A separable concentric three-drill bit and method for stress relief

Abstract

The present invention discloses a detachable concentric three-drill bit and method for stress relief, comprising a coaxially arranged middle rock drill, a middle ring rock drill, and an external coring drill. A data acquisition device is provided on the drill rod of the middle rock drill, and the data acquisition device is connected to a controller. The data acquisition device is used to obtain data on the initial position of the rock core when the middle rock drill has drilled a preset length and the middle ring rock drill and the external coring drill have not yet drilled, as well as data on the position of the rock core after deformation when the middle rock drill has drilled a preset length and the external coring drill has drilled coplanar with the drill bit of the middle rock drill. The controller is used to determine the deformation value of the excavation area based on the initial and deformed position data of the rock core, and to obtain the ground stress in the excavation area based on the deformation value. This enables accurate measurement of ground stress.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering drilling and ground stress measurement, and in particular to a detachable concentric three-drill bit and a method for stress relief. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Tunnel construction in complex geological environments, especially those with high geostress, often requires advanced horizontal drilling to determine the magnitude and direction of geostress in the pre-excavation area ahead. This is crucial to prevent excessive tectonic stress caused by regional folding and compression, leading to the occurrence of large-scale geological disasters such as rockbursts and large deformations, resulting in severe economic losses, casualties, and significant project delays. Therefore, timely determination of the magnitude and direction of geostress in the pre-excavation area ahead is crucial for preventing major geological disasters during tunnel construction.

[0004] Currently, the more established methods for measuring in-situ stress include hydraulic fracturing, acoustic emission, and casing and core stress relief. The latter is the most widely used method in rock mass measurement. In this method, an annular groove is dug in the rock wall or a hole is drilled into the rock mass, isolating a rock block of a certain size from the surrounding rock mass. This stress is relieved at this location, and strain gauges are used to measure the strain after relief, from which the in-situ stress is calculated. However, using these techniques to obtain in-situ stress leads to three challenges: 1) They require a separate construction process and constant replacement of drill bits and drill rods of varying diameters, significantly delaying the project; 2) the measurement process requires ensuring the borehole is level, resulting in complex and tedious measurement steps and significant influence on measurement accuracy; and 3) the strain generated by the core after stress relief is difficult to obtain and requires a high level of environmental sensitivity. These issues lead to inaccurate in-situ stress measurements. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a detachable concentric three-drill bit and method for stress relief, which realizes accurate measurement of ground stress.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, a detachable concentric three-drill bit for stress relief is proposed, comprising a coaxially arranged middle rock drill, a middle ring rock drill, and an external coring drill, a data acquisition device being provided on the drill rod of the middle rock drill, and the data acquisition device being connected to a controller;

[0008] A data acquisition device is used to obtain the preset drilling length of the middle rock drill, the initial position data of the rock core when the middle ring rock drill and the external coring drill have not drilled, and the position data of the rock core after deformation when the middle rock drill has drilled the preset length and the external coring drill is drilled to the same plane as the drill bit of the middle rock drill;

[0009] The controller is used to determine the deformation value of the excavation area according to the initial position data of the rock core and the position data of the rock core after deformation, and obtain the ground stress of the excavation area according to the deformation value.

[0010] Secondly, a method for obtaining ground stress using a detachable concentric three-bit drill bit for stress relief is proposed, comprising:

[0011] Drill the medium-sized rock drill to a preset length, and obtain the initial position data of the rock core at this time through the data acquisition device;

[0012] Drill the external coring drill until it is coplanar with the middle rock breaking drill bit, and obtain the position data of the core after deformation at this time through the data acquisition device;

[0013] The controller determines the deformation value of the excavation area based on the initial position data of the core and the position data of the core after deformation, and obtains the ground stress of the excavation area based on the deformation value.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention obtains the initial position data and the position data of the core after deformation by arranging a data acquisition device on the drill rod of the medium-breaking rock drill. The measurement process does not require the replacement of the drill bit and the drill rod, ensuring that the data acquisition device uses the same position reference to obtain different data. When the data is obtained in this way to calculate the ground stress in the excavation area, the accuracy of the obtained ground stress is guaranteed.

[0016] 2. The present invention also calculates the physical and mechanical parameters of the rock based on the propulsion force, torque and rotation speed of the drill rod during the drilling process of the medium-breaking rock drill. The physical and mechanical parameters of the rock can truly reflect the rock properties of the excavation area. Through the physical and mechanical parameters of the rock and the deformation value of the excavation area, the ground stress in the excavation area can be accurately calculated.

[0017] 3. In the whole process of obtaining the initial position data of the core, the position data of the core after deformation and the physical and mechanical parameters of the rock, the present invention does not need to replace the drill bit and drill rod of different diameters, which greatly simplifies the working process of ground stress measurement and greatly saves measurement time.

[0018] 4. The data acquisition device of the present invention adopts a laser scanner, which can acquire the displacement and strain data of the casing core. The data acquisition process does not require operations such as pasting strain gauges, which greatly improves the measurement accuracy, saves measurement time, and reduces the influence of human factors on the measurement data.

[0019] 5. The detachable concentric three-drill bit of the present invention can realize multi-point ground stress measurement in one hole, improve the utilization rate of the drill hole, and obtain multi-point data, which is conducive to sensing the distribution of the ground stress field in a large area.

[0020] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0022] Figure 1 A schematic plan view of three drill bits disclosed in Example 1;

[0023] Figure 2 This is a schematic diagram of the connection structure of the data acquisition device disclosed in Example 1;

[0024] Figure 3 The workflow diagram of the three-drill bit disclosed in Example 1 is as follows;

[0025] Figure 4 Schematic diagram of aperture deformation and stress disclosed in Example 1.

[0026] Among them: 1. External coring drill, 2. Medium-breaking rock drill, 3. Medium-breaking rock drill, 4. Medium-breaking rock drill tool, 5. Medium-breaking rock drill air outlet, 6. Hob, 7. Scraper, 8. Medium-breaking rock drill slag outlet, 9. External coring drill tool, 10. External coring drill slag outlet, 11. Medium-breaking rock drill rod, 12. Data acquisition device, 13. Transparent protective cover, 14. Drive motor, 15. Gear transmission device. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0029] Example 1

[0030] In this embodiment, a detachable concentric triple drill bit for stress relief is disclosed, such as Figure 1 、 Figure 2 As shown, it includes a coaxially arranged middle rock drill 3, a middle ring rock drill 2 and an external coring drill 1, the middle ring rock drill 2 is sleeved on the outside of the middle rock drill 3, and the external coring drill 1 is sleeved on the outside of the middle rock drill 3.

[0031] The medium rock drill 3 includes a medium rock drill bit and a medium rock drill rod 11 connected to each other. The medium rock drill bit is provided with a medium rock drill tool 4 and a medium rock drill air outlet 5 . The medium rock drill air outlet 5 is communicated with the medium rock drill rod 11 .

[0032] The medium rock drill tool 4 is a convex hard hemisphere. Multiple medium rock drill tools 4 are arranged on the medium rock drill bit. Multiple medium rock drill tools 4 are evenly distributed on the medium rock drill bit. When the medium rock drill 3 drills, the medium rock drill tools 4 can cut the rock into fine powder particles.

[0033] The middle rock drill air outlet 5 is connected to the outside world through the middle rock drill rod 11, and the outside wind can be sent to the middle rock drill air outlet 5 through the middle rock drill rod 11 to be blown out, thereby blowing away the powder particles cut out of the rock.

[0034] The external coring drill 1 comprises an external coring drill bit and an external coring drill rod connected to each other. An external coring drill tool 9 is provided on the external coring drill bit, and an external coring drill slag discharge port 10 is provided on the external coring drill tool 9.

[0035] The thickness of the external coring drill tool 9 is the same as the wall thickness of the external coring drill rod. The rigidity of the external coring drill rod and the external coring drill tool 9 can achieve vertical separation of the center rock from the external parent rock during the drilling process of the external coring drill 1.

[0036] During the drilling process of the external coring drill 1 , the rock slag generated by the external coring drill tool 9 cutting the rock is discharged through the external coring drill slag discharge port 10 .

[0037] There are multiple external coring drill tools 9, and the multiple external coring drill tools 9 are evenly distributed on the external coring drill bit. In order to facilitate tool replacement, the external coring drill tool 9 is connected to the external coring drill bit with bolts. When the external coring drill tool 9 is damaged, it is convenient to replace the external coring drill tool 9.

[0038] The medium-fracture ring rock drill 2 comprises a medium-fracture ring rock drill bit and a medium-fracture ring rock drill drill rod connected to each other; a roller cutter 6, a scraper 7 and a medium-fracture ring rock drill slag discharge port 8 are arranged on the medium-fracture ring rock drill bit.

[0039] The height of the roller cutter 6 is higher than that of the scraper 7. During the drilling process of the medium-breaking ring rock drill 2, the roller cutter 6 cuts the rock first, and the scraper 7 collects the rock debris under the roller cutter, and the collected rock debris is discharged through the slag discharge port 8 of the medium-breaking ring rock drill.

[0040] There are multiple roller cutters 6 and scrapers 7, which are evenly distributed on the middle ring rock drill bit, and the roller cutters 6 and scrapers 7 are arranged at intervals.

[0041] In order to facilitate the discharge of soft materials such as rock particles and soil through the rotation of the scraper to the slag discharge port, the scraper 7 is set as a discontinuous part, each scraper 7 includes multiple scraper segments, and a reserved spacing is set between adjacent scraper segments. Rock particles, soil and other soft materials flow through the spacing to the slag discharge port 8 of the middle broken rock drill for discharge.

[0042] In order to facilitate replacement, the hob 6 is detachably connected to the middle ring breaking rock drill bit.

[0043] In order to realize the measurement of ground stress using the three drill bits disclosed in this embodiment, a data acquisition device 12 is set on the medium rock drill rod 11. The data acquisition device 12 is used to obtain rock data during the drilling process of the medium rock drill, the medium ring rock drill and the external coring drill.

[0044] The data acquisition device 12 is connected to the rotary drive device, which can drive the data acquisition device 12 to rotate around the axial direction of the rock breaking drill pipe, thereby obtaining the initial position data of the rock core and the position data of the rock core after deformation in multiple directions.

[0045] The data acquisition device 12 is preferably a laser scanner, which acquires rock data during the drilling process by rotating the laser scanner.

[0046] Specifically, the data acquisition device 12 is used to obtain the initial position data of the core when the middle rock drill 4 drills a preset length, the middle ring rock drill 2 and the external coring drill 1 have not drilled, and the position data of the core after deformation when the middle rock drill 4 drills a preset length and the external coring drill 1 drills to the same plane as the middle rock drill bit.

[0047] The rotation drive device includes a drive motor 14 and a gear transmission device 15. The drive motor 14 is connected to the data acquisition device 12 through the gear transmission device 15. When the drive motor 14 works, the gear transmission device 15 drives the data acquisition device 12 to rotate around the axial direction of the rock drill rod.

[0048] The gear transmission device 15 includes a meshing driving gear and a driven gear. The driving gear is connected to the output shaft of the driving motor 14, and the driven gear is connected to the data acquisition device 12. The driving motor 14 is fixed on the drill rod of the rock drill.

[0049] In order to prevent rock debris from affecting the data acquisition device and the rotary drive device during drilling, this embodiment provides a transparent protective cover 13 on the outside of the data acquisition device and the rotary drive device. The transparent protective cover 13 is connected to the drill rod of the rock breaking drill, and the data acquisition device and the rotary drive device are protected by the transparent protective cover 13.

[0050] The data acquisition device is connected to the controller, which is used to determine the deformation value of the excavation area based on the initial position data of the core and the position data of the core after deformation, and obtain the ground stress of the excavation area based on the deformation value.

[0051] like Figure 4 As shown in Figure 2, the specific process of the controller obtaining the ground stress in the excavation area is as follows:

[0052] Obtain the deformation value of the drilling hole diameter based on the position data of the core after deformation and the initial position data of the core;

[0053] The ground stress in the excavation area is obtained based on the deformation value of the drilling hole and the physical and mechanical parameters of the rock.

[0054] Among them, the physical and mechanical parameters of the rock include the elastic modulus and Poisson's ratio of the rock. The acquisition process is as follows: the thrust force, torque and rotation speed of the drill rod are obtained when the middle rock drill 4 drills a preset length, the external core drill 1 drills to the same plane as the middle rock drill bit, and the middle ring rock drill 2 drills to the same plane as the middle rock drill bit; the controller calculates the physical and mechanical parameters of the rock based on the thrust force, torque and rotation speed of the drill rod.

[0055] In order to ensure the accuracy of the calculation of the ground stress in the excavation area, the deformation values ​​in the three directions of the drilling aperture are calculated. Through these three deformation values, the ground stress in the excavation area is accurately calculated, avoiding the error problem caused by using a single direction deformation value for ground stress calculation.

[0056] The controller obtains the ground stress of the excavation area based on the deformation value of the drilling hole, the physical and mechanical parameters of the rock and the ground stress calculation model.

[0057] The calculation model of ground stress is:

[0058]

[0059]

[0060]

[0061] Where σ1 and σ2 are the two principal stress values ​​in the plane perpendicular to the borehole axis; d is the initial drilling diameter, which is the diameter determined based on the initial position data of the core; U1, U2, and U3 are the deformation values ​​in the three aperture directions at 60° intervals in the excavation area; E is the elastic modulus of the rock; ν is the Poisson's ratio; the elastic modulus E and Poisson's ratio ν are calculated using the thrust, torque, and speed of the drill pipe during the drilling process of the medium-fracture rock drill; β is the angle between U1 and σ1, with the angle from U1 counterclockwise to σ1 being positive. The range of β is limited as follows:

[0062] When U2>U3 and U2+U3<2U1, 0°≤β≤45°;

[0063] When U2>U3 and U2+U3>2U1, 45°≤β≤90°;

[0064] When U2<U3 and U2+U3>2U1, 90°≤β≤135°;

[0065] When U2<U3 and U2+U3<2U1, 135°≤β≤180°

[0066] If the borehole axis in the excavation area coincides with a principal stress direction, and the principal stress value in this direction is also known, for example, assuming that the self-weight stress is a principal stress, and the borehole is vertical, then the aperture deformation measurement of a borehole can also determine the three-dimensional stress state at that point; otherwise, the two-dimensional stress state in the plane perpendicular to the borehole axis is determined.

[0067] The specific process of measuring ground stress using a detachable concentric three-drill bit for stress relief disclosed in this embodiment is as follows: Figure 3 As shown, including:

[0068] A detachable concentric three-drill bit for stress relief disclosed in the present embodiment is connected to a drilling rig, the drilling rig is driven to a certain distance in front of the face, and the detachable concentric three-drill bit disclosed in the present embodiment is drilled synchronously, that is, the middle rock-breaking drill, the middle ring rock-breaking drill and the outer coring drill are drilled synchronously to the measurement area; then, the middle rock-breaking drill 3 is drilled forward first, and after drilling a preset length, the middle rock-breaking drill 3 stops rotating, and the data acquisition device 12 is rotated around the axial direction of the middle rock-breaking drill rod for one circle to scan and obtain the initial position data of the rock core; after the initial position data of the rock core is collected, the outer coring drill 1 starts to drill forward and stops after drilling a preset length. At this time, the outer coring drill bit and the middle rock-breaking drill bit reach the same plane. At this time, the rock core is separated from the original rock, and the rock core is deformed due to being separated from the constraint. At this time, the data acquisition device 12 is rotated around the axial direction of the middle rock-breaking drill rod for one circle to scan and obtain the rock core. the position data of the core after deformation; after the position data of the core after deformation is collected, the middle breaking ring rock drill 2 starts to drill forward through different propulsion forces, torques and rotation speeds of the drill rod, and the physical and mechanical parameters of the rock during the drilling process of the middle breaking ring rock drill 2 are obtained according to the propulsion force, torque and rotation speed of the drill rod, and the physical and mechanical parameters of the rock include elastic modulus, Poisson's ratio, etc.; after the middle breaking ring rock drill 2 drills the preset length, the drill bits of the middle breaking ring rock drill, the middle breaking ring rock drill and the external coring drill reach the same plane, and a data collection is completed; the three drill bits can continue to extend forward synchronously and drill, and after reaching the next measurement area, the above three drill bits are separated and drilled, and the next set of data is collected; finally, the controller determines the deformation value of the excavation area according to the initial position data of the core and the position data of the core after deformation, and obtains the ground stress state of the excavation area according to the deformation value and the physical and mechanical parameters of the rock.

[0069] The present embodiment discloses a detachable concentric three-drill bit for stress relief. A data acquisition device is provided on a drill rod of a medium-sized rock-breaking drill to obtain initial position data and position data of the rock core after deformation. The measurement process does not require replacement of the drill bit or drill rod, ensuring that the data acquisition device uses the same position reference to obtain different data. When this method is used to obtain data and calculate the in-situ stress in the excavation area, the accuracy of the in-situ stress is guaranteed. Because there is no need to replace drill bits and drill rods of different diameters during the entire process of obtaining the initial position data of the rock core, the position data of the rock core after deformation, and the physical and mechanical parameters of the rock, the in-situ stress measurement process is greatly simplified, significantly saving measurement time.

[0070] The data acquisition device of this embodiment uses a laser scanner to acquire displacement and strain data of the casing core. The data acquisition process does not require operations such as pasting strain gauges, which greatly improves measurement accuracy, saves measurement time, and reduces the impact of human factors on measurement data.

[0071] The detachable concentric three-bit drill bit of this embodiment can realize multi-point ground stress measurement in one hole, improve the utilization rate of the borehole, and obtain multi-point data to facilitate the perception of the distribution of ground stress field in a large area.

[0072] Example 2

[0073] In this embodiment, a method for obtaining ground stress of a detachable concentric three-bit drill bit for stress relief is disclosed, comprising:

[0074] Drill the medium-sized rock drill to a preset length, and obtain the initial position data of the rock core at this time through the data acquisition device;

[0075] Drill the external coring drill until it is coplanar with the middle rock breaking drill bit, and obtain the position data of the core after deformation at this time through the data acquisition device;

[0076] The controller determines the deformation value of the excavation area based on the initial position data of the core and the position data of the core after deformation, and obtains the ground stress of the excavation area based on the deformation value.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A ground stress measuring device for stress relief, characterized in that: It includes a coaxially arranged middle rock drill, a middle ring rock drill and an external core drill, a data acquisition device is arranged on the drill rod of the middle rock drill, and the data acquisition device is connected to the controller; The data acquisition device is connected to the rotary drive device, and the rotary drive device can drive the data acquisition device to rotate around the axial direction of the rock breaking drill rod; The medium-break rock drill comprises a medium-break rock drill bit and a medium-break rock drill rod connected thereto; The external coring drill comprises an external coring drill bit and an external coring drill rod connected to each other; The medium-fracture ring rock drill comprises a medium-fracture ring rock drill bit and a medium-fracture ring rock drill rod connected to each other; a data acquisition device for acquiring data on the initial position of the rock core when the middle rock drill has drilled a preset length and when the middle ring rock drill and the external coring drill have not yet drilled, and data on the position of the rock core after deformation when the middle rock drill has drilled a preset length and the external coring drill has drilled to the same plane as the drill bit of the middle rock drill; The controller is used to determine the deformation value of the excavation area based on the initial position data of the rock core and the position data of the rock core after deformation, and obtain the ground stress in the excavation area based on the deformation value. The specific process is: according to the position data of the rock core after deformation and the initial position data of the rock core, the deformation value of the drilling aperture is obtained; according to the deformation value of the drilling aperture and the physical and mechanical parameters of the rock, the ground stress in the excavation area is obtained; wherein, the process of obtaining the physical and mechanical parameters of the rock is as follows: after the middle rock breaking drill has drilled a preset length, after the external coring drill has drilled to the same plane as the drill bit of the middle rock breaking drill, the propulsion force, torque and rotation speed of the drill rod during the process of the middle ring rock breaking drill drilling to the same plane as the drill bit of the middle rock breaking drill; according to the propulsion force, torque and rotation speed of the drill rod, the physical and mechanical parameters of the rock are calculated.

2. A ground stress measuring device for stress relief according to claim 1, characterized in that: The rotation driving device includes a driving motor and a gear transmission device, and the driving motor is connected to the data acquisition device through the gear transmission device.

3. The ground stress measuring device for stress relief according to claim 1, characterized in that: A transparent protective cover is arranged outside the data acquisition device and the rotary drive device, and the transparent protective cover is connected to the drill rod of the middle rock drill.

4. The ground stress measuring device for stress relief according to claim 1, characterized in that: A medium rock drill cutter and a medium rock drill air outlet are arranged on the medium rock drill bit, and the medium rock drill air outlet is connected with the medium rock drill rod.

5. The ground stress measuring device for stress relief according to claim 1, characterized in that: An external core drill tool is arranged on the external core drill bit.

6. The ground stress measuring device for stress relief according to claim 1, characterized in that: The drill bit of the medium-breaking ring rock drill is equipped with a roller cutter and a scraper.

7. The ground stress measuring device for stress relief according to claim 6, characterized in that: There are multiple roller cutters and scrapers, which are arranged at intervals on the drill bit of the medium-breaking ring rock drill.

8. A method for obtaining ground stress of a ground stress measurement device for stress relief according to any one of claims 1 to 7, characterized in that: include: Drill the medium rock drill to a preset length and obtain the initial position data of the core at this time through the data acquisition device; Drill the external coring drill until it is coplanar with the drill bit of the middle rock drill, and obtain the position data of the core after deformation at this time through the data acquisition device; The controller determines the deformation value of the excavation area based on the initial position data of the core and the position data of the core after deformation, and obtains the ground stress of the excavation area based on the deformation value.

Images