A shaft guide well center drill excavation method and a guide well auxiliary excavation tool

Abstract

The application discloses a shaft guide well center drill excavation method and a guide well auxiliary excavation tool, and belongs to the technical field of shaft construction. The method adopts a center drill device to drill in a circular tangent way in the guide well excavation range, and after all the drilling is completed, a plurality of rock-soil columns are left in the middle of the guide well, and then the rock-soil columns are removed by mechanical cutting by using the guide well auxiliary excavation tool. The guide well auxiliary excavation tool comprises a cylindrical steel plate, a round steel pipe, a support plate and a wedge-shaped alloy piece, the wedge-shaped alloy piece is arranged on the cylindrical steel plate and used for cutting the rock-soil column, and the round steel pipe is connected with a water outlet of the center drill and guides cooling water to the cutting position. The application realizes full-face mechanized hole forming of the guide well, avoids drilling and blasting operation, has high construction efficiency and good safety, and the alloy piece cooling system effectively prolongs the service life of the tool.

Description

Technical Field

[0001] This invention relates to the field of vertical shaft construction technology in water conservancy and hydropower engineering, specifically to an excavation method for forming a guide shaft by drilling holes one by one in a circular tangential manner using a central drilling equipment, and an auxiliary excavation tool for cutting the remaining rock and soil column after the guide shaft is completed. Background Technology

[0002] In the fields of water conservancy and hydropower, highway tunnels, and mining construction, vertical shafts are a widely used type of underground structure. Common types include gate shafts, surge tanks, ventilation shafts, and cable shafts. As a core preliminary process for vertical shaft construction, the excavation of the pilot shaft not only determines the overall construction period, cost, and construction safety, but also plays a crucial role in subsequent shaft expansion stages, such as slag chute handling and ventilation. Therefore, the construction technology of pilot shafts has always been a research focus in the field of vertical shaft engineering.

[0003] Currently, the mainstream vertical shaft and pilot shaft excavation technologies in the industry are mainly divided into two categories: drill-and-blast method for main shaft excavation and reverse drilling rig for hole enlargement excavation. Both types of technologies have revealed many unavoidable defects in long-term engineering applications.

[0004] The traditional drill-and-blast method for shaft excavation (such as the vertical shaft drill-and-blast method disclosed in CN114352284A) mainly involves setting up a drilling platform above the shaft, drilling slotting holes and blasting holes sequentially, and then carrying out blasting in sections from top to bottom or bottom to top after hole location verification. After blasting, personnel enter the bottom of the pilot shaft to remove muck, and the process is repeated until the pilot shaft is completed. Finally, full-section enlargement excavation is carried out. This process is highly dependent on manual underground operations. Even with protective measures, there are still significant safety hazards such as falls from height, rockfalls, and blasting injuries when personnel enter the lower part of the pilot shaft to load explosives and remove muck. At the same time, the process is complicated, with drilling and blasting and muck removal carried out alternately, resulting in a large manpower input, low work efficiency, long overall construction period, and high comprehensive construction costs. The construction risks are further amplified when facing complex geological conditions.

[0005] Another mainstream technique is the reverse shaft drilling pilot hole enlargement method (such as the highway tunnel vertical shaft pilot hole enlargement method disclosed in CN119084003A). This method first uses a directional drilling rig to drill a central pilot hole from top to bottom. After the pilot hole is connected to the lower tunnel ventilation duct, the reverse shaft drilling rig is replaced and the enlargement drill bit is installed from bottom to top to complete the formation of the pilot hole. Subsequently, vertical shaft locking, shaft excavation and support, slipform lining and other operations are carried out. Construction debris is transported to the lower roadway by the weight of the pilot hole. While this method optimizes the processes of slag removal, ventilation, and drainage, and improves construction efficiency to some extent, it still has significant shortcomings: First, the procurement, leasing, and transportation costs of large specialized equipment such as raise boring machines and directional drilling machines are high, and the site leveling, equipment installation, and commissioning processes in the early stages of construction are complex and the preparation period is long; Second, the diameter range of the pilot well is limited by the specifications of the drilling equipment, making it difficult to flexibly adapt to vertical shaft projects with different cross-sectional dimensions; Third, the rough well wall after the pilot well is formed results in a large amount of manual slag removal work during the subsequent full-section excavation stage, and small-diameter pilot wells are prone to rock debris jamming and hole blockage. Once hole blockage occurs, methods such as drilling rig dredging and water flushing are required, further delaying the construction period; Fourth, this process still cannot completely eliminate manual assistance. In adverse geological sections such as fractured surrounding rock, developed fissures, and weak interlayers, problems such as hole collapse and hole wall instability are prone to occur, resulting in insufficient construction stability.

[0006] In addition to the two mainstream technologies mentioned above, the existing few improved pilot well construction technologies have also failed to achieve a fundamental breakthrough. They generally suffer from poor equipment compatibility and insufficient mechanization. Most technologies still require manual drilling and blasting, as well as manual slag removal operations, and the safety risks for construction personnel working downhole cannot be completely eliminated. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a method for excavating a vertical shaft pilot shaft using a circular drilling method and auxiliary excavation tools for the pilot shaft. This method solves the problems of large equipment investment, long construction period, low well completion efficiency, and high safety risks in existing pilot shaft construction methods, thereby achieving full-section mechanized excavation of the pilot shaft.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A method for circular drilling excavation of a vertical shaft pilot shaft includes the following steps: S1 Construction layout: Delineate the excavation area of ​​the pilot shaft at the center of the design cross-section of the shaft to be constructed, and mark the outline of the pilot shaft; S2 Tangential drilling operation: Using a circular drilling rig, drilling is carried out from top to bottom in the pilot well excavation area. All holes are arranged in a circular direction, and the circumferential surfaces of two adjacent holes are tangent to each other, until the holes cover the entire pilot well excavation area. S3 Identify Residual Rock Mass: After all boreholes have been drilled, unremoved rock and soil columns form between adjacent boreholes within the pilot shaft excavation area; S4 Mechanical cutting and rock breaking: The guide shaft auxiliary excavation tool is lowered into the guide shaft and driven to rotate to cut and break the rock and soil column; S5 Slag Removal and Well Completion: Rock slag generated during cutting is discharged through the guide shaft channel, completing the overall excavation and construction of the vertical shaft and guide shaft.

[0009] A pilot shaft auxiliary excavation tool, designed to fit the above-mentioned vertical shaft pilot shaft center drilling excavation method, includes: It includes a cylindrical body, a cutting assembly, a cooling and flow guiding assembly, and a reinforcing support assembly; The cylindrical main body is hollow cylindrical in shape, and the outer diameter of the cylindrical main body is smaller than the inner diameter of the guide well; The cutting assembly includes several wedge-shaped alloy plates, which are fixedly disposed on the outer peripheral surface and lower end surface of the cylindrical body, or the wedge-shaped alloy plates are fixedly disposed on the outer peripheral surface or lower end surface of the cylindrical body, for rotating and cutting the rock and soil column; The cooling guide assembly includes a round steel pipe, which is arranged along the central axis of the cylindrical body. One end of the round steel pipe is connected to the water supply interface of the centering drill equipment, and the other end extends into the interior of the cylindrical body for transporting cooling water. The reinforcing support assembly includes multiple support plates, which are fixedly connected between the inner wall of the cylindrical main body and the outer wall of the circular steel pipe.

[0010] Furthermore, the front end of the wedge-shaped alloy sheet is wedge-shaped, and the rear end is a rectangular base. The wedge-shaped alloy sheet is fixed to the outer surface of the cylindrical steel plate by welding or hot-setting tooth fixing process, and the wedge-shaped tip faces the tool rotation cutting direction.

[0011] Furthermore, the support plate is a trapezoidal plate or a triangular plate, and multiple support plates are evenly spaced along the axial direction of the circular steel pipe.

[0012] Furthermore, the cylindrical body has several slag discharge grooves or slag discharge holes on its cylindrical wall, and the slag discharge grooves or slag discharge holes are evenly distributed along the axial direction of the cylindrical body.

[0013] Furthermore, a water distributor is installed at the bottom of the round steel pipe, and the water distributor is provided with multiple water outlets, each of which is connected to the working area of ​​the wedge-shaped alloy plate through a corresponding pipeline.

[0014] The beneficial effects of this invention compared with the prior art are as follows: This invention eliminates the blasting process and manual downhole operations, relying entirely on the center drill and special auxiliary tools for mechanized construction. It fundamentally avoids the risks of falling rocks, blasting injuries, etc. caused by the loading of explosives and the removal of cuttings in the traditional drilling and blasting method. It also avoids the safety problems of manually clearing blockages and dealing with surrounding rock hazards in the raise boring machine process. In high-risk scenarios such as deep wells, dangerous rocks, and adverse geological conditions, the construction safety assurance capability is significantly enhanced.

[0015] Compared to the raised shaft drilling process, which requires various large and expensive equipment such as directional drilling rigs and raised shaft drilling rigs, this invention can complete the drilling operation using only a center drill. The supporting tools have a simple structure and low manufacturing cost. At the same time, the solution significantly reduces the number of on-site workers and eliminates additional expenses such as blasting consumables, equipment debugging, and temporary ventilation and drainage. It reduces costs in terms of equipment, manpower, and consumables, resulting in outstanding economic benefits.

[0016] This invention employs tangential continuous drilling combined with mechanical cutting operations, resulting in a compact and continuous process, a regular well section, and reduced risk of rock cutting blockage or hole clogging. This effectively shortens the construction period and significantly improves well completion efficiency.

[0017] Compared to the limitations of raised shaft drilling rigs, which are constrained by equipment specifications and have a limited adjustable range for pilot well diameter, this invention allows for flexible adjustment of drill bit size, number of boreholes, and arrangement according to design requirements. It can adapt to pilot well construction of different diameters, making it applicable to a wider range of fields. Furthermore, the mechanical drilling and cutting process causes minimal disturbance to the surrounding rock, maintaining construction stability even in complex geological conditions such as weak interlayers, weathered rock, and fractured areas, demonstrating superior geological adaptability.

[0018] The guide shaft auxiliary excavation tool designed in this invention has a high overall structural strength, and the carbide cutting parts are wear-resistant and durable. The tool integrates a cooling water channel and a slag removal structure, utilizing the existing water supply system to cool the cutting tools and reduce dust on site. At the same time, the water flow helps to guide rock debris and prevent equipment jamming. Furthermore, the tool is easy to assemble and disassemble, and simple to inspect and maintain, ensuring the stable operation of the entire mechanized construction process.

[0019] This invention involves no blasting operations, resulting in less noise and pollutant emissions. Rock debris is directly transported to the lower tunnel through the pilot shaft, eliminating the need for large-scale debris accumulation at the shaft opening. This minimizes the impact on the surrounding surface and ecosystem, demonstrating significant environmental advantages. Attached Figure Description

[0020] Figure 1 A planar structural diagram showing the distribution of multiple boreholes within a pilot well; Figure 2 This is a front view structural diagram of the assembly of the pilot shaft auxiliary excavation tool, flange, and lifting device in Embodiment 2; Figure 3 This is a top view of the pilot shaft auxiliary excavation tool in Example 2; Figure 4 This is a plan view of the pilot shaft auxiliary excavation tool in Example 4.

[0021] Reference numerals in the attached drawings: 1. Cylindrical main body; 2. Main circular steel pipe; 3. Support plate; 4. Wedge-shaped alloy sheet; 5. Connecting flange; 6. Slag discharge trough; 7. Water distributor; 8. Drill hole; 9. Multiple auxiliary circular steel pipes; 10. Guide well outline; 11. Outer cylinder and 12. Inner cylinder; 13. Annular waterway. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0023] Example 1: A method for circular drilling excavation of a vertical shaft pilot shaft This embodiment provides a method for circular drilling excavation of vertical shaft pilot shafts, applicable to the construction of vertical shaft pilot shafts with diameters of 2-8 meters and depths of 50-200 meters in water conservancy and hydropower projects, including the following steps: Step S1: Construction preparation and pilot well outline marking.

[0024] After the ground is leveled, surveyors determine the center position of the designed cross-section of the shaft and mark the outline of the guide shaft excavation around the center position. The diameter of the guide shaft is determined according to the engineering design requirements, generally 30% to 50% of the final diameter of the shaft.

[0025] Step S2: Drilling a circular tangential hole.

[0026] A circular drilling rig is used, with the drilling machine positioned above the center of the pilot well. The circular drilling rig is equipped with drill rod lifting and rotation drive functions, and the drill bit diameter is 300-600mm. Drilling is performed from the ground downwards, with the eight boreholes arranged in a circular, tangential pattern.

[0027] Specifically, the center of each borehole 8 is located within the area of ​​the guide well outline 10. First, a circle of holes is drilled along the inner side of the guide well outline 10, and then the drilling proceeds inward circle by circle. The distance between the centers of two adjacent boreholes 8 within each circle is equal to the sum of the radii of the two boreholes, ensuring that the circumferential surfaces of adjacent boreholes 8 are tangent, without overlapping or leaving gaps.

[0028] like Figure 1 As shown, the diameter and number of boreholes 8 are pre-calculated based on the design diameter of the pilot well using geometric relationships, so that the sum of the coverage areas of all boreholes 8 is equal to or slightly larger than the design cross-sectional area of ​​the pilot well. For example, when the diameter of the pilot well is 3 meters, a drill bit with a diameter of 500 mm can be used, and approximately 28 to 32 boreholes can be arranged in 3 to 4 concentric circles.

[0029] Step S3: Identify residual rock mass.

[0030] After all boreholes 8 were drilled, most of the rock mass within the excavation section of the pilot shaft had been removed. Only a few rock and soil columns with approximately triangular cross-sections remained between three or four adjacent boreholes 8. The rock and soil columns were relatively small, which provided favorable conditions for subsequent mechanical cutting.

[0031] Step S4: Cut and remove the rock and soil column.

[0032] The pilot well auxiliary excavation tool is lowered into the pilot well hole via drill rods or wire ropes. The outer diameter of the cylindrical steel plate of the pilot well auxiliary excavation tool is slightly smaller than the diameter of the pilot well. During descent, the tool is rotated by the drilling rig, and the wedge-shaped alloy blades on the cylindrical steel plate cut and break the rock and soil column. The tool gradually descends from top to bottom, cutting away the entire rock and soil column.

[0033] During the cutting process, the water supply system of the center drill equipment delivers cooling water to the cutting part through a round steel pipe. The water flow cools the wedge-shaped alloy sheet and washes away rock debris and reduces dust.

[0034] Step S5: Well completion and acceptance.

[0035] The rock debris generated from cutting and crushing falls naturally through the pilot shaft to the lower roadway or slag collection area, where it is transported out by the slag removal equipment. After all the rock and soil columns have been cut, the pilot shaft is inspected and accepted, and the pilot shaft excavation is completed.

[0036] Example 2: Guide shaft assisted excavation tool like Figure 2 , Figure 3 This embodiment provides a guide shaft auxiliary excavation tool for cutting and removing the remaining rock and soil column after drilling a circular tangential borehole during vertical shaft guide shaft construction. The tool includes a cylindrical body 1, a cutting assembly, a flow guiding and cooling assembly, and a reinforcing support assembly, the specific structure of which is described below.

[0037] The cylindrical body 1 serves as the main load-bearing structure of the tool. It is made of high-strength steel plate with a thickness of 20-40mm, rolled and welded into a cylindrical shape. The outer diameter of the cylinder is 100-200mm smaller than the diameter of the pilot well, allowing for free lifting, lowering, and rotation within the pilot well. The height of the cylindrical body 1 is 1000-2000mm, and a connecting flange 5 is provided at the top for connecting to the drill rod or lifting device 10 of the centering drill equipment.

[0038] The cutting assembly includes several wedge-shaped alloy plates 4, which are arranged on the outer circumferential surface of the cylindrical body 1 in an array along the circumferential and axial directions, with staggered upper and lower layers. The front end of each wedge-shaped alloy plate 4 is a wedge-shaped pointed corner with an angle of 30°~60°, and the rear end is a rectangular base, fixed to the outer surface of the cylindrical body 1 by welding. The wedge-shaped tip faces the direction of rotational cutting of the tool. The wedge-shaped alloy plates 4 are made of cemented carbide, with a hardness higher than the uniaxial compressive strength of the rock or soil to be cut.

[0039] Alternatively, wedge-shaped alloy plates 4 can be arranged on the lower end face of the cylindrical body 1 for cutting rocks downwards.

[0040] Multiple slag discharge grooves 6 are provided along the circumference of the cylindrical body 1 to discharge rock slag generated during the cutting process and prevent rock slag from accumulating and getting stuck between the tool and the well wall.

[0041] The cooling assembly includes a main circular steel pipe 2 and multiple auxiliary circular steel pipes 9. The main circular steel pipe 2 is located on the central axis of the cylindrical body 1, and its upper end is connected to the drill rod of the centering drill equipment via a connecting flange 5. The main circular steel pipe 2 is also connected to the water supply system of the centering drill equipment, and its lower end extends into the interior of the cylindrical body 1. Meanwhile, multiple auxiliary circular steel pipes 9 are installed on the side of the main circular steel pipe 2 near the top of the cylindrical body 1 via a water distributor 7. The side wall of the cylindrical body 1 has multiple circular holes, and the auxiliary circular steel pipes 9 extend through the circular holes to the outer wall of the cylindrical body 1, respectively leading to wedge-shaped alloy plates 4 at different positions on the outer wall of the cylindrical body 1 for cooling the wedge-shaped alloy plates 4.

[0042] In addition, a water distributor 7 is also installed at the bottom of the round steel pipe 2. The water distributor 7 has multiple water outlets, and the bottom of the cylindrical body is also provided with multiple round holes. Each water outlet of the water distributor 7 passes through a round hole and is led to the wedge-shaped alloy plate 4 at different positions through a flexible hose or rigid pipe. After being guided by the round steel pipe 2, the water is distributed to each cutting part to continuously cool the wedge-shaped alloy plate 4.

[0043] The reinforced support assembly includes multiple support plates 3, which are trapezoidal or triangular steel plates evenly spaced along the axial direction of the cylindrical main body 1. The outer edge of the support plate 3 is welded to the inner wall of the main circular steel pipe 2, and the inner edge is welded to the outer wall of the main circular steel pipe 2, thus connecting the cylindrical main body 1 and the main circular steel pipe 2 to form a stable support structure and enhance the overall rigidity and torsional resistance of the tool.

[0044] Working process: After the pilot shaft auxiliary excavation tool is connected to the drill pipe via connecting flange 5, it is driven by the drilling rig to rotate and slowly lower. During the rotation of the cylindrical main body 1, the wedge-shaped alloy plates 4 on its outer surface cut and break the rock and soil column. Cooling water is introduced from the circular steel pipe 2 and distributed to each alloy plate position through the water distributor 7, which serves to cool, remove slag, and reduce dust. The tool gradually descends from the top of the pilot shaft to the bottom, completing the cutting and removal of all remaining rock and soil columns, and the pilot shaft excavation is completed.

[0045] Example 3 The difference between this embodiment and embodiment two is that the wedge-shaped alloy sheet 4 is fixed to the cylindrical body 1 by a hot-setting tooth fixing process. That is, the mounting hole is pre-machined on the cylindrical body 1, the wedge-shaped alloy sheet 4 is heated and pressed into the mounting hole, and after cooling, an interference fit connection is formed. This connection method is suitable for heavy-load working conditions when drilling rock formations with high strength.

[0046] Example 4 like Figure 4As shown, the difference between this embodiment and embodiment two is that the cylindrical body 1 adopts a double-layer structure, that is, it is composed of an outer cylinder 11 and an inner cylinder 12 with the same center line. An annular water channel 13 is formed between the outer cylinder 11 and the inner cylinder 12. The main circular steel pipe 2 is connected to the annular water channel 13. The annular water channel 13 has water outlet holes at the positions of each wedge alloy plate 4 on the outer cylinder 11. Cooling water is sprayed directly from the annular water channel 13 through the water outlet holes to the working surface of the wedge alloy plate 4.

[0047] The above provides a detailed description of a method for excavating a vertical shaft pilot shaft using a circular drilling system and an auxiliary excavation tool for the pilot shaft, as provided by this invention. The specific embodiments described are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A method for circular drilling excavation of a vertical shaft pilot shaft, characterized in that, Includes the following steps: S1 Construction layout: Delineate the excavation area of ​​the pilot shaft at the center of the design cross-section of the shaft to be constructed, and mark the outline of the pilot shaft; S2 Tangential drilling operation: Using a circular drilling rig, drilling is carried out from top to bottom in the pilot well excavation area. All holes are arranged in a circular direction, and the circumferential surfaces of two adjacent holes are tangent to each other, until the holes cover the entire pilot well excavation area. S3 Identify Residual Rock Mass: After all boreholes have been drilled, unremoved rock and soil columns form between adjacent boreholes within the pilot shaft excavation area; S4 Mechanical cutting and rock breaking: The guide shaft auxiliary excavation tool is lowered into the guide shaft and driven to rotate to cut and break the rock and soil column; S5 Slag Removal and Well Completion: Rock slag generated during cutting is discharged through the guide shaft channel, completing the overall excavation and construction of the vertical shaft and guide shaft.

2. The method for circular drilling excavation of a vertical shaft pilot shaft according to claim 1, characterized in that, In step S2, the drilling is advanced circle by circle in the order of from the outer circle to the inner circle or from the inner circle to the outer circle. The distance between the centers of two adjacent holes in the same circle is equal to the sum of the radii of the two holes.

3. The method for circular drilling excavation of a vertical shaft pilot shaft according to claim 2, characterized in that, In step S2, the diameter of the single-hole drill bit and the number of holes are predetermined based on the geometric relationship between the diameter of the pilot well and the arrangement of the boreholes. The sum of the coverage areas of all the boreholes is greater than or equal to the designed cross-sectional area of ​​the pilot well.

4. The method for circular drilling excavation of a vertical shaft pilot shaft according to claim 1, characterized in that, In step S4, the guide shaft auxiliary excavation tool is lowered at a constant speed from top to bottom while maintaining continuous rotation, gradually completing the cutting operation of the full-height rock and soil column.

5. A method for circular drilling excavation of a vertical shaft pilot shaft according to claim 4, characterized in that, During step S4, cooling water is delivered to the guide shaft auxiliary excavation tool to cool and reduce dust at the cutting parts and to help flush away rock debris.

6. A guide shaft auxiliary excavation tool, applied to the vertical shaft guide shaft center drilling excavation method as described in any one of claims 1-5, characterized in that, include: It includes a cylindrical body, a cutting assembly, a cooling and flow guiding assembly, and a reinforcing support assembly; The cylindrical main body is hollow cylindrical in shape, and the outer diameter of the cylindrical main body is smaller than the inner diameter of the guide well; The cutting assembly includes several wedge-shaped alloy plates, which are fixedly disposed on the outer peripheral surface and lower end surface of the cylindrical body, or the wedge-shaped alloy plates are fixedly disposed on the outer peripheral surface or lower end surface of the cylindrical body, for rotating and cutting the rock and soil column; The cooling guide assembly includes a round steel pipe, which is arranged along the central axis of the cylindrical body. One end of the round steel pipe is connected to the water supply interface of the centering drill equipment, and the other end extends into the interior of the cylindrical body for transporting cooling water. The reinforcing support assembly includes multiple support plates, which are fixedly connected between the inner wall of the cylindrical main body and the outer wall of the circular steel pipe.

7. The guide shaft auxiliary excavation tool according to claim 6, characterized in that, The wedge-shaped alloy sheet has a wedge-shaped tip at the front end and a rectangular base at the rear end. The wedge-shaped alloy sheet is fixed to the outer surface of the cylindrical steel plate by welding or hot-setting tooth fixing process, and the wedge-shaped tip faces the tool rotation cutting direction.

8. A guide shaft auxiliary excavation tool according to claim 6, characterized in that, The support plate is a trapezoidal plate or a triangular plate, and multiple support plates are evenly spaced along the axial direction of the round steel pipe.

9. A guide shaft auxiliary excavation tool according to claim 6, characterized in that, The cylindrical body has several slag discharge channels on its cylindrical wall, which are evenly distributed along the axial direction of the cylindrical body.

10. A guide shaft auxiliary excavation tool according to claim 6, characterized in that, A water distributor is installed on the round steel pipe. The water distributor has multiple water outlets, and each water outlet is connected to the working area of ​​the wedge-shaped alloy plate through a corresponding pipeline.

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