A pile foundation hole-forming system for bridge construction

Abstract

The present invention relates to the technical field of pile foundation drilling technology, and in particular to a pile foundation drilling system for bridge construction, comprising: a drilling mechanism for drilling a hole in the ground at the hole mouth to form a pile foundation hole; a grouting mechanism; a detection mechanism for detecting the maximum deformation rate of the pile foundation hole bottom below the drill rod, the difference in sediment thickness at the pile foundation hole bottom, and the verticality of the drill rod; a control mechanism for adjusting the dwell time of the drill rod based on the maximum deformation rate of the pile foundation hole bottom, or adjusting the angle between the slurry injection direction and the vertical direction based on the verticality, and determining a power redistribution mode for the drill rod based on the number of consecutive times the verticality does not meet the requirements, wherein the alternation ratio of the forward and reverse rotation of the drill rod in the power redistribution mode is adjusted based on the difference in sediment thickness. The present invention improves the structural stability of the pile foundation hole bottom and the drilling accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation hole forming, and in particular to a pile foundation hole forming system for bridge construction. Background Art

[0002] In the existing technology, during the process of drilling pile foundations for bridge construction, the soil or rock is cut by the rotation of the drill bit to gradually form a pile hole. Mud is injected during the drilling process, and its suspension ability is used to carry drill cuttings. The bottom of the pile hole is supported by hydrostatic pressure to prevent collapse. Modern pile foundation drilling equipment has gradually integrated sensors and control systems, which can monitor drilling parameters in real time and adjust construction strategies. However, there are still many deficiencies in the implementation process, such as the risk of collapse of the bottom of the pile hole due to unstable mud properties, untimely monitoring of drill bit wear affecting construction efficiency, and inaccurate control of sediment thickness differences. Under complex geological conditions, conventional drilling processes are difficult to adapt to the changing characteristics of the formation, which can easily cause quality defects such as hole diameter deviation and excessive sediment at the bottom of the pile hole. Existing sensor systems can often only monitor a single parameter and lack the ability to comprehensively evaluate the drilling quality in multiple dimensions.

[0003] Chinese Patent Publication No.: CN111764262B discloses a construction method for an assembled bridge structure, comprising the following steps: Step 1, pouring a pile foundation at a construction site; Step 2, filling the enclosure of the pile foundation with cement concrete mortar, and buckling a prefabricated lower pedestal on top of the pile foundation; Step 3, applying adhesive to the first rectangular protrusion of the lower pedestal, and then buckling the upper pedestal on the lower pedestal; Step 4, connecting the pier columns to the connecting columns of the upper pedestal; Step 5, longitudinally connecting the pier columns one by one; Step 6, installing a laser receiver in a second blind hole below the bridge deck; Step 7, installing a laser transmitter at the bottom end of a protective tube, and passing the protective tube from the light-through hole of the top pier column to the first blind hole of the pile foundation; Step 8, erecting the bridge deck on the topmost pier column. It can be seen from this that the construction method of the described prefabricated bridge structure has problems such as the different hardness of the soil at different depths causing the horizontal vibration of the mechanical structure during the drilling process, resulting in excessive deformation of the bottom of the pile foundation hole in the layered soil, and the drill rod is easily deflected by uneven resistance in the hard rock layer and the pebble layer, resulting in differences in the thickness of the sediment in the hole, which in turn leads to a decrease in drilling accuracy. Summary of the Invention

[0004] To this end, the present invention provides a pile foundation drilling system for bridge construction, which is used to overcome the problems in the prior art that due to the different hardness of the soil at different depths, the mechanical structure vibrates in the horizontal direction during the drilling process, resulting in excessive deformation of the bottom of the pile foundation hole in the layered soil, and the drill rod is easily deflected by uneven resistance in the hard rock layer and the pebble layer, resulting in differences in the thickness of the sediment in the hole and thus a decrease in drilling accuracy.

[0005] To achieve the above object, the present invention provides a pile foundation drilling system for bridge construction, comprising:

[0006] A hole-forming mechanism, for drilling into the hole-forming area of ​​the bridge to form a pile foundation hole, comprising a casing disposed inside the pile foundation hole to support the hole wall of the pile foundation hole and a drill rod disposed inside the casing;

[0007] A grouting mechanism is provided above the hole forming mechanism and is used to inject slurry into the pile foundation hole to form a slurry film on the hole wall of the pile foundation hole;

[0008] a detection mechanism connected to the hole-forming mechanism, for detecting the maximum deformation rate of the bottom of the pile foundation hole below the drill rod, the difference in sediment thickness at the bottom of the pile foundation hole, and the verticality of the drill rod;

[0009] a control mechanism, which is respectively connected to the hole-forming mechanism, the grouting mechanism, and the detection mechanism, and is used to adjust the dwell time of the drill rod according to the maximum deformation rate of the bottom of the pile foundation hole, or to adjust the angle between the injection direction of the slurry and the vertical direction according to the verticality, and to determine the power redistribution method of the drill rod according to the number of consecutive times that the verticality does not meet the requirements,

[0010] Wherein, the alternating ratio of forward and reverse rotation of the drill rod in the power redistribution mode is determined according to the difference in sediment thickness.

[0011] Furthermore, the detection mechanism includes:

[0012] an ultrasonic probe connected to the drill rod, which transmits ultrasonic waves to the bottom of the pile foundation hole and detects echo signals to obtain the maximum deformation rate of the bottom of the pile foundation hole, and calculates the sediment thickness difference according to the time difference of the echo;

[0013] A gyroscope is arranged above the ultrasonic probe and is used to detect the verticality of the drill rod.

[0014] Furthermore, the control mechanism is respectively connected to the ultrasonic probe and the drill rod to obtain the maximum deformation rate of the bottom of the pile foundation hole. If the maximum deformation rate of the bottom of the pile foundation hole is greater than or equal to a preset second rate, the stay time of the drill rod at the current position to maintain the current rotation speed is increased.

[0015] Furthermore, the maximum deformation rate of the bottom of the pile foundation hole is the maximum value of the ratio of the distance difference between the bottom of the pile foundation hole below the drill rod and the ultrasonic probe to the unit ultrasonic detection time;

[0016] The distance difference is the difference between the maximum distance between the bottom of the pile foundation hole below the drill rod and the ultrasonic probe at the end time of the unit ultrasonic detection time and the maximum distance between the bottom of the pile foundation hole below the drill rod and the ultrasonic probe at the start time of the unit ultrasonic detection time.

[0017] Furthermore, the control mechanism is respectively connected to the ultrasonic probe and the grouting mechanism, and is used to obtain the verticality of the drill rod at the current moment under the condition that the maximum deformation rate of the bottom of the pile foundation hole is greater than or equal to a preset first rate and less than a preset second rate. If the verticality is greater than or equal to the preset verticality, the injection direction of the mud and the injection angle of the vertical direction are adjusted to the deviation angle of the drill rod in the vertical plane.

[0018] Furthermore, the injection angle is the acute angle between the injection direction of the mud and the vertical direction; the deviation angle is the acute angle between the drill pipe direction and the vertical direction under the condition that the verticality is greater than or equal to a preset verticality.

[0019] Furthermore, the control mechanism is connected to the drill rod to obtain the consecutive number of times that the verticality of the drill rod is greater than or equal to a preset verticality during the drilling process. If the consecutive number is greater than or equal to the preset number, the drill rod is adjusted from a constant power working mode to a power redistribution working mode.

[0020] Furthermore, the power redistribution works in a manner that the drill pipe rotates forward according to the first power and reversely according to the second power, and the forward and reverse rotations are alternated.

[0021] Furthermore, the control mechanism is connected to the ultrasonic probe and the drill rod respectively to obtain the sediment thickness and calculate the sediment thickness difference. If the sediment thickness difference is greater than or equal to a preset difference, the alternation ratio of the forward and reverse rotation is increased.

[0022] Furthermore, the alternation ratio is the ratio of the number of executions of the forward rotation of the drill rod to the number of executions of the reverse rotation of the drill rod in a single alternation cycle; the sediment thickness difference is the difference between the maximum thickness and the minimum thickness of all sediments below the top of the drill rod in the vertical direction.

[0023] Compared with the prior art, the beneficial effect of the present invention is that the system of the present invention is provided with a hole-forming mechanism, a grouting mechanism, a detection mechanism and a control mechanism. Due to the stratification of the ground soil, the vibration of the mechanical structure in the horizontal direction during the drilling process causes the pile foundation hole bottom of the stratified soil to be too large, thereby causing the drilling accuracy and the stability of the pile foundation hole bottom to decrease. By detecting the maximum deformation rate of the pile foundation hole bottom in the hole mouth stratum below the drill rod, the difference in sediment thickness at the bottom of the hole mouth stratum, and the verticality of the drill rod, it is possible to determine whether the pile foundation hole bottom is too large due to mechanical lateral vibration during the drilling process, or whether the drill rod is easily deflected by uneven resistance in the hard rock layer or the gravel layer, resulting in the sediment thickness in the hole being different. Differences; by adjusting the dwell time of the drill rod, the centrifugal force generated by the rotation of the drill rod and the damping effect of the mud are used to form a stable vortex, thereby effectively reducing the deformation of the bottom of the pile hole and the sediment accumulation problems caused by mechanical vibration or uneven resistance of the formation during the drilling process; by adjusting the injection direction of the mud and the injection angle in the vertical direction to the deviation angle of the drill rod in the vertical plane to correct the direction of the drill rod, the drill rod jamming phenomenon is reduced by alternating forward and reverse operations, and the forward and reverse alternating ratio is dynamically adjusted according to the difference in sediment thickness to ensure more uniform sediment cleaning, avoid the reduction of drilling efficiency due to sediment accumulation, reduce the pores between the pile foundation and the bottom surface of the pile hole, and thus reduce the degree of soil erosion on the pile foundation.

[0024] Furthermore, the system of the present invention increases the dwell time of the drill rod to maintain the rotation speed. When the drilling pressure suddenly changes due to uneven formations, fatigue of the drill rod, or lateral swing occurs due to the resonance effect of the drill rod and the formation, disordered vibration is formed, which leads to deviation of the hole and aggravates the risk of collapse of the bottom of the pile foundation hole. The lateral vibration causes the drill rod to frequently hit the bottom of the pile foundation hole, which not only wears the drilling tool, but also disturbs the formation, accelerates the instability of the bottom of the pile foundation hole, consumes drilling energy through vibration, weakens the rock-breaking efficiency of the drill bit, reduces drilling efficiency, and wears equipment. By increasing the dwell time of the drill rod to maintain the rotation speed, the continuous rotation causes the centrifugal force of the drill rod to extend outward. It automatically searches for the rotation center in the hole to offset the lateral deviation. The rotation of the drill rod in the current soil layer drives the surrounding mud to form an axisymmetric circulation, similar to a fluid bearing. The viscous resistance of the mud consumes vibration energy, reduces the collision of the drill rod with the bottom of the pile hole, avoids mechanical disturbance of the formation, and stabilizes the eddy current to push the mud to adhere evenly to the bottom of the pile hole, strengthens the wall protection effect of the mud, and reduces the risk of hole collapse. After the vibration is weakened, the drilling pressure is effectively transmitted to the drill bit, thereby improving the drilling efficiency, avoiding the deflection caused by vibration, improving the verticality of the hole, and reducing the degree of wear between the drill rod and the formation due to lateral vibration.

[0025] Furthermore, the system of the present invention adjusts the injection direction of the mud and the injection angle of the vertical direction to the deviation angle of the drill rod in the vertical plane. Since the drill rod is easily deflected by uneven resistance in hard rock layers or pebble layers, the drilling direction deviates from the designed axis. The deviated hole causes stress concentration at the bottom of the pile foundation hole, which in turn affects the hole forming accuracy. By adjusting the injection direction of the mud and the injection angle of the vertical direction to the deviation angle of the drill rod in the vertical plane, the mud generates a directional thrust in the hole. The thrust acts on the opposite side of the deviation direction of the drill rod, thereby applying a corrective force to the drill rod, causing it to gradually return to the axial direction, reducing the drill rod deflection phenomenon caused by uneven strata, improving the verticality and linearity of the borehole, improving the accuracy of pile foundation hole forming, compensating for the drill rod offset, avoiding the stress concentration problem at the bottom of the pile foundation hole caused by the deviated hole, reducing the risk of collapse at the bottom of the pile foundation hole, and achieving improved drilling efficiency.

[0026] Furthermore, the system of the present invention adjusts the drill rod from a constant power working mode to a power redistribution working mode. During the tilting working process of the drill rod, rock particles are embedded in the drill bit or the friction between the drill bit of the drill rod and the bottom of the pile hole increases, causing jamming and equipment damage. By setting the power redistribution working mode, the drill rod is rotated forward at the first power and reversed at the second power, breaking the static friction state between the drill rod and the formation and reducing the risk of jamming. During the forward rotation, the drill bit breaks the rock and drives the sediment to move upward, and the reverse rotation helps to loosen the rock cuttings embedded in the drill bit and prevent it from clogging the drill bit gap. The drilling pressure energy is converted into drilling speed kinetic energy through forward and reverse operation, generating vertical resonant waves, loosening the eccentric resistance layer, maintaining the total energy consumption unchanged but converting it into vertical tunneling force in a directional manner, suppressing the deflection and changing the lower soil structure in contact with the drill rod, thereby improving the stability of the hole.

[0027] Furthermore, the system of the present invention increases the alternating ratio of forward and reverse rotation. Due to severe wear of the drill tool, the hole wall shape will be irregular, making it easier for sediment to accumulate in certain depressions, which will lead to uneven distribution of sediment at the bottom of the pile foundation hole, resulting in local excessive accumulation, affecting the uniformity of the pile foundation bearing capacity in the horizontal direction. The position with thick sediment continues to be pressed down during the drilling process, resulting in the hardness of the bottom of the pile foundation hole formed after drilling being greater than the hardness of the bottom of the pile foundation hole with small sediment thickness. By adjusting the alternating ratio of forward and reverse rotation, the area with thick sediment accumulation is cleaned. When it is detected that the difference in sediment thickness increases, the number of forward rotation operations is increased, and the number of times the drill bit pushes and lifts the sediment upward is increased; at the same time, the number of reverse operations is reduced to avoid excessive disturbance of the cleaned area, thereby improving the drilling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the overall structure of a pile foundation hole-forming system for bridge construction according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the casing structure of a pile foundation hole forming system for bridge construction according to an embodiment of the present invention;

[0030] Figure 3 This is a block diagram of the overall structure of a pile foundation hole-forming system for bridge construction according to an embodiment of the present invention;

[0031] Explanation of the accompanying numbers: 1- casing, 2- drill pipe, 3- gyroscope, 4- ultrasonic probe, 5- drill bit. DETAILED DESCRIPTION

[0032] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0033] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0034] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0035] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0036] See also Figure 1 、 Figure 2 、 Figure 3 As shown in FIG, they are respectively a schematic diagram of the overall structure of a pile foundation drilling system for bridge construction according to an embodiment of the present invention, a schematic diagram of the casing structure, and a block diagram of the overall structure. A pile foundation drilling system for bridge construction according to an embodiment of the present invention comprises:

[0037] A drilling mechanism for drilling a hole in a bridge to form a pile foundation hole, comprising a casing 1 provided inside the pile foundation hole to support the hole wall of the pile foundation hole and a drill rod 2 provided inside the casing 1;

[0038] A grouting mechanism is provided above the hole forming mechanism and is used to inject slurry into the pile foundation hole to form a slurry film on the hole wall of the pile foundation hole;

[0039] a detection mechanism connected to the hole-forming mechanism, for detecting the maximum deformation rate of the bottom of the pile foundation hole below the drill rod 2, the difference in sediment thickness at the bottom of the pile foundation hole, and the verticality of the drill rod 2;

[0040] a control mechanism, which is respectively connected to the hole-forming mechanism, the grouting mechanism, and the detection mechanism, and is used to adjust the dwell time of the drill rod 2 according to the maximum deformation rate of the bottom of the pile foundation hole, or to adjust the angle between the injection direction of the slurry and the vertical direction according to the verticality, and to determine the power redistribution method of the drill rod 2 according to the number of consecutive times that the verticality does not meet the requirements,

[0041] The alternating ratio of forward and reverse rotation of the drill rod 2 in the power redistribution mode is determined according to the difference in sediment thickness.

[0042] Specifically, a drill bit 5 for drilling by rotation is provided below the drill rod 2 , and a surface of the drill bit 5 is provided with threads (not shown in the figure).

[0043] Specifically, the formation parameters of the pile foundation drilling system of this embodiment are shown in Table 1:

[0044] Table 1 - Formation parameters

[0045] ,

[0046] Among them, the first layer is plain fill, which is mainly composed of silt and silty clay, contains roots, has a loose structure, and is 0.50m thick.

[0047] Specifically, the grouting mechanism includes:

[0048] Injection nozzle, used to inject slurry into the pile foundation hole;

[0049] a guide plate disposed inside the nozzle to adjust the injection direction of the slurry into the pile foundation hole;

[0050] A guide motor is connected to the guide plate and is used to provide rotational power to the guide plate to adjust the guide angle of the guide plate;

[0051] The mud pipe is connected to the nozzle and is used to input mud into the nozzle.

[0052] In practice, the system of the present invention is provided with a hole-forming mechanism, a grouting mechanism, a detection mechanism and a control mechanism. Due to the stratification of ground soil, the vibration of the mechanical structure in the horizontal direction during the drilling process causes excessive deformation of the pile foundation hole bottom of the stratified soil, thereby causing the drilling accuracy and the stability of the pile foundation hole bottom to decrease. By detecting the maximum deformation rate of the pile foundation hole bottom in the hole mouth stratum below the drill rod 2, the difference in sediment thickness at the bottom of the hole mouth stratum, and the verticality of the drill rod 2, it is determined whether the drill rod 2 has excessive deformation of the pile foundation hole bottom due to mechanical lateral vibration during operation, or whether the drill rod 2 is easily deflected by uneven resistance in the hard rock layer or the pebble layer, resulting in differences in sediment thickness in the hole; by By adjusting the dwell time of the drill rod 2 and utilizing the centrifugal force generated by the rotation of the drill rod 2 and the damping effect of the mud, a stable vortex is formed, thereby effectively reducing the deformation of the bottom of the pile hole and the sediment accumulation problems caused by mechanical vibration or uneven resistance of the formation during the drilling process; by adjusting the injection direction of the mud and the injection angle in the vertical direction to the deviation angle of the drill rod 2 in the vertical plane to correct the direction of the drill rod 2, the jamming of the drill rod 2 is reduced by alternating forward and reverse operations, and the forward and reverse alternating ratio is dynamically adjusted according to the difference in sediment thickness to ensure more uniform sediment cleaning, avoid a decrease in drilling efficiency due to sediment accumulation, reduce the gap between the pile foundation and the bottom surface of the pile hole, and thus reduce the degree of soil erosion on the pile foundation.

[0053] Specifically, the detection mechanism includes:

[0054] an ultrasonic probe 4 connected to the drill rod 2, which transmits ultrasonic waves to the bottom of the pile foundation hole and detects echo signals to obtain the maximum deformation rate of the bottom of the pile foundation hole, and calculates the sediment thickness difference according to the time difference of the echo;

[0055] The gyroscope 3 is arranged above the ultrasonic probe 4 and is used to detect the verticality of the drill rod 2 .

[0056] Specifically, the control mechanism is connected to the ultrasonic probe 4 and the drill rod respectively to obtain the maximum deformation rate of the bottom of the pile foundation hole. If the maximum deformation rate of the bottom of the pile foundation hole is greater than or equal to the preset second rate, the stay time of the drill rod 2 at the current position to maintain the current rotation speed is increased.

[0057] Specifically, the maximum deformation rate of the pile foundation hole bottom is the maximum value of the ratio of the distance difference between the pile foundation hole bottom below the drill rod 2 and the ultrasonic probe 4 to the unit ultrasonic detection time;

[0058] Among them, the distance difference is the difference between the distance between the bottom of the pile foundation hole below the drill rod 2 and the ultrasonic probe 4 at the end time of the unit ultrasonic detection time and the distance between the bottom of the pile foundation hole below the drill rod 2 and the ultrasonic probe 4 at the start time of the unit ultrasonic detection time.

[0059] Specifically, the unit ultrasonic detection time is 10s.

[0060] Specifically, under the conditions that the design bridge deck width is 25m, the automobile load standard is city-A level, the sidewalk load design standard is a uniformly distributed load of 4.0kPa, the average working speed and average downward force of the drill rod 2 are 65r / min and 100kN respectively, and the stratum structure is as shown in Table 1, the general value range of the preset first rate is [4mm / s, 6mm / s], the general value range of the preset second rate is [10mm / s, 20mm / s], the preferred embodiment of the preset first rate is 5mm / s, and the preferred embodiment of the preset second rate is 12mm / s.

[0061] Those skilled in the art will appreciate that the optional range of the preset first rate and the preset second rate provided in this embodiment and the preferred embodiment are the values ​​selected under the conditions of the designed bridge deck width of 25m, the automobile load standard of city-A level, the sidewalk load design standard of 4.0KPa uniformly distributed load, the average working speed and average downward force of the drill rod 2 of 65r / min and 100kN respectively, and the stratum structure as shown in Table 1 to obtain the best effect on the technical problem solved by the technical solution of the present invention. In actual applications or experiments, those skilled in the art can adaptively adjust the preset first rate and the preset second rate according to the actual application environment and application scenario.

[0062] During implementation, if the difference between the maximum deformation rate of the pile foundation hole bottom and the preset second deformation rate is within 1 mm / s, the residence time is increased by 5 s. If the difference between the maximum deformation rate of the pile foundation hole bottom and the preset second deformation rate exceeds 1 mm / s, the residence time is increased by 4 s for every 1 mm / s that exceeds. For example, if the difference between the maximum deformation rate of the pile foundation hole bottom and the preset second deformation rate is 4 mm / s and the current residence time is 0, the residence time is increased to 5 s + 4 s × 3 = 17 s.

[0063] During implementation, the system of the present invention increases the dwell time of the drill rod 2 at a maintained rotation speed. When the drilling pressure suddenly changes due to uneven formations, fatigue of the drill rod 2 during operation, or lateral swing occurs due to resonance effect between the drill rod 2 and the formation, disordered vibration is formed, resulting in skewed holes and aggravated collapse risk of the bottom of the pile foundation hole. The lateral vibration causes the drill rod 2 to frequently hit the bottom of the pile foundation hole, which not only wears the drilling tool, but also disturbs the formation, accelerates the instability of the bottom of the pile foundation hole, consumes drilling energy through vibration, weakens the rock-breaking efficiency of the drill bit 5, reduces drilling efficiency, and wears equipment. By increasing the dwell time of the drill rod 2 at a maintained rotation speed, continuous rotation causes the centrifugal force of the drill rod 2 to extend outward. , automatically finds the rotation center in the hole to offset the lateral deviation. The rotation of the drill rod 2 in the current soil layer drives the surrounding mud to form an axisymmetric circulation, similar to a fluid bearing. The viscous resistance of the mud consumes vibration energy, reduces the collision of the drill rod 2 with the bottom of the pile hole, avoids mechanical disturbance of the formation, and stabilizes the eddy current to push the mud to adhere evenly to the bottom of the pile hole, strengthens the wall protection effect of the mud, and reduces the risk of hole collapse. After the vibration is weakened, the drilling pressure is effectively transmitted to the drill bit 5, thereby improving the drilling efficiency, avoiding the deflection caused by vibration, improving the verticality of the hole, and reducing the degree of wear between the drill rod 2 and the formation due to lateral vibration.

[0064] Specifically, the control mechanism is connected to the ultrasonic probe 4 and the grouting mechanism respectively, and is used to obtain the verticality of the drill rod 2 at the current moment under the condition that the maximum deformation rate of the bottom of the pile foundation hole is greater than or equal to the preset first rate and less than the preset second rate. If the verticality is greater than or equal to the preset verticality, the injection direction of the mud and the injection angle of the vertical direction are adjusted to the deviation angle of the drill rod 2 in the vertical plane.

[0065] In practice, the general value range of the preset verticality is [0.1°, 1.8°], and the preferred embodiment of the preset verticality is 1.5°.

[0066] Specifically, the injection angle is the acute angle between the injection direction of the mud and the vertical direction; the deviation angle is the acute angle between the direction of the drill pipe 2 and the vertical direction under the condition that the verticality is greater than or equal to the preset verticality.

[0067] In practice, the system of the present invention adjusts the injection direction of the mud and the injection angle of the vertical direction to the deviation angle of the drill rod 2 in the vertical plane. Since the drill rod 2 is easily deflected by uneven resistance in hard rock layers or pebble layers, the drilling direction deviates from the designed axis. The deviated hole causes stress concentration at the bottom of the pile foundation hole, which in turn affects the hole forming accuracy. By adjusting the injection direction of the mud and the injection angle of the vertical direction to the deviation angle of the drill rod 2 in the vertical plane, the mud generates a directional thrust in the hole. The thrust acts on the opposite side of the deviation direction of the drill rod 2, thereby applying a corrective force to the drill rod 2, causing it to gradually return to the axial direction, reducing the deflection of the drill rod 2 caused by uneven strata, improving the verticality and linearity of the borehole, improving the accuracy of pile foundation hole forming, compensating for the offset of the drill rod 2, avoiding the stress concentration problem at the bottom of the pile foundation hole caused by the deviated hole, reducing the risk of collapse at the bottom of the pile foundation hole, and achieving improved drilling efficiency.

[0068] Specifically, the control mechanism is connected to the drill rod 2 to obtain the consecutive number of times that the verticality of the drill rod 2 is greater than or equal to the preset verticality during the drilling process. If the consecutive number is greater than or equal to the preset number, the drill rod 2 is adjusted from a constant power working mode to a power redistribution working mode.

[0069] Specifically, the power redistribution works in a manner that the drill rod 2 rotates forward according to the first power and rotates reversely according to the second power, and the forward and reverse rotations are performed alternately.

[0070] Specifically, the relationship between the first power and the rated power satisfies the following expression:

[0071] ,

[0072] in, is the first power, is the formation transfer efficiency, is the forward downward pressure of drill pipe 2, is the forward rotation speed of drill pipe 2, For rated power, is the rated downforce, is the rated drilling speed; =0.7 , =1.2 When the stratum is silt Take 0.85, when the stratum is fine sand Take 0.75, when the stratum is silt clay Take 0.88;

[0073] The relationship between the second power and the rated power satisfies the following expression:

[0074] ,

[0075] in, is the second power, is the reverse downward force of drill pipe 2, is the reverse rotation speed of drill pipe 2, For rated power, is the rated downforce, is the rated drilling speed; =1.1 , =0.7 .

[0076] Specifically, under the conditions that the design bridge deck width is 25m, the automobile load standard is city-A level, the sidewalk load design standard is a uniformly distributed load of 4.0kPa, the average working speed and average downward force of the drill rod 2 are 65r / min and 100kN respectively, and the stratum structure is as shown in Table 1, the general value range of the preset number of times is [3 times, 6 times], and the preferred embodiment of the preset number of times is 4 times.

[0077] Those skilled in the art will appreciate that the optional range of the preset number of times provided in this embodiment and the preferred embodiment are the values ​​selected under the conditions of the designed bridge deck width of 25m, the automobile load standard of city-A, the sidewalk load design standard of 4.0KPa uniformly distributed load, the average working speed and average downward force of the drill rod 2 of 65r / min and 100kN respectively, and the stratum structure as shown in Table 1 to achieve the best effect on the technical problem solved by the technical solution of the present invention. In actual applications or experiments, those skilled in the art can adaptively adjust the preset number of times according to the actual application environment and application scenarios.

[0078] During implementation, the system of the present invention adjusts the drill rod 2 from a constant power working mode to a power redistribution working mode. During the tilting working process of the drill rod 2, rock particles are embedded in the drill bit 5 or the friction between the drill bit 5 of the drill rod 2 and the bottom of the pile hole increases, causing jamming, resulting in equipment damage. By setting the power redistribution working mode, the drill rod 2 is rotated forward at the first power and reversed at the second power, breaking the static friction state between the drill rod 2 and the formation, reducing the risk of jamming. During the forward rotation, the drill bit 5 breaks the rock and drives the sediment to move upward, and the reverse rotation helps to loosen the rock cuttings embedded in the drill bit 5 to prevent it from clogging the gap of the drill bit 5; the drilling pressure energy is converted into drilling speed kinetic energy through forward and reverse operation, generating vertical resonant waves, loosening the eccentric resistance layer, maintaining the total energy consumption unchanged but converting it into vertical excavation force in a directional manner, suppressing the deflection and changing the lower soil structure in contact with the drill rod 2, thereby improving the stability of the hole.

[0079] Specifically, the control mechanism is connected to the ultrasonic probe 4 and the drill rod 2 respectively to obtain the sediment thickness and calculate the sediment thickness difference. If the sediment thickness difference is greater than or equal to the preset difference, the alternation ratio of the forward and reverse rotation is increased.

[0080] Specifically, under the conditions that the design bridge deck width is 25m, the automobile load standard is city-A level, the sidewalk load design standard is a uniformly distributed load of 4.0kPa, the average working speed and average downward force of the drill rod 2 are 65r / min and 100kN respectively, and the stratum structure is as shown in Table 1, the general value range of the preset difference amount is [10mm, 30mm], and the preferred embodiment of the preset difference amount is 15mm.

[0081] Those skilled in the art will appreciate that the optional range of the preset difference amount provided in this embodiment and the preferred embodiment are the values ​​selected under the conditions that the design bridge deck width is 25m, the automobile load standard is city-A level, the sidewalk load design standard is a uniformly distributed load of 4.0KPa, the average working speed and average downward force of the drill rod 2 are 65r / min and 100kN respectively, and the stratum structure is as shown in Table 1, which are the best values ​​for the technical problem solved by the technical solution of the present invention. In actual applications or experiments, those skilled in the art can adaptively adjust the preset difference amount according to the actual application environment and application scenario.

[0082] Specifically, the alternation ratio is the ratio of the number of forward rotations of the drill rod 2 to the number of reverse rotations of the drill rod 2 in a single alternation cycle; the sediment thickness difference is the difference between the maximum thickness and the minimum thickness of all sediments below the vertex of the drill rod 2 in the vertical direction.

[0083] Specifically, the total number of forward rotation executions and the number of reverse rotation executions is 50 times, which constitutes one alternation cycle.

[0084] During implementation, the system of the present invention increases the alternating ratio of forward and reverse rotation. Due to severe wear of the drill tool, the hole wall shape will be irregular, making it easier for sediment to accumulate in certain depressions, which will lead to uneven distribution of sediment at the bottom of the pile foundation hole, resulting in local excessive accumulation, affecting the uniformity of the pile foundation bearing capacity in the horizontal direction. The position with thick sediment continues to be pressed down during the drilling process, resulting in the hardness of the bottom of the pile foundation hole formed after drilling being greater than the hardness of the bottom of the pile foundation hole with small sediment thickness. By adjusting the alternating ratio of forward and reverse rotation, the area with thicker sediment accumulation is cleaned. When it is detected that the difference in sediment thickness increases, the number of forward rotation operations is increased, and the number of times the drill bit 5 pushes and lifts the sediment upward is increased; at the same time, the number of reverse operations is reduced to avoid excessive disturbance of the cleaned area, thereby improving the drilling efficiency.

[0085] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A pile foundation drilling system for bridge construction, characterized in that: include: A hole-forming mechanism, for drilling into the hole-forming area of ​​the bridge to form a pile foundation hole, comprising a casing disposed inside the pile foundation hole to support the hole wall of the pile foundation hole and a drill rod disposed inside the casing; A grouting mechanism is provided above the hole forming mechanism and is used to inject slurry into the pile foundation hole to form a slurry film on the hole wall of the pile foundation hole; a detection mechanism connected to the hole-forming mechanism, for detecting the maximum deformation rate of the bottom of the pile foundation hole below the drill rod, the difference in sediment thickness at the bottom of the pile foundation hole, and the verticality of the drill rod; a control mechanism, which is respectively connected to the hole-forming mechanism, the grouting mechanism, and the detection mechanism, and is used to adjust the dwell time of the drill rod according to the maximum deformation rate of the bottom of the pile foundation hole, or to adjust the angle between the injection direction of the slurry and the vertical direction according to the verticality, and to determine the power redistribution method of the drill rod according to the number of consecutive times that the verticality does not meet the requirements, Wherein, the alternating ratio of forward and reverse rotation of the drill rod in the power redistribution mode is determined according to the difference in sediment thickness.

2. The pile foundation drilling system for bridge construction according to claim 1, characterized in that: The detection mechanism includes: an ultrasonic probe connected to the drill rod, which transmits ultrasonic waves to the bottom of the pile foundation hole and detects echo signals to obtain the maximum deformation rate of the bottom of the pile foundation hole, and calculates the sediment thickness difference according to the time difference of the echo; A gyroscope is arranged above the ultrasonic probe and is used to detect the verticality of the drill rod.

3. The pile foundation drilling system for bridge construction according to claim 2, characterized in that: The control mechanism is connected to the ultrasonic probe and the drill rod respectively to obtain the maximum deformation rate of the bottom of the pile foundation hole. If the maximum deformation rate of the bottom of the pile foundation hole is greater than or equal to a preset second rate, the stay time of the drill rod at the current position to maintain the current rotation speed is increased.

4. The pile foundation drilling system for bridge construction according to claim 3, characterized in that: The maximum deformation rate of the pile foundation hole bottom is the maximum value of the ratio of the distance difference between the pile foundation hole bottom below the drill rod and the ultrasonic probe to the unit ultrasonic detection time; The distance difference is the difference between the maximum distance between the bottom of the pile foundation hole below the drill rod and the ultrasonic probe at the end time of the unit ultrasonic detection time and the maximum distance between the bottom of the pile foundation hole below the drill rod and the ultrasonic probe at the start time of the unit ultrasonic detection time.

5. The pile foundation drilling system for bridge construction according to claim 4, characterized in that: The control mechanism is respectively connected to the ultrasonic probe and the grouting mechanism, and is used to obtain the verticality of the drill rod at the current moment under the condition that the maximum deformation rate of the bottom of the pile foundation hole is greater than or equal to a preset first rate and less than a preset second rate. If the verticality is greater than or equal to the preset verticality, the injection direction of the mud and the injection angle of the vertical direction are adjusted to the deviation angle of the drill rod in the vertical plane.

6. The pile foundation drilling system for bridge construction according to claim 5, characterized in that: The injection angle is the acute angle between the injection direction of the mud and the vertical direction; the deviation angle is the acute angle between the drill pipe direction and the vertical direction under the condition that the verticality is greater than or equal to the preset verticality.

7. The pile foundation drilling system for bridge construction according to claim 6, characterized in that: The control mechanism is connected to the drill rod and is used to obtain the consecutive number of times that the verticality of the drill rod is greater than or equal to a preset verticality during the drilling process. If the consecutive number is greater than or equal to the preset number, the drill rod is adjusted from a constant power working mode to a power redistribution working mode.

8. The pile foundation drilling system for bridge construction according to claim 7, characterized in that: The working mode of the power redistribution is that the drill rod rotates forward according to the first power and rotates reversely according to the second power, and the forward and reverse rotations are alternated.

9. The pile foundation drilling system for bridge construction according to claim 8, characterized in that: The control mechanism is connected to the ultrasonic probe and the drill rod respectively to obtain the sediment thickness and calculate the sediment thickness difference. If the sediment thickness difference is greater than or equal to the preset difference, the alternation ratio of the forward and reverse rotation is increased.

10. The pile foundation drilling system for bridge construction according to claim 9, characterized in that: The alternation ratio is the ratio of the number of forward rotations of the drill rod to the number of reverse rotations of the drill rod in a single alternation cycle; the sediment thickness difference is the difference between the maximum thickness and the minimum thickness of all sediments below the top of the drill rod in the vertical direction.

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