Hard rock rotary excavating grading reaming drill hole deviation obstacle detection method
By using a cutting tooth slag-removing drill bit and a measuring rope to detect the location of obstacles at the bottom of the pile hole during staged enlargement drilling in hard rock, the problem of difficult correction and repair of residual deviated rock mass at the bottom of the pile hole during staged enlargement drilling in hard rock was solved, and efficient and low-cost correction operation was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN GONGKAN GEOTECHN GRP
- Filing Date
- 2023-08-09
- Publication Date
- 2026-07-03
AI Technical Summary
During the rotary drilling and staged enlargement of hard rock, when there is residual skewed rock mass at the bottom of the pile hole, it is difficult to correct and repair the deviation. Existing technologies are inefficient and costly.
Multiple reamers are used to drill in stages to form pile holes. Cutting teeth and slag-removing drill bits are used to detect the planar and vertical positions of obstacles along the inner wall of the casing. The spatial position of obstacles is measured by measuring ropes. The specific location of obstacles is determined by segment numbering and measuring rope marking.
It improves the ease of operation and efficiency of obstacle detection, and reduces the difficulty and cost of correction and repair.
Smart Images
Figure CN117166929B_ABST
Abstract
Description
Technical Field
[0001] This invention patent relates to the technical field of rotary drilling in hard rock, and more specifically, to a method for detecting obstructions during staged enlargement drilling in hard rock rotary drilling. Background Technology
[0002] When encountering a moderately weathered hard rock bearing layer during the drilling process of large-diameter rotary bored piles, a staged enlargement drilling process is usually adopted. This involves drilling from the center of the pile location with a small-diameter rotary drill until the bottom of the pile hole reaches the design elevation, and then gradually enlarging the diameter of the pile hole until the design pile diameter is reached.
[0003] However, when the weathered rock strata are broken or have developed fissures, or when there is an inclined rock surface, it is difficult to control the verticality of the pile hole during the staged expansion drilling process. When the expanded hole enters the rock, it is easy for the hole to deviate, and it is difficult to correct the deviation at the bottom of the subsequent pile hole.
[0004] For example, during actual construction, the foundation piles were designed with a maximum diameter of Φ2mm and an average hole depth of 55m. A Bauer BG46 rotary drilling rig was used for drilling. The drilling was carried out in three stages using 1600mm, 0mm, and 2mm diameter core drills, penetrating 5m into moderately weathered rock to a depth of 58.6m. After the reaming was completed, when cleaning the bottom with a Φ2mm cutting drill bit, it was found that the drill bit got stuck at a depth of 57.5m and could not be lowered to the bottom, initially indicating a deviation from the borehole bottom. On-site inspection of the bottom of the pile hole was conducted section by section using a small-diameter cutting drill bit and a measuring rope. A crescent-shaped rock mass, 30cm wide and 1.1m high, was found on the inner side of the bottom. The analysis indicated that the deviation occurred mainly during the first and second stages of reaming, while the third stage, with the same designed pile diameter, was effectively supported by the borehole wall and did not deviate, resulting in the remaining rock column at the bottom of the hole.
[0005] In existing technologies, the treatment of residual skewed rock mass at the bottom of pile holes usually involves using a cutting drill bit with the same diameter as the pile to slowly sweep the hole for correction. During correction, the cutting teeth of the drill bit are easily damaged due to the uneven distribution of hard rock mass at the bottom of the hole. This requires repeated replacement of the cutting teeth and tooth base, resulting in difficulty in correcting the deviation inside the hole, long repair time, low treatment efficiency, and increased construction costs. Summary of the Invention
[0006] The purpose of this invention is to provide a method for detecting obstacles in rotary drilling and staged enlargement of hard rock, aiming to solve the problem that it is too difficult to correct and repair the deviation when there is residual deviated rock at the bottom of the pile hole in the prior art.
[0007] This invention is implemented as follows: a method for detecting obstructions during staged enlargement drilling in hard rock rotary drilling, comprising the following construction steps:
[0008] 1) Multiple borehole drills are used to drill in stages at the pile location to form pile holes with the bottom embedded in hard rock, and the pile holes are equipped with protective casings;
[0009] 2) Divide the casing into evenly numbered segments along its circumference to form multiple sequentially arranged circular segments, with the numbers increasing from small to large;
[0010] 3) Using a cutting tooth slag removal drill bit attached to the inner wall of the casing, probe multiple circumferential sections in sequence; during the probe process, the cutting tooth slag removal drill bit is lowered to the bottom of the pile hole and rotates along multiple circumferential sections without advancing a depth to determine the planar position of the obstacle.
[0011] After determining the planar position of the obstacle, the cutting tooth slag removal drill bit is lowered from top to bottom through the pile hole until it abuts against the obstacle from top to bottom, thus determining the vertical position of the obstacle; based on the planar and vertical positions of the obstacle, the spatial position of the obstacle is determined.
[0012] Furthermore, in the construction step 1), the diameters of the multiple reaming drills increase sequentially, and the drilling diameter increases from small to large. The multiple reaming drills are used to drill sequentially and in stages along the center of the pile position.
[0013] Furthermore, in construction step 2), the casing is divided into an even number of segments along its circumference.
[0014] Furthermore, in construction step 3), during the process of the cutting tooth slag removal drill bit rotating without advancing at the bottom of the pile hole, when the cutting tooth slag removal drill bit does not encounter any obstacles at the bottom of the pile hole, the cutting tooth slag removal drill bit sequentially translates and rotates along each circumferential segment.
[0015] Furthermore, in construction step 3), during the process of the cutting tooth slag removal drill bit rotating without advancing at the bottom of the pile hole, when the cutting tooth slag removal drill bit encounters an obstacle at the bottom of the pile hole, the cutting tooth slag removal drill bit moves along the inner side of the obstacle until the cutting tooth slag removal drill bit abuts against the inner wall of the casing. The planar position of the obstacle is determined based on the trajectory of the cutting tooth slag removal drill bit moving along the inner side of the obstacle.
[0016] Furthermore, in the construction step 3), when the cutting tooth slag removal drill bit abuts against the inner side of the obstacle, the abutting position of the cutting tooth slag removal drill bit against the inner side of the obstacle is the inner abutting point.
[0017] When the cutting tooth slag removal drill bit moves a set distance to the inside of the obstacle, a measuring rope is vertically lowered into the pile hole until the bottom of the measuring rope reaches the inner contact point. Then, the distance between the measuring rope and the inner side of the inner wall of the casing is measured.
[0018] During the process of the cutting tooth slag removal drill bit moving inward against the inside of the obstacle, multiple inner distances are obtained sequentially by lowering the measuring rope, and the inner trajectory of the obstacle is obtained through the multiple inner distances.
[0019] Furthermore, the inner contact position of the first end of the cutting tooth slag removal drill bit with the inner trajectory of the obstacle is the inner contact position of the first end, and the inner contact position of the first end is marked as the first end position on the casing; the inner contact position of the last end of the cutting tooth slag removal drill bit with the inner trajectory of the obstacle is the inner contact position of the last end, and the inner contact position of the last end is marked as the last end position on the casing.
[0020] In construction step 3), after the inner trajectory of the obstacle is measured, the measuring rope is lowered into the pile hole within the range from the first end position to the last end position until the bottom of the measuring rope reaches the bottom of the pile hole. Then, the measuring rope is moved towards the outside of the obstacle until the measuring rope touches the outside of the obstacle.
[0021] When the measuring rope comes into contact with the outside of the obstacle, the measuring rope is moved a set distance along the outside of the obstacle, and the distance between the measuring rope and the outside of the inner wall of the casing is measured.
[0022] As the measuring rope moves along the outside of the obstacle, multiple outer distances are obtained sequentially, and the outer trajectory of the obstacle is obtained through these multiple outer distances; the inner trajectory and the outer trajectory of the obstacle form the planar position of the obstacle.
[0023] Furthermore, in construction step 3), the cutting tooth slag-removing drill bit is attached to the inner wall of the casing and drills multiple circumferential segments counterclockwise in sequence.
[0024] Furthermore, the measuring rope includes a rope body marked with graduations, a gravity hammer is provided at the bottom of the rope body, the upper part of the gravity hammer is a straight cylindrical section, the lower part of the gravity hammer is a conical section that is smaller at the bottom and larger at the top, the bottom of the rope body is connected to the top of the straight section, and the conical section is connected to the bottom of the straight cylindrical section.
[0025] The outer periphery of the straight section is provided with multiple circumferential grooves, which are arranged at intervals along the height direction of the straight section and are arranged around the circumference of the straight section; multiple ellipsoidal rolling balls are provided in the circumferential grooves, and the rolling balls are movably placed in the circumferential grooves.
[0026] The inner end of the rolling ball is movably placed in the circumferential groove, and the outer end of the rolling ball is exposed outside the circumferential groove; the rolling ball has a hollow area, and the hollow area is eccentrically arranged with respect to the center of the rolling ball;
[0027] In construction step 3), after the gravity hammer is placed at the bottom of the pile hole, the straight section of the gravity hammer is moved toward the outside of the obstacle until the rolling ball of the straight section abuts against the outside of the obstacle.
[0028] As the straight section moves along the outside of the obstacle, the rolling ball rolls eccentrically along the circumferential groove.
[0029] Furthermore, there is a rotational gap between the bottom of the circumferential groove and the inner end of the rolling ball, and the bottom of the conical forging has a tip that extends outward to form a horizontally arranged balance plate, the outer diameter of which is smaller than the outer diameter of the straight section.
[0030] In construction step 3), as the straight section of the gravity hammer moves along the outside of the obstacle, the balance plate limits the swing amplitude of the gravity hammer.
[0031] Compared with existing technologies ， The present invention provides a method for detecting obstacles in rotary drilling and graded enlargement of hard rock. The method involves placing a cutting tooth slag-removing drill bit at the bottom of the pile hole. While rotating without advancing the drill bit, the cutting tooth slag-removing drill bit moves along the side of the obstacle to determine the planar position of the obstacle. Then, by abutting against the obstacle from top to bottom, the vertical position of the obstacle is detected, thereby obtaining the spatial position of the obstacle. The method is convenient to operate and has high detection efficiency. Attached Figure Description
[0032] Figure 1 This is a flowchart illustrating the method for detecting obstructions in staged enlarged borehole drilling in hard rock provided by the present invention.
[0033] Figure 2 This is a front view schematic diagram of the uniformly segmented casing provided by the present invention;
[0034] Figure 3 This is a front view schematic diagram of obstacles inside the pile hole provided by the present invention;
[0035] Figure 4 This is a front view schematic diagram of the planar position of an obstacle determined by a cutting tooth slag-removing drill bit provided by the present invention;
[0036] Figure 5 This is a front view schematic diagram of the gravity hammer provided by the present invention. Detailed Implementation
[0037] 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 merely illustrative and not intended to limit the invention.
[0038] The implementation of the present invention will be described in detail below with reference to specific embodiments.
[0039] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0040] Reference Figure 1-5 The image shown is a preferred embodiment of the present invention.
[0041] The method for detecting obstructions during staged enlargement drilling in hard rock rotary drilling includes the following construction steps:
[0042] 1) Multiple borehole drills are used to drill in stages at the pile location to form a pile hole 200 with the bottom embedded in hard rock. A protective casing 100 is installed inside the pile hole 200.
[0043] 2) Divide the casing 100 into evenly numbered segments along its circumference to form multiple sequentially arranged circular segments 101, with the numbers increasing from small to large.
[0044] 3) Using a cutting tooth slag removal drill bit 500 attached to the inner wall of the casing 100, probe multiple circumferential sections 101 in sequence; during the probe process, the cutting tooth slag removal drill bit 500 is lowered to the bottom of the pile hole 200 and rotates along multiple circumferential sections 101 in sequence without advancing a length to determine the planar position of the obstacle 201.
[0045] After determining the planar position of obstacle 201, the cutting tooth slag removal drill bit 500 is lowered from top to bottom through the pile hole 200 until it abuts against obstacle 201 from top to bottom, thus determining the vertical position of obstacle 201; based on the planar and vertical positions of obstacle 201, the spatial position of obstacle 201 is determined.
[0046] The above-mentioned method for detecting obstacles in rotary drilling and graded enlargement of hard rock involves placing a cutting tooth slag-removing drill bit 500 at the bottom of the pile hole. While rotating without advancing, the cutting tooth slag-removing drill bit 500 moves along the side of the obstacle 201 to determine the planar position of the obstacle 201. Then, by abutting against the obstacle 201 from top to bottom, the vertical position of the obstacle 201 is detected, thereby obtaining the spatial position of the obstacle 201. This method is convenient to operate and has high detection efficiency.
[0047] In construction step 1), the diameters of the multiple reaming drills increase sequentially. Based on the drilling diameter from small to large, the multiple reaming drills are used to drill sequentially in stages along the center of the pile position. In this way, the large-diameter pile hole of 200 can be formed by multiple stages of reaming.
[0048] In this embodiment, in construction step 2), the casing 100 is divided into an even number of segments along the circumference of the casing 100. The specific segmentation can be determined according to actual needs.
[0049] In this embodiment, during construction step 3), as the cutting tooth slag-removing drill bit 500 rotates without advancing at the bottom of the pile hole 200, when the cutting tooth slag-removing drill bit 500 does not encounter an obstacle 201 at the bottom of the pile hole 200, the cutting tooth slag-removing drill bit 500 sequentially translates and drills along each circumferential segment 101. By measuring the translational trajectory of the cutting tooth slag-removing drill bit 500, the trajectory of the side of the obstacle 201 can be obtained.
[0050] In construction step 3), during the process of the cutting tooth slag removal drill bit 500 rotating without advancing at the bottom of the pile hole 200, when the cutting tooth slag removal drill bit 500 encounters an obstacle 201 at the bottom of the pile hole 200, the cutting tooth slag removal drill bit 500 moves along the inner side of the obstacle 201 until the cutting tooth slag removal drill bit 500 abuts against the inner wall of the casing 100 and moves along the inner wall of the casing 100. Based on the trajectory of the cutting tooth slag removal drill bit 500 moving along the inner side of the obstacle 201, the planar position of the obstacle 201 is determined.
[0051] In construction step 3), when the cutting tooth slag removal drill bit 500 abuts against the inner side of the obstacle 201, the abutting position between the cutting tooth slag removal drill bit 500 and the inner side of the obstacle 201 is the inner abutting point.
[0052] When the cutting tooth slag removal drill bit 500 moves a set distance along the inner side of the obstacle 201, a measuring rope is vertically lowered into the pile hole 200 until the bottom of the measuring rope reaches the inner contact point. Then, the inner distance between the measuring rope and the inner wall of the casing 100 is measured. During the process of the cutting tooth slag removal drill bit 500 moving along the inner side of the obstacle 201, multiple inner distances are obtained in sequence by lowering the measuring rope. The inner trajectory of the obstacle 201 is obtained through multiple inner distances.
[0053] The inner contact position of the first end of the cutting tooth slag removal drill bit 500 and the inner trajectory of the obstacle 201 is the inner contact position of the first end, and the inner contact position of the first end is marked as the first end position on the casing 100; the inner contact position of the last end of the cutting tooth slag removal drill bit 500 and the inner trajectory of the obstacle 201 is the inner contact position of the last end, and the inner contact position of the last end is marked as the last end position on the casing 100.
[0054] In construction step 3), after the inner trajectory of obstacle 201 is measured, the measuring rope is lowered into the pile hole 200 within the range from the first end position to the last end position until the bottom of the measuring rope reaches the bottom of the pile hole 200. Then, the measuring rope is moved towards the outside of obstacle 201 until the measuring rope touches the outside of obstacle 201.
[0055] When the measuring rope comes into contact with the outside of the obstacle 201, the measuring rope is translated along the outside of the obstacle 201 by a set distance, and the distance between the measuring rope and the outside of the inner wall of the casing 100 is measured. During the process of the measuring rope translating along the outside of the obstacle 201, multiple outside distances are obtained in sequence, and the outside trajectory of the obstacle 201 is obtained through multiple outside distances. The inner trajectory and the outer trajectory of the obstacle 201 form the planar position of the obstacle 201.
[0056] Reference Figure 1 As shown, the detailed planar position of obstacle 201 in actual operation is as follows:
[0057] 1) When the cutting tooth slag removal drill bit 500 is moving along the inner wall of the casing 100 at the bottom of the pile hole 200, until it encounters the obstacle 201 and can no longer move along the inner wall of the casing 100, stop and mark point A. Lower the measuring rope to the intersection of the cutting tooth slag removal drill bit 500 and the obstacle 201, and mark it as point B on the casing 100. The distance between the measuring rope and the casing 100 is measured to be 180mm.
[0058] 2) The cutting tooth slag removal drill bit 500 moves along the inner side of the obstacle 201 until it can move along the inner side wall of the casing 100. Stop and mark it as point C. Lower the measuring rope to the intersection of the cutting tooth slag removal drill bit 500 and the obstacle 201, and mark it as point D on the casing 100. The distance between the measuring rope and the casing 100 is measured to be 150mm.
[0059] 3) When the cutting tooth slag removal drill bit 500 moves along the inner side of the obstacle 201, the distance between the lowered measuring rope and the casing 100 is measured every mm at the intersection of the cutting tooth slag removal drill bit 500 and the obstacle 201, with a maximum distance of mm. The inner trajectory of the obstacle 201 can be determined based on the distance at each point;
[0060] 4) Lower the measuring rope along the edge of the casing 100 every mm between points B and D until it reaches the bottom of the pile hole 200. Then, move the measuring rope into the pile hole 200. After finding the obstacle 201, measure the minimum distance between the obstacle 201 and the edge of the casing 100. The outer trajectory of the obstacle 201 can be determined based on the distance between each point.
[0061] In construction step 3), the cutting tooth slag removal drill bit 500 is attached to the inner wall of the casing 100, and multiple circumferential segments 101 are probed in a counterclockwise sequence. Alternatively, based on the preliminary judgment, clockwise probing can also be used.
[0062] In this embodiment, the measuring rope includes a rope body marked with graduations, a gravity hammer is provided at the bottom of the rope body, the upper part of the gravity hammer is a straight cylindrical section 600, and the lower part of the gravity hammer is a conical section 603 that is smaller at the bottom and larger at the top. The bottom of the rope body is connected to the top of the straight section, and the conical section 603 is connected to the bottom of the straight cylindrical section 600.
[0063] The outer periphery of the straight section 600 is provided with multiple circumferential grooves 601, which are arranged at intervals along the height direction of the straight section 600 and are arranged around the circumference of the straight section 600. Multiple ellipsoidal rolling balls 602 are provided in the circumferential grooves 601, and the rolling balls 602 are movably placed in the circumferential grooves 601.
[0064] The inner end of the rolling ball 602 is movably placed in the circumferential groove 601, and the outer end of the rolling ball 602 is exposed outside the circumferential groove 601; the rolling ball 602 has a hollow area, which is eccentrically arranged with respect to the center of the rolling ball 602.
[0065] In construction step 3), after the gravity hammer is placed at the bottom of the pile hole 200, the straight section 600 of the gravity hammer is moved toward the outside of the obstacle 201 until the rolling ball 602 of the straight section 600 abuts against the outside of the obstacle 201; as the straight section 600 moves along the outside of the obstacle 201, the rolling ball 602 rolls eccentrically along the circumferential groove 601.
[0066] Using a gravity hammer ensures the verticality of the measuring rope. The combination of multiple circumferential grooves 601 and rolling balls 602 facilitates the movement of the straight section 600 along the outside of the obstacle 201, preventing the gravity hammer from deviating from the outside of the obstacle 201 due to direct collision.
[0067] The rolling ball 602 is ellipsoidal, and the hollow area is eccentrically arranged with respect to the center of the rolling ball 602. As the straight section 600 moves along the outside of the obstacle 201, it has an undulating and bouncing step, which makes it easier for the user to perceive the movement of the straight section 600. Since the outside of the obstacle 201 is not flat, the ellipsoidal arrangement of the rolling ball 602 facilitates the movement of the straight section 600 along the outside of the obstacle 201.
[0068] In this embodiment, there is a rotational gap between the bottom of the circumferential groove 601 and the inner end of the rolling ball 602, and the bottom of the conical section 603 has a tip that extends outward to form a horizontally arranged balance plate 604. The outer diameter of the balance plate 604 is smaller than the outer diameter of the straight section 600.
[0069] In construction step 3), as the straight section 600 of the gravity hammer moves along the outside of the obstacle 201, the balance plate 604 limits the swing amplitude of the gravity hammer to prevent the swing amplitude of the gravity hammer from being too large during the movement of the straight section 600 along the outside of the obstacle 201, thereby reducing the detection efficiency.
[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for detecting obstructions during staged enlargement drilling in hard rock rotary drilling, characterized in that, The construction steps include the following: 1) Multiple borehole drills are used to drill in stages at the pile location to form pile holes with the bottom embedded in hard rock, and the pile holes are equipped with protective casings; 2) Divide the casing into evenly numbered segments along its circumference to form multiple sequentially arranged circular segments, with the numbers increasing from small to large; 3) Using a cutting tooth slag-removing drill bit attached to the inner wall of the casing, probe multiple circumferential sections in sequence; during the probe process, the cutting tooth slag-removing drill bit is lowered to the bottom of the pile hole and rotates along multiple circumferential sections without advancing a bit to determine the planar position of the obstacle. After determining the planar position of the obstacle, the cutting tooth slag removal drill bit is lowered from top to bottom through the pile hole until it abuts against the obstacle from top to bottom, thus determining the vertical position of the obstacle; based on the planar and vertical positions of the obstacle, the spatial position of the obstacle is determined. In construction step 3), when the cutting tooth slag removal drill bit abuts against the inner side of the obstacle, the abutting position of the cutting tooth slag removal drill bit against the inner side of the obstacle is the inner abutting point. When the cutting tooth slag removal drill bit moves a set distance to the inside of the obstacle, a measuring rope is vertically lowered into the pile hole until the bottom of the measuring rope reaches the inner contact point. Then, the distance between the measuring rope and the inner side of the inner wall of the casing is measured. During the process of the cutting tooth slag removal drill bit moving along the inner side of the obstacle, multiple inner distances are obtained sequentially by lowering the measuring rope, and the inner trajectory of the obstacle is obtained through the multiple inner distances; The measuring rope includes a rope body marked with graduations, a gravity hammer at the bottom of the rope body, a straight cylindrical section at the top of the gravity hammer, and a conical section at the bottom of the gravity hammer that is smaller at the bottom and larger at the top. The bottom of the rope body is connected to the top of the straight cylindrical section, and the conical section is connected to the bottom of the straight cylindrical section. The outer periphery of the straight section is provided with multiple circumferential grooves, which are arranged at intervals along the height direction of the straight section and are arranged around the circumference of the straight section; multiple ellipsoidal rolling balls are provided in the circumferential grooves, and the rolling balls are movably placed in the circumferential grooves. The inner end of the rolling ball is movably placed in the circumferential groove, and the outer end of the rolling ball is exposed outside the circumferential groove; the rolling ball has a hollow area, and the hollow area is eccentrically arranged with respect to the center of the rolling ball; In construction step 3), after the gravity hammer is placed at the bottom of the pile hole, the straight section of the gravity hammer is moved toward the outside of the obstacle until the rolling ball of the straight section abuts against the outside of the obstacle. As the straight section moves along the outside of the obstacle, the rolling ball rolls eccentrically along the circumferential groove.
2. The method for detecting obstructions in staged enlarged borehole drilling in hard rock as described in claim 1, characterized in that, In construction step 1), the diameters of the multiple reaming drills increase sequentially, and the drilling diameter increases from small to large. The multiple reaming drills are used to drill sequentially in stages along the center of the pile position.
3. The method for detecting obstructions in staged enlarged borehole drilling in hard rock as described in claim 1, characterized in that, In construction step 2), the casing is divided into an even number of segments along its circumference.
4. The method for detecting obstructions in staged enlarged borehole drilling in hard rock as described in any one of claims 1 to 3, characterized in that, In construction step 3), during the process of the cutting tooth slag removal drill bit rotating without advancing at the bottom of the pile hole, when the cutting tooth slag removal drill bit does not encounter any obstacles at the bottom of the pile hole, the cutting tooth slag removal drill bit sequentially translates and rotates along each circumferential segment.
5. The method for detecting obstructions in staged enlarged borehole drilling in hard rock as described in claim 4, characterized in that, In construction step 3), during the process of the cutting tooth slag removal drill bit rotating without advancing at the bottom of the pile hole, when the cutting tooth slag removal drill bit encounters an obstacle at the bottom of the pile hole, the cutting tooth slag removal drill bit moves along the inner side of the obstacle until the cutting tooth slag removal drill bit abuts against the inner wall of the casing. The planar position of the obstacle is determined according to the trajectory of the cutting tooth slag removal drill bit moving along the inner side of the obstacle.
6. The method for detecting obstructions in staged enlarged borehole drilling in hard rock as described in claim 5, characterized in that, The inner contact position of the first end of the cutting tooth slag removal drill bit with the inner track of the obstacle is the inner contact position of the first end, and the inner contact position of the first end is marked as the first end position on the casing; the inner contact position of the last end of the cutting tooth slag removal drill bit with the inner track of the obstacle is the inner contact position of the last end, and the inner contact position of the last end is marked as the last end position on the casing. In construction step 3), after the inner trajectory of the obstacle is measured, the measuring rope is lowered into the pile hole within the range from the first end position to the last end position until the bottom of the measuring rope reaches the bottom of the pile hole. Then, the measuring rope is moved towards the outside of the obstacle until the measuring rope touches the outside of the obstacle. When the measuring rope comes into contact with the outside of the obstacle, the measuring rope is moved a set distance along the outside of the obstacle, and the distance between the measuring rope and the outside of the inner wall of the casing is measured. As the measuring rope moves along the outside of the obstacle, multiple outer distances are obtained sequentially, and the outer trajectory of the obstacle is obtained through these multiple outer distances; the inner trajectory and the outer trajectory of the obstacle form the planar position of the obstacle.
7. The method for detecting obstructions in staged enlarged borehole drilling in hard rock as described in claim 5, characterized in that, In construction step 3), the cutting tooth slag-removing drill bit is attached to the inner wall of the casing and drills multiple circumferential segments counterclockwise in sequence.
8. The method for detecting obstructions in staged enlarged borehole drilling in hard rock as described in claim 5, characterized in that, There is a rotational gap between the bottom of the circumferential groove and the inner end of the rolling ball. The bottom of the conical section has a tip that extends outward to form a horizontally arranged balance plate. The outer diameter of the balance plate is smaller than the outer diameter of the straight section. In construction step 3), as the straight section of the gravity hammer moves along the outside of the obstacle, the balance plate limits the swing amplitude of the gravity hammer.