Method for transferring tangential concentrated stress of excavation tunnel face and tunnel wall to deep surrounding rock
By designing cut joints along the direction of the minimum main stress on the palm surface and the tunnel wall, the tangential stress concentration of the surrounding rock during tunnel excavation is transferred to the deep, and the problems of plate crack failure and rock burst caused by stress concentration in tunnel construction under high ground stress environment are solved, and construction safety and efficiency are improved.
Patent Information
- Application Number
- CN202510433355.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-08
- Publication Date
- 2025-06-17
AI Technical Summary
Under high ground stress environments, slab crack damage and rock burst power disasters are prone to occur during tunnel excavation, resulting in reduced construction efficiency, equipment damage and casualties. The existing technology is difficult to effectively reduce the concentration level of tangential stress in surrounding rocks.
By designing the cut joints along the direction of the minimum main stress on the palm surface and hole wall of the tunnel, the tangential concentration stress of the excavated palm surface and hole wall is transferred to the deep surrounding rock to reduce the stress concentration level. The position, width and depth of the cut joints are comprehensively determined based on the rock mass condition and the maximum principal stress level, and are continuously monitored and optimized during the construction process.
It effectively reduces the stress concentration level of the surrounding rocks on the palm surface and the tunnel wall after tunnel excavation, reduces the risks of large deformation of high-stress surrounding rocks, plate crack damage and rock burst power disasters, and improves the safety and efficiency of tunnel construction.
Smart Images
Figure CN120159451A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of tunnel construction, and particularly relates to a method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock. Background Art
[0002] When tunneling (in a tunnel) in a relatively intact rock mass under a high in-situ stress environment, unloading occurs in the direction perpendicular to the excavation face at the excavation face, and stress concentration occurs in the direction parallel to the excavation face. Under the conditions of radial unloading and tangential stress concentration on the tunnel wall, slab cracking failure and rockburst dynamic disasters will occur, significantly reducing the construction efficiency. In severe cases, it will lead to equipment damage and casualties. How to reduce the stress concentration level is the key to reducing the levels of high-stress slab cracking failure and rockburst dynamic disasters. Existing engineering measures such as spraying water on the excavation face and the tunnel wall to reduce the modulus of the surrounding rock, and advanced drilling for pressure relief in front of the excavation face have insignificant effects; while methods such as advanced pre-splitting blasting and hydraulic fracturing are limited in application because of the large operation difficulty and large damage to the surrounding rock, which increase the subsequent support workload. Therefore, in order to reduce high-stress slab cracking failure and rockburst dynamic disasters, it is necessary to study a method for reducing the tangential stress concentration level of the surrounding rock with significant effects, convenient construction, and small disturbance to the surrounding rock, so as to ensure the safe and efficient tunneling of the tunnel (in a tunnel) under high-stress conditions.
[0003] In addition, under high-stress conditions, large deformations of soft rock and time-dependent rheology of hard rock will both cause the surrounding rock to converge and encroach on the limit. By reducing the stress concentration level around the tunnel, the large deformation of the high-stress surrounding rock can be reduced to a certain extent, and the risk of arch replacement and excavation due to large deformation encroaching on the limit can be reduced. Summary of the Invention
[0004] The object of the present invention is to provide a method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock in view of the problems existing in the prior art, so as to successfully cope with the risks of large deformation of high-stress surrounding rock, surrounding rock slab cracking failure and rockburst dynamic disasters, and solve the problem of safe and efficient tunneling of the tunnel (in a tunnel) under high-stress conditions.
[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock, the method comprising the following steps: Determine the principal stress direction of the cross-sectional plane perpendicular to the tunnel, and the principal stress direction of the cross-sectional plane includes the maximum principal stress direction and the minimum principal stress direction; Cut slots in the surrounding rock of the excavation face and the tunnel wall along the minimum principal stress direction; The position, width and depth of the slots are comprehensively determined according to the rock mass conditions of the tunnel, the maximum principal stress level, the tunnel diameter of the tunnel excavation and the slotting equipment capabilities; Continuously observe the convergence and deformation of the surrounding rock after cutting the slots, monitor the characteristics of the surrounding rock rupture and rockburst, and evaluate the effect of the slots in transferring the concentrated stress to the deep surrounding rock and reducing the stress concentration level of the surrounding rock around the tunnel excavation face; If the effect of reducing the stress concentration level of the surrounding rock around the excavation face is not obvious, re-design the direction, position, width, and depth of the slots to optimize the slotting scheme; If the width of the slot is too wide and it fails to close in the later stage, fill the slot with cement slurry.
[0006] The method of transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock can effectively transfer the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock by specifically designing a simple slotting method, reduce the tangential stress concentration level of the excavation face and the tunnel wall, is convenient for construction, has little disturbance to the surrounding rock, and effectively combines reducing the stress concentration degree of the surrounding rock and maintaining the integrity and stability of the surrounding rock.
[0007] Furthermore, if rock mass structural planes develop in the surrounding rock at the upper part of the excavation face and above the arch waist of the tunnel wall, the slot should avoid intersecting with the rock mass structural plane at the upper part.
[0008] Furthermore, the position of the slot is set at the center and the lower part of the excavation face, and below the arch waist of the tunnel wall.
[0009] Furthermore, the width of the slot ranges from a few millimeters to a few centimeters. The higher the maximum principal stress level, the wider the required slot.
[0010] Furthermore, the slot is a wide slot with a width of more than one centimeter, or the slot is a plurality of parallel narrow cracks arranged.
[0011] Furthermore, let the depth of the slot be H, and the tunnel diameter or equivalent tunnel diameter be D. The relationship between H and D is as follows: When preventing medium rockburst, H ≥ D / 20; When preventing strong rockburst, H ≥ 2D / 20; When preventing extremely strong rockburst: H ≥ 3D / 20; When preventing damage and collapse of the surrounding rock of the high-stress tunnel wall, H ≥ 0.5m.
[0012] Furthermore, for the slots on the excavation face, there is an overlap length h between two consecutive slots. In the tunnel section where rockburst frequently occurs on the excavation face, h ≥ 0.3m.
[0013] Furthermore, the slots on the tunnel wall advance forward with the excavation of the tunnel. In the tunnel section where rockburst frequently occurs, the front end of the slots on the tunnel wall closely follows the excavation face.
[0014] Furthermore, in the evaluation step, the objects of evaluation and comparison are the surrounding rock convergence deformation before slitting, and the monitoring of surrounding rock fracture and rockburst characteristics; if the slitting operation is performed continuously, it is also necessary to evaluate whether the slitting has achieved a treatment effect acceptable to the project.
[0015] Furthermore, when optimizing the slit plan, the stress direction of the cross-sectional plane is re-evaluated, the direction and position of the slit are adjusted, the width and depth of the slit are adjusted according to the closing condition after the slit, and the depth of the slit is adjusted according to the fracture and deformation of the surrounding rock of the cave wall after the slit.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The method of transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock can effectively realize the transfer of the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock through a targeted design of a simple cutting method, thereby reducing the tangential stress concentration level of the face and the tunnel wall. The construction is convenient, the disturbance to the surrounding rock is small, and the reduction of the degree of stress concentration of the surrounding rock and the maintenance of the integrity and stability of the surrounding rock are effectively combined; 2. By pre-cutting the surrounding rock of the face and the tunnel wall, the concentrated stress is transferred to the deep surrounding rock, and the stress concentration level of the face and the tunnel wall surrounding rock after excavation is reduced, thereby reducing the risk of large deformation of high-stress surrounding rock, surrounding rock slab cracking and damage, and rock burst dynamic disasters, and reducing The purpose of improving the safety and efficiency of tunnel (tunnel) construction is to reduce the local collapse of the face and tunnel wall surrounding rock caused by the expansion and penetration of high-stress cracks due to light high stress, so as to improve the safety and efficiency of tunnel (tunnel) construction; 3. In this method, the slit construction can be organically combined with tunneling, such as mounting the slit equipment on the TBM or rock drilling rig to achieve seamless connection between the slit cutting and tunneling excavation processes, and even the tunnel wall slit cutting operation can be carried out while the TBM is tunneling, so as to achieve safe and efficient construction; 4. Slit cutting along the direction of minimum principal stress, that is, the slit cutting is perpendicular to the direction of maximum principal stress in the cross-sectional plane, which can relieve the concentrated stress from the face surface / tunnel wall surface to the bottom of the crack, and transfer the concentrated stress to the deep surrounding rock at a certain distance from the face and tunnel wall at the bottom of the crack. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 A schematic diagram of cutting slits in a tunnel wall and arranging sensors in a method of transferring tangential concentrated stress of an excavation face and a tunnel wall to deep surrounding rock according to the present invention; Figure 2 for Figure 1 Schematic diagram of the middle AA section; Figure 3 It is a schematic cross-sectional view of cutting a seam at a tunnel face in the method of the present invention; Figure 4 for Figure 3 Schematic diagram of the cut in the middle palm face; In the figure: 1. Cutting seam; 2. Palm face; 3. Tunnel wall. Detailed implementation manners
[0018] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative work fall within the protection scope of the present invention.
[0019] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0020] A method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock, in combination with Figures 1 to 4 As shown, the method includes the following steps: Step 1: Determine the direction of the principal stress in the cross-sectional plane perpendicular to the tunnel, and the direction of the principal stress in the cross-sectional plane includes the direction of the maximum principal stress and the direction of the minimum principal stress; Step 2: Cut slots 1 in the surrounding rock of the excavation face 2 and the tunnel wall 3 along the direction of the minimum principal stress; Step 3: The position, width, and depth of the cut slot 1 are comprehensively determined according to the rock mass conditions of the tunnel, the maximum principal stress level, the diameter of the tunnel excavation, and the cutting slot equipment capabilities, etc.; Step 4: Continuously observe the convergence deformation of the surrounding rock, monitor the rupture and rock burst characteristics of the surrounding rock after cutting the slot, and evaluate the effect of transferring the concentrated stress to the deep surrounding rock by the cut slot 1 and reducing the stress concentration level of the surrounding rock around the tunnel excavation; Step 5: If the effect of reducing the stress concentration level of the surrounding rock around the tunnel is not obvious, re-design the direction, position, width, and depth of the cut slot, and optimize the cut slot scheme; Step 6: If the width of the cut slot 1 is too wide and it does not close in the later stage, fill the cut slot 1 with cement slurry.
[0021] The method of transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock can effectively transfer the tangential concentrated stress of the excavation face 2 and the tunnel wall 3 to the deep surrounding rock by specifically designing a simple slotting method, reduce the tangential stress concentration level of the excavation face 2 and the tunnel wall 3, is convenient for construction, has little disturbance to the surrounding rock, and effectively combines reducing the stress concentration degree of the surrounding rock with maintaining the integrity and stability of the surrounding rock.
[0022] In this method, the slotting construction can be organically combined with tunneling. For example, the slotting equipment can be mounted on a TBM or a jumbo to achieve seamless connection between the slotting and tunneling excavation processes. Even while the TBM is tunneling, the slotting operation on the tunnel wall can be carried out to achieve safe and efficient construction.
[0023] The method of transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock pre-cuts the surrounding rock of the excavation face and the tunnel wall, transfers the concentrated stress to the deep surrounding rock, and reduces the stress concentration level of the surrounding rock of the excavation face and the tunnel wall after excavation, so as to achieve the purpose of reducing the large deformation of high-stress surrounding rock, the slab cracking failure of the surrounding rock, and the risk of rockburst dynamic disasters, alleviating the local collapse formed by the extension and penetration of high-stress cracks in the surrounding rock of the excavation face and the tunnel wall caused by high stress, and improving the construction safety and construction efficiency of the tunnel (cavity).
[0024] In the said step 1, the directions of the principal stresses (the maximum principal stress σ1 and the minimum principal stress σ2) perpendicular to the cross-sectional plane of the tunnel are inferred and determined through in-situ stress testing, in-situ stress inversion, or observation of the fracture characteristics of the surrounding rock of the tunnel wall.
[0025] In the said step 2, slotting along the direction of the minimum principal stress, that is, the slotting is perpendicular to the direction of the maximum principal stress in the cross-sectional plane, can unload the concentrated stress from the surface of the excavation face / tunnel wall to the bottom of the crack, and transfer the concentrated stress to the deep surrounding rock at a certain distance from the excavation face and the tunnel wall at the bottom of the crack.
[0026] In the said step 3, the comprehensive determination methods and principles include the following points: (1) If rock mass structural planes develop in the surrounding rock at the upper part of the excavation face 2 and above the arch waist of the tunnel wall 3, the slotting 1 should avoid intersecting with the rock mass structural plane at the upper part to prevent rock block collapse caused by slotting.
[0027] (2) To reduce the risk of rock block collapse caused by slotting, the position of the slotting 1 is set at the center and the lower part of the excavation face 2, and below the arch waist of the tunnel wall 3.
[0028] (3) To reduce the risk of high-stress slab cracking failure and rockburst dynamic disasters, the width of the cut slot 1 ranges from a few millimeters to a few centimeters. The higher the maximum principal stress level and the lower the surrounding rock modulus, the wider the required cut slot. In actual operation, the width should also follow the principle that the cut slot saw blade will not be jammed due to the deformation of the surrounding rock during the cut slot operation.
[0029] (4) To reduce the large deformation of high-stress surrounding rock, the cut slot 1 is a wide slot with a width of more than one centimeter, or the cut slot 1 is a plurality of parallel narrow cracks arranged to achieve the purpose of reducing the large deformation of high-stress surrounding rock.
[0030] (5) Determine the depth of the cut slot 1 based on the rockburst grade to be prevented and the diameter of the tunnel to be excavated. Let the depth of the cut slot 1 be H, and the diameter or equivalent diameter of the tunnel (if it is a non-circular cross-section, the equivalent diameter is calculated) be D. Then the relationship between H and D is as follows: When preventing medium rockburst, H ≥ D / 20; When preventing strong rockburst, H ≥ 2D / 20; When preventing extremely strong rockburst: H ≥ 3D / 20; When preventing damage and collapse of the surrounding rock of the high-stress tunnel wall, H ≥ 0.5m.
[0031] (6) For the cut slots on the heading face, there is an overlap length h between two consecutive cut slots. In the tunnel sections where rockbursts frequently occur on the heading face, h ≥ 0.3m.
[0032] (7) The cut slots on the tunnel wall 3 advance forward with the excavation of the tunnel. In the tunnel sections where rockbursts frequently occur, the front end of the cut slots on the tunnel wall 3 closely follows the heading face 2.
[0033] Further, in the evaluation step, the objects of evaluation and comparison are the convergence deformation of the surrounding rock, the monitoring of the rupture of the surrounding rock, and the characteristics of rockbursts before the cut slots are made. If the cut slot operation is carried out continuously, it is also necessary to evaluate whether the cut slots achieve the treatment effect acceptable to the project.
[0034] Further, when optimizing the cut slot scheme, re-evaluate the stress direction in the cross-sectional plane, adjust the direction and position of the cut slots, adjust the width and depth of the cut slots according to the closing situation after the cut slots, and adjust the depth of the cut slots according to the rupture and deformation conditions of the surrounding rock of the tunnel wall after the cut slots.
[0035] If the width of the cut slot is too wide and it does not close in the later stage, cement slurry can be filled into the cut slot to maintain the optimal stress state of the overall ring-shaped bearing of the surrounding rock of the tunnel wall.
[0036] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock, characterized in that: The method comprises the following steps: Determining the principal stress direction of the cross-sectional plane perpendicular to the tunnel, wherein the principal stress direction of the cross-sectional plane includes the maximum principal stress direction and the minimum principal stress direction; Cutting the tunnel face and the surrounding rock of the tunnel wall along the direction of the minimum principal stress; The position, width and depth of the slit are determined comprehensively according to the rock mass conditions of the tunnel, the maximum principal stress level, the tunnel excavation diameter and the slit cutting equipment capacity; After the slit is cut, the surrounding rock convergence deformation is continuously observed, the surrounding rock fracture and rock burst characteristics are monitored, and the effect of the slit in transferring the concentrated stress to the deep surrounding rock and reducing the stress concentration level of the rock around the tunnel excavation hole is evaluated; If the effect of reducing the stress concentration level of the rock around the hole is not obvious, the direction, position, width and depth of the slit are redesigned to optimize the slit scheme; If the width of the cut is too wide and does not close in the later stage, the cut is filled with cement slurry.
2. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: If the surrounding rock at the upper part of the tunnel face and the part above the arch waist of the tunnel wall develops a rock mass structural surface, the cut seam is prevented from intersecting with the rock mass structural surface at the upper part.
3. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: The positions of the cutting seams are arranged at the center and lower part of the tunnel face, and at the part below the waist of the tunnel wall.
4. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: The width of the slit is in the range of several millimeters to several centimeters. The higher the maximum principal stress level is, the wider the slit is required to be.
5. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: The slits are wide slits with a width of more than one centimeter, or the slits are multiple parallel narrow cracks.
6. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: Assuming that the depth of the slit is H, and the diameter of the tunnel or the equivalent diameter is D, the relationship between H and D is as follows: To prevent moderate rock burst, H≥D / 20; To prevent severe rock burst, H≥2D / 20; To prevent extremely strong rock burst: H≥3D / 20; To prevent damage and collapse of high-stress cave wall surrounding rock, H≥0.5m.
7. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: For the cutting seams of the tunnel face, an overlap length h is set between the two cutting seams. In the tunnel section where rock bursts frequently occur on the tunnel face, h≥0.3m.
8. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: The cut of the cave wall advances forward along with the excavation of the tunnel. In the tunnel section where rock bursts frequently occur, the front end of the cut of the cave wall closely follows the tunnel face.
9. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: In the evaluation steps, the objects of evaluation and comparison are the surrounding rock convergence deformation before slitting, monitoring of surrounding rock fracture and rock burst characteristics; if the slitting operation is performed continuously, it is also necessary to evaluate whether the slitting has achieved a treatment effect acceptable to the project.
10. The method for transferring the tangential concentrated stress of the excavation face and the tunnel wall to the deep surrounding rock according to claim 1, characterized in that: When optimizing the slit plan, the stress direction of the cross-sectional plane is re-evaluated, the direction and position of the slit are adjusted, the width and depth of the slit are adjusted according to the closing condition after the slit, and the depth of the slit is adjusted according to the fracture and deformation of the surrounding rock of the cave wall after the slit.