A method for controlling mudslides and water inrushes in the main tunnel section of a vertical shaft

Abstract

This invention discloses a method for controlling mudslides and water inrushes in the main tunnel section of a vertical shaft, comprising: S1, determining the location of the water inrush channel; S2, selecting a suitable location to set up a surface directional sealing drilling site to cut off the source of water inrush; S3, pumping out accumulated water in the shaft and main tunnel; S4, plugging operation, if the pumping in step S3 is effective and there are conditions for construction inside the tunnel, then the plugging is carried out inside the tunnel; if there are no conditions for construction inside the tunnel, the plugging is carried out using surface directional drilling. Simultaneously, in steps S2, S3, and S4, the surface of the subsequent tunnel section is pre-grouted for reinforcement; S5, cleaning debris and repairing the support inside the tunnel. This invention addresses the vertical characteristics of auxiliary shafts by constructing an efficient water interception barrier in the main tunnel section, reducing reliance on a single drainage device and enhancing the response speed for emergency water inrush control. Through the synergistic effect of rapid water plugging and efficient drainage, this invention quickly controls the range and volume of water inrushes, while shortening the construction interruption time and reducing the risk of project delays.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering, specifically relating to a method for controlling mudslides and water inrushes in the main tunnel section of a vertical shaft. Background Technology

[0002] Shaft control of the main tunnel section refers to the construction control or management of a specific section of the main tunnel (main tunnel) through the excavation of auxiliary shafts. Auxiliary shafts allow for the creation of new excavation faces (i.e., "working faces") in the middle of the tunnel, enabling simultaneous construction of multiple sections and significantly shortening the construction period. In tunnel engineering, the method of excavating tunnels using auxiliary shafts is widely used. While this method increases working faces, improves efficiency, and shortens the construction period, it also poses a significant risk of sudden water inrushes when the surrounding rock of the tunnel is highly fractured and the groundwater content is high. Shafts are typically vertically downward passages. In this construction mode, if a sudden water inrush occurs in the tunnel, the equipment and personnel inside the shaft cannot be evacuated as quickly and safely as in an inclined shaft or horizontal tunnel, greatly increasing the risk of casualties and equipment damage. Furthermore, sudden mudslides and water inrushes can force the interruption of tunnel excavation, leading to project delays.

[0003] Currently, most methods for controlling sudden water inrushes in tunnels are designed based on the construction characteristics of auxiliary inclined shafts or horizontal tunnels, such as conventional methods like grouting reinforcement and drainage depressurization. However, these methods have limitations in controlling mudslides and water inrushes in the main tunnel section using vertical shafts. When tunnel excavation is carried out using auxiliary horizontal or inclined shafts, in the event of a mudslide or water inrush accident, water-blocking construction can be quickly carried out in the main tunnel using the passage structure of the auxiliary horizontal or inclined shaft. Equipment and materials can be quickly deployed and transported using the construction work face to form an effective water-blocking barrier in a timely manner. However, due to the vertical spatial characteristics of auxiliary vertical shafts, it is impossible to directly construct a water-blocking wall in the main tunnel as with horizontal or inclined shafts. Compared with horizontal tunnels or inclined shafts, vertical shafts have a single drainage and pressure reduction path. When mudslides or water inrushes occur, equipment such as water pumps need to be vertically hoisted into the shaft. As the water level changes, the position of the water pumps needs to be frequently adjusted, making the operation complex and time-consuming. In addition, it relies too much on pumping equipment, and the drainage capacity is limited, which seriously reduces the efficiency of emergency rescue. It cannot meet the special needs of vertical shaft construction for rapid response to sudden water inrushes, efficient treatment, and ensuring the safe evacuation of personnel and equipment.

[0004] Therefore, there is an urgent need for a method specifically designed to address mudslides and water inrushes in the main tunnel section of auxiliary shaft control tunnels, in order to solve existing technical problems and improve the safety and reliability of shaft construction. Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling mudslides and water inrushes in the main tunnel section controlled by a vertical shaft, so as to solve the problem of controlling mudslides and water inrushes in the main tunnel section controlled by an auxiliary vertical shaft.

[0006] To achieve the above objectives, the technical solution of this invention is as follows:

[0007] A method for controlling mudslides and water inrushes in the main tunnel section of a vertical shaft, the method comprising:

[0008] S1: Determine the location of the water inrush channel;

[0009] S2: After determining the location of the water inflow channel, select a suitable location to set up a ground directional sealing grouting drilling site to cut off the source of water inflow. The suitable location refers to a location with a gentle slope above the water inflow channel area that can be quickly leveled.

[0010] S3: Water pumping. After cutting off the water source, pump out the water in the well first. After the water in the well is pumped out, pump out the water in the main tunnel.

[0011] S4: Plug-in construction work, including determining the plug-in construction method based on the drainage situation in step S3.

[0012] If dewatering is effective and conditions allow for construction inside the tunnel, then an in-tunnel plug should be installed.

[0013] If there are no conditions for construction inside the tunnel, the tunnel plug shall be constructed using ground directional drilling.

[0014] In steps S2, S3, and S4, pre-grouting reinforcement of the ground surface of the subsequent tunnel section is carried out simultaneously.

[0015] S5: Slag removal and support repair inside the tunnel, cleaning up mudslides in the main tunnel, restoring facilities and pipelines inside the shaft, and repairing damaged primary and secondary linings;

[0016] The S4 step of ground directional drilling to install the hole plug includes:

[0017] S41: Select a location with a gentle slope that can be quickly leveled near the ground directly above where the plug needs to be installed to set up the ground directional drilling site for the plug.

[0018] S42: After selecting the drilling site, calculate the length of the water-blocking section based on the unrestricted shear strength;

[0019] S43: After determining the length of the water-blocking section, arrange the feeding holes and arrange two motorized feeding holes;

[0020] S44: After the feeding holes are arranged, the design of the grouting trajectory for the plugs in the directional drilling tunnel on the ground is carried out according to the coordinates of the drilling site opening and the feeding holes.

[0021] S45: During the construction of the plugging material feeding trajectory in the ground directional drilling tunnel, carry out aggregate gradation design;

[0022] S46: After the feeding hole construction is completed, feeding and grouting are carried out according to the designed aggregate gradation.

[0023] Furthermore, step S1 includes:

[0024] S11: Observe changes in water color, temperature and pressure, and preliminarily delineate areas suspected of water inrush;

[0025] S12: Deploy magnetotelluric scanning in the suspected water inrush area to analyze resistivity characteristics in order to locate cracks or cavities;

[0026] S13: Conduct exploratory drilling in the fissure or cavity area to verify and monitor changes in water pressure and water level, and comprehensively compare data from multiple sources to make a preliminary determination of the location of the water inflow channel.

[0027] Furthermore, step S2 includes:

[0028] S21: After initially determining the location of the water inflow channel area, select a location with a gentle slope that can be quickly leveled near the top of the water inflow channel area to set up the ground sealing grouting drilling site.

[0029] S22: After setting up the ground directional sealing drilling site, carry out the design of the ground directional sealing trajectory;

[0030] S23: Use grouting boreholes to further determine the location of the water inflow channel and explore hidden water inflow channels;

[0031] S24: Inject grouting material into the directional sealing hole on the ground to form a sealing body, cut off the source of water inflow, reduce the water inflow at the tunnel excavation face, and reinforce the surrounding rock;

[0032] S25: Based on the observation of lithology, structure, and tectonic features from core samples or rock fragments, determine the distribution location and thickness of different strata, and optimize and adjust the emergency response plan for tunnel water inrush.

[0033] Furthermore, the drilling of the feeding hole adopts a three-stage diameter, two-stage casing construction method, with two branch boreholes, C1 and C2, drilled side-by-side in the first stage of drilling. These two branch boreholes are constructed at a distance of 5 to 10 times the tunnel diameter from the tunnel roof. The drilling structure is divided into three drilling operations:

[0034] The first drilling operation penetrates the soft surface strata, and the surface casing is lowered to fix the wellhead and prevent shallow collapse or groundwater contamination. The well is then lowered to the bedrock section, entering the bedrock 5-10m deep, and the casing is solidified with single-component cement grout.

[0035] The second drilling operation involves continuing drilling within the first casing, and then lowering a technical casing. The technical casing is used to seal high-pressure water layers, easily collapsible strata, or leakage layers. It is lowered to 10-15m from the top of the tunnel and then solidified with single-component cement grout.

[0036] The third drilling operation involves continuing drilling to the target layer within the second casing. After completion, a tailpipe is lowered to prevent formation fluid from flowing through or the wellbore from collapsing. The tailpipe passes through the tunnel roof and enters the tunnel.

[0037] Furthermore, the formula for calculating the length of the water-blocking section is as follows:

[0038] (1)

[0039] In the formula, W Length of the water-blocking section M The ratio of the cross-sectional area to the perimeter of the section subjected to water pressure in the grouting-reinforced water-blocking section; P The water head pressure before and after the formation of the water barrier; Z Overload factor; τ The effective shear strength of the interface between the water-blocking wall and the surrounding rock mass.

[0040] Furthermore, the spacing between the far-end boreholes of the plug inside the ground directional drilling hole should meet the following requirements:

[0041] (2)

[0042] In the formula, S 1 represents the spacing between the end boreholes of the plug inside the ground directional drilling tunnel; A The diameter of the excavated tunnel; the design end distance is taken as 2 / 3. A .

[0043] Furthermore, the number of feeding holes for the plug inside the ground directional drilling hole should satisfy the following formula:

[0044] (3)

[0045] In the formula, D min This represents the minimum number of material feeding holes for the plugs inside the tunnel. W The design length of the water-blocking section; This is the material feeding guarantee coefficient; A The diameter of the tunnel to be excavated; R This is the squared difference of the maximum deviation distance between the feeding hole and the tunnel axis.

[0046] Furthermore, the feeding process includes mixing aggregates of different particle sizes in a certain proportion and then feeding them into the tunnel. The water-to-solid ratio of the injected aggregates is controlled at 6:1 to 10:1, and the aggregate particle size is 5mm to 20mm.

[0047] The technical solution of this invention has the following technical effects:

[0048] 1. The present invention breaks through the bottleneck of water blocking technology when using auxiliary shafts to excavate the main tunnel. In view of the vertical characteristics of auxiliary shafts, the present invention innovatively designs an adaptable water blocking structure and construction process to build an efficient water interception barrier in the main tunnel section, thus filling the technical gap of rapid and effective sealing when water surge occurs when using auxiliary shafts to excavate the main tunnel.

[0049] 2. Improved emergency response efficiency: This invention adopts a multi-level linkage method for treating sudden mud and water inrush, reducing reliance on single drainage equipment and enhancing the response speed of emergency treatment for sudden water inrush.

[0050] 3. Ensure controllable construction period: This invention uses the synergistic effect of rapid water blocking and efficient drainage to quickly control the range and volume of water inrush, while shortening the construction interruption time and reducing the risk of construction delay. Attached Figure Description

[0051] Figure 1 A flowchart illustrating the method for controlling mudslides and water inrushes in the main shaft section.

[0052] Figure 2 A schematic diagram of the layout method for controlling mudslides and water inrushes in the main tunnel section of the vertical shaft.

[0053] Figure 3 This is a design drawing for ground-directed sealing grouting according to an embodiment of the present invention.

[0054] Figure 4 This is a longitudinal section diagram of the borehole layout for the plug inside the ground directional drilling tunnel according to an embodiment of the present invention.

[0055] Figure 5 This is a plan view of the borehole layout for the plug inside the ground directional drilling tunnel according to an embodiment of the present invention.

[0056] Figure 6 This is a design diagram of the drilling trajectory for the plug inside a ground directional drilling tunnel according to an embodiment of the present invention.

[0057] Figure 7 This is a diagram showing the layout and intersection of the pre-grouting sections on the ground in a subsequent tunnel section according to an embodiment of the present invention.

[0058] Figure 8 This is a design diagram of the ground pre-grouting trajectory for the subsequent tunnel section in an embodiment of the present invention.

[0059] Among them: 1-Ground directional sealing grouting drilling site; 2-Ground sealing grouting trajectory; 3-Ground directional drilling site for plugging inside the tunnel; 4-Ground directional drilling site for plug feeding and grouting; 5-Plug; 6-Ground pre-grouting drilling site for subsequent tunnel sections; 7-Ground pre-grouting trajectory for subsequent tunnel sections; 8-Tunnel face location; 9-Shaft; 10-Excavated main tunnel section; 11-Unexcavated main tunnel section; 12-Ground sealing borehole #1; 13-Ground sealing borehole #2-1; 14-Ground sealing borehole #2-2; 15-Ground directional drilling site for plugging inside the tunnel; 16-Ground sealing grouting hole; 17-Unexcavated rock mass inside the tunnel. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only some, not all, of the embodiments of this invention, and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0061] like Figure 1 , Figure 2 As shown, this invention discloses a comprehensive method for controlling mudslides and water inrushes in the main tunnel section controlled by a vertical shaft. The core of this invention lies in constructing a three-dimensional control system that combines emergency response inside the tunnel with proactive prevention and control on the ground. Specifically, dynamic control of water inrush is achieved through a graded drainage system inside the tunnel, precise sealing and grouting are implemented using directional drilling technology on the ground, and a water-stopping barrier is quickly constructed in conjunction with the plug structure inside the tunnel. Finally, a multi-layered protective barrier is formed by pre-grouting reinforcement on the ground. This invention achieves a rapid response mechanism and efficient control goals for sudden water inrush disasters in the main tunnel section controlled by the vertical shaft. By establishing a three-in-one prevention and control chain of "drainage-plugging-reinforcement" through multi-process collaborative operations, it significantly improves the safety level of tunnel construction under complex geological conditions.

[0062] This invention discloses a method for controlling mudslides and water inrushes in the main tunnel section of a vertical shaft. The method includes determining the location of the water inrush channel, designing a surface directional drilling grouting seal, water pumping, plugging design, designing a pre-grouting reinforcement design for subsequent tunnel sections, and cleaning and repairing the tunnel's internal support. The details are as follows:

[0063] S1: Determine the location of the water inflow channel.

[0064] Specifically, it includes:

[0065] S11: Observe changes in water color, temperature and pressure, and preliminarily delineate areas suspected of water inrush;

[0066] S12: Deploy magnetotelluric scanning in the suspected water inrush area to analyze resistivity characteristics and locate fissures or cavities.

[0067] S13: In the fissure or cavity area, exploratory drilling is conducted to verify and monitor changes in water pressure and water level. By cross-referencing multi-source data, the approximate location of the water inflow channel area is determined. The multi-source data includes data such as water pressure and water level.

[0068] S2: Ground directional drilling grouting sealing design.

[0069] Specifically, it includes:

[0070] S21: After roughly determining the location of the water inflow channel area, select a location with a gentle slope near the top of the water inflow channel area that can be quickly leveled to set up the ground directional sealing grouting drilling site 1. Figure 3 The number 16 in the diagram indicates the location of the grouting hole for ground sealing;

[0071] S22: After setting up the ground directional sealing drilling site, design the ground directional sealing trajectory 2;

[0072] S23: Using the L-shaped exploration holes during the grouting process as a detection method, the specific location of the water inflow channel is further determined based on the exploration results, and hidden water inflow channels are also explored;

[0073] S24: Inject grouting material with high adhesion and good filling performance into the directional sealing hole on the ground to form a dense sealing body, cut off the source of water inflow, reduce the water inflow at the tunnel excavation face and reinforce the surrounding rock;

[0074] S25: Based on the lithology, structure, and texture characteristics observed in core samples or rock fragments, determine the distribution location and thickness of different strata, and optimize and adjust the emergency response plan for tunnel water inrush.

[0075] S3: After cutting off the source of water inflow and reinforcing the surrounding rock, pump out the existing water inflow in the channel.

[0076] Specifically, it includes:

[0077] S31: First, pump out the water accumulated in the well.

[0078] S32: After the water in the well shaft is pumped out, the water in the main tunnel will be pumped out.

[0079] S4: Plug application, including determining the plug application method based on the drainage situation in step S3;

[0080] If the drainage is effective, the water pump can successfully pump out the water in the main tunnel, and there is no collapse of the surrounding rock inside the tunnel, the support damage is relatively minor, and there are good conditions for construction inside the tunnel, then the construction plug inside the tunnel will be adopted.

[0081] However, if the surrounding rock inside the tunnel collapses and the support is severely damaged, then the conditions for tunnel construction are not met. In this case, ground directional drilling should be used to construct the tunnel plug.

[0082] The method for constructing plugs in directional drilling includes: ① Selecting a location with a gentle slope that can be quickly leveled near the ground directly above where the plug needs to be constructed, and setting up the drilling site 3 for the directional drilling plug; ② After selecting the drilling site, calculating the length of the water-blocking section based on the unrestricted shear strength; ③ After determining the length of the water-blocking section, arranging the feeding holes. To ensure the water-blocking effect, the feeding holes should be arranged in a sequential manner, with first-order and second-order construction, and two motorized feeding holes should be arranged; ④ After the feeding holes are arranged, designing and constructing the feeding and grouting trajectory 4 for the directional drilling plug based on the coordinates of the drilling site opening and the feeding holes; ⑤ During the construction of the feeding track for the directional drilling plug, carrying out aggregate gradation design; ⑥ After the feeding holes are constructed, feeding and grouting are carried out according to the designed aggregate gradation.

[0083] Among them, the length of the water-blocking section W The calculation is performed using unrestricted shear strength, and the formula is as follows:

[0084] (1)

[0085] In the formula, M The ratio of the cross-sectional area to the perimeter of the section subjected to water pressure in the grouting-reinforced water-blocking section; P The water head pressure before and after the formation of the water barrier; Z Overload factor; τ The effective shear strength of the interface between the water-blocking wall and the surrounding rock mass.

[0086] The cross-sectional area of ​​the grouting reinforcement section of the tunnel under water pressure is 65m². 2 The perimeter is 29.17m. After on-site water head monitoring, the water head pressure before and after the water blocking section wall is 3.98MPa. The effective shear strength of the interface between the grouting reinforced section and the surrounding rock is 0.21MPa. The overload factor is 1.6. Substituting into formula (1), the length of the water blocking section is 59.12m. Considering the borehole layout and spacing design, the design length of the water blocking section is 60m.

[0087] Regarding the sequential arrangement of the grouting holes, based on the requirements for water blocking and considering the engineering geological conditions and on-site construction conditions, the grouting and sealing section is located from chainage DLI26+240 to DLI26+300, with a total length of 60m. To ensure the water blocking effect, the grouting holes are innovatively arranged with "dense at the ends of the water-blocking section away from the working face and sparse in the middle." After the sealing pressure body is formed at the far end, high-pressure grouting is performed on the water-blocking section near the water-rushing working face.

[0088] Figure 5Number 15 in the diagram refers to the borehole for plugging inside a surface directional drilling tunnel. The spacing between the boreholes at the far end of the plug inside the surface directional drilling tunnel should meet the following requirements:

[0089] (2)

[0090] In the formula, S 1 represents the spacing between the end boreholes of the plug inside the ground directional drilling tunnel; A The diameter of the tunnel to be excavated.

[0091] Design end distance is taken It is approximately 6.6m.

[0092] The number of plug feeding holes in the ground directional drilling tunnel should meet the following formula:

[0093] (3)

[0094] In the formula, D min This represents the minimum number of material feeding holes for the plugs inside the tunnel. W The design length of the water-blocking section; This is the material feeding guarantee coefficient; A The diameter of the tunnel to be excavated; R This is the squared difference of the maximum deviation distance between the feeding hole and the tunnel axis.

[0095] The design length of the water-blocking section is 60m, the material feeding guarantee factor is 1.1, the tunnel excavation diameter is 10m, and the maximum deviation of the material feeding hole from the tunnel axis is 6.6m.

[0096] Calculations show that D min The minimum number is 9, but to ensure smooth material feeding, the sealing section is designed with 8 main directional boreholes (T1, T2, T3, and T4 are first-order boreholes; T5, T6, T7, and T8 are second-order boreholes) and two branch directional boreholes (C1 and C2 are motorized boreholes with random locations). Wireless drilling technology is used for directional borehole construction.

[0097] Eight main directional boreholes, two of which are end boreholes, are drilled. The spacing of the remaining boreholes should meet the following requirements: the distance between the farthest feed hole (T3 feed hole) and the farthest end borehole is set as follows: The distance between the feed hole (T7) closest to the working face and the borehole (T8) near the end face should meet the following requirements. ∈[1 / 5 W 1 / 4 W The design spacing is 12.5m; the spacing of the remaining 3 holes is evenly distributed, with a design spacing of 10m.

[0098] Considering the large cross-section of the tunnel excavation, in order to further ensure the sealing effect, during the construction process, two branch holes C1 and C2 of the T4 side drilling were used to supplement aggregate and grout. Figure 5 C1 and C2 are supplementary feeding holes in sequence.

[0099] Regarding the design of the plug trajectory for ground directional drilling, professional trajectory design software is used. The three-dimensional coordinates of the borehole and the feeding hole, as well as the trajectory parameters, are input to design the trajectory.

[0100] The material feeding hole drilling adopted a three-stage diameter, two-stage casing construction process. Two branch boreholes, C1 and C2, were drilled side-drilled from the first-sequence T4 borehole. A side-drilling windowing technique was used to construct the two branch boreholes at a distance of 5-10 times the tunnel diameter from the tunnel roof. The borehole structure was divided into three stages.

[0101] First drilling: The first drilling penetrates the soft surface strata (such as soil, gravel, etc.), and the surface casing is lowered to fix the wellhead and prevent shallow collapse or groundwater contamination. The borehole diameter is Φ311mm. The Φ244.5×8.94mm casing is lowered to the bedrock section, penetrating 5-10m into the bedrock, and the casing is solidified with single-component cement grout.

[0102] Second drilling: The second drilling continues within the first casing, drilling to deeper strata (such as bedrock or stable layers), and then a technical casing is lowered. The technical casing is used to seal high-pressure water layers, easily collapsing strata or leakage layers. The borehole diameter is Φ215.9mm, and a Φ177.8×8.05mm casing is lowered to the top of the tunnel 10-15m, and the casing is solidified with single-component cement grout.

[0103] Third drilling: The third drilling is to continue drilling to the target layer inside the second drilling casing. After completion, the production casing or tailpipe is lowered. The casing or tailpipe is used to prevent formation fluid from flowing through or the well wall from collapsing. The borehole diameter is Φ152.4mm. It passes through the tunnel roof and enters the tunnel. It is a bare hole.

[0104] Regarding the design of aggregate gradation, the water inflow within the tunnel of this project will essentially create a relatively still water state. Aggregates of different particle sizes will be selected, mixed in proportion, and then added to the tunnel. Graded aggregates can minimize the space between aggregates for water flow, increase frictional resistance, and lay the foundation for subsequent grouting. The preliminary design aggregate particle size is 5mm to 20mm. The designed aggregate particle size should facilitate smooth aggregate placement and reduce the likelihood of aggregate clogging the grouting holes.

[0105] Regarding material feeding and grouting, the preliminary design stipulates that aggregate feeding will be carried out in the first sequence of the water-blocking section (4 boreholes away from the tunnel face). During the aggregate feeding in the first sequence T4 borehole, the aggregate accumulation in the tunnel can be observed through the borehole television. If the aggregate does not spread to both sides of the tunnel in place, the side drilling C1 and C2 boreholes of the first sequence T4 borehole will be started to supplement the material feeding, so as to block the water-passing tunnel as much as possible and form a certain accumulation. The adjustment will be made dynamically according to the actual construction situation.

[0106] After the drilling penetrates the tunnel roof, the pump is stopped and the drilling tool is slowly lowered to explore the accumulation of mud and sand inside the tunnel. If the mud and sand accumulation is high, it can be flushed and disturbed before feeding material.

[0107] Aggregate injection adopts a combination of wet feeding method and rotary jetting method.

[0108] (1) Wet feeding method for aggregates

[0109] Simultaneously, aggregate and water are added into the borehole. A three-way funnel, with a feed inlet at the top and a water inlet and outlet at the bottom, connects to a pump at the inlet and the borehole at the outlet. The pump generates a high-speed water flow, rapidly carrying the aggregate through the outlet into the borehole, where it then accumulates inside the tunnel. Field tests have determined that a water-to-solid ratio of 6:1 to 10:1 is optimal for aggregate injection, with the following advantages:

[0110] 1. Ensure smooth aggregate delivery and avoid blockages.

[0111] When the water-to-solid ratio is too low (less than 6:1), the amount of water is insufficient, and the kinetic energy of the high-speed water flow is not enough to effectively move the aggregate (especially aggregates with larger particles or coarser gradations). At this time, the aggregate is prone to stagnation due to "crowding" in the tee funnel, outlet, or borehole, or even blockage, which can lead to interruption of grouting, affect the construction progress, and may also cause equipment failure such as pump overload due to blockage.

[0112] 2. Ensure effective stacking of aggregates within the tunnel and guarantee the quality of the stacking.

[0113] When the water-to-solid ratio is too high (greater than 10:1), excessive water volume will lead to an excessively low concentration of aggregate in the water. High-speed water flow may carry aggregate excessively into the borehole and tunnel, making it difficult for the aggregate to settle and accumulate (or the accumulation speed is too slow). Some aggregate may even be "washed away" or carried out of the accumulation area by the water flow, resulting in insufficient compaction and uneven distribution of the accumulation body, which will affect the stability of the subsequent engineering structure.

[0114] When the water-to-solid ratio is between 6:1 and 10:1, the ratio of water to aggregate is balanced: the water flow can carry the aggregate to the designated area without disrupting the accumulation process due to excessive impact force, allowing the aggregate to settle and accumulate in an orderly manner in the tunnel under the combined action of gravity and water flow deceleration, forming a relatively dense structure.

[0115] 3. Balancing construction efficiency with subsequent drainage costs

[0116] When the water-to-solid ratio is too high, excess water will accumulate in the tunnel, requiring additional drainage equipment and workload. This not only increases construction costs but may also cause the accumulated aggregate to be washed away and disturbed due to the water soaking the material, affecting the quality.

[0117] A water-to-solid ratio of 6:1 to 10:1 can reduce "ineffective water volume," ensuring transportation while reducing drainage pressure, thus balancing construction efficiency and cost control.

[0118] (2) Aggregate delivery by rotary jetting method

[0119] Initially, aggregates were placed using a wet placement method. However, after a certain amount of wet placement, the aggregates piled up and became difficult to disperse. Therefore, a rotary jetting method was used to continue the aggregate placement work. The rotary jetting method was assisted by a drilling rig. The drilling rig lowered a drill string suitable for drilling the annulus into the water-passing space inside the tunnel in advance. Aggregates were placed through the annulus of the borehole and the drill string. The rotary jetting device at the bottom of the drill string sprayed pressurized water to push the aggregates at the bottom of the hole outward.

[0120] In this invention, in steps S2, S3, and S4, the reinforcement of the ground pre-grouting drilling site 6 for the subsequent tunnel section is carried out simultaneously according to the pre-grouting trajectory 7 for the subsequent tunnel section. The purpose of the pre-grouting reinforcement of the ground for the subsequent tunnel section is to pre-treat the risk of mudslides and water inrushes that still exist in the subsequent un-excavated tunnel sections. This measure is implemented simultaneously with the emergency response measures in steps S2, S3, and S4 after the location of the water inrush is determined, so as to minimize the impact on the straight-line construction period of the main tunnel excavation. The specific steps are as follows: ① Determine the length of the ground pre-grouting reinforcement; ② Layout of the ground pre-grouting drilling site; ③ Layout of the ground pre-grouting cross-section; ④ Design of the ground pre-grouting trajectory; ⑤ Grouting. The specific method of simultaneously carrying out the ground pre-grouting reinforcement of the subsequent tunnel section in steps S2, S3, and S4 is prior art and will not be described in detail here.

[0121] S5: Slag Removal and Support Repair in the Tunnel: Clean up the mud spill in the main tunnel, restore the facilities and pipelines in the shaft, and repair the damaged primary support and secondary lining.

[0122] The following example, using the treatment of sudden water inrush in a vertical shaft control main tunnel section of a water diversion project, illustrates the specific implementation steps of this invention:

[0123] S1. Determine the location of the water inflow channel:

[0124] Based on the construction geological logging data and advanced geological forecasting results, the location of the channel for the water (mud) inrush at the face of the main tunnel section controlled by the vertical shaft at chainage DLⅠ26+217.84 is approximately 30m to 70m in front of the face of the tunnel. Figure 2The section labeled 10 is the excavated main tunnel section, and the section labeled 11 is the unexcavated main tunnel section.

[0125] S2, Ground directional drilling grouting and sealing

[0126] like Figure 3 As shown, to expedite the water plugging process, the grouting and sealing boreholes are located within the existing drilling site. Three sealing boreholes are installed, including borehole #1 for surface sealing. Figure 3 Borehole No. 12 has a depth of 560.65m, with a borehole opening section of 50.00m, a vertical section of 100.00m, a directional section of 335.65m, and a grouting section of 75.00m. Borehole No. 2 has a depth of 908.5m, with a borehole opening section of 50.00m, a vertical section of 250.00m, and a grouting section of 608.5m (including the surface plugging of borehole No. 2-1). Figure 3 The grouting section of borehole No. 13 is 290.5m long, and the ground sealing of borehole No. 2-2 is also included. Figure 3 The length of the grouting section of borehole number 14 is 318m.

[0127] S3, Water Pumping

[0128] A two-stage dewatering scheme was adopted to pump out the water accumulated in the vertical shaft and main tunnel. The first stage was to pump out the water in the vertical shaft, and the second stage was to pump out the water within the excavated section 10 of the main tunnel. For emergency pumping, a high-flow-rate, high-lift specialized submersible pump was selected. Based on the on-site water inflow analysis, the pump flow rate was estimated to be 500-700 m³ / h. 3 / h, the pump head is greater than the shaft depth and head loss is taken into account.

[0129] S4, End Cap 5 Construction Operation

[0130] Based on the on-site drainage conditions, it is not feasible to construct a plug inside the tunnel. A surface directional drilling method will be used to construct the plug inside the tunnel. The length of the water-blocking section is calculated to be 59.33m based on unrestricted shear strength. Considering the borehole spacing design, the designed length of the water-blocking section is 60m. Figure 4 , Figure 5 As shown, the tunnel excavation and lining are carried out in three stages. The section from chainage DLI26+217.84 to DLI26+240, where water inrush occurs, is the upper stage of excavation and lining; the section from chainage DLI26+240 to DLI26+300 is the middle stage. Considering the surface construction site and road conditions, as well as the current state of tunnel excavation and lining, the water-blocking section is defined as the section from chainage DLI26+240 to DLI26+300. Figure 4 17 of them are unexcavated rock masses inside the tunnel.

[0131] The sealing section is designed with eight main directional boreholes and two branch directional boreholes, using wireless drilling technology for directional drilling. The layout principle is: the water-blocking sections at the ends are denser than those at the working face, and sparser in the middle.

[0132] like Figure 6 As shown, grouting trajectory design software was used to design the trajectory of the ground directional drilling plug, and material feeding and grouting construction were carried out. Figure 6 In the middle, the green part is andesitic basalt, and the light pink part is dolomitic limestone and limestone.

[0133] In this invention, pre-grouting reinforcement of the ground surface in subsequent tunnel sections is carried out simultaneously in steps S2, S3, and S4:

[0134] Pre-grouting using L-shaped directional drilling on the ground was employed to effectively control water flow in subsequent tunnel sections and pre-reinforce the surrounding rock. The construction site and access road were strategically located. To ensure the theoretical effective thickness of the grouting ring met design requirements, four boreholes were installed around the main tunnel. To minimize the construction period, four drilling rigs were used simultaneously. Based on the on-site geological exploration, the lithology within the range of DLI25+699~DLI26+217.84 was predominantly andesitic basalt, with a designed grout diffusion radius of 11.5m. The grouting holes were located 2.5m beyond the excavation diameter, evenly distributed across a 15m diameter borehole ring with a spacing of 10.6m. The theoretical effective thickness of the grouting ring outside the excavation outline was 10.5m. The cross-sectional layout and grouting junction are shown in [reference needed]. Figure 7 , Figure 7 In this design, the excavation radius R is 5.0m, the theoretical effective thickness of the grouting ring is 10.5m, and the grout spreading radius is 11.5m. Specialized directional drilling trajectory design software is used to design the ground pre-grouting borehole trajectory, such as... Figure 8 As shown. Figure 8 In the middle, the green part is andesitic basalt, and the light pink part is dolomitic limestone and limestone.

[0135] S5. Tunnel cleaning and support repair:

[0136] The work involved clearing the mudslide and water in the main tunnel, restoring the facilities and pipelines within the shaft, and repairing the damaged primary support and secondary lining. This resulted in the rapid and effective control of the mudslide and water inrush in the main tunnel section controlled by Shaft 9.

[0137] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for controlling mudslides and water inrushes in the main shaft section of a vertical shaft, characterized in that... The method includes: S1: Determine the location of the water inrush channel; S2: After determining the location of the water inflow channel, select a suitable location to set up a ground directional sealing grouting drilling site to cut off the source of water inflow. The suitable location refers to a location with a gentle slope above the water inflow channel area that can be quickly leveled. S3: Water pumping. After cutting off the water source, pump out the water in the well first. After the water in the well is pumped out, pump out the water in the main tunnel. S4: Plug-in construction work, including determining the plug-in construction method based on the drainage situation in step S3. If dewatering is effective and conditions allow for construction inside the tunnel, then an in-tunnel plug should be installed. If there are no conditions for construction inside the tunnel, the tunnel plug shall be constructed using ground directional drilling. In steps S2, S3, and S4, pre-grouting reinforcement of the ground surface of the subsequent tunnel section is carried out simultaneously. S5: Slag removal and support repair inside the tunnel, cleaning up mudslides in the main tunnel, restoring facilities and pipelines inside the shaft, and repairing damaged primary and secondary linings; The S4 step of ground directional drilling to install the hole plug includes: S41: Select a location with a gentle slope that can be quickly leveled near the ground directly above where the plug needs to be installed to set up the ground directional drilling site for the plug. S42: After selecting the drilling site, calculate the length of the water-blocking section based on the unrestricted shear strength; S43: After determining the length of the water-blocking section, arrange the feeding holes and arrange two motorized feeding holes; S44: After the feeding holes are arranged, the grouting trajectory of the plugs in the directional drilling tunnel on the ground is designed and constructed according to the coordinates of the drilling site opening and the feeding holes. S45: During the construction of the grouting trajectory for plugging in the ground directional drilling tunnel, aggregate gradation design shall be carried out; S46: After the feeding hole construction is completed, feeding and grouting are carried out according to the designed aggregate gradation.

2. The method for controlling mudslides and water inrushes in the main shaft section according to claim 1, characterized in that... Step S1 includes: S11: Observe changes in water color, temperature and pressure, and preliminarily delineate areas suspected of water inrush; S12: Deploy magnetotelluric scanning in the suspected water inrush area to analyze resistivity characteristics in order to locate cracks or cavities; S13: Conduct exploratory drilling in the fissure or cavity area to verify and monitor changes in water pressure and water level, and comprehensively compare data from multiple sources to make a preliminary determination of the location of the water inflow channel.

3. The method for controlling mudslides and water inrushes in the main shaft section according to claim 1, characterized in that... Step S2 includes: S21: After initially determining the location of the water inflow channel area, select a location with a gentle slope that can be quickly leveled near the top of the water inflow channel area to set up a ground directional sealing grouting drilling site. S22: After setting up the ground directional sealing grouting drilling site, carry out the design of the ground directional sealing trajectory; S23: Use grouting boreholes to further determine the location of the water inflow channel and explore hidden water inflow channels; S24: Inject grouting material into the directional sealing hole on the ground to form a sealing body, cut off the source of water inflow, reduce the water inflow at the tunnel excavation face, and reinforce the surrounding rock; S25: Based on the observation of lithology, structure, and tectonic features from core samples or rock fragments, determine the distribution location and thickness of different strata, and optimize and adjust the emergency response plan for tunnel water inrush.

4. The method for controlling mudslides and water inrushes in the main shaft section according to claim 1, characterized in that... The drilling of the feeding hole adopts a three-stage diameter, two-stage casing construction method, with two branch boreholes, C1 and C2, drilled side-by-side in the first stage. These two branch boreholes are drilled at a distance of 5-10 times the tunnel diameter from the tunnel roof. The drilling structure is divided into three drilling operations: The first drilling operation penetrates the soft surface strata, and the surface casing is lowered to fix the wellhead and prevent shallow collapse or groundwater contamination. The well is then lowered to the bedrock section, entering the bedrock 5-10m deep, and the casing is solidified with single-component cement grout. The second drilling operation involves continuing drilling within the first casing, and then lowering a technical casing. The technical casing is used to seal high-pressure water layers, easily collapsible strata, or leakage layers. It is lowered to 10-15m from the top of the tunnel and then solidified with single-component cement grout. The third drilling operation involves continuing drilling to the target layer within the second casing. After completion, a tailpipe is lowered to prevent formation fluid from flowing through or the wellbore from collapsing. The tailpipe passes through the tunnel roof and enters the tunnel.

5. A method for controlling mudslides and water inrushes in the main shaft section according to claim 1, characterized in that... The formula for calculating the length of the water-blocking section is as follows: (1) In the formula, W The length of the water-blocking section; M The ratio of the cross-sectional area to the perimeter of the section subjected to water pressure in the grouting-reinforced water-blocking section; P The water head pressure before and after the formation of the water barrier; Z Overload factor; τ The effective shear strength of the interface between the water-blocking wall and the surrounding rock mass.

6. The method for controlling mudslides and water inrushes in the main shaft section according to claim 1, characterized in that... The spacing between the far-end boreholes of the plug in the ground directional drilling hole should meet the following requirements: (2) In the formula, S 1 represents the spacing between the end boreholes of the plug inside the ground directional drilling tunnel; A The diameter of the excavated tunnel; the design end distance is taken as 2 / 3. A .

7. The method for controlling mudslides and water inrushes in the main shaft section according to claim 1, characterized in that... The number of feeding holes for the plugs inside the ground directional drilling tunnel should satisfy the following formula: (3) In the formula, D min This represents the minimum number of material feeding holes for the plugs inside the tunnel. W The design length of the water-blocking section; This is the material feeding guarantee coefficient; A The diameter of the tunnel to be excavated; R This is the squared difference of the maximum deviation distance between the feeding hole and the tunnel axis.

8. The method for controlling mudslides and water inrushes in the main shaft section according to claim 1, characterized in that: The feeding process involves mixing aggregates of different particle sizes in a certain proportion and then feeding them into the tunnel. The water-to-solid ratio of the injected aggregates is controlled at 6:1 to 10:1, and the aggregate particle size is 5mm to 20mm.

Images