A soft rock tunnel grouting reinforcement design method, a reinforcement system and a construction method thereof

Abstract

The present application relates to the field of civil engineering, in particular to a soft rock tunnel grouting reinforcement design method, a reinforcement system and a construction method thereof, wherein the anchor rod parameters are determined by determining the anchor rod reinforcement parameters in the local deformation abnormal area, calculating the anchor rod length L, calculating the anchor rod correction length L2' based on the deformation rate, and calculating the number of long anchor rods in the deformation section, the anchor rod parameters are determined, the initial support is applied after excavation, and the grouting pipe is set, then a plurality of monitoring points are set inside the initial support, grouting is carried out at the back cavity of the initial support, and the grouting effect is checked, finally, the anchor rod reinforcement is carried out in the local deformation abnormal area of the initial support, thereby solving the problems of large workload, long time consumption, construction period and cost control in the conventional grouting reinforcement treatment of large cavities and non-dense areas in the soft rock tunnel in the fracture clamping zone, and the anchor rod reinforcement solves the problem of poor treatment effect of the existing technical scheme on the initial support deformation abnormal area.

Description

Technical Field

[0001] This invention relates to the field of civil engineering, and in particular to a design method, reinforcement system and construction method for grouting reinforcement of soft rock tunnels. Background Technology

[0002] During the construction of soft rock tunnels in fractured and interlocking zones, the low strength and easy deformation of the rock mass often lead to voids and fractured surrounding rock areas behind the initial support, causing initial support failure. Due to the special nature of arch construction, problems such as voids behind the initial support are often concentrated in the tunnel arch area, posing significant safety hazards. Voiding of the initial support often results in encroachment and severe deformation of the steel frame. Replacing the arch and addressing the voids behind it is time-consuming and costly. After replacing the arch, construction disturbances can exacerbate the fracture of the surrounding rock, posing significant construction risks. Conventional grouting reinforcement for initial support failure requires drilling grouting holes, which takes a long time when the reinforcement area is large. When reinforcing large areas of fractured rock, the reinforcement effect on deep rock masses is poor. When dealing with abnormal local deformation of the initial support, it is often necessary to reinforce the surrounding rock outside the entire initial support, which requires a huge amount of work. Summary of the Invention

[0003] The purpose of this invention is to address the problems of conventional grouting reinforcement for soft rock tunnels with fractured clamping zones, which involves large workloads, long time consumption, and difficulties in controlling the construction period and costs, as well as the poor effectiveness of existing technologies in treating abnormal deformation zones of the initial support. This invention provides a design and construction method for compensating for deformation space and dynamically reinforcing soft rock tunnels.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A grouting reinforcement design method for soft rock tunnels, used for the design of anchor bolts in areas of abnormal deformation, is as follows:

[0006] Step 1: Calculate the length of the anchor bolts to be used, so that they can be directly selected during subsequent construction;

[0007] Step 2: Correct the length of L2 using the anchor bolt length correction factor Lm;

[0008] Step 3: Calculate the required number of anchor bolts to avoid using too many or too few anchor bolts on site;

[0009] This invention is a design method for grouting reinforcement of soft rock tunnels. By designing and calculating the length and number of anchor bolts, the required anchor bolt information based on the site conditions is obtained, which saves costs and speeds up the construction period.

[0010] As a preferred embodiment of the present invention, the formula for calculating the anchor length L in step one is:

[0011] L = L1 + L2 + L3

[0012] In the formula: L is the length of the anchor bolt, L1 is the length of the anchor bolt outside the rock mass, L2 is the thickness of the fractured rock mass, and L3 is the length of the anchoring section, where L2 is obtained through on-site measurement;

[0013] L1 = L 1i +L 1l +100mm

[0014] In the formula: L1i is the thickness of the pad, and L1l is the thickness of the nut;

[0015]

[0016] In the formula: d is the diameter of the anchor rod, σt is the tensile strength of the rod body, and τc is the bond strength.

[0017] The length of the anchor rod outside the rock mass is calculated by the thickness of the pad and the nut. Then, the length of the anchoring section of the anchor rod is determined by the diameter of the anchor rod, the tensile strength and the bond strength of the rod body. Finally, the length of the anchor rod is obtained by adding the length of the anchor rod outside the rock mass, the thickness of the fractured rock mass and the length of the anchoring section.

[0018] As a preferred embodiment of the present invention, the formula for calculating the corrected length L2' of the anchor rod in step two is as follows:

[0019] L'2=L m (ε θ L2

[0020] In the formula: Lm is the anchor length correction coefficient under the influence of deformation rate; εθ is the deformation amount (rate) of the surrounding rock; L2 is the length of the anchor in the fractured rock mass.

[0021] The corrected length L2' of the anchor is obtained by multiplying the anchor length correction coefficient under the influence of deformation rate, the deformation amount (rate) of the surrounding rock, and the length of the anchor in the fractured rock mass.

[0022] As a preferred embodiment of the present invention, the formula for calculating the number of anchor bolts in step three is as follows:

[0023]

[0024] In the formula: n is the number of anchor bolts, Fz is the anchor bolt quantity reduction coefficient based on construction factors, which is taken as 0.7, g is the deformation range correction coefficient under the influence of deformation rate, which is taken as 1.0 under slight deformation anomaly and 1.35 under moderate deformation anomaly, B is the width of the deformation zone, R is the grout diffusion radius, which is taken as 0.6m; a is the reference number of anchor bolts in the initial design, which is taken as 3.

[0025] The value obtained by multiplying the deformation range correction coefficient under the influence of deformation rate, the deformation amount (rate) of surrounding rock, and the width of the deformation zone, and then comparing it with the grout diffusion radius, is obtained by adding the value to the anchor bolt quantity reduction coefficient based on construction factors, and finally adding it to the reference number of anchor bolts in the initial design to obtain the anchor bolt quantity.

[0026] A grouting reinforcement system for soft rock tunnels is constructed based on the anchor bolt length and quantity determined by a soft rock tunnel grouting reinforcement design method. The method is as follows:

[0027] Step 1: After the initial support is completed, check for voids behind it. If voids are found behind the initial support, grouting is used to reinforce it.

[0028] Step 2: Monitor the deformation inside the tunnel for the grouting repair surface. If the local deformation rate is too high, use long anchor bolts to reinforce the abnormal deformation area.

[0029] This invention is a grouting reinforcement system for soft rock tunnels. When local deformation abnormalities still exist in the cavity area and fractured surrounding rock area behind the initial support after grouting, anchor bolts are used to reinforce them. This invention locally reinforces deep rock mass and effectively avoids the safety hazards caused by the initial support detachment due to the cavity behind the initial support.

[0030] A method for grouting reinforcement of soft rock tunnels, based on the aforementioned anchor bolt design and reinforcement system, involves tunnel construction. The construction method is as follows:

[0031] S1. After construction begins, primary support is first installed inside the tunnel to support the tunnel and facilitate construction.

[0032] S2. Arrange monitoring points for primary support;

[0033] S3. Grouting is performed on the holes and fractured surrounding rock areas behind the initial support to compensate for internal deformation space;

[0034] S4. After grouting, check the effect of grouting and check whether there are still voids;

[0035] S5. Reinforce the abnormal deformation zone of the initial support with anchor bolts to prevent excessive deformation.

[0036] This invention relates to a grouting reinforcement method for soft rock tunnels. Conventional grouting reinforcement of cavities behind the initial support involves complex construction processes and is ineffective in reinforcing deep, fractured rock masses. This invention addresses these issues by pre-drilling grouting holes for surface grouting to repair the surrounding rock, combined with local reinforcement of deep rock masses using long anchor bolts. This effectively avoids the safety hazards caused by initial support detachment due to cavities behind the initial support, reduces construction costs, accelerates construction progress, and significantly improves the treatment of localized abnormal deformation in the initial support. This invention's localized surrounding rock reinforcement method solves the problem of initial support detachment caused by cavities behind the initial support and fractured rock masses during soft rock tunnel construction in fractured zones. By pre-drilling grouting holes and localized reinforcement of deep rock masses, it greatly saves construction time and achieves significant benefits in reducing project costs and ensuring construction safety.

[0037] As a preferred embodiment of the present invention, in step S1, the primary support inside the tunnel is constructed by a steel mesh and a steel frame, and the steel frame is also equipped with a grouting pipe for grouting the cavity.

[0038] As a preferred embodiment of the present invention, the grouting pipes are located behind the arch of the steel frame and the spacing between the grouting pipes is 0.5 to 1.5 m. The spacing of 0.5 to 1.5 m is used because when there are many cavities or the surrounding rock is relatively broken, the spacing between the grouting pipes can be reduced. The grouting pipes are arranged in a quincunx pattern.

[0039] As a preferred embodiment of the present invention, in step S2, the monitoring points are set at the arch top, arch waist, arch foot and side wall of the initial support, so that the monitoring is more comprehensive and accurate.

[0040] As a preferred embodiment of the present invention, in steps S3 and S4, when grouting the cavities behind the initial support and the fractured surrounding rock area, it is important to note that the grouting sequence should be: first grout the side holes, then grout the arch hole. After grouting is completed, cotton yarn should be used to seal the grouting pipe opening to prevent grout from overflowing from the pipe. Subsequently, the ground-penetrating radar method is used to detect the cavities behind the initial support to check the grouting effect. If cavities still exist, grouting filling operations are carried out until the quality and safety requirements are met.

[0041] As a preferred embodiment of the present invention, in step S5, the anchor reinforcement requires that before anchor reinforcement, the drilling points in the deformation section be determined by measurement and layout, the angle of the drilling rig and the drill arm be adjusted, and drilling be started. During the drilling process, the drill rod is continuously extended (1m / section) until the drilling depth reaches the design depth. After the drilling reaches the design depth, the drill rod is withdrawn. During the withdrawal process, the drill rod is removed every 3m. The anchor hole depth should be 10cm greater than the design length of the anchor rod.

[0042] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0043] 1. This invention is a design method for grouting reinforcement of soft rock tunnels. By designing and calculating the length and number of anchor bolts, the required anchor bolt information based on the site conditions is obtained, which saves costs and speeds up the construction period.

[0044] 2. This invention is a grouting reinforcement system for soft rock tunnels. When localized abnormal deformation still exists in the cavity area and fractured surrounding rock area behind the initial support after grouting, anchor bolts are used for reinforcement. This invention locally reinforces deep rock mass, effectively avoiding the safety hazards caused by the initial support detachment due to the cavity behind the initial support.

[0045] 3. This invention relates to a grouting reinforcement construction method for soft rock tunnels. Conventional grouting reinforcement of cavities behind the initial support involves complex construction processes and is ineffective in reinforcing deep fractured rock masses. This invention addresses these issues by pre-reserving grouting holes for surface grouting and surrounding rock repair, combined with long anchor bolts for local reinforcement of deep rock masses. This effectively avoids the safety hazards caused by initial support detachment due to cavities behind the initial support, reduces construction costs, accelerates construction progress, and significantly improves the treatment of local abnormal deformation in the initial support. The local surrounding rock reinforcement method described in this invention solves the problem of initial support detachment caused by cavities behind the initial support and fractured rock mass areas during the construction of soft rock tunnels in fractured zones. By pre-reserving grouting holes and locally reinforcing deep rock masses, it greatly saves construction time and achieves good benefits in reducing project costs and ensuring construction safety. Attached Figure Description

[0046] Figure 1 This is a flowchart of the anchor bolt design method of the present invention;

[0047] Figure 2 This is a flowchart of the construction method of the present invention;

[0048] Figure 3 This is a schematic diagram of the cavity and fractured surrounding rock area behind the initial support of the present invention;

[0049] Figure 4 This is a schematic diagram of shallow grouting of steel pipes according to the present invention;

[0050] Figure 5 This is a schematic diagram of the self-advancing anchor bolt reinforcement for abnormal deformation zones according to the present invention;

[0051] Figure 6 This is a schematic diagram of the connection between the grouting pipe and the steel frame of the present invention;

[0052] Figure 7 This is a schematic diagram of the length of each section of the anchor bolt of the present invention;

[0053] Figure 8 This is a schematic diagram of the anchor bolt grouting of the present invention.

[0054] Icons: 1-Monitoring point; 2-Voids and fractured surrounding rock area behind initial support; 3-Grouting pipe; 4-Abnormal deformation area of ​​initial support; 5-Anchor bolt; 6-Steel frame; 7-Grouting hole. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings.

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0057] Example 1

[0058] A grouting reinforcement design method for soft rock tunnels, used for the design of anchor bolts 5 in areas of abnormal deformation, such as... Figure 2 As shown, the specific design method is as follows:

[0059] Step 1: Calculate the length L of anchor bolt 5. The length of anchor bolt 5 has been determined, as follows: Figure 7 As shown;

[0060] Step 2: Calculate the corrected length L2' of anchor bolt 5 based on the deformation rate;

[0061] Step 3: Calculate the number n of the long anchor bolts 5 in the deformation section.

[0062] The formula for calculating the length L of anchor bolt 5 in step one above is:

[0063] L = L1 + L2 + L3;

[0064] In the formula: L is the length of anchor bolt 5, L1 is the length of anchor bolt 5 outside the rock mass, L2 is the thickness of the fractured rock mass, and L3 is the length of the anchoring section;

[0065] L1 = L 1i +L 1l +100mm;

[0066] In the formula: L1i is the thickness of the pad, and L1l is the thickness of the nut;

[0067]

[0068] In the formula: d is the diameter of the anchor rod, σt is the tensile strength of the rod body, and τc is the bond strength.

[0069] The length of anchor rod 5 outside the rock mass is calculated by the thickness of the pad and the nut. Then, the length of the anchoring section of anchor rod 5 is determined by the diameter of anchor rod 5, the tensile strength and the bond strength of the rod body. Finally, the length of anchor rod 5 is obtained by adding the length of anchor rod 5 outside the rock mass, the thickness of the fractured rock mass and the length of the anchoring section.

[0070] The formula for calculating the corrected length L2' of anchor bolt 5 in step two above is as follows:

[0071] L'2=L m (ε θ L2;

[0072] In the formula: Lm is the length correction coefficient of anchor bolt 5 under the influence of deformation rate; εθ is the deformation amount (rate) of surrounding rock; L2 is the length of anchor bolt 5 in fractured rock mass.

[0073] The corrected length L2' of anchor 5 is obtained by multiplying the length correction coefficient of anchor 5 under the influence of deformation rate, the deformation amount (rate) of surrounding rock, and the length of anchor 5 in fractured rock mass.

[0074] The formula for calculating the number of anchor bolts 5 in step three above is as follows:

[0075]

[0076] In the formula: n is the number of anchor bolts 5, Fz is the reduction coefficient of the number of anchor bolts 5 based on construction factors, which is taken as 0.7, g is the deformation range correction coefficient under the influence of deformation rate, which is taken as 1.0 under slight deformation anomaly and 1.35 under moderate deformation anomaly, B is the width of the deformation section, R is the grout diffusion radius, which is taken as 0.6m; a is the reference number of anchor bolts 5 in the initial design, which is taken as 3.

[0077] The value obtained by multiplying the deformation range correction coefficient under the influence of deformation rate, the deformation amount (rate) of surrounding rock, and the width of the deformation zone, and then comparing it with the grout diffusion radius, is obtained by adding the value to the anchor bolt 5 quantity reduction coefficient based on construction factors, and finally adding it to the baseline quantity of anchor bolt 5 in the initial design to obtain the quantity of anchor bolt 5.

[0078] Example 2

[0079] A grouting reinforcement system for soft rock tunnels is configured based on the number and length of anchor bolts 5 obtained from the aforementioned soft rock tunnel grouting reinforcement design method. Figure 5 As shown, the steps are as follows:

[0080] Step 1: Inspect the voids and fractured surrounding rock area 2 behind the initial support. If voids are found, use grouting pipe 3 for grouting reinforcement.

[0081] Step 2: Monitor the deformation inside the tunnel for the grouting repair surface. If the local deformation rate is too high, use local long anchor bolts 5 to reinforce the abnormal deformation area.

[0082] Therefore, this invention is a grouting reinforcement system for soft rock tunnels. In practical engineering, the operation is as follows: taking a soft rock tunnel with abnormal deformation as an example, under slight deformation, the corrected length L2' of anchor bolt 5 based on the deformation rate is 5m, L1 is 170mm, L3 is 600mm, and the length L of anchor bolt 5 is 5.77m. For ease of on-site construction, the length of anchor bolt 5 is taken as 6m. Taking the initial support within a 0.8m range of an abnormal deformation section as an example, the number of long anchor bolts 5 is 3.8, rounded to 4. Through calculation and on-site testing, specifically, the length of anchor bolt 5 is 6m for slight large deformation and 8m for moderate large deformation. The number of long anchor bolts 5 arranged in the abnormal deformation area is no less than three.

[0083] Example 3

[0084] A method for grouting reinforcement of soft rock tunnels involves selecting anchor bolts 5 according to the aforementioned anchor bolt design method and then commencing tunnel construction. Figure 1 As shown, the construction method is as follows:

[0085] S1. After construction begins, primary support is first installed inside the tunnel to support the tunnel and facilitate construction.

[0086] S2. Arrange monitoring points 1 for the primary support;

[0087] S3. Grouting is performed on the holes behind the initial support and the fractured surrounding rock zone 2 to compensate for the internal deformation space;

[0088] S4. After grouting, check the effect of grouting and check whether there are still voids;

[0089] S5. Reinforce the abnormal deformation zone 4 of the initial support with anchor bolts 5 to prevent excessive deformation.

[0090] In step S1 above, the primary support inside the tunnel is constructed using a steel mesh and a steel frame 6. The steel frame 6 is also equipped with grouting pipes 3 for grouting the cavities. Figure 4 and Figure 6 As shown.

[0091] The aforementioned grouting pipe 3 is located behind the arch of the steel frame 6, and the spacing between the grouting pipes 3 is 0.5 to 1.5m. The 0.5 to 1.5m spacing is used because when there are many cavities or the surrounding rock is relatively broken, the spacing between the grouting pipes 3 can be reduced. The grouting pipes 3 are arranged in a quincunx pattern.

[0092] In step S2 above, monitoring point 1 is set at the arch crown, arch waist, arch foot, and sidewalls of the initial support, making the monitoring more comprehensive and accurate. Figure 3 As shown.

[0093] In steps S3 and S4 above, when grouting the cavities behind the initial support and the fractured surrounding rock zone 2, it is important to note the grouting sequence: grout the side holes first, then the arch hole. After grouting, the opening of the grouting pipe 3 should be sealed with cotton yarn to prevent grout from overflowing. Subsequently, the cavities behind the initial support are detected using ground-penetrating radar to verify the grouting effect. If cavities still exist, grouting filling operations are performed until the quality and safety requirements are met. Figure 5 As shown.

[0094] In step S5 above, when reinforcing anchor bolt 5, it is important to note that before reinforcing anchor bolt 5, the drilling points for grouting holes 7 in the abnormal deformation zone 4 of the initial support should be determined by measurement and layout. The angle of the drill arm of the drilling rig should be adjusted, and drilling should begin. During the drilling of grouting holes 7, drilling should be carried out continuously and the drill rod should be continuously extended so that the depth of grouting holes 7 reaches the design depth. After the grouting holes 7 are drilled to the design depth, the drill rod should be withdrawn. During the withdrawal process, the drill rod should be removed every 3m. The depth of the anchor bolt hole should be 10cm greater than the design length of anchor bolt 5.

[0095] The present invention relates to a construction method for compensating deformation space and dynamically reinforcing soft rock tunnels. The operational steps in the field are as follows: After tunnel excavation, a steel mesh and steel frame 6 are constructed inside the tunnel. The steel mesh and steel frame 6 are used to build the initial support. Before the initial support is shotcreted, grouting pipes 3 are embedded in the arch of the initial support. The grouting pipes 3 are connected to the steel frame 6 by welding. The spacing of the grouting pipes 3 is 0.5–1.5 m, arranged in a staggered pattern. The grouting pipes 3 are Φ42 mm steel pipes with a wall thickness of 3.5 mm, and a length of 0.5 m. The orifice pipes should be firmly embedded. After the initial support and grouting pipe 3 are installed, the initial support shotcrete construction begins. Monitoring points 1 are set up on the arch of the initial support, at the arch crown, arch waist, arch foot, and sidewalls. Ground-penetrating radar is then used to detect cavities behind the initial support. If a cavity is detected, grouting reinforcement is performed using grouting pipe 3. The grouting material is 1:1 cement slurry. After connecting grouting pipe 3 to the grouting machine, air is removed from the pipe, the grouting pressure is adjusted, and the grouting machine is started. Grouting should be performed at a distance from the sealed bottom edge. Grouting is carried out 5m away from the arch surface. During grouting, the side holes are grouted first, followed by the arch crown hole. The grouting pressure is generally 0.3–0.5 MPa, with a final pressure of 0.5 MPa. Pressure and flow rate changes are continuously monitored during grouting. As the pressure gradually increases and the flow rate gradually decreases, the grouting pressure is stabilized for 2 minutes after reaching the final pressure before the grouting is completed. Displacement at each monitoring point 1 needs to be monitored during grouting. If the deformation rate is too high, the grouting pressure needs to be adjusted appropriately. After grouting is completed, the grouting pipe 3 is sealed with cotton yarn to prevent grout from overflowing. After grouting is completed, ground-penetrating radar is used to detect cavities behind the initial support. To check the grouting effect, if voids still exist, grouting filling operations are carried out until the quality and safety requirements are met. After grouting repairs the surface voids, the deformation inside the hole is monitored. If the local deformation rate is too high, local long anchor rod reinforcement measures are required. The drilling points in the deformation section are determined by measurement and layout. The angle of the drill arm of the drilling rig is adjusted, and drilling begins. During the drilling process, the drill rod is continuously extended (1m / section) until the drilling depth reaches the design depth. When the drilling reaches the design depth, the drill rod is withdrawn. During the withdrawal process, the drill rod is removed every 3m. The anchor rod hole depth should be 10cm greater than the design length of the anchor rod 5.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for grouting reinforcement of soft rock tunnels, characterized in that, This includes the design of the length and number of reinforcing anchors (5) during construction, and the design method is as follows: S1. Calculate the length of the anchor rod (5) used for reinforcement; S2. The length of L2 is corrected by the length correction factor of the Lm anchor rod (5); S3. Calculate the required number of anchor bolts (5); In step S2, the anchor rod (5) is corrected to a certain length. The calculation formula is: In the formula: Lm is the anchor rod (5) length correction coefficient under the influence of deformation rate; L1 represents the deformation of the surrounding rock; L2 represents the length of the anchor bolt (5) in the fractured rock mass. The formula for calculating the number of anchor bolts (5) in step S3 is as follows: ； In the formula: n is the number of anchor rods (5), Fz is the reduction coefficient of the number of anchor rods (5) based on construction factors, which is taken as 0.7, g is the deformation range correction coefficient under the influence of deformation rate, which is taken as 1.0 under slight deformation abnormality and 1.35 under moderate deformation abnormality, B is the width of the deformation zone, R is the grout diffusion radius, which is taken as 0.6m; a is the reference number of anchor rods (5) in the initial design, which is taken as 3; This represents the deformation of the surrounding rock.

2. The grouting reinforcement design method for soft rock tunnels according to claim 1, characterized in that, The formula for calculating the length L of the anchor rod (5) in step S1 is as follows: In the formula: the length of the anchor rod (5) outside the rock body L 1. Thickness of fractured rock mass L 2. Anchorage section length L 3.

3. A grouting reinforcement system for soft rock tunnels, characterized in that, The reinforcement system includes a grouting reinforcement design method for soft rock tunnels as described in any one of claims 1-2, wherein the reinforcement system setup steps are as follows: S51. Inspect the cavities and fractured surrounding rock area (2) behind the initial support. If cavities are found, use grouting pipe (3) for grouting reinforcement. S52. Monitor the deformation inside the tunnel for the grouting repair surface. If the local deformation rate is too high, use local anchor bolts (5) to reinforce the abnormal deformation area.

4. A method for grouting reinforcement of soft rock tunnels, characterized in that, The soft rock tunnel grouting reinforcement system according to claim 3, wherein the construction method is as follows: S61. Construction work carried out inside the tunnel after excavation; S62. Arrangement of monitoring points (1) for the initial support of the tunnel inner wall; S63. Grouting treatment shall be carried out on the holes behind the initial support and the fractured surrounding rock area (2) inside the tunnel; S64. Inspect the grouting effect; S65. Locally reinforce the abnormal deformation zone (4) of the initial support with anchor bolts (5).

5. The method for grouting reinforcement of soft rock tunnels according to claim 4, characterized in that, In step S61, a steel mesh and a steel frame (6) are built inside the tunnel. The steel mesh and the steel frame (6) constitute the initial support. The steel frame (6) is equipped with a grouting pipe (3).

6. According to claim 5, the grouting reinforcement construction method for soft rock tunnels, the grouting pipe (3) is set behind the arch of the steel frame (6), and the grouting pipe (3) is spaced 0.5~1.5m apart and arranged in a quincunx pattern.

7. According to claim 4, the monitoring point (1) in step S62 is arranged at the arch crown, arch waist, arch foot and sidewall of the initial support.

8. According to the soft rock tunnel grouting reinforcement construction method of claim 4, in step S65, local anchor rod (5) reinforcement is carried out. Before the anchor rod (5) reinforcement is carried out, the drilling point of the grouting hole (7) in the deformation section needs to be determined by measurement and layout. During the drilling process, the drill rod is continuously extended so that the depth of the grouting hole (7) reaches the design depth. When the grouting hole (7) is drilled to the design depth, the drill rod is withdrawn. During the withdrawal process, the drill rod is removed every 3m. The depth of the anchor rod hole should be 10cm greater than the design length of the anchor rod (5).

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