Construction method for reverse circulation drilling slag extraction under complex geological conditions

Abstract

The invention relates to the technical field of bottom layer drilling, and provides a construction method for reverse circulation drilling slag extraction under complex geological conditions, and the construction method comprises the following steps: construction preparation: positioning and re-checking a total station; a pile casing is embedded, specifically, the pile casing is placed at the drilling position to be positioned; drilling equipment comprises a connecting rod, an air injection pipe and a slurry pumping pipe are arranged on the inner side of the connecting rod, the lower end of the air injection pipe is connected with an air adjusting structure, the lower end of the connecting rod is movably connected with a connecting rod through a bolt, the surface of the connecting rod is fixedly connected with a slag drawing cylinder through a support, and the lower end of the slag drawing cylinder is fixedly connected with a fixing frame; the surface of the fixing frame is fixedly connected with an alloy tool bit, the surface of the alloy tool bit is fixedly connected with a jacking structure, and the jacking structure is used for enhancing the drilling effect of the alloy tool bit. By means of the technical scheme, the problems that according to an existing reverse circulation drilling slag drawing construction method, drilling cannot be conducted when large-particle-size boulders or pebbles are encountered, the construction efficiency is greatly reduced, and the construction period is delayed are solved.

Description

Technical Field

[0001] The invention relates to the technical field of bottom drilling, and in particular to a reverse circulation drilling and slag removal construction method for complex geological conditions. Background Art

[0002] The traditional construction method of reverse circulation construction is slow in drilling speed or even impossible to advance in areas with complex geological conditions at the riverside or riverbank and isolated rocks.

[0003] After searching, the application publication number is CN117072081A, which is a reverse circulation drilling construction method. The application uses the reverse circulation drill pipe to suck out the circulating mud with drill cuttings, greatly reducing the ineffective labor of repeatedly grinding drill cuttings, and can greatly improve the drilling efficiency. At the same time, this application uses the reverse circulation pump suction and slurry replacement to clean the hole from top to bottom, changes the pump suction point during hole cleaning, strengthens the local mud and slurry replacement and discharge effect, and effectively improves the operation efficiency and quality;

[0004] However, the above-mentioned existing reverse circulation drilling and slag removal construction method cannot drill when encountering large-size boulders or pebbles, which will greatly reduce the construction efficiency and delay the construction period. For this reason, we propose a reverse circulation drilling and slag removal construction method for complex geological conditions. Summary of the invention

[0005] The present invention proposes a reverse circulation drilling and slag removal construction method for complex geological conditions, which solves the problem mentioned in the background technology that the existing reverse circulation drilling and slag removal construction method cannot drill when encountering large-diameter boulders or pebbles, which will greatly reduce the construction efficiency and delay the construction period.

[0006] The technical solution of the present invention is as follows:

[0007] A reverse circulation drilling and slag removal construction method for complex geological conditions, the construction method comprising the following steps:

[0008] Construction preparation: total station positioning and review;

[0009] Casing burial: Place the casing at the drilling location;

[0010] Drilling: The drilling equipment includes a connecting rod, an air injection pipe and a slurry extraction pipe are respectively arranged on the inner side of the connecting rod, the lower end of the air injection pipe is connected to an air regulating structure, the lower end of the connecting rod is movably connected to a connecting rod through a bolt, the surface of the connecting rod is fixedly connected to a slag removal barrel through a bracket, the lower end of the slag removal barrel is fixedly connected to a fixing frame, the surface of the fixing frame is fixedly connected to an alloy cutter head, the surface of the alloy cutter head is fixedly connected to a jacking structure, the jacking structure is used to enhance the drilling effect of the alloy cutter head, and the air regulating structure is used to achieve uniform blowing of different areas at the same height inside the connecting rod;

[0011] The reverse circulation drilling rig drives the connecting rod and the coupling rod to rotate and drill, and the drilling is carried out through the alloy cutter head and the jacking structure, and the ventilation is carried out through the air adjustment structure, and the mud in the hole is extracted through the slurry extraction pipe;

[0012] The slag removal barrel can squeeze the oversized stones into the inside of the slag removal barrel, and then lift the stones in the slag removal barrel to the ground and pour them out from the side wall hole;

[0013] Hole cleaning: Replace the slurry and clean the inside of the drilled hole;

[0014] Casting: vertically hang the prefabricated steel cage from the hole and cast concrete with the strength required by the drawing.

[0015] As a further technical solution of the present invention, a connecting piece is movably connected between the connecting rod and the connecting rod, and the connecting piece is used to protect the bolts connecting the connecting rod and the connecting rod. The top end of the connecting rod is fixedly connected to an end plate, and a group of brackets are arranged at the axis of the slag removal barrel. A steel wire rope is fixedly connected between the bracket and the inner wall of the slag removal barrel, and the steel wire rope is fixedly connected to the slag removal barrel through a fastening ring. The lower side wall of the slag removal barrel is provided with an openable hole, and the openable hole is used for the circulation of slurry inside and outside the slag removal barrel.

[0016] As a further technical solution of the present invention, the air adjusting structure includes a connecting pipe movably connected to the lower end of the air injection pipe, one end of the connecting pipe is fixedly connected to an annular pipe, one end of the connecting pipe is fixedly connected to an air guide pipe, the inside of the annular pipe is movably connected to a movable plate, the lower end of the movable plate is fixedly connected to a protrusion, the inner side of the movable plate is fixedly connected to a baffle, and the surface of the protrusion is fixedly connected to an air outlet pipe.

[0017] As a further technical solution of the present invention, the pushing structure includes a cavity opened between the alloy cutter head and the fixed frame, the cavity includes an upper cavity and a lower cavity that are interconnected, a movable column is movably connected between the upper cavity and the lower cavity, the lower end of the movable column is fixedly connected to a limiting block, the upper end of the movable column is fixedly connected to a movable cutter head, and a pushing spring is arranged inside the upper cavity.

[0018] As a further technical solution of the present invention, the movable plate is slidably connected to the annular tube, the movable plate slides along the length direction of the annular tube, and the protrusion penetrates from the inside of the annular tube to the outside thereof.

[0019] As a further technical solution of the present invention, the baffles are in several groups and distributed in a ring array, the movable plate is an arc-shaped plate structure matching the inner wall of the annular tube, and the movable plate is a circular ring structure.

[0020] As a further technical solution of the present invention, the number of the air outlet pipes is several groups and distributed in a ring array, and the air outlet pipes are connected to the inner side of the protrusion, and the baffle is blown by the air guide pipe to realize the rotation and sliding of the movable plate, the protrusion, the baffle and the air outlet pipe inside the annular tube.

[0021] As a further technical solution of the present invention, the alloy cutter head is arranged in a "cross" shaped conical structure, and the movable column is slidably connected to the alloy cutter head and the fixed frame.

[0022] As a further technical solution of the present invention, the diameter of the limit block matches the diameter of the lower cavity, and the upper and lower ends of the movable column are respectively fixed to the movable cutter head and the limit block by welding.

[0023] As a further technical solution of the present invention, the chamfer of the upper end of the movable cutter head matches the alloy cutter head, the movable cutter head and the limit block move up and down with the movable column, the inner diameter of the push spring is larger than the diameter of the movable column, and the outer diameter is smaller than the diameter of the limit block.

[0024] The working principle and beneficial effects of the present invention are:

[0025] 1. In the present invention, the jacking structure can enhance the drilling effect during reverse circulation drilling of the formation by the alloy cutter head. The jacking and contraction structure can greatly enhance the drilling effect of the alloy cutter head on the bottom layer, and effectively enhance the drilling effect on harder rocks.

[0026] 2. In the present invention, the air regulating structure can cooperate with the slurry extraction effect of the slurry extraction pipe during use to increase the buoyancy of the mud, drive the mud to move upward, and increase the volume of the mud, forming a negative pressure below the gas-liquid mixing section. The mud in the lower part of the section is continuously replenished, which can greatly enhance the slurry extraction effect during construction and improve the efficiency of hole cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] Figure 1 It is a partial structural schematic diagram of the structure of the present invention;

[0029] Figure 2 It is a schematic diagram of the partial structure of one end of the slag removal barrel of the present invention;

[0030] Figure 3 It is a schematic diagram of the local structure of the lower end of the air injection pipe of the present invention;

[0031] Figure 4 For the present invention Figure 3 Schematic diagram of the cutaway local structure;

[0032] Figure 5 For the present invention Figure 4 A schematic diagram of a local structure cut away from another perspective;

[0033] Figure 6 A schematic diagram of a local structure of the present invention at the top moving structure

[0034] Figure 7 It is a partial front cross-sectional view when the present invention is used;

[0035] Figure 8 It is a partial front cross-sectional view of another side of the present invention.

[0036] In the figure: 1, slag removal cylinder; 2, connecting rod; 3, air injection pipe; 4, fixing frame; 5, alloy cutter head; 6, jacking structure; 60, cavity; 61, upper cavity; 62, lower cavity; 63, movable column; 64, limit block; 65, movable cutter head; 66, jacking spring; 7, air adjustment structure; 70, connecting pipe; 71, annular pipe; 72, air guide pipe; 73, movable plate; 74, protrusion; 75, baffle; 76, air outlet pipe; 8, slurry extraction pipe; 9, connecting piece; 10, connecting rod; 11, end plate; 12, wire rope;

[0037] A is the casing; B is the mud liquid level; C is the sediment; D is the openable hole. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] like Figure 1 to Figure 5 and Figure 7-Figure 8 As shown, this embodiment proposes a reverse circulation drilling and slag removal construction method for complex geological conditions, and the construction method includes the following steps:

[0041] Construction preparation: total station positioning and review;

[0042] Casing A burial: Place casing A at the drilling position;

[0043] Drilling: The drilling equipment includes a connecting rod 2, the inner side of which is respectively provided with an air injection pipe 3 and a slurry extraction pipe 8, the lower end of the air injection pipe 3 is connected with an air regulating structure 7, the lower end of the connecting rod 2 is movably connected with a connecting rod 10 through a bolt, the surface of the connecting rod 10 is fixedly connected with a slag removal barrel 1 through a bracket, the lower end of the slag removal barrel 1 is fixedly connected with a fixing frame 4, the surface of the fixing frame 4 is fixedly connected with an alloy cutter head 5, the surface of the alloy cutter head 5 is fixedly connected with a jacking structure 6, the jacking structure 6 is used to enhance the drilling effect of the alloy cutter head 5, and the air regulating structure 7 is used to achieve uniform blowing of different areas at the same height inside the connecting rod 10;

[0044] The reverse circulation drilling rig drives the connecting rod 2 and the connecting rod 10 to rotate and drill, and the drilling is performed through the alloy cutter head 5 and the jacking structure 6, and ventilation is performed through the air regulating structure 7, and the mud in the hole is extracted through the slurry extraction pipe 8;

[0045] The slag removal barrel 1 can squeeze oversized granular stones into the interior of the slag removal barrel 1, and then the granular stones in the slag removal barrel 1 can be lifted out to the ground and poured out from the side wall hole;

[0046] Hole cleaning: Replace the slurry and clean the inside of the drilled hole;

[0047] Casting: vertically hang the prefabricated steel cage from the hole and cast concrete with the strength required by the drawing.

[0048] A connecting piece 9 is movably connected between the connecting rod 10 and the connecting rod 2. The connecting piece 9 is used to protect the bolts connecting the connecting rod 10 and the connecting rod 2. The top of the connecting rod 2 is fixedly connected with an end plate 11. A group of brackets are provided at the axis of the slag removal barrel 1. A steel wire rope 12 is fixedly connected between the bracket and the inner wall of the slag removal barrel 1. The steel wire rope 12 is fixedly connected to the slag removal barrel 1 through a fastening ring. An openable hole D is provided on the lower side wall of the slag removal barrel 1. The openable hole is used for the circulation of slurry inside and outside the slag removal barrel 1.

[0049] The alloy cutter head 5 is a "cross"-shaped conical structure, and the movable column 63 is slidably connected to the alloy cutter head 5 and the fixed frame 4.

[0050] The air regulating structure 7 includes a connecting tube 70 movably connected to the lower end of the air injection tube 3, one end of the connecting tube 70 is fixedly connected to an annular tube 71, one end of the connecting tube 70 is fixedly connected to an air guide tube 72, the inside of the annular tube 71 is movably connected to a movable plate 73, the lower end of the movable plate 73 is fixedly connected to a protrusion 74, the inner side of the movable plate 73 is fixedly connected to a baffle 75, and the surface of the protrusion 74 is fixedly connected to an air outlet pipe 76.

[0051] The movable plate 73 is slidably connected to the annular tube 71, and the movable plate 73 slides along the length direction of the annular tube 71, and the protrusion 74 penetrates from the inside of the annular tube 71 to its outside; the number of baffles 75 is several groups and distributed in a ring array, the movable plate 73 is an arc-shaped plate structure matching the inner wall of the annular tube 71, and the movable plate 73 is a circular ring structure; the number of air outlet pipes 76 is several groups and distributed in a ring array, and the air outlet pipes 76 are connected to the inner side of the protrusion 74, and the baffle 75 is blown by the air guide pipe 72 to realize the rotation and sliding of the movable plate 73, the protrusion 74, the baffle 75 and the air outlet pipe 76 inside the annular tube 71.

[0052] In this embodiment, during use, the slurry extraction effect of the slurry extraction pipe 8 can be used to increase the buoyancy of the mud, drive the mud to move upward, and increase the volume of the mud, forming a negative pressure below the gas-liquid mixing section. The mud in the lower part of this section is continuously replenished, which can greatly enhance the slurry extraction effect during construction and improve the efficiency of hole cleaning.

[0053] During the process of inflating the mud inside the connecting rod 2 through the air injection pipe 3, the air flow is filled into the interior of the connecting pipe 70 from the air injection pipe 3, and the air flow is blown to the surface of the baffle 75 through the air guide pipe 72, thereby pushing the baffle 75 to rotate together with the movable plate 73 and the protrusion 74, and finally the gas is discharged into the mud through the air outlet pipe 76. The follow-up rotation of the air outlet pipe 76 can increase the uniformity of the blowing effect of the device, thereby further enhancing the slurry extraction and hole cleaning effects during the construction process.

[0054] Example 2

[0055] like Figure 6 As shown, on the basis of Example 1, it is further proposed that the pushing structure 6 includes a cavity 60 opened between the alloy cutter head 5 and the fixed frame 4, the cavity 60 includes an upper cavity 61 and a lower cavity 62 which are interconnected, a movable column 63 is movably connected between the upper cavity 61 and the lower cavity 62, the lower end of the movable column 63 is fixedly connected to a limiting block 64, the upper end of the movable column 63 is fixedly connected to a movable cutter head 65, and a pushing spring 66 is arranged inside the upper cavity 61.

[0056] The diameter of the limit block 64 matches the diameter of the lower cavity 62, and the upper and lower ends of the movable column 63 are fixed to the movable cutter head 65 and the limit block 64 by welding respectively; the upper end chamfer of the movable cutter head 65 matches the alloy cutter head 5, and the movable cutter head 65 and the limit block 64 move up and down with the movable column 63. The inner diameter of the push spring 66 is larger than the diameter of the movable column 63, and the outer diameter is smaller than the diameter of the limit block 64.

[0057] In this embodiment, the drilling effect can be enhanced during reverse circulation drilling of the formation by the alloy cutter head 5. The structure that can be pushed and contracted can greatly enhance the drilling effect of the alloy cutter head 5 on the bottom layer, and effectively enhance the drilling effect on harder rocks.

[0058] During the drilling process, the movable cutter head 65 can be pushed upward by the pushing spring 66, so that the movable cutter head 65 presents a floating drilling effect up and down, which can enhance the drilling effect during the construction process. At the same time, the limit block 64 limits the maximum distance that the movable cutter head 65 can be pushed outward. When the top of the movable cutter head 65 receives pressure, it will be flush with the surface of the alloy cutter head 5, and at most will shrink to the inner side of the alloy cutter head 5. At this time, the limit block 64 moves to the uppermost position of the lower cavity 62, thereby enhancing the drilling ability of the alloy cutter head 5 through the pushing and contraction of the pushing spring 66.

[0059] During use, the connecting rod 2 can be driven by the drilling rig to drive the connecting rod 10 to rotate, and the connecting rod 10 can drive the slag removal barrel 1 to rotate, thereby driving the fixed frame 4, the alloy cutter head 5 and the jacking structure 6 to drill. During the drilling process, gas is filled into the air injection pipe 3 through the air compressor, and the air flow is output to the inside of the mud through the air regulating structure 7. At the same time, the mud is extracted through the suction pipe 8 through the suction pump; oversized gravel can be squeezed into the barrel through the slag removal barrel 1, supported by the wire rope 12, and then the gravel accumulated in the barrel can be lifted to the ground and poured out from the side wall hole. The device structure of this use method can effectively solve the problem that large-diameter boulders or pebbles cannot be drilled during reverse circulation drilling construction.

[0060] It should be noted that, in the secondary hole cleaning, high-pressure gas is generated by the air compressor and then sprayed out, mixed with the mud in the connecting rod 2, and dispersed in the connecting rod 2 to form bubbles. The bubbles are affected by the upward buoyancy of the mud and drive the mud to move upward, and the pressure decreases and the volume increases during the rising process; therefore, negative pressure is formed below the gas-liquid mixing section, which is continuously replenished by the mud in the lower part of this section. The sediment C at the bottom of the hole enters the connecting rod 2 driven by the movement of the mud, and is discharged out of the hole with the mud, forming a continuous circulation process, which greatly improves the hole cleaning efficiency.

[0061] It should be noted that before the reverse circulation drilling rig starts drilling, check again whether the center of the drill bit coincides with the center of the casing A and the center of the pile, check the horizontality of the drilling rig, and only proceed to the next process after the inspection is correct; start the drill bit, do not advance the footage, turn on the mud circulation, and start drilling after the mud circulation is normal; the first 2 meters of the footage should maintain a low drilling speed and slow footage to ensure the verticality of the drill rod. During the drilling process, adjust the drilling speed and footage speed according to the geological conditions, and observe the mud discharge at any time, detect and record the mud indicators every hour, and retain the sample residue; add a sample residue at the transition point of the formation; during the drilling process, the footage speed should be controlled, and the drilling depth and the observation of the sample residue should be compared with the geological data on the design drawings. If there is any discrepancy, the owner, supervisor, survey, and design unit should be notified in time to improve the construction measures according to the differences.

[0062] When the drilling process fails to advance for a long time, it can be concluded that there are isolated rocks below by comparing the sample slag with the geological data. The traditional conical drill bit is replaced with a slag barrel 1 drill bit to continue drilling, squeeze the oversized gravel into the barrel, and then lift the gravel in the barrel to the ground and pour it out from the side wall hole. Because the drilling geology is a sand layer, after successful advancement, it is promptly replaced with a traditional conical drill bit to carry out drilling operations to prevent the collapse of the hole during the construction of the slag barrel 1 drill bit.

[0063] When the drilling process fails to advance for a long time and the slag barrel 1 drill bit still cannot solve the problem, it can be concluded that there is a large area of ​​hard objects below, such as: abandoned concrete revetment, steel pipes and other complex situations; at this time, low-headroom rotary drilling rigs can be introduced for drilling construction. Low-headroom rotary drilling rigs have the advantages of high drilling efficiency, low height and convenient assembly, but they are not suitable for clay and medium-coarse sand formations, and are prone to hole collapse, and the construction noise is relatively large. After successful advancement, it should be promptly replaced with a reverse circulation drill to continue drilling construction.

[0064] The drilling process should be carried out continuously without long pauses.

[0065] Determination of final hole elevation: Final hole elevation = drill plate elevation - (drill rod length + drill bit length - drill bit cone foot length).

[0066] After drilling, the mud indicators are tested and the hole is cleaned for the first time.

[0067] It should be noted that in the process of inflating the mud inside the connecting rod 2 through the air injection pipe 3, the air flow is filled into the interior of the connecting pipe 70 from the air injection pipe 3, and the air flow is blown to the surface of the baffle 75 through the air guide pipe 72, thereby pushing the baffle 75 to rotate together with the movable plate 73 and the protrusion 74, and finally the gas is discharged into the mud through the air outlet pipe 76. The follow-up rotation of the air outlet pipe 76 can increase the uniformity of the blowing effect of the device, thereby further enhancing the slurry extraction and hole cleaning effects during the construction process.

[0068] It should be noted that during the drilling process, the movable cutter head 65 can be pushed upward by the pushing spring 66, so that the movable cutter head 65 presents a floating drilling effect up and down, which can enhance the drilling effect during the construction process. At the same time, the limit block 64 limits the maximum distance that the movable cutter head 65 can be pushed outward, and the top of the movable cutter head 65 will be flush with the surface of the alloy cutter head 5 when receiving pressure, and will at most shrink to the inner side of the alloy cutter head 5. At this time, the limit block 64 moves to the uppermost position of the lower cavity 62, thereby enhancing the drilling ability of the alloy cutter head 5 through the pushing and contraction of the pushing spring 66.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A reverse circulation drilling and slag removal construction method for complex geological conditions. It is characterized in that The construction method includes the following steps: Construction preparation: total station positioning and review; Casing burial: Place the casing at the drilling location; Drilling: The drilling equipment comprises a connecting rod (2), the inner side of which is respectively provided with an air injection pipe (3) and a slurry extraction pipe (8), the lower end of the air injection pipe (3) is connected with an air adjustment structure (7), the lower end of the connecting rod (2) is movably connected with a connecting rod (10) via a bolt, the surface of the connecting rod (10) is fixedly connected with a slag removal barrel (1) via a bracket, the lower end of the slag removal barrel (1) is fixedly connected with a fixing frame (4), the surface of the fixing frame (4) is fixedly connected with an alloy cutter head (5), the surface of the alloy cutter head (5) is fixedly connected with a jacking structure (6), the jacking structure (6) is used to enhance the drilling effect of the alloy cutter head (5), and the air adjustment structure (7) is used to achieve uniform blowing of different areas at the same height inside the connecting rod (10); The reverse circulation drilling rig drives the connecting rod (2) and the connecting rod (10) to rotate and drill, and the drilling is performed through the alloy cutter head (5) and the jacking structure (6), and ventilation is performed through the air adjustment structure (7), and the mud in the hole is extracted through the slurry extraction pipe (8); The slag removal barrel (1) can squeeze oversized granular stones into the interior of the slag removal barrel (1), and then lift the granular stones in the slag removal barrel (1) to the ground and pour them out from the hole on the side wall; Hole cleaning: Replace the slurry and clean the inside of the drilled hole; Casting: vertically hang the prefabricated steel cage from the hole and cast concrete with the strength required by the drawing.

2. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 1, It is characterized in that A connecting piece (9) is movably connected between the connecting rod (10) and the connecting rod (2), and the connecting piece (9) is used to protect the bolts connecting the connecting rod (10) and the connecting rod (2). The top of the connecting rod (2) is fixedly connected to an end plate (11). A group of brackets are provided at the axis of the slag removal barrel (1), and a steel wire rope (12) is fixedly connected between the brackets and the inner wall of the slag removal barrel (1). The steel wire rope (12) is fixedly connected to the slag removal barrel (1) through a fastening ring. An openable hole is provided on the lower side wall of the slag removal barrel (1), and the openable hole is used for the circulation of slurry inside and outside the slag removal barrel (1).

3. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 1, It is characterized in that The air regulating structure (7) comprises a connecting pipe (70) movably connected to the lower end of the air injection pipe (3); one end of the connecting pipe (70) is fixedly connected to an annular pipe (71); one end of the connecting pipe (70) is fixedly connected to an air guide pipe (72); a movable plate (73) is movably connected inside the annular pipe (71); a protrusion (74) is fixedly connected to the lower end of the movable plate (73); a baffle (75) is fixedly connected to the inner side of the movable plate (73); and an air outlet pipe (76) is fixedly connected to the surface of the protrusion (74).

4. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 3, It is characterized in that The push-up structure (6) comprises a cavity (60) opened between the alloy cutter head (5) and the fixed frame (4), the cavity (60) comprises an upper cavity (61) and a lower cavity (62) which are connected to each other, a movable column (63) is movably connected between the upper cavity (61) and the lower cavity (62), the lower end of the movable column (63) is fixedly connected to a limit block (64), the upper end of the movable column (63) is fixedly connected to a movable cutter head (65), and a push-up spring (66) is arranged inside the upper cavity (61).

5. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 3, It is characterized in that The movable plate (73) is slidably connected to the annular tube (71); the movable plate (73) slides along the length direction of the annular tube (71); and the protrusion (74) penetrates from the inside of the annular tube (71) to the outside thereof.

6. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 5, It is characterized in that The baffles (75) are provided in a plurality of groups and are distributed in a ring array. The movable plate (73) is an arc-shaped plate structure matching the inner wall of the annular tube (71), and the movable plate (73) is a circular ring structure.

7. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 6, It is characterized in that The number of the air outlet pipes (76) is several groups and they are distributed in a ring array, and the air outlet pipes (76) are connected to the inner side of the protrusion (74), and the baffle plate (75) is blown by the air guide pipe (72) to realize the rotation and sliding of the movable plate (73), the protrusion (74), the baffle plate (75) and the air outlet pipe (76) inside the annular pipe (71).

8. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 4, It is characterized in that The alloy cutter head (5) is arranged in a "cross"-shaped conical structure, and the movable column (63) is slidably connected to the alloy cutter head (5) and the fixed frame (4).

9. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 8, It is characterized in that The diameter of the limit block (64) matches the diameter of the lower cavity (62), and the upper and lower ends of the movable column (63) are respectively fixed to the movable cutter head (65) and the limit block (64) by welding.

10. The reverse circulation drilling and slag removal construction method for complex geological conditions according to claim 9, It is characterized in that The chamfered upper end of the movable cutter head (65) matches the alloy cutter head (5); the movable cutter head (65) and the limit block (64) move up and down following the movable column (63); the inner diameter of the push spring (66) is larger than the diameter of the movable column (63), and the outer diameter is smaller than the diameter of the limit block (64).

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