete anchors + primary lining baffles, applies prestress to the anchors, and then transmits the force to the surrounding rock through the lining baffles, thereby changing the unidirectional stress state of the blocky surrounding rock into a three-directional stress state, making the surrounding rock and support a synergistic system.

[0037] Specifically, the blocky surrounding rock stabilization structure and its control method of this deep engineering project is to apply prestressed anchor rods / anchor cables to the surrounding rock of the cavern, and through the expansion effect of the expansive concrete, while achieving axial reinforcement of the anchor rods / anchor cables, generate lateral (circumferential) pressure perpendicular to the axial direction of the anchor rods and anchor cables, thereby forming a compaction and pressurization effect on the rock mass. At the same time, the axial reinforcement force of the anchor rods / anchor cables is applied to the surrounding rock through the primary lining baffle, generating a radial effect perpendicular to the free surface of the cavern, thereby forming a three-dimensional reinforcement of the support-surrounding rock, thereby improving the support effect and achieving the purpose of reducing investment.

[0038] The technical solution of the present application is further described below through specific embodiments:

[0039] The deep engineering block rock stabilization structure and control method aims to increase the strength of the surrounding rock by applying axial pressure to the surrounding rock mass through anchor rods / anchor cables, while generating circumferential force on the internal surrounding rock through expansive concrete; and transmit the axial force of the anchor rods / anchor cables to the surface surrounding rock of the cavern through the primary lining baffle, thereby improving its stress state and further improving its own stability, realizing the three-dimensional synergy of surrounding rock and support, and achieving the purpose of increasing support effect and saving investment.

[0040] The deep engineering block surrounding rock stability control method described in this application refers to: by using expansive concrete in anchor rods / anchor cables, under the action of lateral expansion of the expansive concrete, a circumferential force is applied to the internal surrounding rock, and the axial force of the anchor rods / anchor cables is transmitted to the surface surrounding rock of the cavern through the primary lining baffle, and a radial force is applied to it, thereby improving the strength and stability of the surrounding rock itself, so that the reinforcement body and the surrounding rock mass form a three-dimensional reinforced whole, thereby improving the support effect. At the same time, by reserving drainage holes inside the surrounding rock, the water is drained to the drainage channel through the pea gravel layer filled in the primary lining and the excavation boundary, thereby reducing the effect of groundwater inside the confining pressure.

[0041] Embodiment 1

[0042] In specific implementation, the deep engineering block rock stabilization structure and control method of this application include the following steps:

[0043] 1. Excavation of deep engineering caverns, and drilling, forming and cleaning of anchor bolts / anchor cables at the designed positions by drilling rigs, and drilling drainage holes;

[0044] 2. Lay out threaded steel bars in the completed drilled holes and fix them with simple brackets;

[0045] 3. Inject expansive concrete into the drilled hole;

[0046] 4 After the expansive concrete has a certain strength, the fixed primary lining baffle can be prefabricated and a drainage channel can be reserved at the bottom of the cavern;

[0047] 5. After installing the lining baffle, fill the pea gravel layer between the baffle and the surrounding rock surface;

[0048] 6 After the filling is completed, a certain prestress is applied to the threaded steel bars;

[0049] 7 After applying prestress, the baffle and anchor rod / anchor cable are connected and fixed through the anchor head;

[0050] 8. Arrange a gasket type stress gauge at the threaded steel bar at the end of the anchor head;

[0051] 9 After setting up the stress gauge, set the fastening bolts at the ends of the threaded steel bars;

[0052] 10After installation is completed, secondary lining is carried out on the primary lining surface;

[0053] 11 Repeat steps 1 to 10 to carry out surrounding rock support for the next section of the cavern.

[0054] 12 After the support is completed (operation and maintenance period), the stress state of the anchor rod / anchor cable is monitored by the installed stress gauge. When the stress is reduced, the axial prestress of the anchor rod / anchor cable can be reinforced by tightening the bolts.

[0055] The key points of this application technology are:

[0056] 1. While applying axial pressure to the surrounding rock mass through anchor rods / anchor cables, the expansive concrete generates circumferential force on the internal surrounding rock to improve the surrounding rock strength;

[0057] 2. Through the primary lining baffle, the axial force of the anchor rod / anchor cable is transmitted to the surrounding rock on the surface of the cavern, improving its stress state and thus improving its own stability;

[0058] 3. A method to achieve the three-dimensional synergy of surrounding rock and support by improving the surrounding rock stress and applying axial anchoring force, thereby increasing the support effect and saving investment;

[0059] 4. The primary lining baffle can be prefabricated and overlapped to quickly complete the primary lining construction, reducing the possibility of surrounding rock instability after the cavern excavation and before the lining is completed;

[0060] 5. The support system composed of multiple anchor rods / anchor cables and primary lining can make the support body and the supported surrounding rock mass form a whole under the action of circumferential, radial and axial forces, which is conducive to overall stability;

[0061] 6. By reserving drainage holes in the surrounding rock, the groundwater is drained to the drainage channel through the pea gravel filling layer, thereby draining the groundwater inside the surrounding rock.

[0062] The existing conventional surrounding rock or slope support is mainly based on anchor cables or anchor rods, which mainly achieve the supporting effect of surrounding rock or slope through the anchoring force between the anchor body and the surrounding rock mass. The supporting effect on the block surrounding rock of deep engineering is not obvious, and there are problems of local block instability and block falling. The deep engineering block surrounding rock stability control method involved in this application, while using the traditional anchoring method, uses the circumferential force generated by the expansive concrete on the surrounding rock, and uses the axial support force generated by the anchor cable / anchor rod to transmit the force to the shallow surrounding rock of the cavern through the primary lining baffle, improve the stress state of the surrounding rock, and can improve the surrounding rock's own strength and stability, so that the reinforcement body and the surrounding rock mass form a three-dimensional reinforced whole, thereby achieving the improvement of the support effect, with the advantages of low investment and full use of the surrounding rock's own strength to improve the support effect.

[0063] In addition, the pea gravel layer filled between the primary lining and the surrounding rock can improve the drainage capacity of groundwater in the surrounding rock and coordinate the deformation and stress state of the surface surrounding rock.

Claims

1. A support structure for a deep engineering cavern with massive surrounding rock, comprising excavating a deep engineering cavern (1), characterized in that: The support structure also includes a three-dimensional reinforcement system and a drainage system. The three-dimensional reinforcement system is arranged on the surface of the deep excavation engineering cavern and in the adjacent blocky surrounding rock (2). The groundwater in the rock mass above the bottom plane of the deep excavation engineering cavern is discharged to the outside of the deep excavation engineering cavern (1) through the drainage system. During operation, the blocky surrounding rock (2) around the deep excavation engineering cavern (1) is kept stable by the three-dimensional reinforcement system.

2. The supporting structure for deep engineering blocky surrounding rock cavern according to claim 1 is characterized by: The drainage system comprises drainage holes (3) and drainage ditches. The drainage holes (3) are drilled in the side wall rock mass and the arc-shaped top wall rock mass of the excavated deep engineering cavern along the circumferential direction. The drainage ditches are arranged on the bottom plane of the excavated deep engineering cavern. The water outlet ends of the drainage holes (3) are connected to the drainage ditches. The collected water in the excavated deep engineering cavern (1) is discharged to the outside of the excavated deep engineering cavern (1) through the drainage ditches.

3. The supporting structure for deep engineering blocky surrounding rock cavern according to claim 1 or 2, characterized in that: The three-dimensional reinforcement system comprises a radial reinforcement structure, a shaft-ring composite reinforcement structure and a surface consolidation reinforcement structure. The shaft-ring composite reinforcement structure is inserted into the block surrounding rock (2) of the side wall and the arc-shaped top wall of the excavated deep engineering cavern at intervals in the circumferential and axial directions through the radial reinforcement structure embedded in the shaft-ring composite reinforcement structure, and consolidation stress is applied to the block surrounding rock (2) in the radial, circumferential and axial directions; the outer end of the radial reinforcement structure is fixed on the wall surface of the excavated deep engineering cavern (1) through the surface consolidation reinforcement structure and the wall pressure is applied.

4. The supporting structure for deep engineering blocky surrounding rock cavern according to claim 3 is characterized in that: Installation holes are drilled in the blocky surrounding rocks (2) of the side walls and the arc-shaped top wall of the excavated deep engineering cavern, and the shaft-ring composite reinforcement structure is arranged in the blocky surrounding rocks (2) of the side walls and the arc-shaped top wall of the excavated deep engineering cavern through the installation holes in cooperation with the radial reinforcement structure.

5. The supporting structure for deep engineering blocky surrounding rock cavern according to claim 4 is characterized in that: The installation holes are anchor holes or anchor cable holes drilled in the blocky surrounding rock (2) of the side walls and arc-shaped top walls of the excavated deep engineering cavern, and the radial reinforcement structure is a prestressed anchor rod or prestressed anchor cable (4) arranged in the anchor hole or anchor cable hole.

6. The supporting structure for deep engineering blocky surrounding rock cavern according to claim 5 is characterized in that: The shaft-ring composite reinforcement structure is the corresponding expansion type concrete (5) filled in each anchor rod hole or anchor cable hole, and the corresponding prestressed anchor rod or prestressed anchor cable (4) is embedded in the expansion type concrete (5).

7. The supporting structure for deep engineering blocky surrounding rock cavern according to claim 6 is characterized by: The surface consolidation reinforcement structure comprises an anchor head (6), a consolidation nut (7), a prefabricated primary lining module (8) and a secondary lining cast-in-place layer (9). A connecting thread is provided at the free end of each prestressed anchor rod or prestressed anchor cable (4). The anchor head (6) is arranged on each prestressed anchor rod or prestressed anchor cable (4) respectively and in cooperation with the connecting thread through the consolidation nut (7). The prefabricated primary lining module (8) is padded between the anchor head (6) and the side wall and arc-shaped top wall corresponding to the excavated deep engineering cavern. The prefabricated primary lining module (8) is covered with a secondary lining cast-in-place layer (9).

8. The supporting structure for deep engineering blocky surrounding rock cavern according to claim 7 is characterized in that: The surface consolidation reinforcement structure also includes a gasket-type stress gauge (10) and a pea gravel filling layer (11), wherein the gasket-type stress gauge (10) is cushioned between the consolidation nut (7) and the anchor head (6), and the pea gravel filling layer (11) is coated on the blocky surrounding rock (2) of the side wall and the arc-shaped top wall of the excavated deep engineering cavern.

9. The construction method for the support structure for deep engineering blocky surrounding rock caverns according to claim 8, characterized in that: The construction method comprises the following steps in sequence: excavating deep engineering caverns in sections, drilling drainage holes and anchor holes or anchor cable holes, laying anchor rods or anchor cables, pouring expansive concrete, installing prefabricated primary lining modules and filling a pea gravel filling layer between the prefabricated primary lining modules and the surrounding rock free surface, applying prestress to the anchor rods or anchor cables and applying wall pressure consolidation through the anchor head in cooperation with the consolidation nut and the gasket-type stress gauge, and finally pouring a secondary cast-in-place layer. The above steps are repeated to carry out the construction of the next section of the deep engineering cavern until the construction of all the deep engineering caverns is completed.

10. The construction method according to claim 9, characterized in that: After drilling the drainage holes and anchor holes or anchor cable holes, the holes need to be cleaned first, and then the anchor rods or anchor cables are laid. During the laying of the anchor rods or anchor cables, they are fixed with simple brackets and then poured with expansive concrete. After the expansive concrete reaches the specified strength, the prefabricated primary lining module is installed. After the overall support is completed, the corresponding anchor rods or anchor cables with reduced stress are reinforced by consolidation nuts using gasket-type stress gauges.

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