CN116558383A - Method and system for preventing and controlling rockbursts in tunnels - Google Patents

Abstract

The invention provides a method and a system for preventing and controlling tunnel rock burst, and relates to the technical field of geotechnical engineering; determining the size of the kerf according to the number of kerfs and the ground stress of the tunnel; and controlling the cutting equipment to cut on the inner wall of the tunnel along the axial direction of the tunnel to form the kerfs according to the size, the position and the number of the kerfs. The surrounding rock around the tunnel is cut by using the mechanized cutting equipment, so that the surrounding rock is quickly and timely cut, the generated vibration is small, and the inside of the surrounding rock is not damaged; the kerf enables the rock which is originally deformed and is mutually extruded to generate rock burst to obtain a displacement space, the surrounding rock can close the kerf after the surrounding rock is released or most of the stress is released, the surrounding rock on two sides of the kerf generates mutual supporting force to form a complete and closed self-supporting layer, and a good tangential pressure relief effect is generated.

Description

Method and system for preventing and controlling rockbursts in tunnels

technical field

The invention relates to the technical field of geotechnical engineering, in particular to a method and system for preventing and controlling rockbursts in tunnels.

Background technique

Deep-buried hard rock tunnels are widely used in fields such as water conservancy and hydropower, transportation, mining engineering, and nuclear waste disposal. Under high ground stress, hard and brittle rock mass usually releases strain energy rapidly through brittle fracture to produce rockburst. Rockburst brings many unfavorable factors to roadway construction, support and post-maintenance in deep hard rock mining, and may also cause casualties, equipment damage and delay in construction period. huge challenge. In order to ensure the safety and smoothness of construction, active prevention and control measures should be taken to reduce the probability of rockburst occurrence and rockburst intensity level in the excavation of deep tunnels to the rockburst section, so as to ensure the construction safety of the rockburst section.

At present, according to different mechanisms, active rockburst prevention and control measures are mainly divided into three basic types: 1) Increase the radial support stress of the tunnel; commonly used methods include shotcrete and laying prestressed anchor rods. 2) Improve the mechanical properties of the surrounding rock; common methods include strictly controlling the amount of blasting charge, water injection to soften the surrounding rock, laying bolts and grouting in the surrounding rock, etc. 3) Improve the distribution of tangential stress; commonly used methods include deep hole blasting in surrounding rock and shallow hole blasting to relieve pressure.

Among the above methods, the more commonly used method is blasting pressure relief, but there are still some defects in blasting pressure relief. For example, after a single cycle of blasting footage, it is necessary to quickly relieve the pressure and prevent the occurrence of slab cracks in the surrounding rock. However, to form a pressure relief joint by blasting, a row of blastholes needs to be set in the tunnel first. It is difficult to meet the timeliness requirements for pressure relief; in addition, although the purpose of pressure relief is achieved during blasting, it will cause dynamic load damage to the surrounding rock, weaken the strength of the surrounding rock, and reduce the ability of the rock mass to resist rockburst, which is not conducive to rockburst prevention and control.

Contents of the invention

The problem to be solved by the present invention is that the timeliness of the pressure relief of the existing blasting is poor, which will weaken the strength of the surrounding rock and reduce the ability of the rock mass itself to resist the rockburst, which is not conducive to the prevention and control of the rockburst.

In order to solve the above problems, on the one hand, the present invention provides a tunnel rockburst prevention and control method, including:

According to the arc length of the tunnel arch waist, determine the position and quantity of the slits provided on the inner wall of the tunnel;

Determine the size of the kerf according to the number of kerfs and the ground stress of the tunnel;

According to the size, position and quantity of the slits, the cutting device is controlled to cut the inner wall of the tunnel along the axial direction of the tunnel to form the slits.

Optionally, the determining the position and number of slits provided on the inner wall of the tunnel according to the arc length of the tunnel arch waist includes:

According to the arc length of the arch waist of the tunnel, the distance between two adjacent slits is set;

The number and position of the slits are determined according to the distance between the slits and the length of the arc.

Optionally, the determining the size of the kerf according to the number of kerfs and the ground stress of the tunnel includes:

Analyzing the strain produced by the surrounding rock of the tunnel according to the ground stress and the stress-strain relationship of the tunnel;

determining the width of the slit according to the strain and the distance between two adjacent slits;

According to the length of a single cycle footage of the tunnel, the length and depth of the incision are determined.

Optionally, the determining the width of the slit according to the strain and the distance between two adjacent slits includes:

a≤εΔL, wherein a is the width of the slits, ε is the strain, and ΔL is the distance between the slits.

Optionally, the determining the length and depth of the incision according to the length of a single cycle footage of the tunnel includes:

g≤L2, wherein, g is the length of the slit, and L2 is the length of a single cycle footage of the tunnel;

0.5m≤b≤2m, wherein, b is the depth of the slit.

Optionally, according to the size, position and quantity of the slit, controlling the cutting device to cut and form the slit on the inner wall of the tunnel along the axial direction of the tunnel includes:

According to the size, position and quantity of the slits, control the cutting equipment to move along the axial direction of the tunnel on the inner wall of the tunnel according to the set cutting sequence of the slits and the shape of the slits Cutting forms the slits.

Optionally, the cutting sequence of the slit includes:

When the number of the slits is an even number, the arch waists on the left and right sides of the tunnel are alternately cut to form a plurality of slits symmetrical to the left and right of the tunnel centerline on the tunnel driving surface;

When the number of the slits is odd, one slit is firstly cut on the vault of the tunnel, and then the arch waists on the left and right sides of the tunnel are alternately cut.

Optionally, the occurrence of the kerf includes:

The length direction of the slit is parallel to the hole axis of the tunnel, the inclination angle of the slit changes with the position of the slit, and the inclination direction of the slit is the same as the The excavation interface of the tunnel is vertical.

Optionally, according to the size, position and number of the slits, after the control cutting equipment cuts the inner wall of the tunnel along the axial direction of the tunnel to form the slits, the tunnel rockburst prevention and control Methods also include:

The cutting device is controlled to process the slit at the slit opening, so that the width of the slit opening of the slit becomes larger.

Optionally, after determining the size of the kerf according to the number of kerfs and the ground stress of the tunnel, the method for preventing and controlling rockburst in the tunnel further includes:

According to the size of the kerf, the filling of the kerf is selected, wherein the filler is intended to be placed in the kerf, and the stiffness of the filler is greater than the stiffness of the surrounding rock of the tunnel.

Optionally, before the filling is fixed in each of the kerfs, the method for preventing and controlling rockburst in the tunnel further includes:

The surface treatment equipment is controlled to treat the surface of the filler to increase the surface friction coefficient of the filler.

In another aspect, the present invention also provides a tunnel rockburst prevention and control system, including:

The analysis module is used to determine the position and number of slits set on the inner wall of the tunnel according to the arc length of the tunnel arch waist; the size of the slit;

A control module, configured to control cutting equipment to cut the inner wall of the tunnel along the axial direction of the tunnel to form the slit according to the size, position and quantity of the slit;

The cutting device is used for cutting rocks to construct the kerf.

Compared with the prior art, the present invention has the following beneficial effects:

The method and system for preventing and controlling rockburst in a tunnel provided by the present invention analyze and obtain the number and position of the incisions according to the arc length of the tunnel arch waist, and further determine the appropriate size of the incisions according to the ground stress of the tunnel. After deformation, the rocks that should be squeezed together to produce rockbursts can obtain displacement space, and after the surrounding rock releases or releases most of the ground stress, the surrounding rock can close the kerf, and the surrounding rock on both sides of the kerf can generate mutual support Force, form a complete and closed self-supporting layer, produce better tangential pressure relief effect, enhance the stability of the surrounding rock, avoid rockburst, use mechanized cutting equipment to cut the surrounding rock around the tunnel, quickly and timely , the vibration generated is small and will not cause damage to the interior of the surrounding rock.

Description of drawings

Fig. 1 shows the schematic flow sheet of tunnel rockburst prevention and control method in the embodiment of the present invention;

Fig. 2 shows a schematic cross-sectional view of the tunnel perpendicular to the axis of the tunnel in an embodiment of the present invention;

Fig. 3 shows the schematic diagram of the slotting position of the tunnel section in the embodiment of the present invention;

Fig. 4 shows the uniaxial loading stress-strain graph of tunnel surrounding rock in the embodiment of the present invention;

Fig. 5 shows a schematic view of the surface of a steel plate with a surface rolling pattern in an embodiment of the present invention;

Fig. 6 shows a schematic view of the arch bearing area in the embodiment of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

It should be noted that the terms "first" and "second" in the description and claims of the present invention and the above drawings are used to distinguish similar objects, but not necessarily used to describe a specific order or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein can be practiced in sequences other than those illustrated or described herein.

In the description of this specification, descriptions with reference to the terms "an embodiment", "an embodiment" and "an implementation" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or implementation are included in this specification. In at least one embodiment or implementation of the invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or implementations.

Tunnel excavation is similar to taking out rock pillars from the depths of the ground. After the rock pillars are taken out, the supporting effect of the original rock pillars on the rocks around the tunnel disappears. While the radial stress of the tunnel decreases, the tangential stress increases and the tangential stress increases. It is the main cause of slab cracks in the surrounding rock and subsequent rockbursts. The tangential stress cannot only be reduced, otherwise the surrounding rock will be difficult to stabilize.

Fig. 1 shows a schematic flow chart of a method for preventing and controlling a rockburst in a tunnel in an embodiment of the present invention. The method for preventing and controlling a rockburst in a tunnel includes:

S1: According to the arc length of the tunnel arch waist, determine the position and quantity of the slits set on the inner wall of the tunnel;

Specifically, facing the face of the tunnel, as shown in Figure 2 and Figure 3, number the incisions from the left arch waist of the tunnel (the range from the arch foot to the vault top), and the first incision at the left arch foot is recorded as 1 #Incision, 1# incision is marked as 2# incision on the right arch waist at the symmetrical position of the tunnel center line; then mark the incision adjacent to 1# incision in a clockwise direction as 3# For the slit, mark the slit on the right arch waist at the symmetrical position of the 3# slit as the 5# slit, and so on until the last slit is numbered. The arc length from the 1# slit to the arch foot is L1, 0<L1<L, where L is the arc length of the arch waist on one side of the tunnel, and the distance between each adjacent slit is equal to ΔL; the distance between the slits ΔL should be greater than the kerf depth b and less than 2 times the kerf length g. The total arc length of the tunnel can be calculated according to the arc length of the arch waist, and then the arc length L1 from the 1# kerf to the arch foot and the kerf spacing can be calculated. ΔL, the number and position of the slits can be obtained.

Exemplarily, in this embodiment, a certain railway tunnel is used as the object of pressure relief through incision. The maximum principal stress is in the horizontal direction, the buried depth is 2000m, the vertical stress and horizontal stress are both 50MPa, and the lateral pressure coefficient is close to 1. The tunnel The cross-sectional schematic diagram perpendicular to the hole axis is shown in Figure 2. The arc from the arch foot to the top of the arch is the arch waist, which is divided into left and right sides, respectively L=15m, and the total length is 30m. For this tunnel, the number of slots can be set at 5.

S2: Determine the size of the kerf according to the number of kerfs and the ground stress of the tunnel;

Specifically, since the surrounding rock is destroyed after the tunnel completes a single cycle blasting, the radial stress decreases, while the shear stress on the surrounding rock around the tunnel increases under the action of the in-situ stress generated by gravity and environmental factors , so that the instability of the tunnel becomes larger, and the possibility of rockburst increases when the tunnel is not decompressed. The surrounding rock will be deformed due to in-situ stress, and these deformations will gather together and produce extrusion. When the energy is accumulated to a certain extent, a rockburst will occur, and the kerf will allow the deformed rocks that should be squeezed to produce a rockburst to gain displacement space. , so it is necessary to calculate the size of the slit so that after the surrounding rock is released or most of the in-situ stress is released, the surrounding rock at the slit can close the slit, so that the surrounding rocks on both sides of the slit can also generate mutual supporting force , forming a complete and closed self-supporting layer, resulting in a better tangential pressure relief effect.

S3: According to the size, position and quantity of the slits, control the cutting device to cut the slits on the inner wall of the tunnel along the axial direction of the tunnel to form the slits.

Specifically, after the single-cycle blasting in the tunnel is completed and the risk is eliminated, the pressure relief must be cut immediately, and the mechanized cutting machine equipment should be used to carry out the pressure relief in a short period of time. Prevent cutting time from being too late, resulting in too many circumferential cracks in the surrounding rock during the stress adjustment process. If conditions permit, advanced hydraulic support can be used for support.

In this embodiment, according to the arc length of the tunnel arch waist, the number and position of the slits are analyzed, and the appropriate size of the slits is determined according to the ground stress of the tunnel. The slits should be squeezed together after deformation. The rock of the rockburst obtains displacement space, and after the surrounding rock releases or releases most of the ground stress, the surrounding rock can close the slit, and the surrounding rock on both sides of the slit generates mutual support, forming a complete and closed self-contained structure. The support layer produces a better tangential pressure relief effect, enhances the stability of the surrounding rock, and avoids rock bursts. The mechanized cutting equipment is used to cut the surrounding rock around the tunnel, which is fast and timely, and the vibration generated is small. No damage will be done inside the rock.

In an embodiment of the present invention, the determining the position and number of slits provided on the inner wall of the tunnel according to the arc length of the tunnel arch waist includes:

According to the arc length of the arch waist of the tunnel, the distance between two adjacent slits is set;

The number and position of the slits are determined according to the distance between the slits and the length of the arc.

Specifically, first set a reasonable distance and quantity according to the arc length of the arch waist. The number of slits is n. When the arc length of the arch waist is long, the distance between the two slits can be appropriately increased. Or increase the number of slits. In order to ensure the uniformity of slit distribution, in principle, the distance between two adjacent slits should be set to be consistent, but sometimes there are special conditions in tunnel rock walls, such as difficult to cut or cutting places If there are cracks, etc., the position of the original slit can be fine-tuned to make the cutting work go smoothly. Exemplarily, for a railway tunnel in southwest China, the arc length from 1# kerf to arch foot is L1=5m; 2# kerf is cut at the arch waist on the right side of the tunnel, 2# kerf and 1# kerf are about the tunnel centerline symmetry. The distance between every adjacent slit is equal, set ΔL=5m. Other slits and numbers are shown in Figure 3.

In an embodiment of the present invention, determining the size of the kerf according to the number of kerfs and the ground stress of the tunnel includes:

Analyzing the strain produced by the surrounding rock of the tunnel according to the ground stress and the stress-strain relationship of the tunnel;

Specifically, it is assumed that the deep tunnel is under hydrostatic pressure, and the vertical and horizontal stresses are both σMPa. According to Gilsch solution, the maximum tangential stress around the tunnel is 2σMPa. From the stress-strain curve of the surrounding rock during uniaxial loading, it is obtained that when the stress is 2σMPa, the strain produced by the surrounding rock is ε. Exemplarily, it is assumed that the deep tunnel is under hydrostatic pressure, and the vertical and horizontal stresses are both 50 MPa. According to Gilsch solution, the maximum tangential stress around the tunnel is 100MPa. Figure 4 is the stress-strain curve of the surrounding rock during uniaxial loading, where the abscissa represents the strain and the ordinate represents the stress. According to Fig. 4, it can be obtained that when the stress is 100 MPa, the strain produced by the surrounding rock is ε = 0.15%.

determining the width of the slit according to the strain and the distance between two adjacent slits;

According to the length of a single cycle footage of the tunnel, the length and depth of the incision are determined.

Specifically, as shown in Figure 3, the kerf is a cuboid in the tunnel cross-sectional view. The slit size mainly includes width a (tangential length), depth b (radial length) and length g (axial length). In practice, the size of the width a can be estimated by the following method.

In this embodiment, the determining the width of the slit according to the strain and the distance between two adjacent slits includes:

a≤εΔL, wherein a is the width of the slits, ε is the strain, and ΔL is the distance between the slits.

Specifically, when the distance between two adjacent slits is ΔL, the surrounding rock within the range of ΔL/2 on one side of the slit and the surrounding rock within the range of ΔL/2 on the other side are all decompressed, and the required cutting The slot width is a=εΔL. This can ensure that after the pressure relief of the slit, the slit will be closed during the automatic adjustment process of the surrounding rock stress, and the surrounding rock within the depth range of the slit still bears part of the pressure. In practical application, a=εΔL can be taken first.

Exemplarily, when the distance between two adjacent slits is ΔL=5m, the surrounding rock within the range of ΔL/2 on one side of the slit and the surrounding rock within the range of ΔL/2 on the other side are all decompressed, so The required slit width is a=εΔL=7.5mm. This can ensure that the surrounding rock within the range of the kerf still bears part of the pressure after the kerf is relieved of pressure. Similarly, the number n of slits cannot be too large, otherwise it is difficult to ensure that the slits are closed. The above-mentioned setting of the number n of slits to 5 meets the constraints:

In this embodiment, the determining the length and depth of the kerf according to the length of a single cycle footage of the tunnel includes:

g≤L2, where g is the length of the slit, and L2 is the length of a single cycle footage of the tunnel;

0.5m≤b≤2m, wherein b is the depth of the slit.

Specifically, the cutting depth is b, and the suggested range of b is 0.5m to 2m. b If it is too small, the radial thickness of the formed arch load-bearing structure is thin, and it is difficult to play a good bearing role; if it is too large, the construction is more difficult, and it is difficult to ensure the timeliness requirements of the pressure relief of the slit. In addition, it is recommended to use a large-scale cutting machine with high efficiency for mechanical cutting. The slit length g is less than or equal to the length of drilling and blasting construction cycle footage. Generally, the length of a single cycle footage is 3m. In addition, the slit spacing ΔL is greater than the slit depth b, and less than twice the slit length g. Within this range, after the slits are filled with steel plates, the range of force exerted by the steel plates on the rock overlaps, which can increase the integrity and stability of the surrounding rock. Supporting effect. In addition, the slit spacing ΔL should not be too small, otherwise the workload of cutting slits and filling materials will increase, and it will take more time.

In one embodiment of the invention, according to the size, position and quantity of the slit, controlling the cutting device to cut and form the slit on the inner wall of the tunnel along the axial direction of the tunnel includes:

According to the size of the slit, the cutting device is controlled to cut the inner wall of the tunnel along the axial direction of the tunnel to form the Slit. The occurrence of the kerf includes direction, inclination and inclination. During the cutting process, the vibration and the internal stress changes of the surrounding rocks that may be caused by the cutting are minimized, and it can also ensure that the left and right deformations of the surrounding rocks are basically the same, avoiding the introduction of more stress changes due to the inconsistency of the left and right deformations, and will not aggravate the surrounding rocks of instability.

In this embodiment, the cutting sequence of the slit includes:

When the number of the slits is an even number, the arch waists on the left and right sides of the tunnel are alternately cut to form a plurality of slits symmetrical to the left and right of the tunnel centerline on the tunnel driving surface;

When the number of the slits is odd, one slit is firstly cut on the vault of the tunnel, and then the arch waists on the left and right sides of the tunnel are alternately cut.

For example, when cutting five slits, cut the vault first and then cut the arch waist. For each slit on the left arch waist, immediately turn to the corresponding position on the right arch waist that is symmetrical to the center line of the tunnel. In this way, due to the uniform deformation of the surrounding rock, the uniformity of stress release is ensured, the local stress concentration is suppressed, the damage of the surrounding rock is reduced, and its integrity is increased. waist seam. For example, as shown in Figure 3, the chronological order of incision is: 5# incision>1# incision>2# incision>3# incision>4# incision.

In this embodiment, the occurrence of the kerf includes:

The length direction of the slit is parallel to the hole axis of the tunnel, the inclination angle of the slit changes with the position of the slit, and the inclination direction of the slit is the same as the The excavation interface of the tunnel is vertical.

Specifically, the direction of each kerf is parallel to the axis of the hole; the inclination angle of the kerf varies with the position of the kerf, for example, when the kerf is made on the vault, the kerf is perpendicular to the horizontal plane, and the inclination angle is 90 degrees; The excavation interface is vertical; the inclination of the cutting joints is directed from the surrounding rock to the direction of the tunnel.

In one embodiment of the invention, according to the size, position and number of the slits, after the cutting device is controlled to cut the inner wall of the tunnel along the axial direction of the tunnel to form the slits, the Methods for preventing and controlling rockbursts in tunnels also include:

The cutting device is controlled to process the slit at the slit opening, so that the width of the slit opening of the slit becomes larger.

Specifically, the incision is at the intersection of the incision and the excavation interface, and it is a rectangular slit before processing. When the pressure relief and deformation of the surrounding rock are completed, the stress concentration is most likely to occur at the cut opening. In order to suppress the stress concentration at the kerf, it needs to be further cut. The purpose of cutting is to cut off the corners on both sides of the rectangular slit, transform the rectangular slit into a trapezoidal slit, and reduce stress concentration. The width of the bottom of the trapezoidal opening is c mm, the width of the top is a mm, and the depth is d mm. Exemplarily, the width of the bottom of the trapezoidal opening is c=100mm, the depth d=100mm, c should not be too large, and it is recommended to be within 100mm. The trapezoidal kerf formed after kerf treatment is shown in Figure 3.

In one embodiment of the invention, after the size of the kerf is determined according to the number of kerfs and the ground stress of the tunnel, the method for preventing and controlling rockburst in the tunnel further includes:

According to the size of the slit, the filling of the slit is selected, wherein the filling is placed in the slit.

Specifically, in order to increase the integrity of the surrounding rock within the cut range, the cut should be filled in time after the cut is completed. The choice of filler is critical, the filler should have a high tensile strength, and the stiffness of the filler is greater than the stiffness of the rock surrounding the tunnel. Generally, a steel plate with a thickness of e mm can meet this requirement, e>1mm. The surface treatment equipment is controlled to treat the surface of the filler, and the surface of the steel plate can be treated with rolling patterns to increase the surface friction coefficient of the filler, which can better exert the end surface friction effect of the steel plate and increase the resistance of the surrounding rock. tensile strength.

Therefore, the conditions to be satisfied by a can be further limited as: e<a≤εΔL, where e is the thickness of the filler, and the thickness of the steel plate used to fill the slit should be smaller than the width of the slit, which must satisfy a mm>e>1mm ; The width of the steel plate is equal to the depth of the kerf; the length f of the steel plate is slightly less than the length L2 of the footage in a single cycle. In addition, the greater the length g of the kerf, the greater the length of the steel plate that can be filled, the better the integrity of the surrounding rock within the scope of the steel plate, and the better the supporting effect. Sometimes for the convenience of filling, a small piece of steel plate can be used, but the total length of the steel plate is still f, and the length of the steel plate can be taken as less than 1m, but this will weaken the supporting effect of the steel plate on the surrounding rock.

Exemplarily, the thickness of the steel plate is taken as e=2mm. In order to increase the surface friction coefficient of the steel plate, the surface of the steel plate used should be rolled with patterns on both sides (see Figure 5), and the protrusion of the pattern should be controlled within 0.5mm, which can better exert the end surface friction effect of the steel plate and increase the tensile strength of the surrounding rock. The thickness of the steel plate for filling the kerf should be smaller than the width of the kerf, satisfying 1mm<e<a=7.5mm; the width of the steel plate is equal to the depth of the kerf minus d, which is 900mm; the length of the steel plate is f=2900mm, which is slightly less than the footage in a single cycle The distance L2=3000mm. Sometimes for the convenience of filling, a small piece of steel plate can be used, and the length of the steel plate should be less than 1m, but this will weaken the supporting effect of the steel plate on the surrounding rock.

According to the size of the kerf, the filler for the kerf is selected, wherein after the filler is placed in the kerf, the tunnel rockburst prevention and control method further includes:

The padding is secured in each of the slits.

Specifically, the choice of filling time. After the cutting is completed, the width of the kerf will become smaller and smaller during the pressure relief process of the surrounding rock. If the filling is too late, the kerf will be closed and it will be difficult to complete the filling. It is recommended to fill the plate immediately after cutting. For some slits, the inclination angle is relatively large, and the steel plate will slide down under the action of gravity after filling, such as vault slits, etc. For this kind of kerf, when the steel plate is filled, the filler should be fixed in the kerf first, such as smearing a fast-setting cementing agent such as 502 on the surface of the steel plate to help the rapid bonding of the steel plate and the kerf surface, preventing The steel plate fell off automatically, injuring workers.

In order to verify the implementation effect of the above prevention and control methods, a stress box can be buried in the surrounding rock around the tunnel before the pressure relief cutting, and the stress change of the surrounding rock before and after pressure relief can be measured in real time to verify the pressure relief effect.

This pressure relief method can also form an arched load-bearing structure with a thickness b in the surrounding rock within the range of the kerf, provide greater radial support stress for the internal surrounding rock, reduce the occurrence of slab cracks inside the surrounding rock, and increase surrounding rock strength. The crack suppression effect can be detected and compared by drilling cores or using drilling peepers.

Ideally, the steel plate filled in the slit can generate greater friction after being compressed; if the slit is too wide, the surface of the slit will not be fully contacted and squeezed after the pressure relief of the surrounding rock is completed, and the friction of the steel plate will It is difficult to fully exert the effect. The method of steel plate pull-out test can be used to check whether the width of the slit is appropriate, and the results can be used to further optimize the parameters of the slit or select a steel plate that matches the width of the slit after deformation.

For the tunnel rockburst prevention and control method and system provided by the present invention, firstly, the above method uses mechanical cutting to construct the slit, and does not use explosives for blasting, so as to reduce the damage to the internal stress and stability of the surrounding rock and will not aggravate the damage of the surrounding rock. Rockburst process, and faster mechanical cutting.

Secondly, the above method can achieve a better tangential pressure relief effect, significantly reduce the tangential stress of the surrounding rock around the tunnel, and can also transfer the tangential stress to the depth of the surrounding rock, greatly reducing the energy released by the rockburst.

Then, the above method can also improve the mechanical properties of the surrounding rock. The steel plate is filled in the kerf. Since the steel plate is more rigid than the rock, it can produce a radial friction effect as shown in Figure 6 after being compressed, which is equivalent to providing a radial stress. The longer steel plate is filled into the surrounding rock, which can Improve the integration of the surrounding rock, increase the integrity of the surrounding rock, make an arch bearing area around the tunnel, provide greater radial support stress for the deep surrounding rock, and inhibit the occurrence of slab cracks and rockbursts in the surrounding rock. Effectively improve the tensile strength and stability of surrounding rock.

To sum up, the present invention simultaneously achieves multiple effects such as radial stress relief, improvement of the mechanical properties of the surrounding rock, exerting the self-supporting effect of the surrounding rock, and suppressing slab cracks in deep surrounding rock, and belongs to a comprehensive rockburst active prevention and control method.

In another embodiment of the present invention, a tunnel rockburst prevention and control system is also provided, including:

The analysis module is used to determine the position and number of slits set on the inner wall of the tunnel according to the arc length of the tunnel arch waist; the size of the slit;

A control module, configured to control cutting equipment to cut the inner wall of the tunnel along the axial direction of the tunnel to form the slit according to the size, position and quantity of the slit;

The cutting device is used for cutting rocks to construct the kerf.

The technical effect of the tunnel rockburst prevention and control system in the embodiment of the present invention is similar to that of the tunnel rockburst prevention and control method described above, and will not be repeated here.

Although the present invention is disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Claims (12)

1. A tunnel rockburst prevention and control method is characterized in that, comprising: According to the arc length of the tunnel arch waist, determine the position and quantity of the slits provided on the inner wall of the tunnel; Determine the size of the kerf according to the number of kerfs and the ground stress of the tunnel; According to the size, position and quantity of the slits, the cutting device is controlled to cut the inner wall of the tunnel along the axial direction of the tunnel to form the slits. 2. The tunnel rockburst prevention and control method according to claim 1, characterized in that, according to the arc length of the tunnel arch waist, determining the position and quantity of the slits provided on the inner wall of the tunnel comprises: According to the arc length of the arch waist of the tunnel, the distance between two adjacent slits is set; The number and position of the slits are determined according to the distance between the slits and the length of the arc. 3. The tunnel rockburst prevention and control method according to claim 2, wherein said determining the size of said kerf according to the number of said kerfs and the in-situ stress of said tunnel comprises: Analyzing the strain produced by the surrounding rock of the tunnel according to the ground stress and the stress-strain relationship of the tunnel; determining the width of the slit according to the strain and the distance between two adjacent slits; According to the length of a single cycle footage of the tunnel, the length and depth of the incision are determined. 4. The tunnel rockburst prevention and control method according to claim 3, wherein, according to the strain and the distance between two adjacent kerfs, determining the width of the kerf comprises: a≤εΔL, wherein a is the width of the slits, ε is the strain, and ΔL is the distance between the slits. 5. The tunnel rockburst prevention and control method according to claim 3, characterized in that, determining the length and depth of the kerf according to the length of the single cycle footage of the tunnel comprises: g≤L2, wherein, g is the length of the slit, and L2 is the length of a single cycle footage of the tunnel; 0.5m≤b≤2m, wherein, b is the depth of the slit. 6. The tunnel rockburst prevention and control method according to claim 1, characterized in that, according to the size, position and quantity of the slits, the cutting equipment is controlled on the inner wall of the tunnel along the axial direction of the tunnel. Directional cutting to form the kerf includes: According to the size, position and quantity of the slits, control the cutting equipment to move along the axial direction of the tunnel on the inner wall of the tunnel according to the set cutting sequence of the slits and the shape of the slits Cutting forms the slits. 7. The tunnel rockburst prevention and control method according to claim 6, wherein the cutting sequence of the kerf comprises: When the number of the slits is an even number, the arch waists on the left and right sides of the tunnel are alternately cut to form a plurality of slits symmetrical to the left and right of the tunnel centerline on the tunnel driving surface; When the number of the slits is odd, one slit is firstly cut on the vault of the tunnel, and then the arch waists on the left and right sides of the tunnel are alternately cut. 8. The tunnel rockburst prevention and control method according to claim 6, characterized in that, the occurrence of the kerf comprises: The length direction of the slit is parallel to the hole axis of the tunnel, the inclination angle of the slit changes with the position of the slit, and the inclination direction of the slit is the same as the The excavation interface of the tunnel is vertical. 9. The tunnel rockburst prevention and control method according to any one of claims 1-8, characterized in that, according to the size, position and quantity of the slits, the cutting equipment is controlled to move along the inner wall of the tunnel. After the tunnel is cut in the axial direction to form the slit, it also includes: The cutting device is controlled to process the slit at the slit opening, so that the width of the slit opening of the slit becomes larger. 10. The tunnel rockburst prevention and control method according to any one of claims 1-8, characterized in that, after determining the size of the kerf according to the number of kerfs and the in-situ stress of the tunnel, Also includes: According to the size of the kerf, the filling of the kerf is selected, wherein the filler is intended to be placed in the kerf, and the stiffness of the filler is greater than the stiffness of the surrounding rock of the tunnel. 11. The tunnel rockburst prevention and control method according to claim 10, characterized in that, before fixing the filler in each of the kerfs, further comprising: The surface treatment equipment is controlled to treat the surface of the filler to increase the surface friction coefficient of the filler. 12. A tunnel rockburst prevention and control system, characterized in that it comprises: The analysis module is used to determine the position and number of slits set on the inner wall of the tunnel according to the arc length of the tunnel arch waist; the size of the slit; A control module, configured to control cutting equipment to cut the inner wall of the tunnel along the axial direction of the tunnel to form the slit according to the size, position and quantity of the slit; The cutting device is used for cutting rocks to construct the kerf.