Telescopic drill rod and method of using the same

Abstract

The present invention discloses a telescopic drill rod and a method for using the same. The telescopic drill rod comprises an outer rod and an inner rod arranged inside the outer rod. The outer rod comprises an outer tube and a clamping piece fixedly arranged on the upper part of the inner wall of the outer tube. The inner rod comprises an inner tube. The outer wall of the inner tube is provided with a groove unit slidingly matched with the clamping piece along the length direction. The method for using the same comprises the following steps: 1. installation of the telescopic drill rod; 2. preliminary drilling; 3. lifting the inner rod; 4. drilling again; 5. preliminary lifting of the telescopic drill rod and grouting; 6. retraction of the inner rod; 7. lifting the telescopic drill rod again and grouting. The present invention arranges the groove unit to cooperate with the clamping piece so that the inner rod and the outer rod can be detachably connected. The structure is simple, the weight of the telescopic drill rod itself is greatly reduced, and the transportation and loading and unloading are convenient. No electrical control device is required to control the extension and retraction of the telescopic drill rod. The control process is simple and clear, the number of controlled objects is reduced, the operation is easy, and the application is convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation construction, and particularly relates to a telescopic drill rod and a use method thereof. Background Art

[0002] The existing long screw pile driving and drilling pile machine must be equipped with a pile machine tower of a certain height according to the depth of the hole to be drilled. Usually, the depth of the drilling hole is more than 20 meters, and the deepest is even more than 30 meters. This requires the configuration of a pile machine tower of a corresponding height. The increase in the height of the pile machine tower not only wastes a lot of steel and increases the cost, but also makes the long screw pile driving and drilling pile machine bulky, and the moving cost also increases accordingly. Therefore, the use of a retractable drill rod installed on the long screw pile driving and drilling pile machine can greatly reduce the required height of the pile machine tower. However, the existing retractable drill rod has a complex structure and is not easy to assemble, install and maintain. Although it reduces the construction cost of the pile machine tower, it also virtually increases the maintenance cost of the drill rod. Therefore, a retractable drill rod with a simple structure, convenient installation and easy maintenance is now needed. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a telescopic drill rod in view of the deficiencies in the above-mentioned prior art. The telescopic drill rod is provided with a groove unit and cooperates with a clamping piece so that an inner rod and an outer rod can be detachably connected. The structure is simple, and the weight of the telescopic drill rod itself is greatly reduced, which is convenient for transportation and loading and unloading. There is no need to control additional electrical control devices to control the extension and retraction of the telescopic drill rod. The control process is simple and clear, the number of controlled objects is reduced, the operation is easy, and it is convenient for promotion and use.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a telescopic drill rod, characterized in that it includes an outer rod and an inner rod arranged inside the outer rod and slidably matched with the outer rod, the outer rod includes an outer tube and a clamping piece fixedly arranged on the upper part of the inner wall of the outer tube, the inner rod includes an inner tube and a mounting tube arranged at the upper end of the inner tube and used to match with the power device of the pile driver, and the outer wall of the inner tube is provided with a groove unit slidably matched with the clamping piece along the length direction;

[0005] The groove unit includes a first groove opened along the length direction of the outer wall of the inner tube, the first groove is unidirectionally expanded to form a second groove at one end close to the mounting tube, and the first groove is unidirectionally expanded to form a third groove at one end away from the mounting tube. The expansion directions of the second groove and the third groove are the same, and an offset groove is opened on the outer wall of the inner tube, which is offset from the first groove and is used for the clamping part to enter the third groove. The width of the clamping part is less than or equal to the width of the first groove, and the width of the offset groove is greater than or equal to the width of the clamping part and less than the width of the third groove.

[0006] The above-mentioned telescopic drill rod is characterized in that: the offset groove is a trapezoidal groove, the small end of the trapezoidal groove is arranged close to the third groove, and the width of the small end of the trapezoidal groove is greater than or equal to the width of the clamping piece and less than the width of the third groove.

[0007] The above-mentioned telescopic drill rod is characterized in that the outer diameter of the mounting tube is larger than the inner diameter of the outer tube and smaller than or equal to the outer diameter of the outer tube.

[0008] The above-mentioned telescopic drill rod is characterized in that: the clamping piece is a fan-shaped clamping piece, the number of the fan-shaped clamping pieces is multiple, and the multiple fan-shaped clamping pieces are arranged circumferentially along the inner wall of the outer tube; the number of the groove units is multiple, and the number of the groove units is the same as the number of the clamping pieces and corresponds one to one.

[0009] The above-mentioned telescopic drill rod is characterized in that the depth of the second groove, the depth of the third groove, the depth of the first groove and the depth of the offset groove are all the same.

[0010] The telescopic drill rod is characterized in that a drill bit is arranged at the lower end of the outer tube, and a slurry outlet communicating with the interior of the inner tube is opened on the drill bit.

[0011] At the same time, the present invention also discloses a method for using a telescopic drill rod with simple steps, reasonable design and simple control process, characterized in that the method comprises the following steps:

[0012] Step 1: Installation of telescopic drill rod:

[0013] Step 101, connecting the installation pipe to the power device of the pile driver, controlling the power device to move and drive the inner pipe to rotate, so that the offset groove of the inner pipe is aligned with the clamping piece of the outer pipe, and the power device drives the inner pipe to descend so that the clamping piece passes through the offset groove and completely enters the third groove;

[0014] Step 102, controlling the power device to drive the inner tube to rotate until the clamping piece is completely located at the intersection of the third groove and the first groove, and then the power device drives the inner tube to descend until the top of the clamping piece abuts against the top of the second groove, so that the clamping piece passes through the first groove and completely enters the second groove;

[0015] Step 103, controlling the power device to drive the inner tube to reverse until the clamping piece moves horizontally out of the intersection of the second groove and the first groove, so that the clamping piece cannot move downward due to the restriction of the bottom of the second groove, thereby completing the installation of the telescopic drill rod;

[0016] Step 2, initial drilling: keep the telescopic drill rod in the retracted state, move the pile driver to the side of the pile position to be constructed and align the telescopic drill rod with the pile position; the power device drives the telescopic drill rod to reverse and drill downward until the distance between the top of the power device and the ground is 0.5m to 1m, at which time, stop drilling;

[0017] Step 3: Lift the inner rod:

[0018] Step 301, controlling the power device to drive the inner tube to rotate forward until the clamping member is completely located at the intersection of the second groove and the first groove;

[0019] Step 302, controlling the power device to drive the inner tube to lift until the bottom of the clamping member abuts against the bottom of the third groove, thereby completing the lifting of the inner rod;

[0020] Step 4, drilling again: keep the telescopic drill rod in the extended state, control the power device to drive the inner tube to reverse downward and drill, during which the clamping piece moves horizontally out of the intersection of the third groove and the first groove, and then the clamping piece is abutted against the top of the third groove by the force of the inner tube reverse downward, and drives the outer tube to reverse downward and drill again; until the hole is drilled to the designed hole depth;

[0021] Step 5, preliminarily lifting the telescopic drill rod and grouting: keep the telescopic drill rod in an extended state, control the power device to drive the inner tube to lift upward in a positive direction, during which the clamping piece completely enters the intersection of the third groove and the first groove, and then the clamping piece is abutted against the bottom of the third groove by the positive upward force of the inner tube, and drives the outer tube to lift upward in a positive direction until the power device is lifted to a height threshold. During the process of lifting the telescopic drill rod upward in a positive direction, the grouting equipment is connected to the inner tube to synchronously perform concrete pouring construction, and the first pile section is constructed;

[0022] Step 6, retracting the inner rod: stop the concrete pouring construction; control the power device to drive the inner tube down until the top of the clamping piece abuts against the top of the second groove, so that the clamping piece passes through the first groove and completely enters the second groove, completing the retraction of the telescopic drill rod;

[0023] Step seven, lift the telescopic drill rod again and inject grout: keep the telescopic drill rod in the retracted state, control the power device to drive the inner tube to reverse and lift upward, during this process, the clamping piece moves horizontally out of the intersection of the second groove and the first groove, and then the clamping piece is abutted against the bottom of the second groove by the force of the inner tube reversing upward, and drives the outer tube to reverse and lift upward until the telescopic drill rod is lifted out of the formed drill hole; during the process of the telescopic drill rod reversed and lifted upward, the grouting equipment is connected through the inner tube to simultaneously carry out concrete pouring construction to form the second pile section.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The telescopic drill rod used in the present invention, by setting a groove unit and cooperating with a clamping piece, no redundant electrical control device is provided to control the extension and retraction of the telescopic drill rod. The structure is simple, the weight of the telescopic drill rod itself is greatly reduced, and transportation and loading and unloading are convenient.

[0026] 2. The telescopic drill rod adopted by the present invention has a mounting tube arranged on the inner tube and connected to the power device. The rotation and up and down movement of the inner tube are controlled to control the rotation and up and down movement of the entire telescopic drill rod. The control process is simple and clear, easy to learn and operate, which reduces the learning time required for operating the equipment and improves construction efficiency.

[0027] 3. The detachable connection between the inner rod and the outer rod in the telescopic drill rod adopted by the present invention makes the maintenance of the equipment more convenient. When one of the inner rod or the outer rod is worn, the worn rod can be replaced without repurchasing or manufacturing the entire telescopic drill rod, thus saving construction costs and increasing the service life of the equipment within a limited construction cost. It is economical and practical.

[0028] 4. The method adopted by the present invention has simple steps. A power device is used to drive the inner rod to rotate so that the clamping part slides in the groove unit. The drilling and lifting of the outer rod are controlled by controlling the position of the clamping part in the groove unit. The method is easy to operate, does not need to control extra electrical devices, reduces the number of controlled objects, is easy to operate, and is convenient for promotion and use.

[0029] In summary, the design of the present invention is novel and reasonable. By arranging the groove unit and cooperating with the clamping piece, the inner rod and the outer rod can be detachably connected. The structure is simple, and the weight of the telescopic drill rod itself is greatly reduced, which is convenient for transportation and loading and unloading. There is no need to control the extension and retraction of the telescopic drill rod with redundant electrical control devices. The control process is simple and clear, the number of controlled objects is reduced, the operation is easy, and it is convenient for promotion and use.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the inner rod of the telescopic drill rod of the present invention.

[0032] Figure 2 for Figure 1 Top view after the mounting tube is removed.

[0033] Figure 3 It is a schematic structural diagram of the outer rod of the telescopic drill rod of the present invention.

[0034] Figure 4 for Figure 3 Top view of the .

[0035] Figure 5The figure is a schematic diagram of the installation relationship between the inner rod, the outer rod and the drill bit of the telescopic drill rod of the present invention.

[0036] Figure 6 This is a diagram of the use state of the clamping member of the present invention when it is matched with the second groove.

[0037] Figure 7 This is a diagram of the use state when the clamping member of the present invention is in contact with the bottom of the third groove.

[0038] Figure 8 This is a diagram of the use state when the clamping member of the present invention is in contact with the top of the third groove.

[0039] Fig. 9 for Figure 5 Diagram of the usage status when the middle inner rod is extended.

[0040] Fig.10 The figure is a flowchart of the method for using the present invention.

[0041] Description of reference numerals:

[0042] 1—outer tube; 2—connector; 3—inner tube;

[0043] 4—mounting tube; 5—second groove; 6—first groove;

[0044] 7—third groove; 8—offset groove; 9—drill bit. DETAILED DESCRIPTION

[0045] like Figures 1 to 5 A telescopic drill rod shown in the figure comprises an outer rod and an inner rod arranged inside the outer rod and slidably matched with the outer rod, wherein the outer rod comprises an outer tube 1 and a clamping piece 2 fixedly arranged on the upper part of the inner wall of the outer tube 1, and the inner rod comprises an inner tube 3 and a mounting tube 4 arranged on the upper end of the inner tube 3 and used to match with the power device of the pile driver, and the outer wall of the inner tube 3 is provided with a groove unit slidably matched with the clamping piece 2 along the length direction;

[0046] The groove unit includes a first groove 6 opened along the length direction of the outer wall of the inner tube 3. The first groove 6 is unidirectionally expanded at one end close to the mounting tube 4 to form a second groove 5. The first groove 6 is unidirectionally expanded at one end away from the mounting tube 4 to form a third groove 7. The second groove 5 and the third groove 7 have the same expansion direction. An offset groove 8 is opened on the outer wall of the inner tube 3, which is offset from the first groove 6 and is used for the clamping part 2 to enter the third groove 7. The width of the clamping part 2 is less than or equal to the width of the first groove 6. The width of the offset groove 8 is greater than or equal to the width of the clamping part 2 and less than the width of the third groove 7.

[0047] It should be noted that in general pile construction, the drilling is carried out from left to right in a counterclockwise direction. Figure 1As shown, in this embodiment, the second groove 5 and the third groove 7 are both grooves formed by the first groove 6 expanding to the left, so as to prevent the clamping member 2 from sliding up and down along the left side of the groove unit when the drill rod rotates from left to right to drill, thereby ensuring that the telescopic drill rod can work normally; in actual use, if the drill is drilled clockwise, the second groove 5 and the third groove 7 are both grooves formed by the first groove 6 expanding to the right, and the other sizes and positional relationships remain unchanged, and the application range is wide;

[0048] It should be noted that, by providing the groove unit in cooperation with the clamping member 2, no redundant electrical control device is required to control the extension and retraction of the telescopic drill rod, the structure is simple, the weight of the telescopic drill rod itself is greatly reduced, and transportation and loading and unloading are facilitated;

[0049] By arranging the mounting tube 4 on the inner tube 3 and connecting it to the power device, the rotation and up and down movement of the inner tube 3 are controlled to control the rotation and up and down movement of the entire telescopic drill rod. The control process is simple and clear, easy to learn and operate, reducing the learning time required for operating the equipment and improving the construction efficiency.

[0050] The detachable connection between the inner rod and the outer rod makes the maintenance of the equipment more convenient. When one of the inner rod or the outer rod is worn, the worn rod can be replaced without repurchasing or manufacturing the entire telescopic drill rod, thus saving construction costs and increasing the service life of the equipment within a limited construction cost. It is economical and practical.

[0051] In this embodiment, the offset groove 8 is a trapezoidal groove, the small end of which is arranged close to the third groove 7 , and the width of the small end of which is greater than or equal to the width of the clamping member 2 and less than the width of the third groove 7 .

[0052] It should be noted that the small end of the trapezoidal groove is arranged close to the third groove 7, so that the clamping member 2 can more conveniently enter the third groove 7 from the large end of the trapezoidal groove, reducing the difficulty of the clamping member 2 entering the third groove 7 and improving the installation speed;

[0053] In this embodiment, the outer diameter of the mounting tube 4 is larger than the inner diameter of the outer tube 1 and smaller than or equal to the outer diameter of the outer tube 1 .

[0054] It should be noted that the mounting tube 4 is clamped outside the outer tube 1, so that the inner rod can better drive the outer tube 1 to drill, and at the same time can reduce the amount of dust entering the gap between the outer tube 1 and the inner tube 3 during drilling, thereby reducing the wear intensity between the clamping member 2 and the groove unit, extending the service life of the equipment, and being economical and practical;

[0055] In this embodiment, the clamping member 2 is a fan-shaped clamping member, and the number of the fan-shaped clamping members is multiple, and the multiple fan-shaped clamping members are arranged circumferentially along the inner wall of the outer tube 1. The number of the groove units is multiple, and the number of the groove units is the same as the number of the clamping members and corresponds one to one.

[0056] It should be noted that by providing a plurality of the fan-shaped annular clamping parts and a plurality of the groove units, the strength of the telescopic drill rod structure is ensured. If one of the fan-shaped annular clamping parts is damaged, the remaining fan-shaped annular clamping parts can also work normally, thereby gaining response time for equipment maintenance and avoiding construction accidents. In this embodiment, the number of the fan-shaped annular clamping parts is three;

[0057] In this embodiment, the depth of the second groove 5 , the depth of the third groove 7 , the depth of the first groove 6 and the depth of the offset groove 8 are all the same.

[0058] It should be noted that the depths of the second groove 5, the third groove 7 and the first groove 6 are the same, which ensures the smoothness of the sliding of the clamping member 2 in the groove unit, and the design is reasonable;

[0059] In this embodiment, a drill bit 9 is provided at the lower end of the outer tube 1 , and a slurry outlet communicating with the interior of the inner tube 3 is opened on the drill bit 9 .

[0060] like Figures 6 to 10 A method for using a telescopic drill rod as shown comprises the following steps:

[0061] Step 1: Installation of telescopic drill rod:

[0062] Step 101, connecting the installation tube 4 to the power device of the pile driver, controlling the power device to move and drive the inner tube 3 to rotate, so that the offset groove 8 of the inner tube 3 is aligned with the clamping piece 2 of the outer tube 1, and the power device drives the inner tube 3 to descend so that the clamping piece 2 passes through the offset groove 8 and completely enters the third groove 7;

[0063] It should be noted that, by providing the offset groove 8, the clamping member 2 can slide out of the third groove 7 to the outside of the inner tube 3, so that the inner rod and the outer rod are detachably connected. In this embodiment, the offset groove 8 is a trapezoidal groove, and the small end of the trapezoidal groove is arranged close to the third groove 7. The width of the small end of the trapezoidal groove is greater than or equal to the width of the clamping member 2 and less than the width of the third groove 7. Therefore, during the installation process of the inner rod and the outer rod, the offset groove 8 can be more conveniently aligned with the clamping member 2, and the clamping member 2 can slide into the third groove 7 without precise alignment, thereby speeding up the installation speed, reducing the need for precise control of the equipment, and facilitating learning and operation.

[0064] Step 102, control the power device to drive the inner tube 3 to rotate until the clamping member 2 is completely located at the intersection of the third groove 7 and the first groove 6, and then the power device drives the inner tube 3 to descend until the top of the clamping member 2 abuts against the top of the second groove 5, so that the clamping member 2 passes through the first groove 6 and completely enters the second groove 5;

[0065] In this embodiment, Figure 1 As shown, the second groove 5 and the third groove 7 are both grooves formed by expanding the diameter of the first groove 6 to the left, so the direction of rotation of the inner tube 3 in step 102 is clockwise;

[0066] Step 103, control the power device to drive the inner tube 3 to reverse until the clamping member 2 moves horizontally out of the intersection of the second groove 5 and the first groove 6, so that the clamping member 2 is restricted by the bottom of the second groove 5 and cannot move downward, and the installation of the telescopic drill rod is completed;

[0067] It should be noted that in step 103, the direction in which the inner tube 3 is reversed is counterclockwise rotation;

[0068] It should be noted that, since the width of the second groove 5 is greater than that of the first groove 6, a limit block is formed at the lower part of the second groove 5 where the diameter is enlarged compared to the first groove 6, which is used to limit the up and down movement of the clamping member 2 located in the second groove 5, thereby ensuring that the structure is stable during the initial drilling process after the installation of the telescopic drill rod is completed;

[0069] During the installation of the telescopic drill rod, the restriction of the top of the third groove 7 and the restriction of the bottom of the second groove 5 are cleverly utilized, and no extra detection means are required, and there is no need to pre-set the inner rod rotation angle required for installing the telescopic drill rod in the pile driver, so that the installation of the telescopic drill rod can be conveniently completed, the operation is convenient, and the use effect is good;

[0070] Step 2, initial drilling: keep the telescopic drill rod in the retracted state, move the pile driver to the side of the pile position to be constructed and align the telescopic drill rod with the pile position; the power device drives the telescopic drill rod to reverse and drill downward until the distance between the top of the power device and the ground is 0.5m to 1m, at which time, stop drilling;

[0071] It should be noted that, during the initial drilling process, when the distance between the top of the power device and the ground is 0.5m to 1m, the current drilling depth is the maximum depth that can be drilled when the telescopic drill rod is in a retracted state due to the height limit of the tower of the supporting pile driver. When the maximum depth does not reach the designed hole depth, the telescopic drill rod needs to be extended so as to continue drilling when the tower height is constant. Compared with increasing the tower height, the cost of drilling with the telescopic drill rod is lower. At the same time, the use of a tower with a lower height facilitates the disassembly and transportation of the tower during the overall construction process, which is beneficial to improving the efficiency of the overall construction, reducing the construction cost, and being economical and practical.

[0072] Step 3: Lift the inner rod:

[0073] Step 301, controlling the power device to drive the inner tube 3 to rotate forward until the clamping member 2 is completely located at the intersection of the second groove 5 and the first groove 6;

[0074] Step 302, control the power device to drive the inner tube 3 to lift, until the bottom of the clamping member 2 abuts against the bottom of the third groove 7, and the lifting of the inner rod is completed;

[0075] Step 4, drilling again: keep the telescopic drill rod in the extended state, control the power device to drive the inner tube 3 to reverse and drill downward, during which the clamping member 2 moves horizontally out of the intersection of the third groove 7 and the first groove 6, and then the clamping member 2 is abutted against the top of the third groove 7 by the reverse downward force of the inner tube 3, and drives the outer tube 1 to reverse and drill downward again; until the hole is drilled to the designed hole depth;

[0076] Step 5, preliminarily lifting the telescopic drill rod and grouting: keep the telescopic drill rod in the extended state, control the power device to drive the inner tube 3 to lift upward in the positive direction, during which the clamping member 2 completely enters the intersection of the third groove 7 and the first groove 6, and then the clamping member 2 is abutted against the bottom of the third groove 7 by the positive upward force of the inner tube 3, and drives the outer tube 1 to lift upward in the positive direction until the power device is lifted to the height threshold. During the process of the telescopic drill rod being lifted upward in the positive direction, the grouting equipment is connected through the inner tube 3 to synchronously perform concrete pouring construction, and the first pile section is constructed;

[0077] Step 6: Retract the inner rod: stop the concrete pouring construction; control the power device to drive the inner tube 3 to descend until the top of the clamping member 2 abuts against the top of the second groove 5, so that the clamping member 2 passes through the first groove 6 and completely enters the second groove 5, completing the retraction of the telescopic drill rod;

[0078] Step seven, lift the telescopic drill rod again and inject grout: keep the telescopic drill rod in the retracted state, control the power device to drive the inner tube 3 to reverse and lift upward, during which the clamping piece 2 moves horizontally out of the intersection of the second groove 5 and the first groove 6, and then the clamping piece 2 is abutted against the bottom of the second groove 5 by the force of the inner tube 3 reversing upward, and drives the outer tube 1 to reverse and lift upward until the telescopic drill rod is taken out of the formed drill hole; during the process of the telescopic drill rod reversing and lifting upward, the grouting equipment is connected through the inner tube 3 to simultaneously carry out concrete pouring construction to form the second pile section.

[0079] In actual use, when threaded drill teeth are provided on the outer wall of the outer tube 1, the first pile section formed during construction is a threaded section pile body; since during the process of lifting the telescopic rod again and grouting, the power device drives the inner tube 3 to reverse and lift upward to perform a screw sweeping operation, the second pile section formed during construction is a straight rod section pile body, and the straight rod section pile body has better pressure-bearing performance. The straight rod section pile body and the threaded section pile body are used in combination to make the entire pile body have better use effect and stronger bearing capacity under a certain grouting amount.

[0080] In summary, the design of the present invention is novel and reasonable. By setting the groove unit and cooperating with the clamping piece 2, the inner rod and the outer rod are detachably connected. The structure is simple, which greatly reduces the weight of the telescopic drill rod itself, facilitates transportation and loading and unloading, and does not require the control of redundant electrical control devices to control the extension and retraction of the telescopic drill rod. The control process is simple and clear, the number of controlled objects is reduced, the operation is easy, and it is convenient for promotion and use.

[0081] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A telescopic drill rod, characterized in that: The invention comprises an outer rod and an inner rod arranged inside the outer rod and slidably matched with the outer rod, the outer rod comprises an outer tube (1) and a clamping piece (2) fixedly arranged on the upper part of the inner wall of the outer tube (1), the inner rod comprises an inner tube (3) and a mounting tube (4) arranged at the upper end of the inner tube (3) and used to match with the power device of the pile driver, and the outer wall of the inner tube (3) is provided with a groove unit slidably matched with the clamping piece (2) along the length direction; The groove unit comprises a first groove (6) provided along the length direction of the outer wall of the inner tube (3); the end of the first groove (6) close to the mounting tube (4) is unidirectionally expanded to form a second groove (5); the end of the first groove (6) away from the mounting tube (4) is unidirectionally expanded to form a third groove (7); the second groove (5) and the third groove (7) have the same expansion direction; an offset groove (8) is provided on the outer wall of the inner tube (3) and is offset from the first groove (6) and is used for the clamping member (2) to enter the third groove (7); the width of the clamping member (2) is less than or equal to the width of the first groove (6); the width of the offset groove (8) is greater than or equal to the width of the clamping member (2) and is less than the width of the third groove (7); The dislocation groove (8) is a trapezoidal groove, the small end of the trapezoidal groove is arranged close to the third groove (7), and the width of the small end of the trapezoidal groove is greater than or equal to the width of the clamping member (2) and less than the width of the third groove (7); The clamping piece (2) is a fan-shaped clamping piece, and there are a plurality of the fan-shaped clamping pieces, which are arranged circumferentially along the inner wall of the outer tube (1). There are a plurality of the groove units, which are the same as the number of the clamping pieces and correspond one to one.

2. A telescopic drill rod according to claim 1, characterized in that: The outer diameter of the mounting tube (4) is greater than the inner diameter of the outer tube (1) and is less than or equal to the outer diameter of the outer tube (1).

3. The telescopic drill rod according to claim 1, characterized in that: The depth of the second groove (5), the depth of the third groove (7), the depth of the first groove (6) and the depth of the offset groove (8) are all the same.

4. The telescopic drill rod according to claim 1, characterized in that: A drill bit (9) is provided at the lower end of the outer tube (1), and a slurry outlet communicating with the interior of the inner tube (3) is provided on the drill bit (9).

5. A method for using the telescopic drill rod according to claim 1, characterized in that: The method comprises the following steps: Step 1: Installation of telescopic drill rod: Step 101, connecting the installation tube (4) to the power device of the pile driver, controlling the power device to move and drive the inner tube (3) to rotate, so that the offset groove (8) of the inner tube (3) is aligned with the clamping member (2) of the outer tube (1), and the power device drives the inner tube (3) to descend so that the clamping member (2) passes through the offset groove (8) and completely enters the third groove (7); Step 102, controlling the power device to drive the inner tube (3) to rotate until the clamping member (2) is completely located at the intersection of the third groove (7) and the first groove (6), and then the power device drives the inner tube (3) to descend until the top of the clamping member (2) abuts against the top of the second groove (5), so that the clamping member (2) passes through the first groove (6) and completely enters the second groove (5); Step 103, controlling the power device to drive the inner tube (3) to reverse until the clamping member (2) moves horizontally out of the intersection of the second groove (5) and the first groove (6), so that the clamping member (2) is restricted by the bottom of the second groove (5) and cannot move downward, thereby completing the installation of the telescopic drill rod; Step 2, initial drilling: keep the telescopic drill rod in the retracted state, move the pile driver to the side of the pile position to be constructed and align the telescopic drill rod with the pile position; the power device drives the telescopic drill rod to reverse and drill downward until the distance between the top of the power device and the ground is 0.5m to 1m, at which time, stop drilling; Step 3: Lift the inner rod: Step 301, controlling the power device to drive the inner tube (3) to rotate forward until the clamping member (2) is completely located at the intersection of the second groove (5) and the first groove (6); Step 302, controlling the power device to drive the inner tube (3) to lift until the bottom of the clamping member (2) abuts against the bottom of the third groove (7), thereby completing the lifting of the inner rod; Step 4, drilling again: keeping the telescopic drill rod in the extended state, controlling the power device to drive the inner tube (3) to reverse and drill downward, during which the clamping member (2) moves horizontally out of the intersection of the third groove (7) and the first groove (6), and then the clamping member (2) is abutted against the top of the third groove (7) by the force of the inner tube (3) reversing and drilling downward, and drives the outer tube (1) to reverse and drill downward again; until the designed hole depth is reached; Step 5: Preliminary lifting of the telescopic drill rod and grouting: the telescopic drill rod is kept in an extended state, and the power device is controlled to drive the inner tube (3) to lift forward in a positive rotation. During this process, the clamping member (2) completely enters the intersection of the third groove (7) and the first groove (6), and then the clamping member (2) is abutted against the bottom of the third groove (7) by the positive rotation upward force of the inner tube (3), and drives the outer tube (1) to lift forward in a positive rotation upward until the power device is lifted to a height threshold. During the process of lifting the telescopic drill rod forward in a positive rotation upward, the grouting equipment is connected to the inner tube (3) and concrete pouring construction is carried out synchronously to form a first pile section; Step 6: retracting the inner rod: stop the concrete pouring construction; control the power device to drive the inner tube (3) to descend until the top of the clamping member (2) abuts against the top of the second groove (5), so that the clamping member (2) passes through the first groove (6) and completely enters the second groove (5), completing the retraction of the telescopic drill rod; Step 7, lifting the telescopic drill rod again and injecting grout: the telescopic drill rod is kept in the retracted state, and the power device is controlled to drive the inner tube (3) to reverse and lift upward. During this process, the clamping member (2) moves horizontally out of the intersection of the second groove (5) and the first groove (6), and then the clamping member (2) is abutted against the bottom of the second groove (5) by the force of the inner tube (3) to reverse upward, and drives the outer tube (1) to reverse and lift upward until the telescopic drill rod is lifted out of the formed drill hole; during the process of the telescopic drill rod being reversed and lifted upward, the grouting equipment is connected through the inner tube (3) to synchronously perform concrete pouring construction, so as to form a second pile section.

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