Disturbance-grabbing-sucking linkage reverse circulation drilling large pebble rapid obstacle removing device and method

Abstract

The invention relates to the technical field of geotechnical engineering and foundation construction, in particular to a perturbation-grabbing-suction linkage reverse circulation drilling cobble rapid obstacle removing device and a perturbation-grabbing-suction linkage reverse circulation drilling cobble rapid obstacle removing method. The device comprises an upper linkage mechanism installed at the bottom of a hollow drill rod, a multi-finger clamping mechanism, a disturbance rocker arm assembly, a reverse circulation suction and discharge channel and a control and communication unit. The control and communication unit receives torque and negative pressure signals, after a pebble jamming event is recognized, the disturbance rocker arm assembly is automatically controlled to loosen pebbles, the multi-finger clamping mechanism clamps and locks the pebbles, meanwhile, negative pressure is instantly enhanced, the pebbles are sucked out of a drill hole through the reverse circulation suction and exhaust channel, and finally drilling is recovered. According to the method, online recognition and integrated rapid removal of the cobblestones are achieved, the drill jamming risk and the hole wall instability possibility are remarkably reduced, the obstacle removal efficiency and the pile forming quality are improved, and the method is suitable for bored pile construction of the sandy cobble stratum.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical engineering and foundation construction, in particular to a disturbance-grabbing-suction integrated anti-circulation drilling large cobble rapid obstacle clearing device and method. BACKGROUND

[0002] With the continuous extension of deep foundation engineering to complex strata, large-diameter cobble with a size of ≥150mm in sand and cobble strata poses a serious challenge to anti-circulation drilling construction. Such strata generally have high permeability, strong embedding and extruding properties, and low cementation. During drilling, large boulders are prone to be stuck on the cutting surface of the drill bit or the debris discharge channel, causing risks such as drill bit sticking, drill pipe sticking, and even hole wall instability. The traditional countermeasures mainly include stopping the machine and manually removing the cobble with a grab bucket, increasing the negative pressure suction of the mud, or replacing the impact breaking drill bit to directly crush the obstacles. However, these methods have significant drawbacks in practical application: manual grab bucket operation requires repeated lifting of the drilling tools, frequent process interruptions, long time consumption, and low efficiency for each obstacle removal; high-pressure pump suction can improve the debris discharge capacity, but the adsorption force of high-density large particles is limited, and sudden changes in negative pressure can disturb the balance of the hole wall, leading to hole collapse; and using impact breaking can crush the boulders, but the intense vibration aggravates the wear of the drilling tools and may damage the surrounding strata structure, further threatening the quality and safety of hole formation.

[0003] Among them, the anti-circulation drilling process itself relies on a stable mud circulation and continuous debris discharge mechanism, but when encountering large cobble obstruction, the existing system lacks the ability to actively identify and intervene obstacles. Conventional monitoring methods only focus on a single parameter such as torque or pump pressure, making it difficult to accurately determine the size and location of the cobble, leading to delayed response or misjudgment. At the same time, the obstacle removal action is mostly passive waiting or rough handling, which cannot achieve precise disturbance, stable clamping, and efficient discharge of target particles without interrupting the drilling. Especially in high-gravel-content strata, repeated stopping for obstacle removal not only prolongs the construction period, but also easily causes structural defects such as pile bottom sediment accumulation, pile body stone inclusion, and insufficient bearing capacity, seriously affecting the integrity and long-term service performance of the pile foundation.

[0004] Therefore, in the anti-circulation drilling construction of sand and cobble strata, there is an urgent need for a "disturbance-grabbing-suction" integrated obstacle removal method that can identify large cobble online, actively implement disturbance and loosening, reliably clamp and lock, and cooperatively enhance the negative pressure for rapid suction, to achieve efficient, safe, and intelligent removal of large-diameter obstacles, fundamentally reduce the risk of drill pipe sticking, ensure the stability of the hole wall, shorten the hole formation period, and comprehensively improve the quality and reliability of the pile foundation engineering. SUMMARY

[0005] To address the shortcomings of existing technologies, this invention provides a device and method for rapid removal of large pebbles in reverse circulation drilling, which can identify large pebbles online, actively implement disturbance and loosening, reliably clamp and lock them, and synergistically enhance negative pressure for rapid suction and lifting. This achieves efficient, safe, and intelligent removal of large-diameter obstacles, fundamentally reducing the risk of stuck drill, ensuring borehole stability, shortening the drilling cycle, and comprehensively improving the quality and reliability of pile foundation engineering.

[0006] Therefore, the purpose of this invention is to provide a rapid obstacle removal device for large pebbles in reverse circulation drilling, which integrates a disturbance-grabbing-suction linkage and is installed at the bottom end of the hollow drill rod of a reverse circulation drilling rig, comprising:

[0007] The upper linkage mechanism includes a ring main beam structure and a main spindle sleeve located at its center and coaxial with the hollow drill rod. The main spindle sleeve is tightly fitted with the hollow drill rod so that the two rotate synchronously. A torque sensor for monitoring the drill bit torque is installed on the main spindle sleeve. The reverse circulation suction and discharge channel is located on the side of the upper linkage mechanism and is connected to the hollow drill pipe; the end of the reverse circulation suction and discharge channel is connected in series with a quick-opening valve and a variable frequency negative pressure pump to form a negative pressure enhancement unit; the reverse circulation suction and discharge channel uses the enhanced negative pressure suction to suck the clamped pebbles and their associated slag to the wellhead as a whole; The multi-finger gripping mechanism includes at least three gripping fingers evenly distributed along the circumference of the main shaft sleeve at the bottom of the upper linkage mechanism and corresponding gripping finger drive cylinders. The root of each gripping finger is hinged to the rotating seat on the lower surface of the linkage mechanism. Each gripping finger root is equipped with a gripping force sensor, and the pebble is locked when the combined force of the multiple fingers reaches a preset threshold. The lower guide ring includes a retaining ring coaxial with the upper linkage mechanism; the hollow drill pipe passes through the center of the retaining ring; The disturbance rocker arm assembly includes multiple telescopic disturbance arms disposed on the lower guide ring for applying tangential disturbance force to the large pebbles at the bottom of the hole; Control and communication units; all are signal-connected to the control and communication units; The control and communication unit is configured to receive and process real-time signals from the torque sensor and the negative pressure enhancement unit. When the changes in the torque signal and the negative pressure signal synchronously exceed a preset threshold and continue for a set time, a pebble jamming event is determined to have occurred. The unit then automatically and sequentially controls the movement of the disturbance rocker arm assembly to loosen the pebble, the movement of the multi-finger gripping mechanism to grip and lock the pebble, and the movement of the negative pressure enhancement unit to instantaneously increase the negative pressure.

[0008] As a preferred technical solution, the locking of the pebbles is achieved by a locking mechanism, which is a hydraulic pin-type locking mechanism.

[0009] As a preferred technical solution, the hydraulic pin-type locking mechanism includes a locking pin driven by a hydraulic cylinder. When a locking command is received from the control and communication unit, the hydraulic cylinder pushes the locking pin into a special locking groove set at the base of the finger clamp to form a rigid mechanical limit.

[0010] As a preferred technical solution, the control and communication unit adopts a PLC controller to acquire real-time signals from the torque sensor, the clamping force sensor, and the negative pressure pulsating pressure gauge located on the reverse circulation suction and discharge channel at a sampling frequency of not less than 1kHz.

[0011] As a preferred technical solution, the end of the telescopic disturbance arm is equipped with a replaceable spiral disturbance head or a high-pressure water jet nozzle.

[0012] As a preferred technical solution, a grading and screening unit located at the wellhead is also included, which is used to classify the pebbles lifted to the wellhead according to their particle size.

[0013] The present invention also discloses a method for clearing obstacles using the above-mentioned device, comprising the following steps: S1. Real-time acquisition of drill bit torque signal and system negative pressure signal during the initial stage of drilling; S2. The control and communication unit determines whether the triggering conditions for the pebble jamming event are met based on the received signal. S3. If the conditions are met, the obstacle clearing process will be automatically triggered, and the drill bit will be controlled to slow down or stop feeding; the disturbance rocker assembly will be controlled to extend and apply disturbance force to the stuck pebbles, so that they are separated from the surrounding strata. S4. The control and communication unit controls the multi-finger gripping mechanism to open and close to grip the pebble, and locks the pebble when the gripping force reaches the preset locking threshold. S5. After the pebbles are locked, the quick-opening ball valve is fully opened, and the negative pressure enhancement unit instantly increases the negative pressure of the system. The enhanced suction force is used to suck the clamped pebbles and their associated slag to the wellhead as a whole. S6. After the monitoring signal returns to normal, control the multi-finger clamping mechanism to unlock and reset, restore the normal drilling parameters and continue construction; the grading and screening unit classifies the pebbles and slag according to their particle size.

[0014] As a preferred technical solution, the process by which the control and communication unit determines the occurrence of a pebble jamming event is as follows: (1) Torque mutation threshold: ; in , The average torque over the last 5 seconds; (2) Negative pressure pulsation threshold: , in, The average value of negative pressure pulsations over the last 5 seconds; (3) Composite criterion: when and If the duration is greater than or equal to 0.3 seconds, the system determines that the pebble jamming event has been triggered.

[0015] As a preferred technical solution, in S6, pebbles with a diameter of not less than 150mm enter the waste hopper, pebbles with a diameter of 50-150mm are discharged through a secondary screen, and pebbles with a diameter of less than 50mm enter the hydrocyclone for separation.

[0016] As a preferred technical solution, the method is applicable to complex strata with a sand and gravel content of 50%–90% and a pebble compressive strength not exceeding 120 MPa.

[0017] The advantages and positive effects of this invention are: This invention effectively solves the problem of large-diameter pebbles blocking boreholes in sandy and gravelly strata, achieving intelligent and efficient obstacle removal operations. By automatically identifying obstacles through a composite criterion of torque and negative pressure signals, it coordinates a series of operations including disturbance, grasping, and enhanced suction, controlling the obstacle removal time for a single operation to within 90 seconds without interrupting drilling. Engineering applications show that this method reduces the number of obstacle removal operations per pile by approximately 68%, shortens the borehole formation time by 24%, and completely avoids drill jamming accidents, significantly improving construction safety and continuity. Simultaneously, the thickness of sediment at the pile bottom is stably controlled at a low level, reliably ensuring pile quality. The overall economic benefits are significant, with a reduction of approximately 16% in single-pile construction costs. This invention transforms the obstacle removal process from a passive and inefficient traditional model to a proactive and integrated intelligent process, providing a reliable technical solution for drilling construction in complex strata. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a reverse circulation drilling rig. Figure 2 This is a general structural diagram of the rapid obstacle clearing device of the present invention; Figure 3 This is a schematic diagram of a multi-finger gripping mechanism. Figure 4 A real-time torque-negative pressure curve used to determine the triggering of gravel jamming events during reverse circulation drilling; Figure 5 A schematic diagram of the rocker arm assembly structure for disturbance; Figure 6 This is a schematic diagram illustrating the working principle of the rapid obstacle clearing device of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Reverse circulation drilling rig; 2. Hollow drill rod; 3. Upper linkage mechanism; 31. Annular main beam structure; 32. Main spindle sleeve; 33. Rotary seat; 4. Multi-finger clamping mechanism; 41. Clamping finger; 5. Disturbance rocker arm assembly; 51. Telescopic disturbance rocker arm; 6. Control and communication unit; 7. Lower guide ring; 71. Wear-resistant liner; 8. Column; 9. Torque sensor; 10. Instantaneous negative pressure enhancement interface; 11. Quick-opening valve; 12. Variable frequency negative pressure pump; 13. Negative pressure pulsation pressure gauge; 14. Pressure sensor; 15. Grading and screening unit. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below; obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figures 1-6 This invention discloses a rapid obstacle removal device for large pebbles in reverse circulation drilling, which is installed at the bottom end of the hollow drill rod 2 of the reverse circulation drilling rig 1. The whole device includes an upper linkage mechanism 3, a multi-finger clamping mechanism 4, a disturbance rocker arm assembly 5, a reverse circulation suction and discharge channel, and a control and communication unit 6. The upper linkage mechanism 3, the multi-finger clamping mechanism 4, and the lower guide guard ring 7 are all connected to the hollow drill rod 2 through quick-change flanges and positioning pins to adapt to the replacement needs of different borehole diameters of 1.0~3.0m.

[0022] The upper linkage mechanism 3 is a ring main beam structure 31 with built-in cross stiffening ribs to improve overall rigidity; the ring main beam structure 31 has a main spindle sleeve 32 coaxially located on the outside of the hollow drill rod 2 at its center, and the main spindle sleeve 32 is tightly fitted with the hollow drill rod 2 so that the two can rotate synchronously; a MEMS torque sensor 9 is installed on the main spindle sleeve 32 for real-time monitoring of drill bit torque; an instantaneous negative pressure enhancement interface 10 is provided on the outside of the ring main beam for connecting the negative pressure enhancement unit.

[0023] The multi-finger gripping mechanism 4 includes at least three gripping fingers 41 evenly distributed around the circumference of the main shaft sleeve 32 at the bottom of the upper linkage mechanism 3, and corresponding gripping finger 41 drive cylinders. The root of each gripping finger 41 is hinged to a connecting seat on the lower surface of the linkage mechanism. The corresponding gripping finger 41 rotation drive cylinder is installed on one side of the connecting seat. Each gripping finger 41 is equipped with a gripping force sensor at its root. When the combined force of the multiple fingers reaches a preset threshold, the locking mechanism is triggered to lock the pebble. The multi-finger gripping mechanism 4 grips the large pebble through opening and closing actions and rotates in a circumferential manner to hold it.

[0024] In some preferred embodiments, the multi-finger gripping mechanism 4 includes three replaceable gripping fingers 41. Taking a φ1.5m drilling diameter as an example, the maximum opening diameter of the multi-finger gripping mechanism 4 is ≥450mm, and the effective gripping diameter range is approximately 180–450mm. It automatically locks when the combined force of the three gripping fingers 41 is ≥25kN. Preferably, the gripping fingers 41 are made of 30CrNiMo alloy steel, and the claw ends are embedded with carbide teeth. Preferably, the multi-finger gripping mechanism 4 can also be equipped with an angle encoder or position sensor to measure the angle of the gripping fingers 41 in real time and provide feedback for closed-loop control.

[0025] Preferably, the locking mechanism includes a high-precision strain gauge force sensor located at the base of each gripping finger 41. This sensor monitors the actual gripping force of its corresponding gripping finger 41 in real time at a frequency of not less than 1 kHz. Multiple signals are synchronously transmitted to the control and communication unit 6 to calculate and determine the total gripping force of the multi-finger gripping mechanism 4 in real time. When the total gripping force is determined to reach or exceed the preset threshold, the control and communication unit 6 immediately sends a trigger command to the locking actuator. This design ensures that the locking action is initiated only when the gripping force is sufficient and the gripping state is stable, thus avoiding the slippage of pebbles due to insecure gripping.

[0026] The locking mechanism is a hydraulically driven or mechanically self-locking structure, specifically a hydraulic pin-type locking mechanism. This mechanism includes a locking pin driven by a small hydraulic cylinder. When the locking command is received from the control and communication unit 6, the hydraulic cylinder pushes the locking pin to move radially and precisely insert it into the special locking groove set at the root of the clamping finger 41. Once inserted, it forms a rigid mechanical limit, so even if the hydraulic system subsequently loses pressure, the clamping finger 41 cannot open on its own, thus achieving fault-safe locking.

[0027] After the obstacle removal process is completed, the clamping finger 41 needs to be unlocked. At this time, the control and communication unit 6 issues a reset command, driving the hydraulic cylinder of the locking mechanism to reverse its movement, causing the locking pin to exit from the locking groove or the wedge block to slide out of the gap, thus releasing the mechanical constraint. Afterwards, the clamping finger 41 drive cylinder can control the clamping finger 41 to open, releasing the pebbles or resetting to the standby state. This unlocking process can be linked with the wellhead slag discharge signal to achieve a fully automatic cycle.

[0028] The lower guide ring 7 is connected to the upper linkage mechanism 3 as a whole through the column 8 or the diagonal brace. Specifically, it includes a guard ring coaxially located below the multi-finger clamping mechanism 4; the hollow drill rod 2 passes through the center of the guard ring; the guard ring is provided with a space that limits the movement range of the clamping fingers 41, and the space is embedded with a wear-resistant liner 71; its functions are: first, to guide the movement trajectory of the end of the clamping fingers 41; second, to prevent large pebbles from rebounding and damaging the mechanism; and third, to act as an interceptor or limiting component to prevent the clamping fingers 41 from opening excessively.

[0029] The disturbance rocker arm assembly 5 functions to agitate large pebbles through symmetrical left-right swinging during drilling or before and after clamping, breaking up any adhesion or jamming around them to facilitate clamping or extraction. Specifically, it includes multiple retractable disturbance arms 51 positioned around the lower guide ring 7, driven by short-stroke hydraulic cylinders or electric push rods, with a stroke of 200–250 mm. Each disturbance arm is equipped with a replaceable helical disturbance head made of Hardox 450 wear-resistant steel, used to apply tangential disturbance force to the large pebbles at the bottom of the hole, preferably 12–15 kN, to release them from their embedded state with the surrounding strata. The disturbance arm end can also be optionally equipped with a high-pressure water jetting device for pre-grooving smooth pebbles, with a jetting pressure of not less than 15 MPa.

[0030] The reverse circulation suction and discharge channel is connected to the hollow drill rod 2 and is located on the side of the upper linkage mechanism 3. It is connected in series with a quick-opening valve 11 and a variable frequency negative pressure pump 12 to form an instantaneous negative pressure enhancement unit. The negative pressure enhancement unit includes a negative pressure pulsating pressure gauge 13 located upstream of the reverse circulation suction and discharge channel and is equipped with an anti-clogging filter cap or a swirling anti-sand structure to monitor suction fluctuations.

[0031] The quick-opening valve 11, with a DN150~DN200 specification, can be fully opened within 0.1s. Combined with the variable frequency negative pressure pump 12, it can increase the negative pressure by 30-40% within 6-10s. The variable frequency negative pressure pump 12 has a rated flow rate of 250m³ / h. 3 / h, head 45m, frequency adjustment range is 20Hz~60Hz.

[0032] The control and communication unit 6 uses a PLC or equivalent industrial controller to acquire signals from the torque sensor 9, negative pressure pulsating pressure gauge 13, and clamping force sensor at a sampling frequency of not less than 1kHz. The control unit determines whether a "pebble jamming event" is triggered based on a preset composite threshold, and sequentially controls the extension of the disturbance rocker arm assembly, the opening and retraction of the clamping fingers 41, the action of the locking mechanism, and the instantaneous increase of negative pressure to achieve fully automatic obstacle clearing.

[0033] The control and communication unit 6 is a PLC control terminal or an equivalent industrial controller. It uses a preset composite threshold to judge torque and negative pressure pulsation, and sets a duration criterion to avoid false triggering.

[0034] The main load-bearing components of the device are made of Q345D or equivalent strength steel, the easily worn parts are made of wear-resistant plate Hardox450 or equivalent material, the clamping fingers 41 are made of 30CrNiMo quenched and tempered steel, and the clamping ends of the clamping fingers 41 are made of cemented carbide YG type.

[0035] During the clamping and locking period, the control and communication unit 6 controls the spindle to maintain a micro-rotation of no more than 2 r / min to ensure that the clamping finger 41 is coaxially attached to the pebble before performing instantaneous negative pressure enhancement.

[0036] It also includes a grading and screening unit 15 located at the wellhead. Pebbles no smaller than 150mm enter the waste hopper, pebbles between 50 and 150mm pass through a secondary screen and are discharged, and pebbles smaller than 50mm enter a hydrocyclone for separation. After the system confirms that the torque and negative pressure have returned to normal, drilling continues under the original operating conditions. The entire obstacle clearing process usually does not exceed 90 seconds and is recorded in the log for quality traceability.

[0037] The obstacle clearing method of the above-described rapid obstacle clearing device of the present invention includes the following steps: S1. In the initial stage of drilling, conventional crushing and slag removal are carried out with a rotation speed of 20–30 r / min, a feed force of 80–120 kN, and a mud specific gravity of 1.08–1.15 g / cm³. During this period, drill bit torque T and negative pressure ΔP data are collected and uploaded in real time as dynamic benchmark references.

[0038] S2. The control and communication unit 6 determines whether the triggering conditions for a pebble jamming event are met based on the received signal; specifically, the process by which the control and communication unit 6 determines the occurrence of a "pebble jamming event" is as follows: (1) Torque mutation threshold: ; in (Empirical coefficient) This represents the average torque over the last 5 seconds.

[0039] (2) Negative pressure pulsation threshold: , in, This represents the average value of negative pressure pulsations over the last 5 seconds.

[0040] (3) Composite criterion: when and If the duration is greater than or equal to 0.3 seconds, the system determines that the "pebble jamming event" has been triggered.

[0041] To accurately detect large pebble blockage characteristics, the system uses torque and negative pressure pulsation as dual parameters for judgment. The real-time torque signal is compared with the average value over the past 5 seconds. If the sudden increase reaches 35%–45% of the average value, it can be considered that the drill bit has encountered localized hard resistance. Simultaneously, if the pulsating pressure in the suction channel increases by 25%–30%, it further indicates that there are large pebble particles blocking the bottom of the hole. Only when both indicators exceed the limits simultaneously and persist for more than 0.3 seconds will the control program trigger a "pebble blockage event." This composite criterion avoids false alarms from a single signal and ensures that the system can respond quickly when a real risk occurs. The threshold coefficients μ1 and μ2 can be calibrated on the first day of drilling, taking into account drilling rig power, hole diameter, and formation density, and dynamically fine-tuned as construction progresses to maintain recognition sensitivity and stability.

[0042] S3. If a pebble jamming event occurs, the obstacle clearing process will be automatically triggered, and the drill bit speed will be reduced or the feed will be paused. Then the following actions will be performed: the drill bit speed will be automatically reduced to 5 r / min, the feed will be paused, the current hole depth will be locked and recorded as H0, which will serve as the position reference for the obstacle clearing operation.

[0043] Extend the telescopic disturbance arm 0.2m at a speed of 0.1m / s, bringing its spiral disturbance head close to the target pebble; start the disturbance arm to rotate counterclockwise three times, applying a tangential disturbance force of 12~15kN to separate the pebble from the surrounding mortar and adjacent gravel; monitor the torque change in real time, and wait until it drops to about 70% of the normal average torque (i.e., 0.7× When the disturbance is complete, stop the disturbance.

[0044] S4. The control and communication unit 6 controls the multi-finger clamping component to open to Φ450mm, and then slowly closes it. At the same time, the clamping force is detected in real time by the pressure sensor 14. When the clamping force reaches 25kN or above, the jaws lock the pebble. During this process, the drill bit maintains a micro-speed rotation of about 2r / min to ensure that the jaws are aligned with the pebble axis and avoid uneven loading.

[0045] S5. After the pebbles are locked, the quick-opening ball valve is fully opened within 0.1s, and the frequency of the variable frequency negative pressure pump 12 is increased to 60Hz, so that the negative pressure of the system is increased by 35%–40% on the original basis; within 6–10s, the pebbles and their associated slag are sucked up to the wellhead by the enhanced negative pressure suction.

[0046] S6. The grading and screening unit 15 at the wellhead performs grading according to particle size: large pebbles ≥150mm are fed into the waste hopper, medium and coarse particles of 50–150mm are screened out through a secondary screening, and fine slag enters the hydrocyclone for further separation. After the system confirms that the torque and negative pressure data have returned to the normal range, it automatically switches back to the original drilling parameters and continues construction; the entire obstacle clearing process is usually completed within 90 seconds, and all operating parameters and time points are recorded in the system log, supporting full-process quality traceability.

[0047] The engineering application scope of the method described in this invention is complex strata with a gravel content of 50%–90% and a pebble compressive strength not exceeding 120MPa, covering the construction needs of pile foundations with pile diameters of 1.0–3.0m and hole depths of 20–120m. During system implementation, the hydraulic system oil temperature should be maintained within the range of 20℃–55℃ to prevent sealing failure and efficiency reduction due to high temperatures. It is recommended that the skeleton oil seal of the negative pressure pump be replaced every 500 hours of operation to ensure stable output of transient negative pressure. The disturbance head and gripper components should be inspected for wear after 1200 hours of cumulative operation, and repaired and reinforced through welding if necessary to ensure structural strength and gripping reliability. Furthermore, key system thresholds such as torque surge and negative pressure pulsation discrimination thresholds must be verified and dynamically calibrated on-site using a three-point loading method on the first day of drilling and at the handover of each shift, matching them with the real-time power of the drilling rig and changes in formation resistance, thereby maintaining the accuracy and adaptability of obstacle clearing judgment.

[0048] Application examples The method described in this invention has been successfully applied to the pile foundation project of the No. 7 main pier of a dual-purpose road-rail bridge. This project requires the construction of 16 bored cast-in-place piles with a diameter of 1.5m and a depth of 42m. The geological conditions are complex: from the surface to 6m, there is a layer of silt interbedded with fine sand; from 6 to 32m, there is a layer of medium-dense sand and gravel with a gravel content of about 70%, and the gravel particle size is mainly 60-400mm, with isolated boulders with a diameter of up to 600mm in some areas; from 32 to 42m, there is a layer of moderately weathered mudstone.

[0049] The method for clearing obstacles using the rapid obstacle clearing device of the present invention includes the following steps: S1. A MEMS torque sensor 9 and a negative pressure pulsation gauge 13 are installed at the bottom of a 300kW reverse circulation drilling rig 1 and connected to the PLC control cabinet. A hydraulic telescopic disturbance arm and a multi-finger clamping component are also integrated. A 10-minute on-site test load is conducted before formal construction to collect baseline data on torque and negative pressure under no-load and conventional crushing conditions. Based on this, threshold values ​​are calibrated: the torque surge threshold ΔTcrit is set to 40% of the average torque, and the negative pressure pulsation threshold ΔPcrit is set to 28% of the average negative pressure. The hydraulic telescopic disturbance arm has a spiral blade outer diameter of 0.25m and a stroke of 0.3m; the multi-finger clamping component has a maximum opening diameter Φ0.45m and a rated clamping force of 30kN. S2. In the initial stage of drilling, the rotation speed is set to 24 r / min, the feed force is 100 kN, and mud with a specific gravity of 1.10 g / cm³ is used and circulated at a flow rate of 130 m³ / h. The PLC system collects and processes torque-negative pressure data in real time at a frequency of 1 kHz to form a continuous monitoring curve.

[0050] S3. When drilling reached a depth of 17.8m, the monitoring system detected a sudden increase in torque from 9.6kN·m to 14.0kN·m, an increase of 46%, while the negative pressure pulsation increased from 48kPa to 63kPa, an increase of 31%. This abnormal state lasted for 0.35s, and the system automatically identified it as a "pebble jamming event" and initiated the linkage obstacle clearing process: S3.1, The drilling rig speed is reduced to 5 r / min and the feed is stopped; S3.2 The telescopic disturbance arm extends 0.2m at a speed of 0.1m / s and rotates counterclockwise three times to disturb the target pebble, thereby reducing the torque to 7.0kN·m; S3.3 The multi-finger clamping component opens to the set diameter and then slowly closes, locking the pebble when the clamping force reaches 27kN; S3.4, the quick-opening valve 11 is fully opened within 0.1s, the frequency of the negative pressure pump is increased to 60Hz, and the system sucks the target gravel to the wellhead within 6s, and the gravel with a diameter of Φ310mm is intercepted by the primary screen. S3.5 After the torque and negative pressure data return to the normal baseline, the system automatically resumes normal drilling.

[0051] Four "pebble jamming events" were triggered during the entire construction of the pile. Each clearing took an average of 1.4 minutes, and the machine did not need to be stopped to change the grab bucket.

[0052] S4. After adopting this method, the average drilling time for a single pile is shortened to 8.7 hours, which is 24.3% lower than that of the traditional method; the thickness of the sediment at the bottom of the pile is controlled between 12 and 18 mm (the allowable value in the specification is ≤50 mm); the proportion of Class I piles in the pile integrity test reaches 98%; and no accidents such as stuck drill, drill bit jamming, or hole wall collapse occur during the entire construction process.

[0053] During the construction of Pier No. 6 using the traditional reverse circulation drilling process, the machine had to be stopped and the grab bucket lowered to clear the obstruction of each pile an average of 3-4 times. The drilling time for a single pile was as long as 11.5 hours, and there were two incidents of stuck drills, which caused serious damage to the equipment and significantly increased the construction safety risks and overall costs.

[0054] The obstacle-clearing method of the present invention, when tested on Pier 7, showed the following significant advantages compared to the traditional reverse circulation drilling method used on Pier 6: Firstly, the efficiency of obstacle removal has been significantly improved: This patented construction method reduces the average number of hole cleanings per pile from 3.4 times to 1.1 times, a reduction of 68%; the corresponding total drilling time is shortened from 11.5 hours to 8.7 hours, saving an overall time of 24%. Regarding safety and reliability, the traditional method resulted in two stuck / clamped drill accidents at Pier 6, while the patented method achieved zero accidents at Pier 7, completely eliminating the risk of major downtime and equipment damage. The quality of pile formation has also been improved simultaneously: the thickness of sediment at the pile bottom has decreased from 40-55 mm to 12-18 mm, a reduction of approximately 65%; the proportion of piles achieving Class I quality on the first attempt has increased from 91% to 98%, demonstrating a more prominent advantage in quality grade.

[0055] In terms of economics, significant benefits are also achieved. The patented construction method reduces wear and tear and downtime, lowering equipment wear costs to 72% of the conventional baseline, a saving of 28%. Taking into account factors such as materials, labor, and downtime losses, the overall construction cost per pile is reduced from 100% of the baseline to 84%, a saving of approximately 16%. Overall, the patented construction method achieves significant optimization in multiple dimensions, including efficiency, quality, reliability, and cost control, providing an effective technical demonstration for deep-hole pile projects in similar gravel strata.

[0056] It should be noted that all contents not mentioned in detail in this invention are existing technologies and will not be elaborated upon in this application.

[0057] The embodiments given above are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions or substitutions made by those skilled in the art based on the technical features of the present invention are within the protection scope of the present invention.

Claims

1. A rapid obstacle removal device for large pebbles in reverse circulation drilling, integrating a disturbance-grabbing-suction linkage, and installed at the bottom end of the hollow drill rod of a reverse circulation drilling rig, characterized in that... include: The upper linkage mechanism includes a ring main beam structure and a main spindle sleeve located at its center and coaxial with the hollow drill rod. The main spindle sleeve is tightly fitted with the hollow drill rod so that the two rotate synchronously. A torque sensor for monitoring the drill bit torque is installed on the main spindle sleeve. The reverse circulation suction and discharge channel is located on the side of the upper linkage mechanism and is connected to the hollow drill pipe; the end of the reverse circulation suction and discharge channel is connected in series with a quick-opening valve and a variable frequency negative pressure pump to form a negative pressure enhancement unit; the reverse circulation suction and discharge channel uses the enhanced negative pressure suction to suck the clamped pebbles and their associated slag to the wellhead as a whole; The multi-finger gripping mechanism includes at least three gripping fingers evenly distributed along the circumference of the main shaft sleeve at the bottom of the upper linkage mechanism and corresponding gripping finger drive cylinders. The root of each gripping finger is hinged to the rotating seat on the lower surface of the linkage mechanism. Each gripping finger root is equipped with a gripping force sensor, and the pebble is locked when the combined force of the multiple fingers reaches a preset threshold. The lower guide ring includes a retaining ring coaxial with the upper linkage mechanism; the hollow drill pipe passes through the center of the retaining ring; The disturbance rocker arm assembly includes multiple telescopic disturbance arms disposed on the lower guide ring for applying tangential disturbance force to the large pebbles at the bottom of the hole; Control and communication units; all are signal-connected to the control and communication units; The control and communication unit is configured to receive and process real-time signals from the torque sensor and the negative pressure enhancement unit. When the changes in the torque signal and the negative pressure signal synchronously exceed a preset threshold and continue for a set time, a pebble jamming event is determined to have occurred. The unit then automatically and sequentially controls the movement of the disturbance rocker arm assembly to loosen the pebble, the movement of the multi-finger gripping mechanism to grip and lock the pebble, and the movement of the negative pressure enhancement unit to instantaneously increase the negative pressure.

2. The apparatus according to claim 1, characterized in that, The pebbles are locked in place by a locking mechanism, which is a hydraulic pin-type locking mechanism.

3. The apparatus according to claim 2, characterized in that, The hydraulic pin-type locking mechanism includes a locking pin driven by a hydraulic cylinder. When a locking command is received from the control and communication unit, the hydraulic cylinder pushes the locking pin into a special locking groove set at the base of the finger clamp to form a rigid mechanical limit.

4. The apparatus according to claim 1, characterized in that, The control and communication unit uses a PLC controller to collect real-time signals from the torque sensor, the clamping force sensor, and the negative pressure pulsating pressure gauge located on the reverse circulation suction and discharge channel at a sampling frequency.

5. The apparatus according to claim 1, characterized in that, The end of the retractable disturbance arm is equipped with a replaceable spiral disturbance head or a high-pressure water jet nozzle.

6. The apparatus according to claim 1, characterized in that, It also includes a grading and screening unit located at the wellhead, used to classify the pebbles lifted to the wellhead according to their particle size.

7. The obstacle clearing method of the device according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Real-time acquisition of drill bit torque signal and system negative pressure signal during the initial stage of drilling; S2. The control and communication unit determines whether the triggering conditions for the pebble jamming event are met based on the received signal. S3. If the conditions are met, the obstacle clearing process will be automatically triggered, and the drill bit will be controlled to slow down or stop feeding; the disturbance rocker assembly will be controlled to extend and apply disturbance force to the stuck pebbles, so that they are separated from the surrounding strata. S4. The control and communication unit controls the multi-finger gripping mechanism to open and close to grip the pebble, and locks the pebble when the gripping force reaches the preset locking threshold. S5. After the pebbles are locked, the quick-opening ball valve is fully opened, and the negative pressure enhancement unit instantly increases the negative pressure of the system. The enhanced suction force is used to suck the clamped pebbles and their associated slag to the wellhead as a whole. S6. After the monitoring signal returns to normal, control the multi-finger clamping mechanism to unlock and reset, restore the normal drilling parameters and continue construction; the grading and screening unit classifies the pebbles and slag according to their particle size.

8. The obstacle clearing method according to claim 7, characterized in that, The process by which the control and communication unit determines the occurrence of a pebble jamming event is as follows: (1) Torque mutation threshold: ； in , The average torque over the last 5 seconds; (2) Negative pressure pulsation threshold: ， in, The average value of negative pressure pulsations over the last 5 seconds; (3) Composite criterion: when and If the duration is greater than or equal to 0.3 seconds, the system determines that the pebble jamming event has been triggered.

9. The obstacle clearing method according to claim 7, characterized in that, In S6, pebbles no smaller than 150mm enter the waste hopper, pebbles between 50 and 150mm are discharged through a secondary screen, and pebbles smaller than 50mm enter a hydrocyclone for separation.

10. The obstacle clearing method according to claim 7, characterized in that, The method is applicable to complex strata with a gravel content of 50%–90% and a pebble compressive strength not exceeding 120 MPa.

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