Support method for soft rock tunnel with high ground stress

Abstract

The present invention discloses a high-stress soft rock tunnel support method, including determining a plurality of conventional support sections and a plurality of reinforced support sections alternately distributed along the tunnel; in the conventional support section, multiple groups of support anchor rods are installed at the tunnel sides and tunnel roof positions of the surrounding rock to complete conventional support; in the reinforced support section, multiple grouting anchor rod groups are installed on the surrounding rock, and the multiple grouting anchor rod groups are spaced along the length direction of the tunnel, and the grouting anchor rod groups include multiple first grouting anchor rods, and the multiple first grouting anchor rods are installed at the tunnel sides and tunnel roof positions, and rotary spraying and hole expansion are performed between two adjacent first grouting anchor rods in sequence to complete reinforced support; conventional support and reinforced support are alternately completed along the length direction of the tunnel until the whole tunnel support is completed. The present invention reduces the risk of anchor rod breakage through the first filling layer, and conventional support gives up a certain surrounding rock deformation space, reduces the risk of rock burst accidents, and maintains the stability of the tunnel surrounding rock.

Description

Technical Field

[0001] The invention belongs to the technical field of high ground stress tunnel support, and in particular relates to a high ground stress soft rock tunnel support method. Background Art

[0002] The surrounding soft rock with high ground stress has poor self-bearing capacity, and the deformation speed after excavation is fast and difficult to control. Instability and collapse often occur. In the early stage of construction, the support cracks and intrusion lead to slow construction progress, which not only increases the construction workload but also causes great losses.

[0003] In the relevant technology, the support method for high-ground stress soft rock is anchor support, but ordinary anchors can hardly bear the stress brought by the surrounding rock, and anchor breakage often occurs, which eventually leads to disasters. As a result, in the excavation of high-ground stress soft rock, the excavation is often preceded by laying down, and the support is performed first and repaired later. This not only prolongs the project period, but also seriously affects the safety of the workers. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, an embodiment of the present invention proposes a high-stress soft rock tunnel support method, which strengthens the first grouting anchor by a first filling layer, reduces the risk of anchor fracture, maintains the stability of the tunnel surrounding rock, and the conventional support between the two reinforced support positions leaves a certain surrounding rock deformation space, reducing the risk of rock burst accidents.

[0005] The high ground stress soft rock tunnel support method of the embodiment of the present invention includes:

[0006] Determine multiple conventional support sections and multiple reinforced support sections in the tunnel according to geological survey, and the multiple conventional support sections and multiple reinforced support sections are alternately distributed along the length direction of the tunnel;

[0007] In the conventional support section, multiple groups of support anchors are installed at the sides of the tunnel and the top of the tunnel in the surrounding rock to complete the conventional support. The multiple groups of support anchors are distributed at intervals along the length direction of the tunnel, and each group of support anchors includes multiple support anchors distributed at intervals along the circumference of the tunnel.

[0008] In the reinforcement support section, multiple grouting anchor rod groups are installed on the surrounding rock, and the multiple grouting anchor rod groups are spaced apart along the length direction of the tunnel. The grouting anchor rod groups include multiple first grouting anchor rods, and the multiple first grouting anchor rods are installed at the two sides of the tunnel and the top plate of the tunnel, and the multiple first grouting anchor rods are spaced apart along the circumference of the tunnel. Rotary jetting and hole expansion are sequentially performed between two adjacent first grouting anchor rods to generate a continuous first empty layer in the surrounding rock, and the slurry enters the first empty layer to form a continuous first filling layer to cover the first grouting anchor rods, thereby completing the reinforcement support;

[0009] Conventional support and reinforced support are completed alternately along the length of the tunnel until the entire tunnel is supported.

[0010] The high-stress soft rock tunnel support method of the embodiment of the present invention strengthens the first grouting anchor by a first filling layer, thereby reducing the risk of anchor fracture and maintaining the stability of the tunnel surrounding rock. The conventional support between the two reinforced support positions leaves a certain amount of surrounding rock deformation space, thereby reducing the risk of impact ground pressure accidents.

[0011] In some embodiments, the reinforcement support further comprises:

[0012] A plurality of clearance grooves are provided at the bottom plate of the roadway, the plurality of clearance grooves correspond to the plurality of grouting anchor rod groups one by one, the length direction of the clearance grooves is orthogonal to the length direction of the roadway, the grouting anchor rod group also includes a plurality of second grouting anchor rods installed on the bottom plate of the roadway, the plurality of second grouting anchor rods are all located in the clearance grooves, and the plurality of second grouting anchor rods are spaced apart along the length direction of the clearance grooves, the upper ends of the second grouting anchor rods are lower than the top ends of the clearance grooves, holes are drilled and expanded by rotary jetting between two adjacent second grouting holes in sequence, so that a continuous second empty layer is generated in the surrounding rock, and the slurry enters the second empty layer to form a continuous second filling layer to cover the second grouting anchor rods;

[0013] The make way groove is backfilled by filling backfill material into the make way groove until the backfill material covers the second grouting anchor rod and is flush with the tunnel bottom plate.

[0014] In some embodiments, the grouting anchor group also includes a third grouting anchor, which is installed at the junction of the tunnel side and the tunnel bottom plate, and rotary jetting is performed between the third grouting anchor and the first grouting anchor adjacent to the third grouting anchor, and rotary jetting is performed between the third grouting anchor and the second grouting anchor adjacent to the third grouting anchor, so that a third void layer connected to the first void layer and the second void layer respectively is generated in the surrounding rock, and the slurry enters the third void layer to form a third filling layer to cover the third grouting anchor, and the third filling layer is connected to the first filling layer and the second filling layer respectively, so that the first filling layer, the second filling layer and the third filling layer form a continuous filling wall along the circumference of the tunnel.

[0015] In some embodiments, the step of rotary spraying and hole expansion includes:

[0016] Drilling a hole in the surrounding rock, when the end of the drill bit reaches a first preset position, high-pressure water is introduced to both sides of the drill bit and slurry is introduced to the end of the drill bit, and the high-pressure water breaks the surrounding rock to form a hollow layer;

[0017] The drill bit is retracted and rotated at the same time, and the slurry enters the empty layer to fill the empty layer to form a filling layer;

[0018] After the end of the drill bit reaches the second preset position, the rotary spraying is stopped and the drill bit is withdrawn;

[0019] The drilled hole is filled to seal it.

[0020] In some embodiments, after the rotary jet hole expansion, the first grouting anchor rod, the second grouting anchor rod and the third grouting anchor rod are pressurized grouting respectively.

[0021] In some embodiments, the third grouting anchor rod is located in the make way groove, and after the make way groove is backfilled, the third grouting anchor rod is buried in the backfill material.

[0022] In some embodiments, after the make way groove is backfilled, a baffle is placed over the make way groove.

[0023] In some embodiments, the high ground stress soft rock tunnel support method further includes:

[0024] Before conventional support and reinforcement support, the two sides and the top of the tunnel are sprayed with concrete to make the tunnel surface smooth. The thickness of the initial sprayed concrete shall not be less than 20mm.

[0025] After conventional support and reinforced support, an anchor net is hung on the tunnel surface and temporarily fixed to the supporting anchor rod and the first grouting anchor rod, and concrete is sprayed on both sides and the top plate of the tunnel. The thickness of the sprayed concrete is not less than 50mm.

[0026] In some embodiments, when the concrete is initially sprayed on the sides and roof of the tunnel, the protruding parts of the tunnel surface are removed.

[0027] In some embodiments, the support anchor is a yield anchor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of a reinforcement support section according to an embodiment of the present invention.

[0029] In the figure: surrounding rock 1; first grouting anchor rod 2; first empty layer 3; concession groove 4; second grouting anchor rod 5; second empty layer 6; third grouting anchor rod 7; third empty layer 8. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0031] The high ground stress soft rock tunnel supporting method according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0032] like Figure 1 As shown, the high ground stress soft rock tunnel support method of the embodiment of the present invention includes:

[0033] S1. According to geological survey, multiple conventional support sections and multiple reinforced support sections are determined in the tunnel, and the multiple conventional support sections and multiple reinforced support sections are alternately distributed along the length direction of the tunnel.

[0034] It should be noted that when the tunnel support strength is too high, a lot of manpower and materials are wasted, so that the funds cannot be fully used. When the support strength is too low, the support technology cannot be fully utilized, so that the tunnel needs to be repaired in a short period of time, which also wastes manpower and material resources. In tunnels with large deformation of surrounding rock, production may even be forced to stop, which brings serious obstacles to the high production and efficiency of mines. Therefore, it is necessary to carry out different support schemes for different surrounding rock conditions through geological survey to avoid wasting manpower and material resources. Through geological survey, the sections that can achieve good results through conventional support are marked as conventional support sections, and the sections that cannot achieve good results through conventional support are marked as reinforced support sections. After the reinforced support sections are reinforced, the monitoring of the reinforced support sections is strengthened, and secondary support is carried out when necessary.

[0035] S2. In the conventional support section, multiple groups of support anchor rods are installed on both sides of the tunnel and the tunnel roof of the surrounding rock to complete conventional support. The multiple groups of support anchor rods are spaced apart along the length direction of the tunnel, and each group of support anchor rods includes multiple support anchor rods spaced apart along the circumference of the tunnel.

[0036] S3. In the reinforcement and support section, multiple grouting anchor groups are installed on the surrounding rock, and the multiple grouting anchor groups are spaced apart along the length direction of the tunnel. The grouting anchor groups include multiple first grouting anchors 2, and the multiple first grouting anchors 2 are installed on the two sides of the tunnel and the top plate of the tunnel, and the multiple first grouting anchors 2 are spaced apart along the circumference of the tunnel. Rotary jetting is sequentially performed between two adjacent first grouting anchors 2 to generate a continuous first empty layer 3 in the surrounding rock, and the slurry enters the first empty layer 3 to form a continuous first filling layer to cover the first grouting anchors 2 to complete the reinforcement and support.

[0037] S4. Complete conventional support and reinforced support alternately along the length of the tunnel until the entire tunnel support is completed.

[0038] It should be noted that, since a part of the first grouting anchor rod 2 is located in the first empty layer 3, and the slurry enters the first empty layer 3 to form a continuous first filling layer, the first grouting anchor rod 2 and the first filling layer constitute an anchor rod-concrete wall, thereby strengthening the first grouting anchor rod 2 and reducing the risk of fracture of the first grouting anchor rod 2; since no filling layer is set in the conventional support section, a certain amount of surrounding rock deformation space is left, thereby reducing the risk of impact ground pressure accidents.

[0039] The high-stress soft rock tunnel support method of the embodiment of the present invention strengthens the first grouting anchor 2 through the first filling layer, reducing the risk of anchor fracture and maintaining the stability of the tunnel surrounding rock. The conventional support between the two reinforced support positions leaves a certain amount of surrounding rock deformation space, reducing the risk of impact ground pressure accidents.

[0040] like Figure 1 As shown, in some embodiments, the reinforcement support further includes:

[0041] A plurality of clearance grooves 4 are provided at the bottom plate of the roadway, and the plurality of clearance grooves 4 correspond to the plurality of grouting anchor rod groups one by one. The length direction of the clearance grooves 4 is orthogonal to the length direction of the roadway. The grouting anchor rod group also includes a plurality of second grouting anchor rods 5 installed on the bottom plate of the roadway. The plurality of second grouting anchor rods 5 are all located in the clearance grooves 4, and the plurality of second grouting anchor rods 5 are spaced apart along the length direction of the clearance grooves 4. The upper end of the second grouting anchor rod 5 is lower than the top of the clearance groove 4. Holes are drilled and expanded by rotary jetting between two adjacent second grouting holes in sequence, so that a continuous second empty layer 6 is generated in the surrounding rock, and the slurry enters the second empty layer 6 to form a continuous second filling layer to cover the second grouting anchor rods 5.

[0042] The clearance groove 4 is filled with backfill material (such as concrete, or a mixture of concrete and gangue) to backfill the clearance groove 4 until the backfill material covers the second grouting anchor rod 5 and is flush with the tunnel floor.

[0043] It should be noted that under the pressure of the tunnel, the tunnel floor may rise, affecting the transportation and passage of the tunnel, and in serious cases, the tunnel may be blocked. The second filling layer and the second grouting anchor 5 strengthen the support for the bottom position of the tunnel, control the deformation of the surrounding rock at the bottom position of the tunnel, and reduce the accident of tunnel floor rising; by backfilling the giveway groove 4 and burying the second grouting anchor 5 in the backfill material, the impact of the giveway groove 4 and the second grouting anchor 5 on the transportation and passage of the tunnel is reduced.

[0044] like Figure 1 As shown, in some embodiments, the grouting anchor group also includes a third grouting anchor 7, which is installed at the junction of the tunnel side and the tunnel bottom plate, and rotary jetting is performed between the third grouting anchor 7 and the first grouting anchor 2 adjacent to the third grouting anchor 7, and rotary jetting is performed between the third grouting anchor 7 and the second grouting anchor 5 adjacent to the third grouting anchor 7, so that a third void layer 8 connected to the first void layer 3 and the second void layer 6 respectively is generated in the surrounding rock, and the slurry enters the third void layer 8 to form a third filling layer to cover the third grouting anchor 7, and the third filling layer is connected to the first filling layer and the second filling layer respectively, so that the first filling layer, the second filling layer and the third filling layer form a continuous filling wall along the circumference of the tunnel.

[0045] It should be noted that by forming a continuous filling wall extending along the circumference of the tunnel with the first filling layer, the second filling layer and the third filling layer, the first filling layer, the second filling layer and the third filling layer are mutually restricted, thereby further improving the control over the deformation of the surrounding rock of the high ground stress tunnel.

[0046] In some embodiments, the step of rotary spraying and hole expansion includes:

[0047] Drilling a hole in the surrounding rock, when the end of the drill bit reaches a first preset position, high-pressure water is introduced to both sides of the drill bit and slurry is introduced to the end of the drill bit, and the high-pressure water breaks the surrounding rock to form a hollow layer;

[0048] The drill bit is retracted and rotated at the same time, and the slurry enters the empty layer to fill the empty layer to form a filling layer;

[0049] After the end of the drill bit reaches the second preset position, the rotary spraying is stopped and the drill bit is withdrawn;

[0050] The drilled hole is filled to seal it.

[0051] In some embodiments, after the rotary jet hole expansion, the first grouting anchor rod 2, the second grouting anchor rod 5 and the third grouting anchor rod 7 are pressurized and grouted respectively.

[0052] It should be noted that through pressurized grouting, the slurry can be well filled into the cracks and cavities of the rock mass, resulting in cement stone and rock mass bonding into a whole, thereby improving the integrity and self-bearing capacity of the broken surrounding rock and improving the anchoring characteristics of the support rod and rock. The segmented construction of the tunnel cutting and the full anchor cable support technology of the top plate have achieved safe construction of large-span switching, and the deformation of the tunnel has been better controlled.

[0053] In some embodiments, the third grouting anchor rod is located in the make way groove, and after the make way groove is backfilled, the third grouting anchor rod is buried in the backfill material.

[0054] It can be understood that by burying the third grouting anchor in the backfill material, the impact of the clearance groove and the second grouting anchor on the transportation and passage of the tunnel is reduced.

[0055] In some embodiments, after the make way groove is backfilled, a baffle is placed over the make way groove.

[0056] It can be understood that the baffle shields the clearance groove and the backfill material in the clearance groove, reducing the impact of the backfill material on the passage of workers and equipment.

[0057] In some embodiments, the high ground stress soft rock tunnel support method further includes:

[0058] Before conventional support and reinforcement support, the two sides and the top of the tunnel are sprayed with concrete to make the tunnel surface smooth. The thickness of the initial sprayed concrete shall not be less than 20mm.

[0059] After conventional support and reinforced support, an anchor net is hung on the tunnel surface and temporarily fixed to the supporting anchor rod and the first grouting anchor rod, and concrete is sprayed on both sides and the top plate of the tunnel. The thickness of the sprayed concrete is not less than 50mm.

[0060] It can be understood that by hanging anchor nets and spraying concrete on the tunnel, the supporting effect of the tunnel is further improved.

[0061] In some embodiments, when the concrete is initially sprayed on the sides and roof of the tunnel, the protruding parts of the tunnel surface are removed.

[0062] In some embodiments, the support anchor is a yield anchor.

[0063] It can be understood that the compression anchor absorbs the deformation of the surrounding rock, so that the energy of the tunnel surrounding rock can be reasonably released and the self-bearing capacity of the surrounding rock can be fully mobilized, allowing the tunnel surrounding rock to have a certain deformation and ensuring the stability of the tunnel.

[0064] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0065] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0066] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0068] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0069] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A high ground stress soft rock tunnel support method, characterized in that: include: Determine multiple conventional support sections and multiple reinforced support sections in the tunnel according to geological survey, and the multiple conventional support sections and multiple reinforced support sections are alternately distributed along the length direction of the tunnel; In the conventional support section, multiple groups of support anchors are installed at the sides of the tunnel and the top plate of the tunnel to complete conventional support. The multiple groups of support anchors are distributed at intervals along the length direction of the tunnel. Each group of support anchors includes multiple support anchors distributed at intervals along the circumference of the tunnel. The support anchors are yield anchors. The conventional support section can yield space for surrounding rock deformation. In the reinforcement support section, multiple grouting anchor rod groups are installed on the surrounding rock, and the multiple grouting anchor rod groups are spaced apart along the length direction of the tunnel. The grouting anchor rod groups include multiple first grouting anchor rods, and the multiple first grouting anchor rods are installed at the two sides of the tunnel and the top plate of the tunnel, and the multiple first grouting anchor rods are spaced apart along the circumference of the tunnel. Rotary jetting and hole expansion are sequentially performed between two adjacent first grouting anchor rods to generate a continuous first empty layer in the surrounding rock, and the slurry enters the first empty layer to form a continuous first filling layer to cover the first grouting anchor rods, thereby completing the reinforcement support; Conventional support and reinforced support are alternately completed along the length of the tunnel until the entire tunnel is supported; The reinforcement support also includes: A plurality of makeshift grooves are provided at the bottom plate of the roadway, the plurality of makeshift grooves correspond to the plurality of grouting anchor rod groups one by one, the length direction of the makeshift grooves is orthogonal to the length direction of the roadway, the grouting anchor rod group further comprises a plurality of second grouting anchor rods installed on the bottom plate of the roadway, the plurality of second grouting anchor rods are all located in the makeshift grooves, and the plurality of second grouting anchor rods are spaced apart along the length direction of the makeshift grooves, the upper ends of the second grouting anchor rods are lower than the top ends of the makeshift grooves, holes are drilled in sequence between two adjacent second grouting anchor rods and the holes are expanded by rotary jetting, so that a continuous second empty layer is generated in the surrounding rock, and the slurry enters the second empty layer to form a continuous second filling layer to cover the second grouting anchor rods; Fill the make-way groove with backfill material to backfill the make-way groove until the backfill material covers the second grouting anchor rod and is flush with the tunnel floor; The grouting anchor group also includes a third grouting anchor, which is installed at the junction of the tunnel side and the tunnel bottom plate, and rotary jetting is performed between the third grouting anchor and the first grouting anchor adjacent to the third grouting anchor, and rotary jetting is performed between the third grouting anchor and the second grouting anchor adjacent to the third grouting anchor, so that a third void layer connected to the first void layer and the second void layer is generated in the surrounding rock, and the slurry enters the third void layer to form a third filling layer to cover the third grouting anchor, and the third filling layer is connected to the first filling layer and the second filling layer respectively, so that the first filling layer, the second filling layer and the third filling layer form a continuous filling wall along the circumference of the tunnel; The steps of rotary spray hole expansion include: Drilling a hole in the surrounding rock, when the end of the drill bit reaches a first preset position, high-pressure water is introduced to both sides of the drill bit and slurry is introduced to the end of the drill bit, and the high-pressure water breaks the surrounding rock to form a hollow layer; The drill bit is retracted and rotated at the same time, and the slurry enters the empty layer to fill the empty layer to form a filling layer; After the end of the drill bit reaches the second preset position, the rotary spraying is stopped and the drill bit is withdrawn; The drilled hole is filled to seal it.

2. The high ground stress soft rock tunnel support method according to claim 1 is characterized in that: After the hole is expanded by rotary jetting, the first grouting anchor rod, the second grouting anchor rod and the third grouting anchor rod are pressurized and grouted respectively.

3. The high ground stress soft rock tunnel support method according to claim 1 is characterized in that: The third grouting anchor rod is located in the make way groove. After the make way groove is backfilled, the third grouting anchor rod is buried in the backfill material.

4. The high ground stress soft rock tunnel support method according to claim 1 is characterized in that: After the make way groove is backfilled, a baffle is installed above the make way groove.

5. The high ground stress soft rock tunnel support method according to claim 1 is characterized in that: Also includes: Before conventional support and reinforcement support, the two sides and the top of the tunnel are sprayed with concrete to make the tunnel surface smooth. The thickness of the initial sprayed concrete shall not be less than 20mm. After conventional support and reinforced support, an anchor net is hung on the tunnel surface and temporarily fixed to the supporting anchor rod and the first grouting anchor rod, and concrete is sprayed on both sides and the top plate of the tunnel. The thickness of the sprayed concrete is not less than 50mm.

6. The high ground stress soft rock tunnel support method according to claim 1 is characterized in that: When spraying concrete for the first time on the sides and roof of the tunnel, the protruding parts of the tunnel surface should be removed.

Images