JP5352900B2 - An underground pile forming head and an attachment for a crushed stone pile forming apparatus including the underground pile forming head - Google Patents

Description

  The present invention relates to an apparatus for improving the ground, and more particularly to an underground pile forming head for improving a ground by forming a crushed stone pile in the ground and an attachment for a crushed stone pile forming apparatus including the underground pile forming head. .

  As a ground improvement method, a method has been proposed in which underground piles are formed to improve the earth strength. These methods are methods that increase the strength of the entire ground by forming a strong underground pile with filling materials such as sand, gravel, crushed stone, and concrete shells, thereby replacing the soft clay layer at a certain rate. . In these methods, for example, the filling material is compacted by vibration, the pressure is applied to the filling material with compressed air, the pressure is applied to the filling material by rotating the thrust screw having a spiral shape, and the thrust screw is moved up and down. Formation of strong underground piles is realized by various methods such as Patent Document 1 (for example).

JP 2002-105942 A JP 2007-211152 A

  However, in the conventional construction method, noise problems occur in the method of compacting the filling material by vibration, and the method of applying pressure to the filling material with compressed air requires a large compressed air generating device, There has been a problem of causing noise problems in air generation. Furthermore, in the construction method using a thrust screw, there is also a problem that a complicated mechanism is required for raising and lowering the thrust screw.

  An object of the present invention is to provide a technique for forming an underground pile by simply discharging the filling material in a method for forming an underground pile in the ground.

The technology disclosed in this specification can provide a technology exemplified as the following configurations and aspects.
The first configuration example is an underground for forming an underground pile while ascending from the ground in a substantially cylindrical portion that can be inserted into the ground to form a space and into which an underground pile forming material can be input. Providing a pile forming head. The underground pile forming head includes an underground excavation blade and at least one additional excavation blade. The underground excavation blade has a first wing shape that rotates in the forward direction and rotates together with the cylindrical portion to excavate the underground downward, and applies pressure to the underground pile forming material by rotation in the reverse direction. Have. The additional excavation wing has a second wing shape for excavating the underground pile forming material thrown into the cylindrical portion by rotation in the reverse direction. The additional excavation blade is separated from the underground excavation blade and is disposed above the underground excavation blade.

  The underground pile forming head of the first configuration example can generate the preliminary pressure by the additional excavating blade that excavates the crushed stone thrown into the cylindrical portion upward. The preliminary pressure is applied to the crushed stone staying in the staying crushed stone chamber which is a space formed between the underground excavating blade separated from the additional excavating blade. Underground excavation blades can apply more pressure to the retained crushed stone that remains in the state where preliminary pressure is applied in this way. It can overcome (earth pressure) and discharge crushed stones.

  Retained crushed stones have a remarkable effect when excavating underground. That is, when the underground excavating blade rotates in the forward direction and rotates downward together with the cylindrical portion to excavate the underground, the accumulated crushed stone in the retained crushed stone chamber is shared with the underground excavating blade and the cylindrical portion. You can turn around and counter ground pressure and groundwater pressure. Further, the present inventors have not only the formation of crushed stone piles but also a method for forming underground piles with natural objects such as natural crushed stones, gravel, sand, or artificial objects such as concrete fragments, waste tiles, and mines. It was also found that this is applicable.

  The second configuration example is the underground pile forming head of the first configuration example, and the additional excavation blade has an upper end portion that forms a tip portion by rotation in the reverse direction. The upper end portion has at least one claw portion protruding upward.

  In the third configuration example, the underground pile forming head of the first or second configuration example is provided with a plurality of blade members in which the underground excavation blades are arranged at symmetrical positions. This configuration is a particularly practical configuration that is simple and excellent in balance.

  The fourth configuration example includes a plurality of blade members in which the additional excavation blades are arranged at symmetrical positions in the underground pile forming head according to any one of the first to third configuration examples. This configuration is also a highly practical configuration that is simple and excellent in balance.

Example fifth configuration, in any one of the underground pile forming head of the first to fourth configuration examples, the earth during excavation blades, a front edge forming the front end portion in the rotation in the forward direction, forward direction And a rear edge portion that forms a rear end portion in the rotation. The front edge portion has a shape that recedes in the direction of the rear end portion as it moves away from the rotation axis of the underground pile forming head when viewed from below.

  In the fifth configuration example, the front edge portion of the underground excavation blade has a shape that recedes in the direction of the rear end portion as it moves away from the rotation axis of the underground pile forming head when viewed from below. Therefore, the excavated earth and sand can be effectively pushed out of the cylindrical portion in the outer peripheral direction. Thereby, it can raise using the helical fin which a cylindrical part has, and can be discharged | emitted smoothly on the ground.

  The sixth configuration example provides an attachment for forming an underground pile that is inserted into the ground to form a space and forms a crushed stone pile in the space while rising from the ground. The attachment includes any one of the first to fifth underground pile forming heads, a cylindrical portion, and an opening / closing lid. The cylindrical portion has an underground pile forming material charging hole, which is at least one long hole having a long axis in the central axis direction, formed on a side surface. The open / close lid can block the underground pile forming material charging hole from the outside of the cylindrical portion.

  In the seventh configuration example, in the attachment of the sixth configuration example, the cylindrical portion has a truss-like reinforcing structure that restrains the shape of the long hole.

  In addition, this invention is not restricted to the above-mentioned apparatus, For example, it can implement | achieve with various structures, such as a control apparatus which controls a crushed stone pile formation method and a crushed stone pile formation apparatus.

  In the method of forming a columnar object in the ground with crushed stone, the present invention can efficiently form a crushed stone pile in the ground by suppressing the circulation of the crushed stone.

Explanatory drawing which shows the structure of the crushed stone pile forming apparatus 100 which concerns on the Example of this invention. Explanatory drawing which shows the state which looked at the attachment T of the Example from another angle. Sectional drawing which shows the structure of the cylindrical part 12 and the underground excavation blade 29 of an Example. The flowchart which shows the process of the crushed stone pile formation method which concerns on the Example of this invention. The enlarged view which shows the press board 110 of an Example, and the structure of the vicinity. Explanatory drawing which shows the crushed stone pile forming apparatus 100 in the grounding state of the press board 110. FIG. Explanatory drawing which shows the crushed stone pile formation apparatus 100 in an excavation preparation process. The side view which shows the state of the cylindrical part 12 and the crushed stone injection | throwing-in apparatus 330 before the crushed stone preliminary injection. The top view which shows the state of the cylindrical part 12 and the crushed stone injection | throwing-in apparatus 330 before crushed stone preliminary | backup injection | throwing-in. The front view which extracts and shows an opening-and-closing door. The side view which shows the state of the cylindrical part 12 and the crushed stone throwing adapter 332 at the time of crushed stone preliminary throwing. The top view which shows the state of the cylindrical part 12 at the time of crushed stone preliminary | backup injection | throwing-in and the crushed stone injection | throwing-in apparatus 330. FIG. Explanatory drawing which shows the crushed stone pile formation apparatus 100 in an excavation process. Explanatory drawing which shows the crushed stone pile forming apparatus 100 in an excavation completion process. Explanatory drawing which shows the crushed stone pile forming apparatus 100 in a crushed stone formation process. Explanatory drawing which shows the state of the crushed stone input apparatus 330 in a crushed stone pile formation process. Explanatory drawing which shows the crushed stone pile forming apparatus 100 in a construction completion process. Explanatory drawing which shows the formation state of the crushed stone pile by the crushed stone pile formation head provided with the underground excavation blade 29 and the crushed stone excavation blade 30. FIG. Explanatory drawing which shows the lower surface of the underground excavation blade 29. FIG. Explanatory drawing which shows the upper surface of the crushed stone excavation blade 30. FIG. Explanatory drawing which shows the state which looked at the underground excavation blade 29v of the 1st modification from upper direction. The figure which looked at underground excavation wing | blade 29v from the direction of the outer side of wing | blade member 29bv. Sectional drawing of the underground excavation wing | blade 29v and the wing | blade member 29bv. Explanatory drawing which shows the truss-like reinforcement structure which restrains the shape of the crushed stone injection hole 14 in a modification. Explanatory drawing which shows the truss-like reinforcement structure which restrains the shape of the crushed stone injection hole 14 in a modification.

The present invention can also be realized as a preferred embodiment by including the following features alone or in combination.
(Feature 1) The underground excavation blade has a claw portion protruding upward at the upper end portion of the underground excavation blade at the inner surface position of the cylindrical portion.
(Characteristic 2) The underground pile is a crushed stone pile mainly composed of crushed stone.

In the following, embodiments of the present invention will be described in the following order in order to clearly describe the operation and effects of the present invention based on the above-described features.
A. Configuration and construction method of a crushed stone pile forming apparatus according to an embodiment of the present invention:
B. Variations:

A. Configuration and construction method of a crushed stone pile forming apparatus according to an embodiment of the present invention:
FIG. 1 is an explanatory diagram showing a configuration of a crushed stone pile forming apparatus 100 according to an embodiment of the present invention. The crushed stone pile forming apparatus 100 includes a small ground improvement machine M as a construction machine, and an attachment T attached to the small ground improvement machine M. As shown in FIG. 1, the small ground improvement machine M includes a ground improvement machine body structure 1, a cabin 7 as a driver's seat, a crawler 6 that is an endless track that can move on rough terrain with low ground pressure, and construction. And an outrigger 5 that suppresses the swing of the small ground improvement machine M at the time.

  The small ground improvement machine M further includes, as a configuration for operating the attachment T, a rotation driving source 11 that supplies a rotation driving force to the attachment T via the motor output shaft 27, and a leader 4 having a lifting guide rail 9. A leader mounting base 2 for supporting the leader 4, a hydraulic cylinder 3 for operating the inclination of the leader 4, and an extension pedestal 10 formed integrally with the leader 4 at the lower end of the leader 4. ing.

  Drawing 2 is an explanatory view showing the state where attachment T of an example was seen from another angle. As shown in FIGS. 1 and 2, the attachment T includes a cylindrical portion 12 provided with fins 13, an underground excavation blade 29, a surrounding frame 32 for steadying the cylindrical portion 12, and a bifurcated fork shape. Hanger stay 64 (FIG. 1) having a top cover case 55 having a cam protrusion 63, a crushed stone throwing device 330, a mounting plate 37 (FIG. 1), a support arm 39 (FIG. 1), and an attachment T. And a construction management device TC (FIG. 1) for managing the construction state. A crushed stone throwing hole 14 is formed in the cylindrical portion 12 (FIG. 1), and the crushed stone throwing hole 14 is closed by an opening / closing lid D, the details of which will be described later.

  FIG. 3 is a cross-sectional view illustrating the configuration of the cylindrical portion 12 and the underground excavation blade 29 according to the embodiment. In the present embodiment, the underground excavation blade 29 is configured integrally with the rotary input shaft 26 and the core rod 22. The rotation input shaft 26 is connected to the motor output shaft 27 of the rotation drive source 11. The rotation input shaft 26 rotates in accordance with the rotation driving force of the motor output shaft 27 and transmits the rotation driving force to the underground excavation blade 29 via the core rod 22 integrally coupled. The underground excavation blade 29 has an underground excavation blade 29 that excavates the ground and applies pressure to the crushed stone, and a crushed stone excavation blade 30 that excavates the crushed stone thrown into the cylindrical portion upward. . In the present embodiment, the underground excavation blade 29 is configured integrally with the rotary input shaft 26 and the core rod 22, but may be configured as a separable component. Details of the structure and function of the underground excavation blade 29 and the crushed stone excavation blade 30 will be described later.

  The core rod 22 is rotatably coupled to the cylindrical portion 12 by a bearing tube 23 and a radiation stay 24, and has a common rotating shaft with the cylindrical portion 12. On the other hand, the cylindrical portion 12 has a spiral fin 13 around it. The fin 13 has a spiral shape in the same direction as the inclination (including the spiral) of the underground excavation blade 29. That is, when excavating, the cylindrical portion 12 and the underground excavation blade 29 rotate in the same direction. As a result, excavated earth and sand generated by excavation of the underground excavation blades 29 are transported to the ground surface by the fins 13.

  A donut auger (double auger) (not shown) is widely known as an excavator equipped with such a double reversing mechanism. However, the donut auger is used as a double reversing mechanism to construct a pile with high vertical accuracy by reducing the load on the leader 4 and the small ground improvement machine M by rotating the casing and the screw in the casing in reverse. It is well known that Therefore, as in the present embodiment, operating the spiral shape integrally in the same direction loses the meaning of the double reversal mechanism, which is contrary to the technical common sense of those skilled in the art.

  Further, the cylindrical portion 12 and the underground excavation blade 29 of the embodiment are different from the conventional donut auger in the following points. That is, in the conventional donut auger, a drilling blade is also provided at the tip of the pipe casing side, whereas a tip of the cylindrical portion 12 of the embodiment is not equipped with a drilling blade. On the other hand, the underground excavation blade 29 of the embodiment has a diameter that allows the tip to protrude from the cylindrical portion 12 and excavate a range corresponding to the diameter of the cylindrical portion 12. Thus, it can be seen that the excavation mechanism in the embodiment is different from that of the conventional donut auger.

  Such an essential difference in the mechanism has an organic relationship with the formation of the crushed stone injection hole 14 in the cylindrical portion 12. Since the formation of the crushed stone injection hole 14 on the side surface of the cylindrical portion 12 reduces the rigidity and strength of the cylindrical portion 12, excavation by the cylindrical portion 12 itself is extremely difficult. However, at the time of excavation, the inventor of the present application causes the underground excavation blade 29 to take charge of excavation and uses the cylindrical portion 12 for transporting excavated earth and sand, thereby obtaining rigidity and strength required for the cylindrical portion 12. It is reduced. As described above, this configuration realizes a unique excavation method in which the underground excavation blade 29 excavates the underground, and the earth and sand generated by the excavation are discharged to the ground surface via the outside of the cylindrical portion 12 by the fins 13. It is doing. Thereby, formation of the crushed stone injection hole 14 to the cylindrical part 12 becomes practically possible. However, the installation of the excavating blade on the cylindrical portion 12 is not completely excluded, and an auxiliary excavating blade may be provided on the cylindrical portion 12 side. This is because the burden on the cylindrical portion 12 during excavation can be reduced even in this way.

  In the present embodiment, the attachment T further includes a one-way clutch mechanism (not shown) between the rotation input shaft 26 and the core rod 22 inside the top cover case 55. The one-way clutch mechanism automatically enters an operating state in which the underground excavation blades 29 and the cylindrical portion 12 rotate as a unit in driving in the rotational direction during excavation. Thereby, the earth and sand excavated with the underground excavation blade 29 as mentioned above can be discharged | emitted on the ground with the fin 13 which the cylindrical part 12 has. On the other hand, in the rotation drive in the direction opposite to the rotation direction during excavation, the underground excavation blade 29 applies pressure to the crushed stone, and the cylindrical portion 12 automatically stops rotating in the rotation direction of the crushed stone introduction hole 14. The position can be fixed.

  As shown in FIG. 1, the attachment T is attached to the small ground improvement machine M in the following form. The enclosure frame 32 and the crushed stone throwing device 330 included in the attachment T are coupled to the extension pedestal 10 of the small ground improvement machine M by a mounting plate 37 and a support arm 39, respectively. The underground excavation blade 29 of the attachment T is connected to the rotation drive source 11 of the small ground improvement machine M through the rotation input shaft 26 and the motor output shaft 27. On the other hand, the hanger stay 64 of the small ground improvement machine M, together with the cam protrusion 63, constitutes a reverse prevention mechanism for allowing the cylindrical portion 12 to rotate only in one direction. The crushed stone pile forming apparatus 100 having such a configuration can form a crushed stone pile in the ground by a process described below.

  FIG. 4 is a flowchart showing the steps of the method for forming a crushed stone pile according to the embodiment of the present invention. In step S100, the operator executes a pile core alignment process in the state shown in FIG. The pile core alignment step is a step of aligning the tip of the underground excavation blade 29 with the center of the crushed stone pile forming position so that the crushed stone pile can be formed at a preset crushed stone pile forming position. This alignment is performed by adjusting the position and direction of the small ground improvement machine M by driving the crawler 6.

  In the pile core alignment step, the operator further operates the outrigger 5 (FIG. 1) to fix the position of the small ground improvement machine M. Thereby, the rocking | swiveling and position shift of the small ground improvement machine M at the time of construction can be suppressed. After confirming that the small ground improvement machine M is fixed by the outrigger 5, the operator confirms the verticality of the leader 4 with respect to the direction of gravity and makes fine adjustments as necessary.

  FIG. 5 is an enlarged view showing the configuration of the press plate 110 of the embodiment and the vicinity thereof. The attachment T further includes a hydraulic actuator 111 that moves the press plate 110 up and down. The hydraulic actuator 111 is supported by the extension leg 10 that is integrally formed at the lower end of the leader 4. The press plate 110 can pressurize the ground surface around the excavation hole excavated by the attachment T.

  FIG. 6 is an explanatory view showing the crushed stone pile forming apparatus 100 when the press plate 110 is in a grounded state. After confirming the verticality, the operator lowers the press plate 110 to the ground surface and grounds it as shown in FIG. The reason why the press plate 110 is grounded is to suppress loosening of the surface layer near the ground surface at the start of excavation. In this way, when the press plate 110 is in a grounded state, the pile core alignment process is completed.

  FIG. 7 is an explanatory diagram showing the crushed stone pile forming apparatus 100 in the excavation preparation process. In step S200, the operator executes an excavation preparation process as shown in the figure. The excavation preparation process is a preparation process for excavation, and includes a reference position setting process, a casing lowering process, and a crushed stone preliminary charging process. The reference position setting step is a step of setting a position that serves as a reference for excavation depth during excavation. In the reference position setting step, the operator sets a reference position by making a predetermined input (for example, pressing a button (not shown)) to the construction management device TC while the press plate 110 is in contact with the ground surface. Can do.

  The casing lowering step is a step of lowering until the lower end of the cylindrical portion 12 contacts the ground surface. As a result, as shown in FIG. 7, the lower end of the cylindrical portion 12 is sealed off by the ground surface in a state where the tip of the underground excavation blade 29 enters the ground and the attachment T is fixed to the ground surface. Become. The raising / lowering amount of the cylindrical portion 12 can be measured by, for example, a potentiometer (not shown) included in the reader 4.

  The crushed stone preliminary charging step is a step of preliminarily charging crushed stone through the crushed stone charging hole 14 from the crushed stone charging device 330. According to the experiment of the inventor of the present invention, it has been confirmed that the amount of crushed stone is preferably about 50 cm (± 10 cm) from the lower end of the cylindrical portion 12. The input crushed stone closes the lower end of the cylindrical portion 12 during excavation by the attachment T, and prevents the excavated soil from entering the inside of the cylindrical portion 12.

  This blockage makes it possible to counter high groundwater pressure as a certainty by the staying crushed stones retained between the underground excavation blades 29 and the crushed stone excavation blades 30 of the underground excavation blades 29. That is, the earth and sand to enter from the clearance of the underground excavation blade 29 applies a load in the rotational direction at the underground excavation blade 29 as an action point of the load. Since it is applied as a translational load in the direction of the rotation axis, an extremely strong reaction is received. This is due to Sambunan's principle. Thus, the separation of the underground excavation blade 29 and the crushed stone excavation blade 30 serves as a configuration that functions effectively even during excavation work. Furthermore, it was confirmed by experiments in a dedicated test site isolated from the surroundings by the present inventors that sand and soil near the ground surface are clogged between crushed stones at the start of excavation and can also be waterproof.

  FIG. 8 is a side view showing a state of the cylindrical portion 12 and the crushed stone throwing device 330 before the crushed stone preliminary throwing. FIG. 9 is a plan view showing a state of the cylindrical portion 12 and the crushed stone throwing device 330 before the crushed stone preliminary throwing. The crushed stone throwing device 330 feeds the medium filling material supplied to the medium filling material accommodation hopper 33 into the cylindrical portion 12 through the medium filling material charging chute 34. The filling material is put into the cylindrical portion 12 through a crushed stone throwing hole 14 formed on the side surface of the cylindrical portion 12. Charging into the crushed stone throwing hole 14 is performed using an open support member 331 and a crushed stone throwing adapter 332 equipped in the crushed stone throwing device 330.

  The open support member 331 includes an open support member base 331b fixed to the filling material input chute 34, and a swing support portion coupled to the open support member base 331b by a hinge (not shown) so as to be rotatable about the Z axis. 331a. On the other hand, the crushed stone throwing adapter 332 is connected to a crushed stone throwing adapter base 332b fixed to the filling material throwing chute 34 and a hinge (not shown) coupled to the crushed stone throwing adapter base 332b so as to be rotatable about the X axis. An adapter portion 332a and a biasing weight 332c attached to the turning adapter portion 332a are provided. The urging weight 332 c is urged upward so that the turning adapter portion 332 a closes the outlet of the filling material charging chute 34.

  The cylindrical portion 12 is formed with a crushed stone insertion hole 14 as a long hole (rectangular in the present embodiment) whose major axis is the rotation axis direction (Z-axis direction) of the cylindrical portion 12. The crushed stone throwing hole 14 is closed from the outside of the cylindrical portion 12 by a planar opening / closing lid D formed of an elastic body. The opening / closing lid D is fastened to the cylindrical portion 12 by a fixing portion Df which is one side of the end portion of the crushed stone throwing hole 14 on the preceding side in the screwing direction F of the cylindrical portion 12, and is opened at the other side. Yes. Thereby, since the force of the direction which closes the crushed stone injection hole 14 is applied from the ground by the rotation at the time of excavation of the cylindrical part 12, it is possible to remarkably reduce the intrusion of earth and sand and water at the time of the rotation at the time of excavation. it can.

  FIG. 10 is a front view showing the opening / closing lid D extracted. The opening / closing lid D is a rectangular opening / closing lid that covers the crushed stone input hole 14. The opening / closing lid D is formed by embedding and integrating a plurality of parallel reinforcing metal bones 18 and a reinforcing cloth (not shown) that prevent breakage and the like, with an elastically deformable film material such as rubber or synthetic resin as a base material. The open / close lid D is fastened to the cylindrical portion 12 with a plurality of fixing bolts 19 (see FIGS. 8 and 9).

  The opening / closing lid D does not necessarily need to be made of an elastic body, and does not need to be flat. However, if it is made of an elastic body, it deforms along the shape of the crushed stone injection hole 14 and the adhering earth and sand due to the pressure from the ground, so that it is possible to realize high confidentiality according to the test and analysis of the present inventors. confirmed. On the other hand, if the opening / closing lid D has a flat shape, it can be manufactured more easily than when it is formed in a three-dimensional shape.

  As can be seen from FIGS. 8 and 9, in the state of the crushed stone feeding device 330 before the crushed stone preliminary feeding, the cylindrical portion 12 can rotate without receiving the interference of the crushed stone feeding device 330. In this state, the turning adapter portion 332a is urged upward by the urging weight 332c as described above so as to close the outlet of the filling material charging chute 34. On the other hand, the turning support part 331a is configured to turn in a direction of automatically retracting even if it contacts the cylindrical part 12 when the cylindrical part 12 rotates. The urging may be performed by a spring.

  In this way, by forming the crushed stone insertion hole 14 that penetrates the cylindrical portion 12 used for excavation of the ground from the side, and by making the opening / closing lid D that closes the crushed stone insertion hole 14 into a flat shape that can be easily manufactured. The configuration in which the cross-sectional shape of the cylindrical portion 12 is non-circular is to cover the technical common sense of those skilled in the art at the time of filing. If a through-hole is formed on the side of the cylindrical portion 12, it is difficult to ensure the confidentiality of the cylindrical portion 12 and it is difficult to prevent intrusion of earth and sand, and in addition, the rigidity and strength of the cylindrical portion 12 are reduced. It was not even considered as a virtually impossible configuration. Further, in a part of the outer diameter of the cylindrical portion 12, for example, in this embodiment, the spiral fins are missing in a portion of 20% or more of the outer diameter, so it is considered that it is difficult to discharge earth and sand. Moreover, if the cross-sectional shape of the cylindrical portion 12 is non-circular, it is considered that excavation itself becomes difficult because the torque at the time of excavation increases excessively in combination with the sediment discharge performance.

  FIG. 11 is a side view showing the state of the cylindrical portion 12 and the crushed stone throwing adapter 332 at the time of crushed stone preliminary throwing. FIG. 12 is a plan view showing the state of the cylindrical portion 12 and the crushed stone throwing device 330 at the time of crushed stone preliminary throwing. In this figure, in order to make the state of the crushed stone throwing adapter 332 easier to see, the open support member 331 is not shown. In preliminary crushed stone input, the operator manually opens and closes the opening / closing lid D, which is an elastic body, and engages and holds the opening / closing lid D with the turning support portion 331a.

  After confirming the holding state, the operator throws crushed stone into the filling material accommodation hopper 33. The thrown crushed stone flows into the filling material throwing chute 34 and pushes the swivel adapter portion 332a with its weight. The turning adapter part 332a is turned by the weight of the crushed stone, and the tip thereof is inserted into the crushed stone introduction hole 14. Thereby, crushed stone is thrown into the inside of the cylindrical portion 12.

  By adopting such a configuration, it is not necessary to move the filling material accommodating hopper 33 of the crushed stone throwing device 330 from the time of excavation to the time of crushed stone pile formation. Furthermore, since the retracted state and the input state are automatically switched according to the input state of the crushed stone, an operation error can be prevented in advance. Thereby, while being able to reduce a burden of an operator notably, the reliability of construction can be improved.

  FIG. 13 is an explanatory view showing the crushed stone pile forming apparatus 100 in the excavation process. In step S300, the operator executes an excavation process as shown in the figure. The excavation process is a process of excavating while monitoring the excavation depth. In this embodiment, the excavation depth is monitored as the amount of protrusion of the tip position of the cylindrical portion 12 from the reference position of the lower end of the press plate 110 (grounded to the ground surface). This reference position is a position set as a reference used in the construction management apparatus TC in step S200. The monitoring of the excavation depth is performed as measurement of the relative position of the press plate 110 and the cylindrical portion 12, and is input to the construction management device TC in real time. The construction management device TC records the output torque to the attachment T and the excavation depth during excavation as time series data.

  When the excavation depth reaches a predetermined depth (for example, 1 m) set in advance, the construction management device TC alerts the operator by voice. In response to this voice, the operator raises the press plate 110 away from the ground surface. The reason why the press plate 110 is kept in contact with the ground surface from the start of excavation to a predetermined depth is to suppress loosening of the ground around the excavation hole due to the start of excavation.

  FIG. 14 is an explanatory view showing the crushed stone pile forming apparatus 100 in the excavation completion process. In step S400, the operator executes an excavation completion process as shown in the figure. As a general rule, the excavation completion step is a step of ending excavation in response to reaching a preset maximum depth. However, even before the operator reaches the preset maximum depth, the operator can complete excavation in response to reaching a relatively strong formation. The comparatively strong formation is a formation having a magnitude greater than that of which the earth strength (for example, N value) is set in advance. Reaching a relatively strong formation can be detected in accordance with, for example, an increase in output torque to the attachment T during excavation or a decrease in excavation speed (amount of excavation depth per unit time).

Such excavation completion method was created by the inventor of the present application, and can substantially increase the earth bearing strength by the crushed stone pile formed in the excavation hole. Specifically, if the excavation is terminated upon reaching a preset maximum depth, the peripheral frictional force of the crushed stone pile can be sufficiently increased. This is because the crushed stone pile is long enough and the diameter changes according to the formation change. On the other hand, if the excavation is completed in response to reaching a relatively strong formation, the crushed stone pile can be supported by a relatively strong formation. The effect of the ground improvement based on it will also be show | played. Such an effect is particularly remarkable in a wooden house having a relatively small required long-term allowable stress level (necessary long-term allowable stress level is about 20 kN / m ^{2 to} 30 kN / m ² : common specifications for wooden house construction). There is an effect. On the other hand, for example, for steel-framed or reinforced concrete houses (including cases where the required long-term allowable stress exceeds 100 kN / m ² ), for example, the number of crushed stone piles per unit area, the diameter of crushed stone piles, and the formation of crushed stone piles It also has a wide applicability that it can be dealt with by adjusting parameters such as the driving torque of the underground excavating blade 29 at the time.

  FIG. 15 is an explanatory view showing the crushed stone pile forming apparatus 100 in the crushed stone forming step. In step S500, the operator executes a crushed stone formation step as shown in the figure. The crushed stone pile forming step is a step of forming a crushed stone pile by charging and pressurizing crushed stone into a space formed by excavation. The input of crushed stone can be performed by the same method as the crushed stone preliminary input process. The input of the crushed stone may be continuously performed with respect to the filling material accommodation hopper 33 by, for example, a belt conveyor, or may be intermittently performed by a power shovel. Pressurization of the crushed stone is performed by rotating the underground excavation blade 29 in the direction opposite to that during excavation.

  The amount of pressure applied to the crushed stone is indirectly controlled by monitoring the magnitude of the driving torque of the underground excavation blade 29. The construction management device TC alerts the operator by voice every time the driving torque of the underground excavation blade 29 reaches the set upper limit torque. In response to this, the operator raises the underground excavation blade 29 by a predetermined amount (for example, 10 cm). The underground excavation blade 29 is lifted by an endless transmission chain provided in the leader 4 and its revolving drive motor (not shown). The ascending driving force is reduced by the reaction force from the crushed stone pile generated due to the rotation of the underground excavation blade 29. Since the cylindrical portion 12 is coupled to the underground excavation blade 29 so as to restrain the relative positional relationship in the rotation axis direction, the cylindrical portion 12 rises together with the underground excavation blade 29. Since formation of the crushed stone pile is managed by such a method, it is possible to form a crushed stone pile of stable quality regardless of whether the crushed stone is continuously or intermittently charged.

  FIG. 16 is an explanatory diagram showing a state of the crushed stone charging device 330 in the crushed stone pile forming step. In the crushed stone pile forming process, the cylindrical portion 12 and the underground excavation blades 29 are gradually raised according to the formation of the crushed stone pile, but the burrowing material accommodation hopper 33 is fixed at a position near the ground, The charging can be performed continuously. This is because the crushed stone insertion hole 14 is a long hole having a long axis in the direction of the rotation axis of the cylindrical portion 12 and is closed by an opening / closing lid D of an elastic body. The crushed stone injection hole 14 is firmly closed by receiving an underground pressure by an open / close lid D that is closed from the outside of the cylindrical portion 12 in the ground, but if it is exposed to the ground and the underground pressure disappears, it supports turning. This is because it is automatically opened by the part 331a.

Such a configuration has the following advantages.
(1) Since the crushed stone input position can be set to a low position, the gravity center position of the crushed stone pile forming apparatus 100 can be lowered, and the crushed stone supply position can be lowered. Thereby, construction with a small and light small ground improvement machine M, monitoring of a crushed stone replenishment state from above, and safe crushed stone replenishment can be made possible.
(2) Since the position of the intermediate filling material accommodation hopper 33 can be fixed, the crushed stone can be easily supplied to the intermediate filling material accommodation hopper 33. Thereby, for example, it is possible to avoid repeated processes such as moving the medium-filling material accommodation hopper to a low position to replenish crushed stones, and raising the medium-filling material accommodation hopper.
(3) The amount of crushed stone falling in the cylindrical portion 12 can be reduced. Particularly, as the cylindrical portion 12 rises and is exposed to the ground, the amount of crushed stone falls, so noise during construction is remarkable. It is possible to reduce it.
Such a feature has a remarkable effect of enabling efficient work particularly in a narrow area or a residential area. Furthermore, since the crushed stone pile formed in a present Example has a remarkable effect on the ground improvement for houses, it turns out that this structure is especially suitable for the ground improvement for houses.

  In this way, when the depth of the underground excavation blade 29 reaches a preset depth (for example, 1 m), the construction management device TC alerts the operator by voice. The operator lowers the press plate 110 in response to this voice. The press plate 110 pressurizes excavated earth and sand formed around the excavation hole from above, thereby effectively preventing in advance the loosening of the ground near the ground surface at the time of crushed stone formation, and sufficient crushed stone near the surface layer. Compaction can be realized effectively. Thereby, after formation of a crushed stone pile, it becomes possible to reduce the necessity of the compaction operation | work of surface layers, such as rammer rolling.

  Furthermore, when the underground excavation blade 29 rises and the excavation depth reaches a preset depth (for example, 0.5 m), the rotational speed of the underground excavation blade 29 is reduced to reduce the formation speed of the crushed stone pile. Thereby, the loosening of the ground near the ground surface at the time of crushed stone pile formation can be suppressed more effectively.

  FIG. 17 is an explanatory view showing the crushed stone pile forming apparatus 100 in the construction completion process. In step S600, the operator executes a construction completion process as shown in the figure. The construction completion process is a post-treatment after the formation of each crushed stone pile. The construction completion process is a process including a press plate raising process, a casing raising process, a leader tilting process, and an outrigger raising process. In this figure, the open support member 331 and the like are omitted in order to make the state of the crushed stone throwing adapter 332 easier to see.

  The press plate ascending step is performed by the operator operating the hydraulic actuator 111 after confirming that the tip of the underground excavation blade 29 is exposed from the ground. The casing raising process is a process of separating the tip of the underground excavation blade 29 from the ground surface by raising the cylindrical portion 12. The leader tilting step is a step of bringing the gravity center position of the crushed stone pile forming apparatus 100 closer to the centroid position on the lower surface of the crawler 6 by tilting the attachment T away from the ground surface in the direction of the small ground improvement machine M. The outrigger raising step is a step in which the outrigger 5 is raised to enable the crawler 6 to move the small ground improvement machine M.

  Thus, since the crushed stone pile forming apparatus 100 of an Example has the cylindrical part 12 in which the crushed stone injection hole 14 was formed in the side surface, a crushed stone is thrown in from the side surface of the cylindrical part 12, and a crushed stone pile is formed in the ground. be able to. Since the crushed stone injection hole 14 is a long hole having a long axis in the direction of the rotation axis, the crushed stone input position is within the range of the length in the long axis direction of the crushed stone injection hole 14 even if the cylindrical portion 12 rises as the crushed stone pile is formed. It is possible to improve the work efficiency by fixing. In the present embodiment, the crushed stone input hole 14 is formed as a single continuous long hole, but may be formed as a plurality of long holes divided in the middle.

  On the other hand, since the cylindrical portion 12 has an open / close lid that closes the crushed stone injection hole 14 from the outside of the cylindrical portion 12, the crushed stone injection hole 14 is closed by the pressure outside the cylindrical portion 12 in the ground to prevent intrusion of earth and sand. Can be suppressed. Thereby, the formation operation of a simple and efficient crushed stone pile is realizable.

  FIG. 18 is an explanatory diagram illustrating a formation state of a crushed stone pile by a crushed stone pile forming head including the underground excavating blade 29 and the crushed stone excavating blade 30. FIG. 19 is an explanatory view showing the lower surface of the underground excavation blade 29. As described above, the underground excavation blade 29 includes an underground excavation blade 29 that excavates the ground and applies pressure to the crushed stone, and a crushed stone excavation blade 30 that excavates the crushed stone thrown into the cylindrical portion upward. have. The underground excavation blade 29 discharges crushed stone into the ground against the underground pressure and groundwater pressure and applies pressure to the crushed stone. The crushed stone excavation blade 30 excavates the crushed stone thrown into the cylindrical portion 12 and accumulated inside, and supplies the crushed stone to the underground excavation blade 29.

  The underground excavation blade 29 includes a pair of blade members 29a and 29b that are asymmetric with respect to the rotation shaft 29x. The pair of wing members 29a and 29b are formed integrally with the rotating shaft 29x (for example, joined together by welding). The wing member 29a includes two underground excavation claws 29ac1 and 29ac2 provided at the front end during normal rotation, and crushed stone excavation claws 29ac3 and 29ac4 formed at the rear end during normal rotation, Wing part main body 29as. The wing member 29b includes three underground excavation claws 29bc1, 29bc2, 29bc3 provided at the front end during normal rotation, and crushed stone excavation claws 29bc4, 29bc5 formed at the rear end during normal rotation. And a wing part main body 29bs.

  In the wing member 29a included in the underground excavation wing 29, the two underground excavation claws 29ac1 and 29ac2 are inclined downward toward the tip end thereof in order to excavate the underground. On the other hand, in the wing member 29b, the three underground excavation claws 29bc1, 29bc2, and 29bc3 are inclined downward toward the tip end thereof in order to excavate the underground. Thus, the five underground excavation claws 29ac1, 29ac2, 29bc1, 29bc2, and 29bc3 form asymmetric shapes. Such an asymmetrical configuration is that when excavating soil that contains solids (for example, stones) in the ground, it is better not to strike the solids at the same location, but to strike at a plurality of shifted positions. The creation based on the knowledge newly found by the present inventors that excavation is possible effectively.

  In the wing member 29a of the underground excavation blade 29, in order to excavate the crushed stone into which the two crushed stone excavation claws 29ac3 and 29ac4 are thrown upward, the wing member 29a is inclined upward. On the other hand, in the wing member 29b, in order to excavate the crushed stone into which the two crushed stone excavation claws 29bc4 and 29bc5 are thrown upward, the wing member 29b is inclined upward toward the tip. Such a symmetric configuration is a configuration adopted in order to realize simple manufacturing in consideration of the ease of excavation of the input crushed stone.

  The four crushed stone excavation claws 29ac3, 29ac4, 29bc4, and 29bc5 can excavate the crushed stones and push them into the lower portions of the wing main bodies 29as and 29bs. The movement of the crushed stone pushed below the wing body 29as, 29bs with respect to the ground is suppressed by the frictional force from the ground. As a result, the crushed stone slides with respect to the rotation of the wing body 29as, 29bs, so that it is pressurized by the inclined shape of the wing body 29as, 29bs and buried in the ground. As described above, the pressure generated by the underground excavation blade 29 is generated as a resultant force of the reaction force from the ground to the crushed stone and the rotational force of the underground excavation blade 29. Therefore, at the boundary between the underground excavation blade 29 and the underground. Pressure for discharging crushed stones and rolling is generated.

  FIG. 20 is an explanatory view showing the upper surface of the crushed stone excavation blade 30. The crushed stone excavation blade 30 includes a pair of blade members 30a and 30b symmetrical to the rotation shaft 29x. The pair of wing members 30a and 30b are formed integrally with the rotating shaft 29x (for example, joined together by welding). The wing member 30a includes crushed stone excavation claws 30ac1 and 30ac2 formed at the front end during reverse rotation, a rear end surface 30ae formed at the rear end during reverse rotation, and a wing body 30as. Yes. The wing member 30b includes crushed stone excavation claws 30bc1 and 30bc2 formed at the front end during reverse rotation, a rear end surface 30be formed at the rear end during reverse rotation, and a wing main body 30bs. Yes.

  In the wing member 30a of the crushed stone excavating blade 30, the two crushed stone excavating claws 30ac1 and 30ac2 are inclined upward toward the tip of the crushed stone excavated claw 30ac1 and 30ac2. On the other hand, in the wing member 30b, the two crushed stone excavation claws 30bc1 and 30bc2 are inclined upward toward the tip end thereof in order to excavate the crushed stone upward. Further, the wing members 30a and 30b are configured so that the clearances L1 and L2 between the wing members 30a and 30b increase as the wing members 30a and 30b rotate when the clearances L1 and L2 are reversed. The reason for this shape is to prevent crushed stones or the like from entering between the inner surface of the cylindrical portion 12 and the outer ends of the wing members 30a and 30b during reversal to generate a large resistance.

  The four crushed stone excavation claws 30ac1, 30ac2, 30bc1, and 30bc2 can excavate the crushed stone and push it below the wing body 30as and 30bs. The movement of the crushed stone pushed below the wing part main bodies 30as, 30bs is suppressed by the frictional force between the crushed stone excavating blade 30 and the ground excavating blade 29. As a result, the crushed stone slides with respect to the rotation of the wing part main bodies 30as and 30bs, so that the crushed stone is pressurized by the inclined shape of the wing part main bodies 30as and 30bs and embedded in the ground.

  As described above, the crushed stone staying between the crushed stone excavating blade 30 and the underground excavated blade 29 is separated from the crushed stone excavating blade 30 and the underground excavated blade 29, so Since it is restrained and has a relative movement with the crushed stone excavation blade 30, it becomes possible to preliminarily pressurize the crushed stone excavation blade 30 in advance. In other words, the Japanese inventors succeeded in forming a virtual underground surface having the same function as the underground surface for the underground excavation blade 29 inside the cylindrical portion 12.

  As described above, in this embodiment, the ground excavation blade 29 can further pressurize the crushed stone preliminarily pressurized by the crushed stone excavation blade 30. Thereby, the ground pressure and the groundwater pressure can be overcome and the crushed stone can be discharged.

  In the staying stone crushing chamber, the bottom end position of the crushing excavation blade 30 is separated from the top end position of the underground excavation blade 29 by a distance of 0.1 to 1 times the inner diameter of the cylindrical portion 12. It is preferable. This range is a quantitative preferred region found by the inventors and is not an essential component. Specifically, when the inner diameter of the cylindrical portion 12 is about 40 cm, it is preferably in the range of about 10 cm to 40 cm.

B. Variations:
Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in the present specification or the drawings can achieve a plurality of objects at the same time, and has technical utility by achieving one of the objects. Specifically, for example, the following modifications can be implemented.

B-1. First Modification: As shown in FIGS. 21 to 24, the underground excavation blade 29v according to the first modification has the shape of the pair of blade members 29av and 29bv in the embodiment. Is different from the underground excavation blade 29 of the embodiment in that a pair of blocking prevention plates 70a and 70b are added. Due to such a difference in configuration, as described below, it is possible to achieve effects such as improvement in the rolling ability of the underground pile, high productivity, and realization of smooth operation.

  FIG. 21 shows a state in which the underground excavation blade 29v of the first modification is viewed from above from the lower end of the cylindrical portion 12. FIG. 22 is a conceptual diagram of the underground excavation blade 29v as viewed from the outside of the blade member 29bv. FIG. 23 is a sectional view of the ground excavation blade 29v and the blade member 29bv. The wing member 29bv is bent at a fold line 60b as shown in FIGS. 21 and 23, and a horizontal rolling surface 62b is formed between the wing member 29bv and the outer contour portion 61b of the wing member 29bv. This planar shape is configured as a substantially planar shape having an inclination such that a rolling load can be applied to the crushed stone or the like almost vertically by the rotation of the underground excavation blade 29v. Similarly, the blade member 29av forms a horizontal rolling surface 62a between the blade member 29av and the outer contour portion 61a of the blade member 29av.

  The pair of horizontal rolling surfaces 62a and 62b can apply a rolling load to the crushed stone or the like almost vertically in the formation of the underground pile as described above (see the load F1 in FIG. 23). As a result, it is possible to effectively apply a rolling load while suppressing excessive lateral diffusion of crushed stones and the like. Such an effect can be combined with a remarkable effect especially in soft ground. In soft ground, especially ultra soft ground such as paddy fields and swamps, crushed stones may not be able to receive sufficient reaction force from the lateral direction. An underground pile to which a rolling load is sufficiently applied can be formed by the pressure surfaces 62a and 62b.

  On the other hand, the pair of blocking prevention plates 70a and 70b (FIGS. 21 to 23) prevent the intrusion of gravel and the like between the underground excavation blade 29 and the cylindrical portion 12 during excavation, thereby realizing smooth operation. Can do. The underground excavation blade 29 rotates while being integrated with the cylindrical portion 12 during excavation and performs excavation, and when the underground pile is formed, the underground excavation blade 29 is reversed with the cylindrical portion 12 fixed. The present inventors have found that the cylindrical portion 12 receives a large torque in the same direction as the underground excavation blade 29 at the start of the reversal. This torque sometimes has a magnitude that hinders the rotation of the underground excavation blade 29 with respect to the cylindrical portion 12.

  The inventors have determined that the cause of this torque is due to the fact that gravel or the like that has entered between the underground excavation blade 29 and the cylindrical portion 12 during excavation is firmly fixed while crushing during excavation, It has been found that such a fixed state can be prevented by additionally providing a pair of blocking prevention plates 70a and 70b. The pair of blocking prevention plates 70a and 70b are preferably formed along the curvature of the cylindrical portion 12 from the viewpoint of effectively preventing gravel and the like from entering.

  The present inventors have further found that the provision of a pair of blocking prevention plates 70a and 70b on the plane opposite to the horizontal rolling surfaces 62a and 62b significantly increases manufacturability. If it carries out like this, since the obstruction | occlusion prevention board 70a, 70b can obtain a flat joint surface with respect to wing | blade member 29av, 29bv, respectively, it can join easily by welding. Further, the blocking prevention plates 70a and 70b have an advantage that the plate can be shaped along the curvature of the cylindrical portion 12 only by bending the flat plate.

B-2. Second Modification: The cylindrical portion 12 of the second modification has a truss-like reinforcing structure Dr that constrains the shape of the crushed stone insertion hole 14 as shown in FIGS. The truss-shaped reinforcing structure Dr can be simply fastened to the cylindrical portion 12 by using, for example, a bolt 19 for fastening the opening / closing lid D to the cylindrical portion 12 or the like. If it carries out like this, while being able to improve the durability of a cylindrical part easily, the freedom degree of design of the shape of a crushed stone injection hole can be enlarged. Furthermore, the crushed stone input hole 14 is not necessarily a configuration essential to the present invention, and may be configured to input crushed stone from the upper part of the cylindrical portion 12. However, the turning support portion 331av and the turning adapter portion 332a are shortened to avoid interference with the truss-like reinforcing structure Dr.

B-3. Third modified example: In the above-described embodiments and modified examples, crushed stone is discharged into the ground to form a crushed stone pile. However, the present invention is a natural object such as natural crushed stone, gravel, sand, or fragments of concrete, It can also be applied to construction methods that form underground piles with artifacts such as waste tiles and mines.

  However, if natural objects are used, soil contamination due to ground improvement can be prevented, and the need for future removal of artifacts can be eliminated in advance by not leaving the artifacts in the ground. Therefore, there is an advantage that the decline in the asset value of the land can be suppressed. On the other hand, if waste such as concrete fragments is used, there is an advantage that the waste can be effectively used as a material for ground improvement.

  On the other hand, although the crushed stone excavation blade is used in the above-described embodiments and modifications, a wing for excavating sand or the like may be used as long as it is an additional excavation blade additionally provided in the underground excavation blade. The number of additional excavation blades may be at least one (one stage), and may be two (two stages) or more. The number of blade members may be at least one, but if it is a plurality of sheets (including odd numbers) arranged symmetrically for each stage of the additional excavation blade, it is particularly simple and excellent in balance. The present inventors have found that the configuration is highly practical. The same applies to underground excavation blades.

B-4. Fourth modified example: In the above-described embodiments and modified examples, an integrated process from excavation to formation of a crushed stone pile is realized by using an attachment. For example, excavation is separately performed by a method of ejecting water and air. After that, a crushed stone pile may be formed with an attachment. However, in each of the above-described embodiments, excavation is performed while using the pipe casing to pressurize and flatten the inner wall of the excavation hole, so that the excavation hole is prevented from being deformed to form a high-quality crushed stone pile or deformed. There is an advantage that it can be applied to the ground that is liable to cause erosion.

  In addition, in each of the above-described embodiments, the integrated processing from the excavation to the formation of the crushed stone pile is realized by using the attachment, and the crushed stone pile is constructed with the quality of the crushed stone pile hardly depending on the skill of the operator. It is possible. Thereby, while being able to stabilize the quality of a crushed stone pile, the construction method very adaptable to the quality assurance (quality assurance based on the validity of a process) by the method of special process management (ISO9000) is realizable.

DESCRIPTION OF SYMBOLS 1 ... Ground improvement machine main body structure 2 ... Leader mounting base 3 ... Hydraulic cylinder 4 ... Leader 5 ... Outrigger 6 ... Crawler 7 ... Cabin 9 ... Lifting guide rail 10 ... Extension leg pillar 11 ... Rotation drive source 12 ... Cylindrical part 13 ... Fin DESCRIPTION OF SYMBOLS 14 ... Crushed stone insertion hole 18 ... Reinforcement metal bone 19 ... Fixing bolt 22 ... Core rod 23 ... Bearing tube 24 ... Radiation stay 26 ... Rotation input shaft 27 ... Motor output shaft 29ac1 ... Outer claw part 29ac2 ... Inner claw part 29bc1 ... Outer claw part 29bc2 ... Inner claw part 29bc2 ... Inner claw part 29 ... Underground excavation blade 30 ... Crumble excavation blade 32 ... Enveloping frame 33 ... Material storage hopper 34 ... Material input chute 37 ... Mounting plate 39 ... Support arm 55 ... Top cover case 63 ... Cam convex 64 ... Hanger stay 100 ... Crushed stone pile forming device 100a ... Crushed stone pile forming device DESCRIPTION OF SYMBOLS 110 ... Press plate 111 ... Hydraulic actuator 330 ... Crushed stone throwing apparatus 331 ... Opening support member 331a ... Turning support part 331b ... Opening support member base 332 ... Crushed stone throwing adapter 332a ... Swing adapter part 332b ... Crushed stone throwing adapter base 332c ... Energizing weight

Claims (6)

It is an underground pile forming head for forming an underground pile ascending from the underground in the inside of a cylindrical portion that can be inserted into the ground to form a space and into which an underground pile forming material can be input. And
Underground having a first wing shape that rotates together with the cylindrical portion by rotation in the forward rotation direction and excavates the underground downward, and applies pressure to the underground pile forming material by rotation in the reverse direction. Drilling wings,
At least one additional excavation blade having a second wing shape for excavating the underground pile forming material thrown into the cylindrical portion by rotation in the reverse direction;
With
The additional excavation blade is separated from the underground excavation blade, and is disposed above the underground excavation blade ;
The additional excavation blade has an upper end portion that forms a tip portion by rotation in the reverse direction;
The underground pile forming head in which the upper end portion has at least one claw portion protruding upward . The underground pile forming head according to claim 1 ,
The underground excavation blade is an underground pile forming head including a plurality of blade members arranged at symmetrical positions. The underground pile forming head according to claim 1 ,
The additional excavation blade is an underground pile forming head including a plurality of blade members arranged at symmetrical positions. The underground pile forming head according to any one of claims 1 to 3 ,
The underground excavation blade has a front edge portion that forms a tip portion in rotation in the forward rotation direction, and a rear edge portion that forms a rear end portion in rotation in the forward rotation direction,
The underground pile forming head which has the shape which the said front edge part retreats in the direction of the said rear-end part as it leaves | separates in the outer peripheral direction from the rotating shaft of the said underground pile forming head when it sees from the downward direction. It is an attachment for forming an underground pile that is inserted into the ground to form a space, and forms a crushed stone pile in the space while rising from the underground,
Underground pile forming head according to any one of claims 1 to 3 ,
A cylindrical portion in which an underground pile forming material charging hole which is at least one long hole having a long axis in the central axis direction is formed on a side surface;
An open / close lid that closes the underground pile forming material charging hole from the outside of the cylindrical portion;
Attachment with. The attachment according to claim 5 ,
An attachment in which the cylindrical portion has a truss-like reinforcing structure that restrains the shape of the long hole.

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