Advanced bolting and grouting reinforcement method for broken zone of surrounding rock of reconstruction and extension tunnel

Abstract

The invention discloses a reorganization and extension tunnel surrounding rock fracture zone advanced bolting and grouting reinforcement method which comprises the following steps: S1, carrying out geological detection on a tunnel surrounding rock body, and determining the distribution condition of a surrounding rock fracture zone; s2, the non-expanded excavation surrounding rock body is reinforced, and the reinforcing range reaches the edge of a surrounding rock fracture zone; and S3, when the tunnel is excavated in an expanded mode to be close to the surrounding rock fracture zone, holes are obliquely drilled in front of the tunnel face to serve as pre-stressed anchor rods, and the pre-stressed anchor rods penetrate through the surrounding rock fracture zone. According to the method, the time-space advantage of the existing tunnel is fully utilized, the key position needing to be pre-reinforced is accurately positioned before tunnel reconstruction and extension construction, advanced grouting filling is conducted on the surrounding rock fracture zone, the overall strength of the surrounding rock is remarkably improved, the stress release and deformation risks caused by the fracture zone in the construction process are reduced, and the construction efficiency is improved. Reconstruction and extension construction efficiency is improved, and good application prospects and economic benefits are achieved. The method can be suitable for tunnel reconstruction and extension projects under various complex geological conditions.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering, and in particular to a method for reinforcing a surrounding rock fracture zone of a tunnel during reconstruction and expansion. Background Art

[0002] During the construction of mountain tunnels, a typical problem is often encountered: crossing the surrounding rock fracture zone. There are a large number of fractures and fragments in the rock mass, which seriously damage the overall stability of the surrounding rock, increase safety risks, and even affect construction efficiency and quality, resulting in losses of manpower and material resources.

[0003] Existing tunnel projects usually roughly judge surrounding rock conditions and determine construction plans based on early geological survey reports combined with engineering analogies. The surrounding rock of the expanded tunnel has been subjected to multiple disturbances, the degree of rock fragmentation has increased, and damage has accumulated. During the construction process of expanding a small-section tunnel into a large-section tunnel, large deformation of the surrounding rock or even collapse accidents are prone to occur. The current advanced detection and grouting compensation need to be advanced with the face, and the positioning and control range of the surrounding rock fracture zone is limited, which seriously reduces the construction progress and is difficult to implement during the construction process.

[0004] Therefore, it is urgent to provide a method for pre-anchoring reinforcement of the broken zone of the surrounding rock of the expanded tunnel to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a method for pre-anchoring reinforcement of the broken zone of the surrounding rock of a tunnel for reconstruction and expansion, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides a method for reinforcing the surrounding rock fracture zone of a tunnel in advance, comprising the following steps:

[0007] S1. Conduct geological survey of the tunnel surrounding rock mass to determine the distribution of surrounding rock fracture zones;

[0008] S2. Reinforce the surrounding rock mass that has not been excavated, and the reinforcement range shall be up to the edge of the surrounding rock fracture zone;

[0009] S3. When the tunnel is expanded to the vicinity of the surrounding rock fracture zone, prestressed anchor rods are installed by oblique drilling in front of the heading face, and the prestressed anchor rods penetrate the surrounding rock fracture zone.

[0010] Preferably, the reinforcement of the unexpanded surrounding rock mass includes:

[0011] Drill grouting holes in the lining and unexpanded surrounding rock mass, and inject the first gradient grout;

[0012] And, after the surrounding rock mass is stabilized, the grouting holes are deepened to the edge of the surrounding rock fracture zone, and the second gradient slurry injection is carried out.

[0013] Preferably, the geological exploration adopts a combination of geological survey method, TSP seismic wave method and geological radar method.

[0014] Preferably, the grouting holes are distributed along the contour line of the existing tunnel, the longitudinal spacing of the grouting holes is 100 cm×100 cm, and the drilling angle of the grouting holes is 0-90°.

[0015] Preferably, the first gradient slurry is a cement-based slurry, which is composed of ordinary Portland cement, aggregate, accelerator and fly ash.

[0016] Preferably, the second gradient slurry is a thixotropic polyurethane slurry, and the thixotropic polyurethane slurry is formed by mixing component A and component B in a volume ratio of 1:1;

[0017] The A component includes 90-130 parts of water glass and 6-12 parts of catalyst;

[0018] The B component includes 90-130 parts of isocyanate substances, 16-32 parts of amino-terminated resins, 8-10 parts of thixotropic agents, and 8-10 parts of dissolution promoters.

[0019] Preferably, the water glass comprises sodium silicate solution and potassium silicate solution, and the volume ratio of the sodium silicate solution to the potassium silicate solution is 4:1; the isocyanate substance is diphenylmethane diisocyanate; the amino-terminated resin is polyaspartic acid ester; the thixotropic agent is fumed silica; and the dissolution promoter comprises one or two of ethylene glycol diacetate and tributyl citrate.

[0020] Preferably, when injecting the second gradient slurry, a dual-liquid grouting pump is used for grouting.

[0021] Preferably, the prestressed anchor rods are arranged along the contour line at an angle of 10° upward, and the longitudinal spacing of the rings of the prestressed anchor rods is 600 cm×150 cm.

[0022] Preferably, the anchoring end of the prestressed anchor rod adopts a resin roll as an anchoring agent, and cement mortar is injected into the gap between the prestressed anchor rod and the wall of the drill hole.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects:

[0024] 1. The method for pre-anchoring reinforcement of the broken zone of the surrounding rock of the expanded and rebuilt tunnel provided by the present invention makes full use of the temporal and spatial advantages of the existing tunnel, accurately locates the key positions that need pre-reinforcement before the construction of the expanded and rebuilt tunnel, and performs pre-grouting filling of the broken zone of the surrounding rock, which significantly improves the overall strength of the surrounding rock, reduces the stress release and deformation risks caused by the broken zone during the construction process, promotes the efficiency of the expanded and rebuilt construction, and has good application prospects and economic benefits; the method can be applied to tunnel expansion projects under various complex geological conditions.

[0025] 2. Through the advance anchoring reinforcement of the surrounding rock fracture zone, the secondary filling and reinforcement of the surrounding rock fracture zone is carried out to repair the large and small cracks and fractures inside the surrounding rock mass, improve the overall bearing capacity of the surrounding rock, and effectively avoid the tunnel collapse and large deformation caused by crossing poor geology.

[0026] 3. The comprehensive forecasting system has various types and complementary advantages. It can realize all-round detection under different geological conditions, accurately determine the specific location of the broken area, and lay a good foundation for subsequent pre-reinforcement measures.

[0027] 4. Prestressed anchor rods, with their good surrounding rock deformation constraint and seismic resistance, fully play their supporting and reinforcing role during tunnel blasting excavation, making up for the shortcoming that traditional mechanical expansion shell prestressed anchor rods are not suitable for use in soft and broken rock masses.

[0028] 5. The double gradient grouting technology and prestressed anchor rods are used to coordinate support, forming a whole with the surrounding rock fracture zone, absorbing the energy released from the rock mass in the surrounding rock fracture zone, reducing deformation during tunnel expansion, and ensuring the stability of the tunnel structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is the construction flow chart of the present invention;

[0031] Figure 2 This is a front view of the advanced anchoring of the present invention;

[0032] Figure 3 It is a side view of the first gradient slurry of the present invention when being injected;

[0033] Figure 4 A side view of the second gradient slurry of the present invention when injected;

[0034] Figure 5 It is a side view of the prestressed anchor support of the present invention;

[0035] In the figure: 1. Broken zone of surrounding rock; 2. Existing tunnel; 3. Cement-based grout; 4. Thixotropic polyurethane grout; 5. Resin prestressed anchor rod. DETAILED DESCRIPTION

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0037] like Figures 1 to 5 As shown, the present invention provides a method for pre-anchoring reinforcement of a broken zone of surrounding rock of a tunnel for reconstruction and expansion, comprising the following steps:

[0038] S1. Conduct geological survey on the tunnel surrounding rock mass to determine the distribution of surrounding rock fracture zone 1;

[0039] The geological survey adopts a joint prediction method. The geological survey collects engineering geological data to preliminarily determine the distribution of the surrounding rock, and predicts the unfavorable broken area ahead based on the existing geological conditions; TSP uses the reflection wave characteristics of seismic waves generated in uneven geological bodies to predict the geological conditions in front of the tunnel face and the surrounding adjacent areas. The effective prediction distance is 100 to 150 meters, with high accuracy, and is suitable for geological prediction of soft formations; geological radar emits electromagnetic waves, and the electromagnetic waves that encounter the reflection interface are received for data processing. The effective prediction distance is 10 to 20 meters, the process is simple, and it is easy to operate. The three can corroborate each other, optimize and correct each other, and accurately predict the broken zone in front of the tunnel face, thereby determining the specific distribution situation;

[0040] S2. Reinforce the surrounding rock mass that has not been excavated, and the reinforcement range is to the edge of the surrounding rock fracture zone 1;

[0041] S3. When the tunnel is expanded to the vicinity of the surrounding rock fracture zone 1, prestressed anchor rods are installed by oblique drilling in front of the heading face, and the prestressed anchor rods penetrate the surrounding rock fracture zone 1.

[0042] The present invention performs advance grouting and anchoring in the unexcavated area of ​​the tunnel, and performs grouting in stages to effectively fill different types of crack blocks inside the surrounding rock, thereby forming two reinforced areas with different strengths and structures. The present invention can be used in areas with changeable geological conditions and relatively broken surrounding rocks.

[0043] Further optimize the plan and reinforce the surrounding rock mass that has not been excavated, including:

[0044] Drill grouting holes in the lining and unexpanded surrounding rock mass, and inject the first gradient grout;

[0045] The drilling rig drilled a hole from the existing tunnel 2 internal lining into the unexcavated rock mass. The initial drilling depth reached half of the range of the broken area. After drilling, the rock debris and other impurities in the hole were cleaned to ensure the free flow of slurry. Before the formal grouting, the grouting pressure was adjusted to avoid causing a large disturbance to the broken area. The first gradient slurry was pumped into the hole with the help of a grouting pump and diffused and solidified in the cracks. The pressure and flow were monitored throughout the grouting process, and adjustments and optimizations were made at any time.

[0046] And, after the surrounding rock mass is stabilized, the grouting hole is deepened to the edge of the surrounding rock fracture zone 1, and the second gradient slurry is injected.

[0047] After the first gradient grouting is completed, the surrounding rock tends to be stable, and the drilling is deepened on the basis of the original hole until it penetrates the broken area; during the grouting process, the grouting pressure is monitored and attention is paid to exhaust so that the slurry fills the gaps between the surrounding rocks to avoid the formation of bubbles in the hole.

[0048] The present invention uses double gradient grouting to pre-reinforce the broken rock mass in stages before tunnel expansion construction. The slurry penetrates into the cracks and solidifies to play a connecting role, thereby improving the overall bearing capacity of the surrounding rock, shortening the construction period, ensuring construction safety and quality requirements, and achieving economic and efficient engineering construction.

[0049] To further optimize the plan, geological exploration adopts a combination of geological survey method, TSP seismic wave method and geological radar method.

[0050] The present invention uses a comprehensive interpretation of "geological survey method + TSP seismic wave method + geological radar method" along the existing tunnel 2, improves the singleness and limitations of traditional forecasting methods, and combines interpretation to accurately identify the surrounding rock fracture zone 1 area and determine its specific location and scope, thereby achieving high precision and high efficiency in advanced forecasting.

[0051] To further optimize the plan, the grouting holes are distributed along the contour line of the existing tunnel 2, the longitudinal spacing of the grouting holes is 100cm×100cm, and the drilling angle of the grouting holes is 0-90°.

[0052] According to a further optimization scheme, the first gradient slurry is a cement-based slurry 3, which is composed of ordinary Portland cement, aggregate, accelerator and fly ash.

[0053] According to a further optimized solution, the second gradient slurry is a thixotropic polyurethane slurry 4, and the thixotropic polyurethane slurry 4 is formed by mixing component A and component B in a volume ratio of 1:1;

[0054] Component A includes 90-130 parts of water glass and 6-12 parts of catalyst;

[0055] Component B includes 90-130 parts of isocyanate substances, 16-32 parts of amino-terminated resins, 8-10 parts of thixotropic agents, and 8-10 parts of dissolution promoters.

[0056] During grouting, the viscosity of the polyurethane material decreases and it becomes fluid, with good injectability. After grouting, the viscosity of the material increases, and it quickly solidifies and hardens, preventing the slurry from flowing back.

[0057] According to a further optimization scheme, water glass includes sodium silicate solution and potassium silicate solution, and the volume ratio of the sodium silicate solution to the potassium silicate solution is 4:1; the isocyanate substance is diphenylmethane diisocyanate; the terminal amino resin is polyaspartic acid ester; the thixotropic agent is fumed silica; and the dissolution agent includes one or two of ethylene glycol diacetate and tributyl citrate.

[0058] To further optimize the plan, a dual-liquid grouting pump is used for grouting when injecting the second gradient slurry.

[0059] To further optimize the solution, the prestressed anchor rods were arranged along the contour line with an upward inclination of 10°, and the longitudinal spacing of the prestressed anchor rod rings was 600cm×150cm.

[0060] The expansion tunnel was excavated in steps according to the construction requirements. When excavating to the vicinity of the fracture zone, prestressed anchor rods were laid along the contour line at an angle of 10° upward in front of the excavation face.

[0061] To further optimize the solution, the prestressed anchor rod adopts a resin prestressed anchor rod 5, the anchoring end of the prestressed anchor rod adopts a resin roll as an anchoring agent, and cement mortar is injected into the gap between the prestressed anchor rod and the wall of the drill hole.

[0062] The prestressed anchor rod is inserted into the bottom of the hole by rotating at a uniform speed. After the anchoring agent takes effect, the anchoring section is tightly bonded to the hole wall. Cement mortar is injected to fill the gap between the anchor rod and the hole wall. Then, a tensioner is used to apply prestress to the anchor rod, and a force sensor is installed to measure the prestress. When the prestress is stretched to the designed prestress, a pad is installed to transfer the prestress to prevent the rock at the anchoring position from breaking. Finally, a nut is used to lock the anchor rod position to maintain the prestressed state.

[0063] The method for pre-anchoring reinforcement of the broken zone of the surrounding rock of the expanded tunnel provided by the present invention makes full use of the temporal and spatial advantages of the existing tunnel 2, accurately locates the key positions that need to be pre-reinforced before the construction of the expanded tunnel, and effectively fills the different types of crack blocks inside the surrounding rock by pre-grouting and anchoring the unexcavated area of ​​the tunnel, forming two reinforcement areas with different strengths and structures, significantly improving the overall strength of the surrounding rock, reducing the stress release and deformation risks caused by the broken zone during the construction process, promoting the efficiency of the expanded construction, having good application prospects and economic benefits, and can be used in areas with variable geological conditions and relatively broken surrounding rocks. The resin prestressed anchor rod 5 used is more effective than the traditional anchoring support in the cracked and loose surrounding rock, and its seismic performance is also applicable in the blasting construction of the expanded tunnel. The method can be applied to tunnel expansion projects under various complex geological conditions. As an important measure to stabilize rocks and constrain deformation in underground space, anchoring technology has also ushered in a new situation of steady innovation.

[0064] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for reinforcing the surrounding rock fracture zone of a tunnel for reconstruction and expansion, characterized in that: The following steps are involved: S1. Conduct geological survey of the tunnel surrounding rock mass to determine the distribution of the surrounding rock fracture zone (1); S2. Reinforce the surrounding rock mass that has not been excavated, with the reinforcement range extending to the edge of the surrounding rock fracture zone (1); S3. When the tunnel is expanded to a location close to the surrounding rock fracture zone (1), prestressed anchor rods are installed by obliquely drilling holes in front of the face of the tunnel. The prestressed anchor rods penetrate the surrounding rock fracture zone (1).

2. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 1 is characterized in that: The reinforcement of the surrounding rock mass that has not been excavated includes: Drill grouting holes in the lining and unexpanded surrounding rock mass, and inject the first gradient grout; And, after the surrounding rock mass is stabilized, the grouting hole is deepened to the edge of the surrounding rock fracture zone (1), and a second gradient slurry injection is performed.

3. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 1 is characterized in that: The geological exploration adopts the combined exploration of geological survey method, TSP seismic wave method and geological radar method.

4. The method for reinforcing the broken zone of surrounding rock of a tunnel in advance according to claim 2 is characterized in that: The grouting holes are distributed along the contour line of the existing tunnel (2), the longitudinal spacing of the grouting holes is 100 cm×100 cm, and the drilling angle of the grouting holes is 0-90°.

5. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 2 is characterized in that: The first gradient slurry is a cement-based slurry (3), and the cement-based slurry (3) is composed of ordinary Portland cement, aggregate, accelerator and fly ash.

6. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 2 is characterized in that: The second gradient slurry is a thixotropic polyurethane slurry (4), and the thixotropic polyurethane slurry (4) is formed by mixing component A and component B in a volume ratio of 1:1; The A component includes 90-130 parts of water glass and 6-12 parts of catalyst; The B component includes 90-130 parts of isocyanate substances, 16-32 parts of amino-terminated resins, 8-10 parts of thixotropic agents, and 8-10 parts of dissolution promoters.

7. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 6 is characterized in that: The water glass comprises sodium silicate solution and potassium silicate solution, and the volume ratio of the sodium silicate solution to the potassium silicate solution is 4:1; the isocyanate substance is diphenylmethane diisocyanate; the amino-terminated resin is polyaspartic acid ester; the thixotropic agent is fumed silica; the dissolution promoter comprises one or two of ethylene glycol diacetate and tributyl citrate.

8. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 2 is characterized in that: When injecting the second gradient slurry, a double-liquid grouting pump is used for grouting.

9. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 1 is characterized in that: The prestressed anchor rods are arranged along the contour line with an upward inclination of 10°, and the longitudinal spacing of the rings of the prestressed anchor rods is 600 cm×150 cm.

10. The method for reinforcing the surrounding rock fracture zone of a tunnel according to claim 1, characterized in that: The anchoring end of the prestressed anchor rod adopts a resin roll as an anchoring agent, and cement mortar is injected into the gap between the prestressed anchor rod and the wall of the drill hole.

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