JP2008063867A - Soil improving equipment and excavating construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide soil improving equipment which can simply and inexpensively measure an angle of inclination of a rotating shaft, and which can contribute to an increase in the vertical accuracy of the rotating shaft. <P>SOLUTION: Four or more horizontal revolving rollers 152 capable of revolving on a vertical shaft are circumferentially arranged at intervals in the frame of a lower steady brace mechanism 150 which is provided at the lower end of a leader 103. The horizontal revolving rollers are each revolvably supported by the frame via a transverse load meter 301. A revolving cylinder 153 is arranged revolvably on a vertical axis in the state of coming into internal contact with the inside of the horizontal revolving roller and stopping falling. Three vertical revolving rollers 154 revolvable on a horizontal shaft are circumferentially arranged at intervals on the inner periphery of the revolving cylinder. The rotating shaft 101 penetrates in such a manner as to come into internal contact with the inside of the vertical revolving roller, so that the angle of the inclination of the rotating shaft can be measured by a balance of a measured value of the transverse load meter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ground improvement device that improves the ground by rotating a rotary shaft having a drilling means at the tip while rotating and a excavation method using the ground improvement device.

  The ground improvement device used in the mixed processing method, etc. is an improvement material (cemented milk etc.) that penetrates the ground vertically while rotating the rotating shaft supported vertically along the leader, and supplies and discharges at the lower end of the rotating shaft Stabilizers) and local soil are agitated and mixed to create improved bodies such as piles and walls underground.

  When excavating the ground using such a ground improvement device, the excavating means provided at the tip of the rotating shaft hits a hard layer or an obstacle in the process of penetrating the rotating shaft. It may shift. Such misalignment (also called “axial misalignment”, “bend”, or “inclination” of the rotating shaft) causes the improvement body to deviate from the design specifications and impairs the construction quality. Has been.

  As a conventional measure, first, a lower steadying mechanism is provided at the lower end of the leader to prevent horizontal rotation of the rotating shaft (see, for example, Patent Document 1). However, since the misalignment of the rotating shaft itself occurs as a phenomenon that the rotating shaft penetrates into the ground while bending with the lower steadying mechanism as a fulcrum, this cannot be effectively prevented by the lower steadying mechanism alone. Especially in the case of long construction, the greater the depth, the greater the amount of displacement of the rotating shaft, so it is necessary to avoid the influence of bending at the beginning of penetration.

Therefore, in general, a method is employed in which the inclination of the rotation shaft is measured with an inclinometer such as a gyro method so that the inclination is not increased (see, for example, Patent Documents 2 and 3).
JP 2001-234527 A JP-A-6-10338 JP 2005-54375 A

  However, when using an inclinometer such as a gyro system, there are problems such as difficulty in selecting the installation location of the inclinometer and the fact that it is easily affected by vibration during construction. Could not be measured.

  In consideration of the above circumstances, the present invention provides a ground improvement device and an excavation method that can measure the inclination of a rotating shaft easily and at low cost and contribute to the improvement of the vertical accuracy of the rotating shaft. For the purpose.

  A ground improvement device according to a first aspect of the present invention includes a rotary shaft that is provided with excavation means at a tip portion thereof, and is supported so as to be vertically movable along a guide of a leader of a base machine, and moves up and down while rotating the rotary shaft. In the ground improvement device comprising: a drive device; and a lower steadying mechanism that is provided at a lower end portion of the reader and surrounds the periphery of the rotation shaft with a frame to prevent horizontal rotation of the rotation shaft. A plurality of rollers for guiding the rotation shaft are provided in the frame of the lower steady rest mechanism so as to surround the rotation shaft, and the rotation shaft extends from the rotation shaft to the roller between the rollers and the frame. A lateral load meter for detecting a horizontal load is provided, and the inclination of the rotating shaft with respect to the vertical line is detected based on a balance of measured values of the respective lateral load meters.

  A second aspect of the present invention is the ground improvement device according to the first aspect, wherein the roller as a roller for guiding the rotation shaft to a position at substantially the same height on the inner periphery of the frame is arranged around a vertical axis. A plurality of three or more rotatable horizontal rotating rollers are arranged at intervals in the circumferential direction, and each of the horizontal rotating rollers is rotatably supported by the frame via the lateral load meter. A rotating cylinder is placed so that it can rotate around a vertical axis while inscribed inside and stopped falling, and it can rotate around a horizontal axis at a circumferential interval around the inner circumference of the rotating cylinder. Three or more vertical rotating rollers are arranged, and the rotating shaft is penetrated so as to be inscribed inside the vertical rotating rollers.

  Invention of Claim 3 is the ground improvement apparatus of Claim 2, Comprising: The said axis | shaft on the 2 straight lines which penetrates the said rotating shaft to the center of the said flame | frame, and crosses the center in a horizontal surface through the center. A total of four of the horizontal rotating rollers are arranged at positions equidistant from each other.

  Invention of Claim 4 is the ground improvement apparatus of Claim 3, Comprising: These two straight lines are a straight line extended in the front-back direction and the straight line extended in the left-right direction seeing from the said leader, These four straight lines are Horizontal rotating rollers are respectively arranged at the front and rear and the left and right of the center of the frame.

  Invention of Claim 5 is the ground improvement apparatus of any one of Claims 1-4, Comprising: The rotational load detection means which detects the rotational load at the time of rotationally driving the said rotating shaft to the said drive device Is provided.

  Invention of Claim 6 is the ground improvement apparatus of any one of Claims 1-5, Comprising: As a drive device which raises / lowers while rotating the said rotating shaft, The rotational drive device which rotationally drives a rotating shaft, A lifting / lowering drive device that suspends and supports the rotation shaft with a wire via the rotation drive device and drives the rotation shaft to move up and down by winding and unwinding the wire, and the wire that supports the rotation shaft with suspension is provided. A speedometer for detecting a wire feeding speed, wound on a drum of a winding device installed on the base machine via the upper end of the reader, and a wire hanging load And a longitudinal load meter for detecting the above.

  The excavation construction method of the invention of claim 7 is an excavation construction method by the ground improvement device according to any one of claims 1 to 6, wherein the excavation method is lowered while rotating the rotating shaft by the driving device, Excavating the ground by the excavating means and penetrating the rotating shaft into the ground, at that time, proceeding to penetrate the rotating shaft at a predetermined speed while monitoring the measured value of the lateral load meter provided in the lower steadying mechanism, When it is detected that the balance of the measured value of the lateral load cell has collapsed beyond a predetermined level, the excavation is continued while limiting the penetration speed. When the speed is returned to a predetermined speed and the balance is not improved, the rotating shaft is once lifted and then re-penetrated.

  The excavation method of the invention according to claim 8 is an excavation method by the ground improvement device according to claim 5, wherein the excavation means excavates the ground by lowering the rotating shaft while rotating by the driving device. Then, the rotary shaft penetrates into the ground, and at that time, the penetration of the rotary shaft is advanced at a predetermined speed while monitoring the measured value of the lateral load meter provided in the lower steady rest mechanism and the detected value of the rotary load detecting means. If it is detected that the balance of the measured values of the lateral load meter has collapsed beyond a predetermined level or the rotational load detected by the rotational load detecting means has increased above a predetermined level, excavation is continued while limiting the penetration speed. When the imbalance of the measured value of the lateral load meter is improved and the increase of the rotational load detected by the rotational load detecting means is improved, the penetration speed is returned to the predetermined speed again, while the measured value of the lateral load meter is of If elevated collapse or rotational load of the lance is not improved after temporarily pulling the rotary shaft, characterized by re-penetration.

  The excavation construction method according to claim 9 is an excavation construction method by the ground improvement device according to claim 6, wherein the detection values of the speedometer and the vertical load meter are monitored, and the wire is prevented from being slackened. While applying a vertical load to the rotating shaft, the rotating shaft is lowered and penetrated into the ground.

  According to the first aspect of the present invention, a plurality of rollers for guiding the rotating shaft are provided in the frame of the lower steady rest mechanism, and a horizontal load applied to the rollers from the rotating shaft is provided between these rollers and the frame. A lateral load meter is provided to detect the inclination of the rotating shaft with respect to the vertical line by balancing the measured values of each lateral load meter, ensuring smooth penetration of the rotating shaft by the guidance of multiple rollers. On the other hand, the lateral load meter can detect the inclination of the rotating shaft at an early stage of penetration without being affected by vibration so much and at a low cost. Therefore, it is possible to prompt the correction of the construction status so as to immediately improve the inclination of the rotating shaft.

  According to the second aspect of the present invention, three or more horizontal rotating rollers are arranged inside the frame, and each of these horizontal rotating rollers is rotatably supported by the frame via the lateral load meter. Since the rotating cylinder is arranged so as to be in contact, and three or more vertical rotating rollers are arranged on the inner periphery of the rotating cylinder, and the rotating shaft is penetrated so as to be inscribed in the vertical rotating rollers, The bending (inclination) of the rotating shaft can be detected by the balance of the measured values. For example, if the measured value of a certain lateral load meter increases, the horizontal load on the horizontal rotating roller supported via the lateral load meter has increased, so the rotating shaft bends to the roller side. Can be detected.

  In addition, a rotating cylinder is supported by a horizontal rotating roller so as to be rotatable around a vertical axis, and the rotating axis is held by a vertical rotating roller disposed on the inner periphery of the rotating cylinder, so that the rotating axis that moves up and down while rotating can be smoothly Can guide.

  According to the invention of claim 3, a total of four horizontal rotating rollers are provided at positions equidistant from the center on two straight lines that pass through the center of the frame and are orthogonal to each other in the horizontal plane. Therefore, the cylindrical body can be rotatably supported in a well-balanced manner. In addition, it is possible to easily analyze the bending of the rotation axis based on the measurement data in the four orthogonal directions, and it is possible to easily cope with the detection of the bending.

  According to the invention of claim 4, the two straight lines are a straight line extending in the front-rear direction and a straight line extending in the left-right direction when viewed from the leader, and the four horizontal rotation rollers are provided in the front-rear direction and the left-right direction of the center of the frame. Since each is arranged, the bending of the front, rear, left and right can be measured independently by a lateral load meter that supports each horizontal rotating roller.

  According to the fifth aspect of the present invention, the bending of the rotating shaft can be confirmed from the surface of the rotating load by detecting the rotating load of the rotating shaft.

  According to the sixth aspect of the present invention, the wire feeding speed is not measured based on the rotation of the drum of the winding device on the base machine, but is measured by a speedometer provided on the wire passage path. Since the direct measurement is performed, an accurate wire feeding speed can be measured regardless of the winding diameter of the wire in the drum. In addition, since the hanging load of the wire is measured with a vertical load meter, an accurate vertical load can be applied to the tip of the rotating shaft without causing loosening of the wire based on the data of the speedometer and the vertical load meter. Can be prevented from being misaligned.

  According to the seventh aspect of the present invention, when it is detected that the balance of the measured values of the lateral load meter has collapsed to a predetermined level or more when the rotary shaft penetrates at a predetermined speed, the excavation is continued while limiting the penetration speed. When the balance of the lateral load cell measurement is improved, the penetration speed is returned to the specified speed again. On the other hand, if the balance is not improved, the rotary shaft is pulled up and then re-penetrated. Therefore, the rotation axis can be vertically penetrated with high accuracy without causing an axis deviation, and the quality of the improved body can be improved.

  According to the eighth aspect of the present invention, when it is detected that the balance of the measured values of the lateral load meter has collapsed above a predetermined value or the rotational load has increased above a predetermined value when the rotary shaft penetrates at a predetermined speed, When the excavation is continued while the balance of the measured value of the lateral load meter is improved and the increase of the rotational load detected by the rotational load detecting means is improved, the penetration speed is again returned to the predetermined speed, If the balance of the measured values of the lateral load meter or the increase in rotational load is not improved, the rotary shaft is lifted once and then re-penetrated, so the rotary shaft can be vertically aligned with high accuracy without causing an axis shift. The quality of the improved body can be improved.

  According to the ninth aspect of the present invention, the detection values of the speedometer and the longitudinal load meter are monitored, and while applying an appropriate vertical load to the rotating shaft while preventing the slack of the wire, the rotating shaft is lowered and penetrated into the ground. Therefore, the rotating shaft can be vertically penetrated with high accuracy, and the quality of the improved body can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the ground improvement device that performs the ground improvement method of the present embodiment includes a rotating shaft 101 that is supported so as to be vertically movable along a guide 103 a of a leader 103 of a base machine 102. , A wire suspension type lifting drive device 104 that lifts and lowers the rotary shaft 101, and a rotary drive device 105 that is installed in the lifting unit of the lift drive device 104. While rotating the rotary shaft 101 with the rotary drive device 105, the ground is excavated by the excavating and stirring means 110 attached to the tip of the rotary shaft 101, and a stabilizer is injected into the excavated soil and stirred and mixed. To improve the ground. The rotary shaft 101 is guided for excavation and penetration by a lower steadying mechanism 150 provided under the leader 103.

  2 is a plan view showing a configuration of the lower steady rest mechanism 150, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG.

  The lower steadying mechanism 150 is for preventing horizontal rotation of the rotating shaft 101, and is provided at a lower end portion of the reader 103 and has a square frame 151 through which the rotating shaft 101 penetrates at the center, and the frame 151. Four horizontal rotary rollers 152 that are positioned at the same height on the inner surface side of the center in the length direction of each of the four sides and that can be rotated about a vertical axis that are supported via a lateral load meter 301, and A rotating cylinder 153 that is inscribed inside the horizontal rotating roller 152 and is supported in a state where the fall is stopped and that can rotate around a vertical axis, and an inner circumference of the rotating cylinder 153 are arranged at intervals in the circumferential direction. And three vertical rotating rollers 154 that can rotate around a horizontal axis. The rotating shaft 101 passes through so as to be inscribed inside the vertical rotating roller 154.

  Accordingly, the horizontal rotation rollers 152 are arranged at positions equidistant from the center O on the center line L1 extending in the front-rear direction passing through the center O of the frame 151 and extending in the horizontal direction and orthogonal to each other in the horizontal plane. A number of horizontal rotating rollers 152 are respectively located on the front and rear and the left and right of the center O of the frame 151. And in this ground improvement apparatus, the inclination with respect to the vertical line of the rotating shaft 101 is detected by the balance of the measured values of the four lateral load meters 301.

  In the lower steady rest mechanism 150, when the rotating shaft 101 moves up and down while rotating, the vertical rotating roller 154 guides the vertical movement of the rotating shaft 101, and the horizontal rotating roller 152 via the rotating cylinder 153 that freely rotates. To guide the rotation of the rotary shaft 101.

  Further, the rotational drive device 105 is provided with rotational load detection means 302 (corresponding to current detection means when the rotational drive device is a motor) for detecting rotational load when the rotational shaft 101 is rotationally driven. A depth meter 302 (corresponding to a movement trajectory measuring device) is provided in the lifting unit on which the device 105 is mounted.

  The lifting / lowering driving device 104 suspends and supports the rotating shaft 101 with a wire 104a via the rotation driving device 105, and drives the rotating shaft 101 up and down by winding and unwinding the wire 104a. The base end side of the wire 104a to be supported by suspension is wound around a drum (not shown) of a winding device provided on the base machine 102 via the upper end of the leader 103. And the speedometer 304 which detects the feeding speed of the wire 104a, and the vertical load meter 305 which detects the hanging load of the wire 104a are provided on the passage route of the wire 104a.

  On the other hand, as shown in FIG. 4, the excavation stirring means 110 is provided with an excavation head 120 at the forefront of the rotating shaft 101, and on the upper side thereof, a plurality of stirring blades 112 and co-rotating plates 113 are vertically arranged. It is provided alternately in the stage. The stirring blade 112 is a bar-shaped member that extends linearly from the rotation shaft 101 in the radial direction, and includes a blade plate that is inclined with respect to the axis of the rotation shaft 101. The lowermost stirring blade 112 has an excavation claw 114 at its lower end so that it can perform not only agitation but also an excavation function. Further, on the back surface in the rotational direction of the upper stirring blade 112, a discharge box 115 for stabilizing material sent through a supply pipe line in the rotary shaft 101 is provided.

  As shown in FIGS. 4 and 5, the excavation head 120 is provided with two spiral blades 121 having a large number of excavation claws 122 at the lower end edge 121 a. The two spiral blades 121 are arranged symmetrically by 180 ° around the rotation axis 101, and each is wound in an angular range of 180 °. That is, each spiral blade 121 is provided for a half pitch.

  In addition, the lower end edge 121a of each spiral blade 121 is linearly inclined upward from the outer peripheral end toward the inner peripheral end, and the tip of the excavation head 120 configured by the lower end edges 121a of the two spiral blades 121 is The center portion is recessed and the peripheral portion protrudes downward. An injection box 130 for friction reducing fluid (water, air, a mixture of water and air, etc.) is provided on the back side in the rotational direction of one spiral blade 121.

  Next, a ground improvement method using the ground improvement device having the above-described configuration will be described.

  In improving the ground, first, the excavation head 120 is lowered toward the ground while rotating the rotary shaft 101 by the lift drive device 104 and the rotary drive device 105. Accordingly, the ground is excavated by the excavation head 120 provided at the tip of the rotary shaft 101, and the rotary shaft 101 penetrates into the ground.

  At the time of the penetration, the penetration of the rotary shaft 101 is advanced at a predetermined speed while monitoring the measured value of the lateral load meter 301 provided in the lower steady rest mechanism 150 and the detected value of the rotational load detecting means 303. When it is sensed that the balance of the measured values has collapsed above a predetermined level or the rotational load detected by the rotational load detection means 303 has increased above a predetermined level, excavation is continued while limiting the penetration speed. When the balance of the measured values of the lateral load meter 301 is improved and the increase in rotational load detected by the rotational load detecting means 303 is improved, the penetration speed is returned to the predetermined speed again. On the other hand, when the balance of the measurement value of the lateral load meter 301 is not lost or the increase of the rotational load is not improved, the rotary shaft 101 is once lifted and then re-penetrated.

  At the same time, the detection values of the speedometer 304 and the longitudinal load meter 305 are monitored, and while the slack of the wire 104a is prevented, an appropriate vertical load is applied to the rotation shaft 101, and the rotation shaft 101 is lowered to penetrate into the ground. .

  As described above, since the inclination of the rotation shaft 101 with respect to the vertical line is detected based on the balance of the measurement values of the lateral load meter 301, smooth penetration of the rotation shaft 101 by the guide of the plurality of rollers 152 and 154 is guaranteed. However, the lateral load meter 301 can detect the inclination of the rotating shaft 101 at an initial stage of penetration without being affected by vibration so much and at a low cost.

  Therefore, it is possible to prompt the correction of the construction status so as to improve the inclination of the rotating shaft 101 immediately. As a specific countermeasure, as described above, when it is detected from the measured value of the lateral load meter 301 that the rotation shaft 101 is inclined, excavation is performed while keeping the penetration speed low (including zero penetration speed). When the balance of the measured value of the lateral load meter 301 is improved and the increase of the rotational load detected by the rotational load detecting means 303 is improved, the penetration speed is returned to the predetermined speed again. On the other hand, when the balance of the measurement value of the lateral load meter 301 is not improved or the increase in the rotational load is not improved, the rotary shaft 101 is once lifted and then penetrated again.

  By doing so, the shaft misalignment at the initial stage of penetration can be eliminated, so that the rotation shaft 101 can be accurately vertically penetrated into the ground by continuing the subsequent penetration work. As a result, the improved body It will be possible to improve the quality.

  Moreover, in this embodiment, since the set of the horizontal rotation roller 152 and the lateral load meter 301 is disposed on the center line L1 extending in the front-rear direction and the center line L2 extending in the left-right direction when viewed from the leader, It is easy to analyze front and rear, left and right bends, and it is easy to take immediate action to correct it.

It is a side view which shows the outline | summary of the whole structure of the ground improvement apparatus which implements the ground improvement construction method of embodiment of this invention. It is a top view which shows the detail of the lower steadying mechanism of a ground improvement apparatus. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. It is a block diagram which shows the structure of the excavation stirring means provided in the front-end | tip of the rotating shaft of the ground improvement apparatus. It is the perspective view seen upside down of the excavation head which comprises the said excavation stirring means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Rotating shaft 102 Base machine 103 Leader 103a Guide 104 Elevating drive device 104a Wire 105 Rotating drive device 110 Excavation stirring means 150 Lower swing prevention mechanism 151 Frame 152 Horizontal rotation roller 153 Rotating cylinder 154 Vertical rotation roller 301 Horizontal load meter 303 Rotation load detection Means 304 Speedometer 305 Longitudinal load meter L1 Center line (straight line) extending in the front-rear direction
L2 Center line (straight line) extending in the left-right direction

Claims (9)

Provided at the lower end of the leader, which is provided with a digging means at the tip, and supported by a rotary shaft that is vertically movable along the guide of the leader of the base machine, a drive device that moves up and down while rotating the rotary shaft In the ground improvement device comprising a lower steadying mechanism that prevents a horizontal shake of the rotary shaft by surrounding the rotary shaft with a frame,
A plurality of rollers for guiding the rotation shaft are provided in the frame of the lower steady rest mechanism so as to surround the rotation shaft, and between the rollers and the frame, from the rotation shaft to the roller. A ground improvement device provided with a lateral load meter for detecting such a horizontal load, and detecting the inclination of the rotating shaft with respect to the vertical line based on a balance of measured values of the respective lateral load meters. The ground improvement device according to claim 1,
As a roller for guiding the rotating shaft at a position of substantially the same height on the inner periphery of the frame, three or more horizontal rotating rollers that can rotate around a vertical axis are spaced apart in the circumferential direction. The horizontal rotating rollers are rotatably supported by the frame via the lateral load meter, and rotate around a vertical axis while being inscribed inside the horizontal rotating rollers and stopped falling. A rotating cylinder is arranged as possible, and three or more vertical rotating rollers that can be rotated around a horizontal axis are arranged on the inner circumference of the rotating cylinder at intervals in the circumferential direction. A ground improvement device characterized in that the rotating shaft is penetrated so as to contact. The ground improvement device according to claim 2,
A total of four horizontal rotating rollers are arranged at positions equidistant from the center on two straight lines passing through the center and orthogonal to each other in the horizontal plane through the center of the frame. Features ground improvement device. The ground improvement device according to claim 3,
The two straight lines are a straight line extending in the front-rear direction and a straight line extending in the left-right direction when viewed from the leader, and the four horizontal rotating rollers are respectively disposed on the front-rear and left-right sides of the center of the frame. A ground improvement device characterized by It is the ground improvement apparatus of any one of Claims 1-4,
A ground improvement device, wherein the drive device is provided with a rotation load detection means for detecting a rotation load when the rotation shaft is rotationally driven. It is the ground improvement apparatus of any one of Claims 1-5,
As a drive device that moves up and down while rotating the rotary shaft, a rotary drive device that rotationally drives the rotary shaft, and the rotary shaft is suspended and supported by a wire through the rotary drive device, and the rotary shaft is wound and fed out. A lifting drive device that drives the lifting shaft, and a wire that supports the rotating shaft is wound around a drum of a winding device installed on the base machine via an upper end of the reader, A ground improvement device characterized in that a speedometer for detecting a wire feeding speed and a vertical load meter for detecting a hanging load of the wire are provided on a wire passage route. It is the excavation construction method by the ground improvement apparatus of any one of Claims 1-6,
The rotary shaft is lowered while being rotated by the drive device, and the ground is excavated by the excavating means to penetrate the rotary shaft into the ground. At that time, the measured value of the lateral load meter provided in the lower steady rest mechanism is obtained. When the penetration of the rotating shaft is advanced at a predetermined speed while monitoring and it is detected that the balance of the measured values of the lateral load meter has collapsed beyond the predetermined level, excavation is continued while limiting the penetration speed, and the lateral load is When the balance of the measured value of the meter is improved, the penetration speed is returned to the predetermined speed again. On the other hand, when the balance is not improved, the rotary shaft is pulled up and then re-penetrated. Construction method. The excavation method by the ground improvement device according to claim 5,
By lowering the rotating shaft while rotating the rotating shaft by the driving device, the excavating means excavates the ground and penetrates the rotating shaft into the ground, and at that time, the measured value of the lateral load meter provided in the lower steadying mechanism and Rotating load detected by the rotating load detecting means whether or not the balance of the measured values of the lateral load meter is broken beyond a predetermined value while the penetration of the rotating shaft is advanced at a predetermined speed while monitoring the detected value of the rotating load detecting means When it is sensed that the load has risen above a predetermined level, the excavation is continued while limiting the penetration speed, the imbalance of the measured value of the lateral load meter is improved, and the rotational load detected by the rotational load detecting means is increased. If the improvement is improved, the penetration speed is returned to the predetermined speed again. On the other hand, if the balance of the measured value of the lateral load meter is not improved or the increase in the rotational load is not improved, the rotary shaft is lifted once and then restarted. Drilling construction method, characterized in that the inlet. An excavation method using the ground improvement device according to claim 6,
Excavation characterized by monitoring the detection values of the speedometer and the longitudinal load meter, and applying a proper vertical load to the rotating shaft while preventing slack of the wire, and lowering the rotating shaft to penetrate into the ground Construction method.

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