A method for treating mudslides and water inrushes in water conservancy tunnels

Abstract

This invention proposes a method for treating mudslides and water inrushes in hydraulic tunnels. Step A: Clear a portion of the inrushed debris to a location 20m from the tunnel face and construct a retaining wall. Step B: After the retaining wall is completed, haul debris from outside the tunnel and pave a road and equipment operating platform above the accumulated material. Step C: Seal the surface of the inrushed debris from the retaining wall to the tunnel face. Step D: Starting from the retaining wall, perform pre-consolidation grouting on the upper part of the accumulated material in front. Step E: Clear the upper debris within a 10m range in front of the retaining wall, retaining a 10m first-cycle consolidation grout stop plate, and construct a grout stop wall. Step F: Starting from the grout stop wall, perform full-section reinforcement pre-grouting in front. This method forms a dense consolidation ring around the surrounding rock, effectively blocking groundwater outside the consolidation ring. Subsequent excavation fully utilizes the self-stability of the surrounding rock consolidation ring, reducing the stress on the pre-support and initial support, ensuring safety during excavation and stability of the initial support.

Description

Technical Field

[0001] This invention belongs to the field of tunnel technology, specifically relating to a method for treating mudslides and water inrushes in water conservancy tunnels. Background Technology

[0002] Traditional methods for managing mudslides and water inrushes mainly involve: first, clearing the silt from the front of the inrush area, preserving part of the inrush body; then, backfilling with slag from outside the tunnel; next, grouting to solidify the inrush body; and finally, backfilling the cavity with poured concrete to ensure compaction. This approach only treats the inrush body and the cavity, without consolidating the surrounding rock, leaving the subsequent excavation with risks of collapse and further mudslides and water inrushes. Summary of the Invention

[0003] To address the problems existing in the prior art, a method for treating mudslides and water inrushes in hydraulic tunnels is provided.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] This invention proposes a method for treating mudslides and water inrushes in hydraulic tunnels, comprising the following steps:

[0006] Step A: Clear some of the gushing slag and construct a retaining wall 20m away from the working face;

[0007] Step B: After the slag retaining wall is completed, slag from outside the tunnel is pulled to pave roads and equipment operation platforms on top of the stockpile.

[0008] Step C: Seal the surface of the gushing slag from the retaining wall to the working face to form a sealing layer;

[0009] Step D: Slag reinforcement begins with pre-consolidation grouting of the upper front slag mass at the slag retaining wall position;

[0010] Step E: After the slag body reinforcement is completed, clean up the upper slag body within 10m in front of the slag retaining wall, retain the first cycle consolidation grout stop plate for 10m, and construct the grout stop wall.

[0011] Step F: Starting from the grout-stopping wall, perform full-section reinforcement and advance grouting in front of it.

[0012] Preferably, in step A, the retaining wall is made of C30 concrete, with a width of 2m and a height level with the slag body; the foundation of the retaining wall is located on the original rock at the top of the original excavation face, and two rows of mortar anchors are added to the contact area between the foundation and the tunnel wall to improve the connection between the retaining wall and the surrounding rock.

[0013] Preferably, the mortar anchor bolts have a diameter of Ф25mm, a length of 2m / bolt, and an insertion length of 1m into the rock; the mortar anchor bolts in the retaining wall foundation are arranged at a spacing of 1.0m, and the mortar anchor bolts in the tunnel side wall are arranged at a spacing of 0.5m.

[0014] Preferably, in step B, a drilling rig is used to drill several drainage holes at a distance of 15m from the working face on the arch and both side walls to divert water to the rear of the working face, so as to reduce the soaking and softening of the slag by groundwater and the pushing effect; wherein, 3 to 5 drainage holes are drilled, the diameter of the drainage holes is 110mm, the depth is 30m, the external insertion angle is 20° to 25°, the holes are equipped with reverse filtration measures, and the hole opening valves are installed.

[0015] Preferably, the specific method for sealing the surface of the gushing slag in step C is as follows: two layers of steel mesh are laid on the surface of the gushing slag, with I20a type I-beams horizontally placed in the middle of the mesh, the I-beams being connected to the initial support steel arch frame, and 50cm thick C25 concrete is sprayed to form a sealing layer.

[0016] Preferably, before laying the steel mesh, several short mortar anchors are installed on the surrounding rock on both sides. The short mortar anchors are 1.0m long, driven 50cm into the surrounding rock, and spaced 50cm apart. After laying the steel mesh, the steel mesh is welded to the short mortar anchors set on the surrounding rock on both sides to strengthen the integrity of the sealing layer and the surrounding rock.

[0017] Preferably, two drainage steel pipes with orifice valves are installed on each side of the slag body under the sealed layer, with a single pipe length of 13m to 15m, to ensure drainage in the early stage.

[0018] Preferably, in step D, the grouting hole diameter is Ф89mm, the grouting hole length is 10m~20m, the final hole position is at the working face, the holes are arranged in a quincunx pattern with a spacing of 1.0*1.0m, the grouting method is forward grouting, the grouting is cement grout, and the grouting pressure is 0.5-1.0MPa.

[0019] Preferably, in step E, the grout-stopping wall is 2m thick and its height is level with the slag body, with a foundation depth of 0.5m. At the same time, the platform within a 12m range behind the grout-stopping wall is sealed with C30 concrete with a thickness of 0.5m to ensure the effect of pre-grouting.

[0020] Preferably, the thickness of the reinforcement grouting ring is 6m, the construction length is 30m, the grouting adopts the forward segmented grouting method, and the grout uses cement grout and cement-water glass dual grout.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] Based on the current implementation results, this scheme has formed a dense consolidation zone around the surrounding rock, effectively blocking groundwater outside the consolidation zone. Subsequent excavation has made full use of the self-stability of the consolidation zone, reducing the stress on the advanced support and initial support, and ensuring safety during the excavation process and the stability of the initial support. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0024] Figure 1 This is a schematic diagram of the longitudinal section structure of the present invention.

[0025] Figure 2 This is a diagram showing the layout of the cross-section openings for curtain grouting.

[0026] Figure 3 This is a longitudinal section view of the AA section curtain grouting.

[0027] Figure 4 yes Figure 3 Enlarged schematic diagram of a local part of the structure.

[0028] Figure 5 This is the layout diagram of the final hole II-II section of the curtain grouting.

[0029] Figure 6 This is a flowchart of the construction process of this invention. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] like Figure 1-6 As shown in this embodiment, a method for treating mudslides and water inrushes in hydraulic tunnels includes the following steps:

[0032] Step A: Clear some of the gushing slag to a position 20m away from the working face and construct a retaining wall; this is used to stabilize the slag in the lower section and ensure safety during the construction of the upper section.

[0033] Step B: After the slag retaining wall is completed, slag from outside the tunnel is pulled to pave roads and equipment operation platforms on top of the stockpile.

[0034] Step C: Seal the surface of the gushing slag from the retaining wall to the working face to form a sealing layer;

[0035] Step D: Slag reinforcement begins with pre-consolidation grouting of the upper front slag mass at the slag retaining wall position;

[0036] Step E: After the slag body reinforcement is completed, clean up the upper slag body within 10m in front of the slag retaining wall, retain the first cycle consolidation grout stop plate for 10m, and construct the grout stop wall.

[0037] Step F: Starting from the grout-stopping wall, perform full-section reinforcement and advance grouting in front of it.

[0038] The following is a detailed description of each of the above steps:

[0039] In step A, the retaining wall is constructed using C30 concrete, with a width of 2m and a height level with the slag mass. The foundation of the retaining wall is located on the original rock at the top of the original excavation face. Two rows of mortar anchors are added to the contact area between the foundation and the tunnel sidewall to improve the connection between the retaining wall and the surrounding rock. The mortar anchors have a diameter of Ф25mm, a length of 2m / anchor, and an embedment length of 1m into the rock. The mortar anchors in the retaining wall foundation are arranged at 1.0m intervals, while the mortar anchors in the tunnel sidewall are arranged at 0.5m intervals.

[0040] In step B, after the lower retaining wall is constructed, the slag from outside the tunnel is used to pave roads and equipment operation platforms on top of the stockpile. Several drainage holes are drilled at a distance of 15m from the tunnel face on the arch and both side walls to divert water behind the tunnel face, reducing the softening and jacking effect of groundwater on the slag. Three to five drainage holes are drilled, each with a diameter of 110mm, a depth of 30m, and an outward inclination of 20° to 25°. The holes are equipped with reverse filtration systems and orifice valves.

[0041] The specific method for sealing the surface of the gushing slag in step C is as follows: Two layers of steel mesh are laid on the surface of the gushing slag. The steel mesh has a specification of Ф6mm@15×15cm. I20a type I-beams are horizontally installed in the middle of the mesh, and the I-beams are connected to the initial support steel arch. A 50cm thick layer of C25 concrete is then sprayed to form a sealing layer. Before laying the steel mesh, several short mortar anchors are installed on the surrounding rock on both sides. The short mortar anchors are 1.0m long, driven 50cm into the surrounding rock, and spaced 50cm apart. After laying the steel mesh, it is welded to the short mortar anchors on both sides of the surrounding rock to strengthen the integrity of the sealing layer and the surrounding rock.

[0042] To ensure drainage in the early stage, two drainage steel pipes with orifice valves are installed on each side of the slag body under the sealing layer, with a single pipe length of 13m to 15m.

[0043] In step D, pre-consolidation grouting is performed on the upper front slag mass starting from the position of the first retaining wall to improve the stability of the upper slag mass. The grouting hole diameter is Ф89mm, the grouting hole length is 10m~20m, and the final hole position is at the working face. The holes are arranged in a quincunx pattern with a spacing of 1.0*1.0m, and a forward grouting method is used. Cement grout is used, and the grouting pressure is 0.5-1.0MPa.

[0044] In step E, the grout-stopping wall is made of C30 concrete, with a thickness of 2m and a height level with the slag body. The foundation depth is 0.5m. At the same time, the platform within a 12m range behind the grout-stopping wall is sealed with C30 concrete with a thickness of 0.5m to ensure the effect of pre-grouting.

[0045] In step F, the thickness of the reinforcement grouting ring is 6m, the construction length is 30m, and the grouting adopts a forward segmented grouting method, using cement grout and / or cement-water glass dual grout. It should be noted that before grouting, 3-5 advance drilling holes are drilled to detect the surrounding rock properties and groundwater occurrence within a 30m range ahead.

[0046] Precautions during steps E and F:

[0047] 1. The thickness of the grout-stopping wall is 2.0m, and the total height is 7.0m (including the 1.5m foundation). Two rows of Φ25 mortar anchors are installed on the base (free of loose slag) and around the perimeter of the grout-stopping wall. The anchors are 3m long, spaced 50cm apart, and circumferentially spaced 1m apart, arranged in a quincunx pattern.

[0048] 2. The grouting reinforcement range is 6m outside the excavation outline, with a grouting length of 30m and an excavation length of 25m, while retaining a 5m grout-stopping rock mass. Grouting is performed within 5m of the bottom of the hole within the excavation outline, and grouting is performed along the entire section outside the excavation outline. No grouting is performed inside the excavation line.

[0049] 3. The grouting holes are arranged in an umbrella-shaped radial pattern from the working face to the excavation direction, with a grout diffusion radius of 2m and a hole bottom spacing of no more than 3m.

[0050] 4. The opening diameter of the grouting hole shall not be less than Φ108mm, and the final hole diameter shall not be less than 91mm.

[0051] 5. A total of 87 grouting holes and 4 inspection holes were installed. A Φ127*4mm, 3.0m long casing was embedded in the grout-stopping wall or grout-stopping rock mass.

[0052] 6. The grouting material is cement grout, and its mixing ratio is as follows:

[0053] Water:Cement (W:C mass ratio) = 0.5 to 1:1;

[0054] 7. The design grouting pressure (final pressure value) is 4.5 to 6 MPa or the hydrostatic pressure at the grouting point plus 2 MPa. It can be adjusted appropriately during construction.

[0055] 8. The grouting sequence should follow the order of perimeter first and then center, with skip-hole operation from the outside to the inside, and the same ring of holes should be constructed at intervals to achieve controlled grouting and compaction and reinforcement of the stratum.

[0056] 9. Grouting completion criteria:

[0057] ① Grouting can be terminated when the grouting pressure of a single hole reaches the design final pressure and is maintained for more than 10 minutes; the grouting flow rate at the end of grouting is less than 20L / min; and the water inflow rate of the inspection hole is less than 0.2L / m*min.

[0058] ② End criteria for the entire section: All grouting holes have met the end conditions for single holes, and there is no leakage of grout; the effective injection range of grout is greater than the design value.

[0059] The effective effects brought about by the implementation of this invention are as follows:

[0060] Based on the current implementation results, this scheme has formed a dense consolidation zone around the surrounding rock, effectively blocking groundwater outside the consolidation zone. Subsequent excavation has made full use of the self-stability of the consolidation zone, reducing the stress on the advanced support and initial support, and ensuring safety during the excavation process and the stability of the initial support.

[0061] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for treating sudden mud and water gushing in a water conservancy tunnel, characterized in that, Includes the following steps: Step A: Clear some of the gushing slag and construct a retaining wall 20m away from the working face; Step B: After the slag retaining wall is completed, slag from outside the tunnel is pulled to pave roads and equipment operation platforms on top of the stockpile. Step C: Seal the surface of the gushing slag from the retaining wall to the working face to form a sealing layer; Step D: Slag reinforcement, starting from the slag retaining wall position, perform pre-consolidation grouting on the upper front slag mass; Step E: After the slag body reinforcement is completed, clean up the upper slag body within 10m in front of the slag retaining wall, retain the first cycle consolidation grout stop plate for 10m, and construct the grout stop wall. Step F: Starting from the grout-stopping wall, perform full-section reinforcement and advance grouting in front of it; The specific method for sealing the surface of the gushing slag in step C is as follows: two layers of steel mesh are laid on the surface of the gushing slag, and I20a type I-beams are set horizontally in the middle of the mesh. The I-beams are connected to the initial support steel arch to increase the strength of the sealing layer. 50cm thick C25 concrete is sprayed to form the sealing layer. Before laying the steel mesh, install several short mortar anchors on the surrounding rock on both sides. The short mortar anchors are 1.0m long, driven 50cm into the surrounding rock, and spaced 50cm apart. After laying the steel mesh, weld the steel mesh to the short mortar anchors set on the surrounding rock on both sides to strengthen the integrity of the sealing layer and the surrounding rock.

2. The method for treating mudslides and water inrushes in hydraulic tunnels according to claim 1, characterized in that, In step A, the retaining wall is made of C30 concrete, with a width of 2m and a height level with the slag body. The foundation of the retaining wall is located on the original rock at the top of the original excavation face. Two rows of mortar anchors are added to the contact area between the foundation and the tunnel wall to improve the connection between the retaining wall and the surrounding rock.

3. A method for treating mudslides and water inrushes in hydraulic tunnels according to claim 2, characterized in that, The mortar anchors are Ф25mm in diameter, 2m long per anchor, and 1m deep into the rock. The mortar anchors in the retaining wall foundation are arranged at 1.0m intervals, and the mortar anchors in the tunnel sidewalls are arranged at 0.5m intervals.

4. The method for treating mudslides and water inrushes in hydraulic tunnels according to claim 1, characterized in that, In step B, a drilling rig is used to drill several drainage holes at a distance of 15m from the working face on the arch and both side walls to divert water to the rear of the working face, thereby reducing the soaking and softening effect of groundwater on the slag and its jacking effect. Among them, 3 to 5 drainage holes are drilled, with a diameter of 110mm, a depth of 30m, an external insertion angle of 20° to 25°, and reverse filtration measures are installed in the holes, and valves are installed at the hole openings.

5. A method for treating mudslides and water inrushes in hydraulic tunnels according to claim 1, characterized in that, Two drainage steel pipes with orifice valves are installed on each side of the slag body under the sealed layer, with a single pipe length of 13m to 15m, to ensure drainage in the early stage.

6. A method for treating mudslides and water inrushes in hydraulic tunnels according to claim 1, characterized in that, In step D, the diameter of the grouting hole is Ф89mm, the length of the grouting hole is 10m~20m, the final hole position is at the working face, and the holes are arranged in a quincunx pattern with a spacing of 1.0*1.0m. The grouting method is forward grouting, the grouting is cement grout, and the grouting pressure is 0.5-1.0MPa.

7. A method for treating mudslides and water inrushes in hydraulic tunnels according to claim 1, characterized in that, In step E, the grout-stopping wall is 2m thick and level with the slag body, with a foundation depth of 0.5m. At the same time, the platform within a 12m range behind the grout-stopping wall is sealed with C30 concrete with a thickness of 0.5m to ensure the effect of pre-grouting.

8. A method for treating mudslides and water inrushes in hydraulic tunnels according to claim 1, characterized in that, The reinforcement pre-grouting ring is 6m thick and 30m long. The grouting adopts a forward segmented grouting method, and the grout is a combination of cement grout and cement-water glass grout.

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