Patent Publication Number: US-10329844-B2

Title: Anchor rod multi-section reaming machine tool and application thereof

Description:
The present application is a 371 of PCT Application Serial No. PCT/CN2015/096252 filed Dec. 3, 2015, which claims the priority of Chinese Invention Patent Application No. 201510210136.X entitled “Anchor Rod Multi-section Reaming Machine Tool and Application Thereof” filed to the Chinese Patent Office on Apr. 29, 2015, which is incorporated herein by reference in its entirety. 
     FIELD OF THE INVENTION 
     The invention relates to the field of engineering construction equipment, and particularly to an anchor rod multi-section reaming machine tool and an application thereof. 
     BACKGROUND OF THE INVENTION 
     In foundation engineering and protective engineering for geological hazards, the anchor rod under-reaming technology is generally employed to support and reinforce the soil mass. During anchor rod reaming construction, the selection of an anchor rod reaming machine tool has an important influence on construction quality and cost. 
     For example, an anchor rod reaming machine tool provided by the prior art generally comprises a pressure rod, gears and reaming blades which are connected with a drill rod of an anchor rod drill rig. During use, firstly, drilling is performed by the drill rod of the anchor rod drill rig, and then the drill rod of the anchor rod drill rig is pressurized at the bottom of a hole to drive gear racks on the pressure rod for rectilinear movement, such that the gears rotate and hence the reaming blades expand or retract at the bottom of the hole to cut hole wall, thereby performing a reaming operation. 
     The inventors have found that the prior art at least has the following problem: 
     The anchor rod reaming machine tool provided by the prior art only can perform reaming at the bottom of the hole by means of blade cutting, which provides a poorer anti-pull-out property. 
     SUMMARY OF THE INVENTION 
     A technical problem to be solved by the embodiments of the invention is to provide an anchor rod multi-section reaming machine tool with high anti-pull-out property and an application thereof. A specific technical solution is as follows: 
     in one aspect, an embodiment of the invention provides an anchor rod multi-section reaming machine tool which is used cooperatively with an anchor rod drill rig and comprises a hydraulic station, a first pipe, a second pipe and a reaming machine head, wherein the reaming machine head comprises a hydraulic cylinder, an arch pressing device fixing disc, an arch pressing device, a base plate and a supporting structure; 
     the hydraulic cylinder is fixed at a lower end of a drill rod of the anchor rod drill rig; 
     the hydraulic cylinder comprises a cylinder body, a piston and a piston rod, the piston is arranged inside the cylinder body and can axially move relative to the cylinder body such that the cylinder body is divided into a hydraulic cylinder upper chamber and a hydraulic cylinder lower chamber which have variable volume, the hydraulic cylinder upper chamber is connected with the hydraulic station through the first pipe, the hydraulic cylinder lower chamber is connected with the hydraulic station through the second pipe, an upper end of the piston rod is fixed at a lower portion of the piston, and a lower end of the piston rod is fixed at an upper portion of the arch pressing device fixing disc; 
     the arch pressing device comprises a pair of upper arch arms and a pair of lower arch arms radially arranged symmetrically to the pair of upper arch arms, upper ends of the pair of upper arch arms are rotatably connected with a central position of a lower portion of the arch pressing device fixing disc, lower ends of the pair of upper arch arms are rotatably connected with upper ends of the pair of lower arch arms, and lower ends of the pair of lower arch arms are rotatably connected with a central position of an upper portion of the base plate; and 
     the supporting structure is fixed between a lower portion of the cylinder body of the hydraulic cylinder and the base plate. 
     Specifically, preferably, the supporting structure is a sleeve, both ends of which are respectively sleeved and fixed at a lower end of the cylinder body of the hydraulic cylinder and on the base plate; 
     the arch pressing device fixing disc contacts an inner wall of the sleeve and can axially move along the inner wall of the sleeve; and 
     side portions relative to each other of the sleeve are provided with gaps for accommodating the arch pressing device such that the arch pressing device radially expands or retracts. 
     Specifically, preferably, the machine tool further comprises a monitoring device which is respectively connected with the first pipe and the second pipe to monitor and display a reaming state of the machine tool. 
     Specifically, the monitoring device comprises a data acquisition unit, a single-chip microcomputer and a display, the data acquisition unit is connected with the first pipe and the second pipe, liquid information in the first pipe and the second pipe is acquired by the data acquisition unit, the single-chip microcomputer is connected with the data acquisition unit, the single-chip microcomputer processes the liquid information acquired by the data acquisition unit, the display is connected with the single-chip microcomputer, and a reaming state of the machine tool is displayed by the display. 
     Specifically, the upper arch arms are rotatably connected with the arch pressing device fixing disc via pins, the upper arch arms are rotatably connected with the lower arch arms via pins, and the lower arch arms are rotatably connected with the base plate via pins. 
     In another aspect, an embodiment of the invention provides a method for anchor rod reaming by the above-mentioned machine tool. 
     Specifically, preferably, the method comprises: 
     step a: drilling in the stratum to a predetermined depth by an anchor rod drill rig to obtain a pile hole; 
     step b: disposing a reaming machine head of the machine tool at a first position in the pile hole and disposing a hydraulic station of the machine tool outside the pile hole; 
     step c: supplying pressure to a hydraulic cylinder of the reaming machine head by the hydraulic station such that a piston is pushed to axially move and then the piston pushes an arch pressing device fixing disc to axially move via a piston rod and allows an arch pressing device to radially expand to squeeze a hole wall at the first position in the pile hole, thereby realizing single squeezing and expansion; and 
     step d: at the first position, rotating the reaming machine head at a preset angle for many times, and after rotating the reaming machine head each time, repeating the step c to realize multiple squeezing and expansion until a complete disc cavity is formed at the first position, thereby realizing anchor rod reaming at the first position. 
     Specifically, preferably, the method further comprises: after the arch pressing device expands in a radial direction, allowing the arch pressing device to retract in the radial direction, then disposing the reaming machine head at a second position in the pile hole, and sequentially repeating the step c and the step d, thereby realizing anchor rod reaming at the second position. 
     Specifically, preferably, the method further comprises monitoring a state of the arch pressing device by a monitoring device to visualize the anchor rod reaming process. 
     The technical solutions provided by the embodiments of the invention have the following beneficial effects: 
     the anchor rod multi-section reaming machine tool provided by the embodiment of the invention is used cooperatively with the anchor rod drill rig by fixing the hydraulic cylinder at the lower end of the drill rod of the anchor rod drill rig; the formation is drilled to a certain depth by the anchor rod drill rig to form a pile hole, the reaming machine head of the anchor rod reaming machine tool of the invention is disposed at a certain position in the pile hole, and the hydraulic station is disposed outside the pile hole; the hydraulic station is connected with the hydraulic cylinder through the first pipe and the second pipe such that the piston in the hydraulic cylinder can be pushed to axially move under the action of a force applied by the hydraulic station and then the arch pressing device is pushed to expand to squeeze a hole wall, thereby achieving the reaming effect; on the one hand, multi-site variable-section reaming can be performed at different positions in the pile hole by such reaming mode, thereby significantly improving the anti-pull-out property of the anchor rod, effectively reducing the drilling depth of the anchor rod and saving construction cost; and on the other hand, the above reaming mode not only avoids the disturbance to the soil layer, but also can compact and reinforce the soil layer at a reaming site while reducing the production of deposit, thus better facilitating improving the subsequent concrete pouring quality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to illustrate the technical solutions in the embodiments of the invention more clearly, the accompanying drawings necessary in the descriptions of the embodiments will be simply introduced below. Apparently, the accompanying drawings in the descriptions below only involve some embodiments of the invention, and one of ordinary skill in the art can also obtain other accompanying drawings without inventive work based on these accompanying drawings. 
         FIG. 1  is a schematic structural view of an anchor rod reaming machine tool provided by an embodiment of the invention. 
     
    
    
     Reference numerals respectively represent as follows:
     M anchor rod drill rig   M 1  drill rod     1  hydraulic station     2  first pipe     3  second pipe     4  reaming machine head     41  hydraulic cylinder     411  cylinder body     4111  hydraulic cylinder upper chamber     4112  hydraulic cylinder lower chamber     412  piston     413  piston rod     42  arch pressing device fixing disc     43  arch pressing device     431  upper arch arm     432  lower arch arm     44  base plate     45  supporting structure     5  monitoring device     51  data acquisition unit     52  single-chip microcomputer     53  display     6  pin   

     DETAILED DESCRIPTION OF THE INVENTION 
     Unless otherwise defined, all technical terms used in the embodiments of the invention have the same meaning as commonly understood by those skilled in the art. 
     Some terms for understanding the embodiments of the invention will be defined before the embodiments of the invention will be further described in detail. 
     The “axial direction” in the embodiments of the invention refers to an axis direction of a rotating central shaft of a drill rod of an anchor rod drill rig, and may also be construed as a rectilinear direction of a line connecting two circle centers of two end faces of the drill rod of the anchor rod drill rig. Correspondingly, the “radial direction” refers to a direction perpendicular to the “axial direction”. 
     In order to make the objectives, technical solutions and advantages of the invention clearer, the embodiments of the invention will be further described below in detail with reference to the accompanying drawings. 
     In a first aspect, an embodiment of the invention provides an anchor rod multi-section reaming machine tool, as shown in  FIG. 1 . The anchor rod reaming machine tool is used cooperatively with an anchor rod drill rig M. The anchor rod reaming machine tool comprises a hydraulic station  1 , a first pipe  2 , a second pipe  3  and a reaming machine head  4 , wherein the reaming machine head  4  further comprises a hydraulic cylinder  41 , an arch pressing device fixing disc  42 , an arch pressing device  43 , a base plate  44  and a supporting structure  45 . 
     The hydraulic cylinder  41  is fixed at a lower end of a drill rod M 1  of the anchor rod drill rig M. 
     The hydraulic cylinder  41  comprises a cylinder body  411 , a piston  412  and a piston rod  413 . The piston  412  is arranged inside the cylinder body  411  and can axially move relative to the cylinder body  411  such that the cylinder body  411  is divided into a hydraulic cylinder upper chamber  4111  and a hydraulic cylinder lower chamber  4112  which have variable volume. The hydraulic cylinder upper chamber  4111  is connected with the hydraulic station  1  through the first pipe  2 , the hydraulic cylinder lower chamber  4112  is connected with the hydraulic station  1  through the second pipe  3 , an upper end of the piston rod  413  is fixed at a lower portion of the piston  412 , and a lower end of the piston rod  413  is fixed at an upper portion of the arch pressing device fixing disc  42 . 
     Further, the arch pressing device  43  comprises a pair of upper arch arms  431  and a pair of lower arch arms  432  radially arranged symmetrically to the pair of upper arch arms  431 . Upper ends of the pair of upper arch arms  431  are rotatably connected with a central position of a lower portion of the arch pressing device fixing disc  42 ; lower ends of the pair of upper arch arms  431  are rotatably connected with upper ends of the pair of lower arch arms  432 ; and lower ends of the pair of lower arch arms  432  are rotatably connected with a central position of an upper portion of the base plate  44 . 
     The supporting structure  45  is fixed between a lower portion of the cylinder body  411  of the hydraulic cylinder  41  and the base plate  44 . 
     The operating principle of the anchor rod multi-section reaming machine tool provided by the embodiment of the invention is as follows: 
     Firstly, the anchor rod multi-section reaming machine tool provided by the embodiment of the invention is used cooperatively with the anchor rod drill rig M by fixing the hydraulic cylinder  41  at the lower end of the drill rod M 1  of the anchor rod drill rig M. The stratum is drilled by the anchor rod drill rig M to form a pile hole with a certain depth, the reaming machine head  4  of the anchor rod reaming machine tool of the invention is disposed at a certain position in the pile hole, and the hydraulic station  1  is disposed outside the pile hole (e.g. on the ground). 
     The hydraulic cylinder  41  is divided by the piston  412  into the hydraulic cylinder upper chamber  4111  and the hydraulic cylinder lower chamber  4112  which have variable volume, the hydraulic cylinder upper chamber  4111  is connected with the hydraulic station  1  through the first pipe  2 , and the hydraulic cylinder lower chamber  4112  is connected with the hydraulic station  1  through the second pipe  3 . With such arrangement, the flow direction of liquid in the first pipe  2  and the second pipe  3  can be controlled by the hydraulic station  1  so as to control a pressure difference between the hydraulic cylinder upper chamber  4111  and the hydraulic cylinder lower chamber  4112 , and allow the piston  412  to axially move up and down in the cylinder body  411  under the action of the pressure difference. Since the upper end of the piston rod  413  is fixed at the lower portion of the piston  412  and the lower end of the piston rod  413  is fixed at the upper portion of the arch pressing device fixing disc  42 , the axial up-and-down movement by the piston  412  can drive the piston rod  413  to synchronously move up and down, and then the piston rod  413  drives the arch pressing device fixing disc  42  fixedly connected therewith to synchronously move up and down axially. Specifically, when liquid is fed to the hydraulic cylinder upper chamber  4111 , and meanwhile, the liquid is returned from the hydraulic cylinder lower chamber  4112 , the piston  412  axially moves downwards such that the piston rod  413  pushes the arch pressing device fixing disc  42  to axially move downwards and then the arch pressing device fixing disc  42  applies a downward force to the arch pressing device  43  arranged at its lower portion. 
     The arch pressing device  43  comprises a pair of upper arch arms  431  and a pair of lower arch arms  432  radially arranged symmetrically to the pair of upper arch arms  431 . Upper ends of the pair of upper arch arms  431  are rotatably connected with a central position of a lower portion of the arch pressing device fixing disc  42 ; lower ends of the pair of upper arch arms  431  are rotatably connected with upper ends of the pair of lower arch arms  432 ; and lower ends of the pair of lower arch arms  432  are rotatably connected with a central position of an upper portion of the base plate  44 . When the arch pressing device fixing disc  42  applies a downward force, the upper arch arms  431  rotate around their connection point with the arch pressing device fixing disc  42  (a right arm of the upper arch arms  431  rotates counterclockwise along its connection point with the arch pressing device fixing disc  42 , while a left arm thereof rotates clockwise along the connection point), in contrast, the upper arch arms  431  drive the lower arch arms  432  to rotate around their connection point with the base plate  44  (a right arm of the lower arch arms  432  rotates clockwise along its connection point with the base plate  44 , while a left arm thereof rotates counterclockwise along the connection point). It can be understood that, when the upper arch arms  431  and the lower arch arms  432  rotate as described above, the upper arch arms  431  and the lower arch arms  432  also rotate relative to each other so as to ensure that the center of the arch pressing device  43  axially moves downwards and the arch pressing device radially expands as a whole to squeeze a hole wall, thereby achieving the reaming effect. When the piston  412  moves to a lowermost end in the cylinder body  411 , the arch pressing device  43  expands to a maximum extent, i.e. the arch pressing device  43  has a maximum squeezing and expansion distance. 
     However, correspondingly, when liquid is returned from the hydraulic cylinder upper chamber  4111 , and meanwhile, the liquid is fed to the hydraulic cylinder lower chamber  4112 , the piston  412  axially moves upwards such that the piston rod  413  pulls the arch pressing device fixing disc  42  to axially move upwards likewise and then the arch pressing device  43  receives a pulling force applied by the arch pressing device fixing disc  42 , thus allowing the upper arch arms  431  and the lower arch arms  432  thereof to move oppositely as compared to the above pushing process, i.e. the center of the arch pressing device  43  axially moves upwards and the arch pressing device radially retracts as a whole, thereby finishing a complete reaming process. 
     After a complete reaming process is finished, the drill rod M 1  of the anchor rod drill rig M is rotated such that the reaming machine head  4  of the anchor rod reaming machine tool of the invention is disposed at another position in the pile hole; and the above reaming process is repeated until a complete disc-shaped cavity is formed on the same horizontal plane, thereby completing reaming a disc cavity. Subsequently, the reaming machine head  4  of the invention is taken out of the pile hole and the above reaming process is performed in other pile holes. 
     In addition, those skilled in the art can understand that, the supporting structure  45  is fixed between the lower portion of the cylinder body  411  of the hydraulic cylinder  41  and the base plate  44  to fix the base plate  44 , thus ensuring that the base plate  44  does not move along with the lower arch arms  432 . 
     As can be seen from the above, in the above reaming mode of the reaming machine tool provided by the embodiment of the invention, firstly, multi-site variable-section reaming (i.e. multi-section reaming) can be performed at different positions in a pile hole to form a complete disc-shaped cavity, thereby significantly improving the anti-pull-out property of the anchor rod, effectively reducing the drilling depth of the anchor rod and saving construction cost. Secondly, the above reaming mode not only avoids the disturbance to the soil layer, but also can compact and reinforce the soil layer at a reaming site while reducing the production of deposit, thus better facilitating improving the subsequent concrete pouring quality. Thirdly, a pressure difference between the upper and lower chambers in the hydraulic cylinder  41  is controlled by the hydraulic station  1  so as to better control pressure, thus effectively avoiding the problem that the arch pressing device  43  fails to expand or retract normally. Fourthly, since concrete and reinforcing bar are disposable materials, the reaming machine tool provided by the embodiment of the invention can allow much less concrete and reinforcing bar to be buried underground, which is more environmental-friendly. 
     Preferably, the supporting structure  45  is a sleeve, both ends of which are respectively sleeved and fixed at a lower end of the cylinder body  411  of the hydraulic cylinder  41  and on the base plate  44 ; the arch pressing device fixing disc  42  contacts an inner wall of the sleeve and can axially move along the inner wall of the sleeve; and side portions relative to each other of the sleeve are provided with gaps for accommodating the arch pressing device  43  such that the arch pressing device  43  radially expands or retracts. The supporting structure  45  is arranged as a sleeve with a cylindrical structure, which can not only effectively fix the base plate  44  to avoid its movement, but also protect the hydraulic cylinder  41  from damage. The reason is that, in the reaming process, a counterforce of the soil layer received by the arch pressing device  43  is transmitted to the sleeve via the base plate  44  and the arch pressing device fixing disc  42 , such that the sleeve bears the counterforce of the soil layer received by the arch pressing device  43 , which avoids the hydraulic cylinder from bearing the counterforce, and further avoids a moment of force (generated by an uneven force in each direction received by the arch pressing device  43  due to non-uniformity of the soil layer) from acting on the piston rod  413 , thus preventing the piston rod  413  from being bent and broken. It can be understood that, the outside diameter of the arch pressing device fixing disc  42  matches the inside diameter of the sleeve such that an annular side portion of the arch pressing device fixing disc  42  fully contacts with the inner wall of the sleeve to transfer the above counterforce to the sleeve. Further, a smooth abrasion-resistant coating (e.g. a ceramic coating, an alloy coating, etc.) can be coated on the inner wall of the sleeve to reduce the friction between the sleeve and the arch pressing device fixing disc  42 . 
     Furthermore, in the embodiment of the invention, side portions relative to each other of the sleeve are also provided with gaps for accommodating the arch pressing device  43  such that the arch pressing device  43  radially expands or retracts. The gaps are preferably sized and constructed such that the upper arch arms  431  and the lower arch arms  432  can pass and rotate. It follows that the supporting structure  45  configured as a sleeve has a greater force bearing area and a longer service life than a rod-shaped supporting structure  45 . 
     Further, an embodiment of the invention provides a machine tool with a more preferred structure, wherein the machine tool further comprises a monitoring device  5  which is respectively connected with the first pipe  2  and the second pipe  3  to monitor and display a reaming state of the machine tool. 
     Currently, a reaming device is generally located deeply underground and soaked in slurry for most of the time during construction, so a reaming state of the device cannot be monitored on the ground, the construction quality is hence completely determined by operators according to their personal experience, and construction data is manually recorded. Accordingly, the reaming quality cannot be ensured or even the reaming diameter is unqualified, thus affecting the engineering quality. In the embodiment of the invention, since the liquid feeding process is separated from the liquid return process, the liquid feeding amount and the liquid return amount of the hydraulic cylinder  41  can be determined by acquiring liquid flowing information in the first pipe  2  and the second pipe  3 , thus liquid information at every moment in the first pipe  2  and the second pipe  3  can correspond to a specific reaming state. The monitoring device  5  is arranged on the ground, and configured to monitor an underground-reaming state by detecting the liquid feeding amount and the liquid return amount in the first pipe  2  and the second pipe  3  so as to ensure stable reaming quality and provide a qualified reaming diameter, thus ensuring the engineering quality. 
     Specifically, the monitoring device  5  comprises a data acquisition unit  51 , a single-chip microcomputer  52  and a display  53 , wherein the data acquisition unit  51  is connected with the first pipe  2  and the second pipe  3 , liquid information in the first pipe  2  and the second pipe  3  is acquired by the data acquisition unit  51 , the single-chip microcomputer  52  is connected with the data acquisition unit  51 , the single-chip microcomputer  52  processes the liquid information acquired by the data acquisition unit  51 , the display  53  is connected with the single-chip microcomputer  52 , and a reaming state of the machine tool is displayed by the display  53 . 
     In the embodiment, the data acquisition unit  51  is used to acquire flow rate information in the first pipe  2  and the second pipe  3  and transmit the acquired liquid information to the single-chip microcomputer  52 ; the single-chip microcomputer  52  processes corresponding liquid information and generates data of the reaming state of the invention; the single-chip microcomputer  52  transmits the reaming state data of a hole to the display  53 ; and the reaming state of the invention is displayed by the display  53 . Indeed, those skilled in the art can understand that, a printer can also be connected to the single-chip microcomputer  52  so that the reaming state of the invention can be directly printed. 
     Specifically, the upper arch arms  431  are rotatably connected with the arch pressing device fixing disc  42  via pin  6 , the upper arch arms  431  are rotatably connected with the lower arch arms  432  via pin  6 , and the lower arch arms  432  are rotatably connected with the base plate  44  via pin  6 . 
     In the embodiment of the invention, the upper arch arms  431  and the arch pressing device fixing disc  42 , the lower arch arms  432  and the base plate  44 , and the upper arch arms  431  and the lower arch arms  432  are connected via the pin  6 , which provides a simple structure, reasonable force bearing and mounting convenience. Indeed, those skilled in the art can know that the above connection can also be achieved by other ways of connection, as long as the upper arch arms  431  can rotate relative to the arch pressing device fixing disc  42  in a plane on which their connection point with the arch pressing device fixing disc  42  and an axis of the arch pressing device fixing disc  42  are present, the lower arch arms  432  can rotate relative to the base plate  44  in a plane on which their connection point with the base plate  44  and an axis of the base plate  44  are present, and the upper arch arms  431  and the corresponding lower arch arms  432  can rotate relative to each other in a plane on which their connection points and their respective connection point with the arch pressing device fixing disc  42  or the base plate  44  are present. 
     In a second aspect, an embodiment of the invention further provides an application of the anchor rod multi-section reaming machine tool in anchor rod reaming, i.e. a method for anchor rod reaming by any one anchor rod multi-section reaming machine tool as described above. Specifically, the method comprises the steps of: 
     step  101 : drilling in the stratum to a predetermined depth by an anchor rod drill rig M to obtain a pile hole; 
     step  102 : disposing a reaming machine head  4  of the anchor rod reaming machine tool at a first position in the pile hole and disposing a hydraulic station  1  of the anchor rod reaming machine tool outside the pile hole (e.g. on the ground); 
     step  103 : supplying pressure to a hydraulic cylinder  41  of the reaming machine head  4  by the hydraulic station  1  such that a piston  412  is pushed to axially move and then the piston  412  pushes an arch pressing device fixing disc  42  to axially move via a piston rod  413  and allows an arch pressing device  43  to radially expand to squeeze a hole wall at the first position in the pile hole, thereby realizing single reaming; and 
     step  104 : at the first position, rotating the reaming machine head  4  at a preset angle for many times, and after rotating the reaming machine head  4  each time, repeating the step  103  to realize multiple squeezing and expansion until a complete disc cavity is formed at the first position, thereby realizing anchor rod reaming at the first position. 
     Those skilled in the art can understand that, the first position may be any position in the pile hole according to the actual reaming demand, and therefore does not have a specific meaning herein. In addition, the above complete disc cavity formed in the construction carried out by the machine tool provided by the embodiment of the invention has an inner diameter of about 500-1000 mm, e.g. 550 mm, 600 mm, 650 mm, 700 mm, 750 mm, 800 mm, 850 mm, 900 mm, 950 mm, 1000 mm, etc. 
     It follows that the anchor rod multi-section reaming machine tool provided by the embodiment of the invention can perform anchor rod multi-section reaming in the soil layer and can effectively support and reinforce the soil mass. 
     Further, the method further comprises step  105 : after the arch pressing device  43  expands in a radial direction, allowing the arch pressing device  43  to retract in the radial direction, then disposing the reaming machine head  4  at a second position in the pile hole, and repeating the step  103  and the step  104  again, thereby realizing anchor rod reaming at the second position. 
     It follows that, by repeating the step  105  for many times, multi-site variable-section reaming can be performed at different positions in the pile hole to form a complete disc-shaped cavity, thereby significantly improving the anti-pull-out property of the anchor rod, effectively reducing the drilling depth of the anchor rod and saving construction cost. 
     Specifically, preferably, in the above reaming process, a state of the arch pressing device  43  is monitored by the monitoring device  5  to visualize the anchor rod reaming process. Monitoring a reaming state of the arch pressing device  43  underground by the monitoring device  5  can ensure stable reaming quality and provide a qualified reaming diameter, thus ensuring the engineering quality. 
     The above description only refers to preferred embodiments of the invention and is not intended to limit the invention. Any modification, equivalent replacement, improvement and the like made within the sprit and principle of the invention shall be included within the protection scope of the invention.