JP4903620B2 - Excavation device for pile construction and pile construction method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a pile construction excavation apparatus and a pile construction method, and more particularly, to construct a pile on a ground excavated using the pile construction excavation apparatus for excavating the ground during the construction of the pile. It relates to the construction method of piles.

Conventionally, as a drilling device for pile construction, while rotating a casing having a drilling blade at the tip, it is pressed into the ground and excavated, and excavated using a excavator such as a hammaglab inserted into the casing, and the casing When the tip of the arm reaches the hard ground such as the intermediate layer, support layer, and rock, remove the hammer maglab, etc., insert the small-diameter rotary drilling casing into the casing from the top, and core the hard ground while adjusting the cutting edges of the inner and outer casings. 2. Description of the Related Art A drilling device that drills into a shape is known (for example, see Patent Document 1).
Further, a small-diameter casing tube similar to the small-diameter rotary excavation casing of Patent Document 1, and a grip mechanism that is detachably connected to the small-diameter casing tube and that expands in the casing and engages the inner periphery of the casing, There has also been proposed a drilling device that can easily remove excavated soil taken into the small diameter casing tube by removing the small diameter casing tube from the grip mechanism (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 61-24723 JP 2001-214682 A

However, in the conventional excavation device described in Patent Document 1, although the hard ground portion is excavated with a casing while soiling using a hammaglab or the like, the hard ground portion is moved to a drilling operation using a small-diameter casing. There is a problem that the work becomes two stages and the construction labor is increased. Furthermore, each time the excavated soil is taken into the small-diameter rotary excavation casing to excavate the hard ground into a core shape, the small-diameter rotary excavation casing is pulled out of the casing and vibrated with a vibrator etc. on the ground. Since it is necessary to take out the excavated soil from the casing, there is also a problem that the excavation work cannot be carried out continuously and the work time is prolonged.
On the other hand, even in the conventional excavator described in Patent Document 2, every time the excavated soil is taken into the small diameter casing tube, it is necessary to pull out the small diameter casing tube from the casing and remove the excavated soil on the ground. As with other excavator, there is a problem that the excavation work time is prolonged.

  The objective of this invention is providing the excavation apparatus for pile construction which can implement excavation work efficiently by excavating excavated soil continuously, and can shorten construction time, and the construction method of a pile.

  The excavation apparatus for pile construction according to claim 1 of the present invention is an excavation apparatus for pile construction that excavates the ground during the construction of the pile, and has an outer pipe that is rotationally driven with an excavation bit at the tip, An inner pipe which is provided inside the outer pipe and has a drilling bit at the tip and is driven to rotate, and a discharge means which is provided inside the outer pipe and above the inner pipe and discharges excavated soil to the ground. The inner tube has an internal crushing means for crushing the soil inside the inner tube.

According to the above excavation apparatus for pile construction, by providing the discharge means for discharging the excavated soil excavated by the outer pipe and the inner pipe to the ground, the excavation by the outer pipe and the inner pipe can be continuously performed. Unlike the excavator, there is no need to take out the excavated soil in the inner pipe on the ground, and excavation work can be performed efficiently and the construction time can be shortened. In addition, by providing an internal crushing means for crushing the soil inside the inner pipe, the core-shaped soil mass taken into the inner pipe can be made finer and discharged by the discharging means, and the excavation work can be sped up further. can do.
In addition, by excavating with a double pipe consisting of an outer pipe and an inner pipe each provided with a drill bit at each end, it is possible to drill with relatively low torque even on a hard ground part, and increase the size of the drilling device And an increase in manufacturing cost can be prevented.

At this time, in the excavation apparatus for pile construction according to the present invention, it is preferable that the internal pulverizing means has at least one bit provided on the inner peripheral surface of the inner pipe.
Furthermore, in the excavation apparatus for pile construction according to the present invention, the inner peripheral surface of the inner pipe includes a plurality of bits arranged in the circumferential direction on the inner peripheral surface, or a plurality of bits arranged in a spiral on the inner peripheral surface. It is preferable to be configured in any one of the arranged spiral bit strings.
According to such a configuration, the core provided in the inner tube can be crushed by the bit provided on the inner peripheral surface of the inner tube, and a plurality of bits can be arranged in the circumferential direction or spirally formed. By arranging a plurality, it is possible to improve the crushing performance and improve the soil removal efficiency by the discharging means.

Moreover, in the excavation apparatus for pile construction of the present invention, the inner pipe is connected to an upper portion of the inner pipe and rotationally supports the inner pipe, and a connecting portion crushing means provided in the connecting portion. It is preferable to have it.
According to such a configuration, the connecting portion crushing means is provided in the connecting portion connected to the upper portion of the inner tube (for example, the connecting support portion between the rod and the inner tube extending from the drive unit that rotationally drives the inner tube). Thus, the lump rising inside the inner pipe can be reliably pulverized in the vicinity of the discharging means, and the soil discharging efficiency can be improved.

In the excavation apparatus for pile construction according to the present invention, the inner pipe includes an external crushing means for crushing soil between the inner pipe and the outer pipe, and the outer crushing means It is preferable to have at least one bit provided on the outer peripheral surface of the tube.
Furthermore, in the excavation apparatus for pile construction according to the present invention, a plurality of bits on the outer peripheral surface of the inner pipe are arranged in a plurality of rows in at least one bit line arranged in the circumferential direction on the outer peripheral surface, or in a spiral form on the outer peripheral surface. It is preferably configured in the form of any one of the spiral bit strings.
According to such a configuration, the bit provided on the outer peripheral surface of the inner pipe constitutes the external crushing means, and the outer crushing means crushes the earth lump that has entered between the inner pipe and the outer pipe, thereby further excavating. Capacity and soil removal efficiency can be increased, and excavation work can be speeded up.

Moreover, in the excavation apparatus for pile construction according to the present invention, at least one bit for pulverizing soil between the inner pipe and the inner pipe of the outer pipe is provided on the inner pipe of the outer pipe. Is preferably configured in the form of one of a plurality of bit strings arranged in the circumferential direction on the inner circumferential surface or a spiral bit string arranged in a plurality of spirals on the inner circumferential surface.
According to such a configuration, the excavation capacity and the soil removal efficiency can be further improved by pulverizing the clot that has entered between the inner tube and the outer tube with the bit provided on the inner peripheral surface of the outer tube. it can.

In the excavation apparatus for pile construction according to the present invention, one common drive unit that rotationally drives the outer tube and the inner tube, or an outer tube drive unit that independently rotates the outer tube and the inner tube. And the inner tube drive unit, and the outer tube and the inner tube are rotationally driven in the same direction or independent directions by the one drive unit or the plurality of drive units. It is preferable.
According to such a configuration, each of the outer tube and the inner tube can be driven to rotate independently in the same direction or in the opposite direction, thereby increasing the excavation capacity and extremely high hardness of the rock or the like. It is possible to drill holes even on the ground. At this time, the outer tube and the inner tube may be rotated in the same direction, the outer tube and the inner tube may be rotated in the opposite directions, and the same direction and the opposite direction depending on the state of the ground. The outer tube and the inner tube may be rotated while appropriately switching between them, and may be driven by the common drive unit, or the outer tube drive unit and the inner tube drive unit.

At this time, in the excavation apparatus for pile construction according to the present invention, the discharging means moves the excavating soil upward by rotation of a screw provided on an outer periphery of a rod connecting the inner pipe and the common driving section or the inner pipe driving section. A screw device that transports the excavated soil through the inside of the rod, and a mud lift device that sucks up the excavated soil through the rod together with the water supplied to the inside of the outer pipe. preferable.
According to such a configuration, excavation work efficiency can be achieved by configuring the soil removal means by selecting an arbitrary device according to the characteristics of the ground, the type of pile, and the size from the screw device, the air lift device, and the muddy water lift device. It is possible to construct an economical drilling rig while increasing the height.

On the other hand, the pile construction method according to claim 10 of the present invention is a pile construction method for constructing a pile on the ground excavated by using any of the above-mentioned pile construction excavating apparatuses, and for the pile construction The ground is excavated by the outer pipe and the inner pipe constituting the excavator, the soil inside the inner pipe is crushed by the internal crushing means, and the crushed soil is discharged to the ground by the discharging means.
According to such a pile construction method, similarly to the above-described pile construction excavator, the outer pipe and the inner pipe can be continuously excavated, the excavation work can be carried out efficiently, and the construction time can be shortened. Can do.

At this time, in the pile construction method of the present invention, the excavation apparatus for pile construction is configured such that one common drive unit that rotationally drives the outer tube and the inner tube, or the outer tube and the inner tube are independent of each other. And driving the outer tube and the inner tube in the same direction by the one driving unit or the plurality of driving units. It is preferable to excavate the ground or excavate the ground by rotating the outer pipe and the inner pipe in opposite directions.
According to such a configuration, as described above, each of the outer tube and the inner tube can be driven to rotate independently in the same direction or in the opposite direction, thereby increasing the excavation ability and Holes can be drilled even on very hard ground.

Further, in the pile construction method of the present invention, the outer pipe is constituted by a steel pipe pile that constitutes the pile, and after the outer pipe is penetrated into the support layer of the ground, the common drive section or the outer pipe drive section and It is preferable to release the connection.
According to such a configuration, by using the steel pipe pile that supports the structure as an outer pipe, the steel pipe pile driving is completed at the same time as the excavation is completed. Costing can be promoted. That is, after the excavation by the pile construction excavator is completed, the outer pipe is extracted, and after the main pile (such as a steel pipe pile, PC pile, or cast-in-place pile) is placed, However, if the outer pipe is used as a main pile as it is, the labor and time can be saved and the construction cost can be reduced.

Further, in the pile construction method of the present invention, the excavation by the inner pipe is stopped above the support layer, and the outer pipe is excavated from the upper surface of the support layer to a depth not less than the outer diameter dimension of the outer pipe. It is preferable to penetrate the support layer.
Furthermore, in the pile construction method of the present invention, it is preferable that the penetration dimension of the outer pipe into the support layer is set in a range of 2 to 5 times the outer diameter dimension of the outer pipe.
According to such a configuration, the excavation of the inner pipe is stopped above the support layer, and only the outer pipe is excavated into the support layer to penetrate the outer pipe, thereby requiring the support layer and the ground in the vicinity thereof. The tip of the outer pipe can be penetrated into the support layer to a predetermined depth without being roughened as described above, and the tip support force as a steel pipe pile can be reliably obtained.

Further, in the pile construction method of the present invention, the excavation of the excavated soil by the discharging means is stopped before the completion of the excavation of the outer pipe, and the outer diameter of the outer pipe is more than three times the outer diameter of the outer pipe. It is preferable to leave a soil of depth.
According to such a configuration, the tip of the outer pipe as a steel pipe pile is made to remain in the tip of the outer pipe by leaving the soil having a depth of three times or more the outer diameter of the outer pipe. The tip supporting force can be improved due to the root hardening effect caused by the blocking.

Further, in the pile construction method of the present invention, after the excavation using the pile construction excavator, the outer pipe and the inner pipe are extracted from the excavation hole, and concrete is placed in the excavation hole to form a cast-in-place pile. Alternatively, an embedded pile may be constructed by burying an existing concrete pile or a steel pipe pile in the excavation hole.
According to such a structure, the excavation hole for cast-in-place pile construction or the excavation hole for embedding an embedded pile can be excavated for a short time and at low cost using the excavation apparatus for pile construction. In this case, since the outer tube is also extracted from the excavation hole after completion of excavation, the outer tube can be used many times.

  According to the excavation apparatus for pile construction and the pile construction method of the present invention as described above, the excavation work can be efficiently carried out by continuously excavating the excavated soil, and the construction time can be shortened. With the double pipe, even a hard ground portion can be drilled with a relatively low torque, and an increase in the size of the excavator and an increase in manufacturing cost can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an excavation apparatus for pile construction according to an embodiment of the present invention. FIG. 2 is a perspective view showing a main part in the excavation apparatus for pile construction. FIG. 3 is a cross-sectional view showing an inner pipe in a pile construction excavator. FIG. 4 is a cross-sectional view illustrating a pile construction method using the pile construction excavation apparatus.
1 and 2, the excavation apparatus for pile construction includes a biaxial donut auger 1 as a common drive unit supported by a pile driving machine M so as to be slidable up and down, and rotation outside the biaxial donut auger 1. An outer steel pipe 2 as an outer pipe supported by the part support part, a rod 3 supported by a rotating part support part inside the biaxial donut auger 1 and inserted into the outer steel pipe 2, An inner steel pipe 4 as an inner pipe fixed to the tip end portion is provided.
Here, in the present embodiment, the outer steel pipe 2 and the inner steel pipe 4 are rotationally driven independently. That is, the outer steel pipe 2 and the inner steel pipe 4 are arbitrarily rotated / stopped and rotated (in the same direction or in the reverse direction). A biaxial donut auger 1 that can be driven and controlled is used as a common drive unit. As the configuration of this common drive unit, for example, it has an outer drive shaft connected to a drive source such as a motor, and an inner drive shaft connected to the outer drive shaft via a gear or the like. The outer steel pipe 2 can be rotationally driven by a rotational driving force, and the inner steel pipe 4 can be rotationally driven by rotating the inner drive shaft via a gear or the like.

The driving means for rotationally driving the outer steel pipe 2 and the inner steel pipe 4 may be those having an outer pipe driving section and an inner pipe driving section for independently driving the outer steel pipe 2 and the inner steel pipe 4 to rotate. Good. As such a driving means, for example, the outer steel pipe 2 is rotated in one direction by using an all-around turning machine or the like for the outer pipe driving section, and a three-point pile driving machine or the like is used for the inner pipe driving section. The inner steel pipe 4 can be rotated in one direction or the opposite direction as required, and the outer steel pipe 2 and the inner steel pipe 4 can be gripped independently and freely rotated in the same or opposite direction. A biaxial donut auger or the like having a driving unit (an outer tube driving unit and an inner tube driving unit) can be employed. Further, in addition to the outer tube drive unit and the inner tube drive unit, a drive unit having a third drive unit may be used. As this drive unit, for example, an all-around swirler that rotates the outer steel pipe 2 in one direction. And the like, and a two-axis donut auger or the like having two drive parts that can independently rotate the inner steel pipe 4 and the rod 3 and rotate freely in the same or opposite directions. The inner tube drive unit and the third drive unit may be used. And it is possible to move the outer side steel pipe 2 and the inner side steel pipe 4 up and down relatively by using each structure as mentioned above.
Further, as the driving means, it is preferable that the rotation of the outer steel pipe 2 and the inner steel pipe 4 can be controlled in independent directions (the same and the reverse can be freely performed), but the same without rotation control in the independent directions. It may be of a type that is rotationally driven only in a predetermined direction of either the direction or the reverse direction. However, in order to pulverize a clot or rock, it is effective means to apply a shearing force. By rotating the outer steel pipe 2 and the inner steel pipe 4 in the same direction and in the opposite direction as needed, the clot or It is possible to apply a shearing force to the rock.

  Excavation bits 2A and 4A are provided at the respective tips of the outer steel pipe 2 and the inner steel pipe 4, and the two-axis donuts are arranged so that the rotation directions of the outer steel pipe 2 and the inner steel pipe 4 are opposite to each other. The outer steel pipe 2 and the inner steel pipe 4 penetrate into the ground G and are excavated by being rotationally driven and press-fitted by the auger 1. And the front-end | tip of the rod 3 is connected with the inner surface of the upper end part of the inner side steel pipe 4 via the connection support part 3A, and the helical screw 3B is provided in the outer periphery along the axial direction of the rod 3. . The screw 3B is a screw device that transports the excavated soil from below to above as the rod 3 rotates, and the rod 3 having such a screw 3B constitutes the soil discharging means in the present embodiment. Further, the biaxial donut auger 1 is provided with a hopper 1A for discharging the soil conveyed by the screw 3B to the outside.

  Next, as shown in FIG. 3, the inner steel pipe 4 is provided with a plurality of crushing bits 4B provided so as to protrude from the inner peripheral surface thereof, and the crushing bits 4B serve as internal crushing means in the present embodiment. It is configured. The plurality of crushing bits 4B form a spiral bit string arranged in a spiral, and this spiral bit string is taken into the inner steel pipe 4 in the same arrangement direction as the screw 3B of the rod 3, that is, as the rod 3 rotates. It is lined up in the direction to transport the mud. The interval between the pulverization bits 4B is preferably set to about three times the particle size of the target ground to be excavated, but by providing a large number of pulverization bits 4B, the crushability of the taken-up mass improves. Therefore, the interval between the pulverization bits 4B may be close to about 1 time the particle size of the target ground to be excavated. The excavation bit 4A at the tip of the inner steel pipe 4 and the pulverization bit 4B on the inner peripheral surface are preferably made of carbide bits so that they can withstand repeated use. The inner steel pipe 4 can be welded, brazed, or the like. It is attached.

  Such an inner steel pipe 4 is rotationally press-fitted through the rod 3 by driving the biaxial donut auger 1 to excavate the ground G into a core shape with the excavating bit 4A and take in the clot inside. The taken-up mass is pulverized finely with the pulverization bit 4B. The crushed soil is conveyed upward by the screw 3B and discharged from the hopper 1A. Moreover, the connection support part 3A of the rod 3 and the inner steel pipe 4 is composed of a cross-shaped column extending in four directions from the tip of the rod 3, and is difficult to prevent the movement of the crushed soil mass. In addition, as the connection support part 3A, it may be configured by struts or the like arranged in a staggered manner with different positions in the height direction, and a form in which the resistance is further reduced with respect to the rising of the crushed soil mass.

Next, an excavation procedure using the excavation apparatus for pile construction according to the present embodiment will be described.
Here, as the ground G excavated by the pile construction excavator, as shown in FIGS. 1 and 4, a relatively soft first soft layer G1 containing a lot of sand and clay from the ground surface side, 1 relatively soft intermediate layer G2 containing a lot of gravel and the like located below the soft layer G1, a relatively soft second soft layer G3 located below the intermediate layer G2, and a second soft layer It is assumed that it is composed of a hard support layer G4 made of gravel, bedrock or the like located below the layer G3.

As an excavation procedure, first, in order to connect the outer steel pipe 2 and the rod 3 to which the inner steel pipe 4 is connected to the biaxial donut auger 1, the crane is once lifted, and the inner steel pipe 4 and After inserting the rods 3, these rods 3 and the outer steel pipe 2 are respectively mounted on the inner and outer rotation support portions of the biaxial donut auger 1.
Next, after the tips of the outer steel pipe 2 and the inner steel pipe 4 are set at the excavation position, the outer steel pipe 2 and the rod 3 are rotated in the opposite directions and pushed down by the biaxial donut auger 1 respectively, and the outer steel pipe 2 and the inner steel pipe 2 are pushed down. The ground G is excavated using the excavation bits 2A and 4A at the tip of the steel pipe 4, and the outer steel pipe 2 and the inner steel pipe 4 are penetrated into the first soft layer G1, the intermediate layer G2, and the second soft layer G3.
During this penetration, the excavated soil lump that has entered the inside of the inner steel pipe 4 is sent to the upper screw 3B while being crushed by the crushing bit 4B of the inner steel pipe 4, and the crushed earth is conveyed upward by the screw 3B. , Discharged from the hopper 1A to the outside.

  Next, if it is detected that the tips of the outer steel pipe 2 and the inner steel pipe 4 have reached the support layer G4 based on the torque value of the biaxial donut auger 1, as shown in FIG. Is stopped above the support layer G4, the rotation and press-fitting of the rod 3 by the biaxial donut auger 1 are stopped, and the earth removal by the screw 3B is also stopped. Then, the rotation and press-fitting of the outer steel pipe 2 are continued with the biaxial donut auger 1, and the support layer G4 is excavated by the excavating bit 2A at the distal end of the outer steel pipe 2, and the distal end of the outer steel pipe 2 is penetrated into the support layer G4. . Here, it is preferable that the penetration depth to the support layer G4 at the distal end of the outer steel pipe 2 is a depth dimension (for example, about four times) twice to five times the outer diameter dimension of the outer steel pipe 2. Then, as described above, the earth removal is stopped by stopping the rotation of the inner steel pipe 4, thereby leaving a core-like soil mass inside the outer steel pipe 2. It is preferable that the height dimension from the front end of the outer steel pipe 2 of the soil block to remain is at least three times the outer diameter dimension of the outer steel pipe 2. When the pile head of the outer steel pipe 2 is penetrated below the surface of the ground G, the outer steel pipe 2 and the biaxial donut auger 1 are once separated at a position corresponding to the depth, and the outer steel pipe 2 After connecting a connecting jig (not shown) such as a yatco between the pile head and the biaxial donut auger 1, the outer steel pipe 2 is rotated and press-fitted through this connecting jig to a predetermined depth. It may penetrate.

  After the front end of the outer steel pipe 2 is inserted into the support layer G4 as described above, the outer steel pipe 2 is separated from the biaxial donut auger 1 (or a connecting jig such as a Yatsuko), and together with the inner steel pipe 4 and the rod 3 The biaxial donut auger 1 is raised and the inner steel pipe 4 and the rod 3 are extracted from the outer steel pipe 2. In addition, when using the biaxial donut auger 1 which cannot drive the outer steel pipe 2 and the rod 3 independently, before the tip of the outer steel pipe 2 is rooted in the support layer G4, the inner steel pipe 4 and the rod 3 may be extracted from the outer steel pipe 2, and the outer steel pipe 2 may be inserted into the support layer G4. And, in order to use the outer steel pipe 2 as a steel pipe pile of the main construction, the pile head portion is post-treated, and the pile driving machine M is moved to the next excavation position together with the inner steel pipe 4 and the rod 3, or the inner steel pipe 4 and the rod 3 are removed from the biaxial donut auger 1 to complete the pile construction work.

In addition, as the inner side steel pipe 4, not only the form mentioned above but various forms as shown in the following FIGS. 5-7 are applicable.
In the inner steel pipe 4 shown in FIG. 5, a plurality of pulverization bits 4B are formed in a single-stage bit string arranged in the circumferential direction, and the internal pulverization means is constituted by this bit string. These crushing bits 4B are preferably fixed about 1 time above the diameter from the tip of the inner steel pipe 4, but may be changed according to the gravel diameter of the target ground to be excavated. Note that the bit string of the pulverization bit 4B is not limited to a one-stage one, and may be provided in a plurality of stages. Further, the internal crushing means provided on the inner peripheral surface of the inner steel pipe 4 is not limited to the one in which the plurality of crushing bits 4B are arranged in a row as described above, and has at least one crushing bit 4B. What is necessary is just to be made, and the thing by which the some grinding | pulverization bit 4B was arrange | positioned at random may be used.

Further, in the inner steel pipe 4 shown in FIG. 6, a plurality of crushing bits 4C are provided on the connecting support portion 3A with the rod 3 located inside thereof, and the crushing bits 4C constitute a connecting portion crushing means. Yes. The pulverization bit 4C is fixed downward from the connection support portion 3A, and is configured to pulverize the core-shaped soil mass that is taken into the inner steel pipe 4 and rises before the screw 3B.
Furthermore, the inner steel pipe 4 shown in FIG. 7 is provided with a spiral bit string composed of a plurality of pulverization bits 4D arranged in a spiral on the outer peripheral surface thereof, and the spiral bit string constitutes external pulverization means. These crushing bits 4D are configured to crush the soil that has entered between the inner steel pipe 4 and the outer steel pipe 2. The external crushing means is not limited to a plurality of crushing bits 4D arranged in a spiral shape, and may be composed of at least one bit string arranged in the circumferential direction, or one crushing bit 4D or random It may be composed of a plurality of crushing bits 4C arranged in
On the other hand, also as the outer steel pipe 2, a form as shown in the following FIG. 8 is applicable.
In the outer steel pipe 2 shown in FIG. 8, a plurality of crushing bits 2B are provided on the inner peripheral surface facing the inner steel pipe 4 in the vicinity of the tip, and the crushing bits 2B allow the inner steel pipe 4 and the outer steel pipe 2 to be connected. It is configured to crush the soil that has entered between.

According to this embodiment, there are the following effects.
(1) That is, the ground G is excavated by the outer steel pipe 2 and the inner steel pipe 4 that are rotated and press-fitted by the biaxial donut auger 1, and the excavated excavated soil is transported to the ground by the screw 3B and discharged from the hopper 1A. Thus, excavation of the outer steel pipe 2 and the inner steel pipe 4 by the excavation bits 2A and 4A can be continuously performed, and excavation work can be efficiently performed to shorten the construction time.

(2) Further, the inner steel pipe 4 is provided with a crushing bit 4B as an internal crushing means. By crushing the earth lump taken into the inner steel pipe 4 with this crushing bit 4B, the core-like earth lump is made finer and the screw 3B. The excavation work can be made faster and the excavation work can be speeded up. Similarly, when the inner steel pipe 4 is provided with the pulverization bit 4C as the connecting portion pulverization means and the pulverization bit 4D as the outer pulverization means, the inner steel pipe 4 is provided between the inner and inner steel pipes 4 and the outer steel pipe 2. It can be easily crushed by removing the soil. Furthermore, when the crushing bit 2B is provided on the inner peripheral surface of the outer steel pipe 2, the soil between the inner steel pipe 4 and the outer steel pipe 2 can be easily crushed.

(3) Further, by excavating the ground G with a double pipe comprising the outer steel pipe 2 and the inner steel pipe 4 provided with the excavating bits 2A and 4A at the respective ends, relatively low torque can be obtained even in a hard ground portion. It is possible to excavate, and an increase in the size of the excavator and an increase in manufacturing cost can be prevented. Furthermore, by excavating by rotating the outer steel pipe 2 and the inner steel pipe 4 in mutually opposite rotation directions, even a very hard ground such as a rock can be excavated at high speed.

(4) When the support layer G4 is reached, the rotary press-fitting of the inner steel pipe 4 is stopped, and only the outer steel pipe 2 is penetrated into the support layer G4 by a predetermined depth, thereby making the outer steel pipe 2 a steel pipe pile for permanent installation. It is possible to secure the depth of penetration when using it and to obtain the supporting force with certainty. At this time, the tip of the steel pipe pile can be closed by leaving a core-shaped soil block of a predetermined height in the inside of the tip of the outer steel pipe 2, and the tip support force can be improved by the rooting effect by the blockage. it can.

(5) Furthermore, by using the outer steel pipe 2 as a steel pipe pile for main construction, the placement of the steel pipe pile will be completed at the same time as the completion of excavation, and the shortening of construction time and cost reduction of the pile construction will be promoted. Can do.

In addition, this invention is not limited to the said embodiment, Including other structures etc. which can achieve the objective of this invention, the deformation | transformation etc. which are shown below are also contained in this invention.
For example, in the above-described embodiment, only the outer steel pipe 2 is penetrated into the support layer G4 by a predetermined depth and used as a steel pipe pile for permanent installation. However, the present invention is not limited to this application, and the excavation apparatus for pile construction according to the present invention is used. It may be used for the construction of cast-in-place concrete piles, or for the construction of embedded piles such as precast concrete piles or steel pipe piles. Moreover, in the said embodiment, although the earth discharging means was comprised with the screw 3B provided in the rod 3, it is not restricted to this, You may use the earth discharging means as shown in the following FIG.

FIG. 9 shows a pile construction excavation apparatus according to a modification of the present invention.
In this modification, the structure of the soil discharging means is different from that in the above embodiment. Specifically, the excavation apparatus for pile construction shown in FIG. 9 includes an air lift device that sucks excavated soil inside the outer steel pipe 2 and the inner steel pipe 4 through the inside of the rod 3 and constitutes a soil discharging means. This air lift device includes an air pump (not shown) provided in a biaxial donut auger 1, a hollow cylindrical rod 3 connected to the air pump, and a discharge unit 1B that discharges excavated soil sucked up by the rod 3 to the outside. And is configured. Here, the soil discharging means is not limited to the air lift device, but may be a muddy water lift device that sucks excavated soil through the inside of the rod 3 together with the water supplied to the inside of the outer steel pipe 2.

  Moreover, in the excavation apparatus for pile construction of FIG. 9, not only the outer steel pipe 2 penetrates into the support layer G4 as in the above embodiment, but both the outer steel pipe 2 and the inner steel pipe 4 penetrate into the support layer G4. The point which forms a drilling hole is different from the said embodiment. That is, in the pile construction method in FIG. 9, after excavating the support layer G4 to a predetermined depth to form an excavation hole, both the outer steel pipe 2 and the inner steel pipe 4 are extracted from the excavation hole, and concrete is poured into the excavation hole. The cast-in-place piles are constructed to install them, or the built-in piles are constructed by embedding existing concrete piles or steel pipe piles in the excavation holes. Thus, if the excavation apparatus for pile construction of this invention is used, the excavation hole for embedding a cast-in-place pile or the excavation hole for embedding an embedded pile can be excavated in a short time and at low cost. In this case, since the outer steel pipe 2 is also extracted from the excavation hole after completion of excavation, the outer steel pipe 2 can be used many times.

  In the above-described embodiment, the example in which the pulverization bit 4B as the internal pulverization unit, the pulverization bit 4C as the coupling unit pulverization unit, and the pulverization bit 4D as the external pulverization unit are provided separately on the inner steel pipe 4 is described. These internal pulverizing means, connecting part pulverizing means and external pulverizing means may be appropriately selected and used in combination. Furthermore, the pulverization bit 2B provided on the inner peripheral surface of the outer steel pipe 2 as shown in FIG. 8 and the internal pulverization means, the connecting part pulverization means, and the external pulverization means of the inner steel pipe 4 can be used together as appropriate.

In addition, Fig. 10 shows the construction torque and pressure input showing the construction load when conducting an experiment in which a steel pipe pile with a drill bit at the tip is rotated on a solid ground such as a support layer. , The amount of penetration rapidly rises about 3 times the outer diameter of the steel pipe. Furthermore, as shown in FIG. 11, in order to investigate the degree of blockage by the soil taken into the pipe at the tip of the steel pipe, a test was conducted to push out the pipe soil for each penetration amount. This is because the model steel pipe pile 5 provided with a drilling bit at the tip is press-fitted several times the outer diameter of the model steel pipe pile 5 into the model ground having the same hardness as the ground actually used as the support layer. Then, the model steel pipe pile 5 is pulled out from the model ground, and the pipe soil 5 that is the part of the model ground taken inside the tip end portion of the model steel pipe pile 5 is pressed against the cradle 7, and the model steel pipe pile 5 is directed toward the cradle 7. This is a test in which a loading load F is applied to the pipe soil 6 to push it out. The part of the model ground taken inside the tip end of the model steel pipe pile 5 will be called closed soil. As shown in FIG. 12, the result shows a tendency similar to the construction torque shown in FIG. 10, and the punching resistance value increases rapidly when the penetration amount is about three times the outer diameter of the steel pipe. From this experimental result, the inner steel pipe used in the present invention is particularly suitable when the earth lump and the inner steel pipe 4 are liable to co-rotate and it is difficult to crush the earth lump with the crushing bit 4B. By making the length of 4 within 3 times the outer diameter of the inner steel pipe 4, it is possible to prevent the inner steel pipe 4 from being blocked, and to suppress an increase in the construction load.
The experimental results shown in FIGS. 10 and 12 are the results of an experiment using a single tube instead of a double tube. Regarding the blockage in the tube, only the relationship between the soil mass entering the inside of the tube and the inner surface of the tube is shown. Therefore, there is no effect on the test results regardless of whether the tube is a double tube or a single tube.

In addition, the best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described with particular reference to certain specific embodiments, but without departing from the spirit and scope of the invention, Various modifications can be made by those skilled in the art in terms of material, quantity, and other detailed configurations.
Therefore, the description limiting the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

It is sectional drawing which shows the excavation apparatus for pile construction which concerns on embodiment of this invention. It is a perspective view which shows the principal part in the said excavation apparatus for pile construction. It is sectional drawing which shows the inner side pipe in the said excavation apparatus for pile construction. It is sectional drawing which shows the construction method of the pile using the said excavation apparatus for pile construction. It is sectional drawing which shows the modification of the said inner side pipe | tube. It is sectional drawing which shows the modification of the said inner side pipe | tube. It is a perspective view which shows the modification of the said inner side pipe | tube. It is sectional drawing which shows the modification of the said excavation apparatus for pile construction. It is sectional drawing which shows the construction method of the pile which concerns on the modification of this invention. It is the graph which showed the relationship of the magnification with respect to the pile diameter of the penetration amount of the steel pipe pile with respect to the torque and pressure input which show construction load. It is a figure explaining the condition of a model test. It is the graph which showed the relationship between the punching resistance of a model test result, and the magnification with respect to the pile diameter of the penetration amount of a model steel pipe pile.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Biaxial donut auger as a common drive part, 2 ... Outer steel pipe as an outer pipe, 2A ... Excavation bit, 2B ... Grinding bit, 3 ... Rod, 3A ... Connection support part, 3B ... Screw, 4 ... Inside Inner steel pipe as pipe, 4A ... excavation bit, 4B ... crushing bit as internal crushing means, 4C ... crushing bit as connecting part crushing means, 4D ... crushing bit as external crushing means, 5 ... model steel pipe pile, 6 ... inner soil, 7 ... cradle, G ... ground, G4 ... support layer.

Claims (16)

A pile construction excavator for excavating the ground when constructing a pile,
An outer tube having a drilling bit at the tip and being driven to rotate; an inner tube provided inside the outer tube and having a drilling bit at the tip and being driven to rotate; and the inside of the outer tube and the And a discharge means provided above the inner pipe and discharging the excavated soil to the ground,
The excavation apparatus for pile construction characterized in that the inner pipe has an internal crushing means for crushing the soil inside the inner pipe. In the pile construction excavation device according to claim 1,
The pile digging apparatus according to claim 1, wherein the internal crushing means includes at least one bit provided on an inner peripheral surface of the inner pipe. In the excavation apparatus for pile construction according to claim 2,
Bits on the inner peripheral surface of the inner tube are in the form of either at least one bit row arranged in the circumferential direction on the inner peripheral surface or a spiral bit sequence arranged in a plurality of spirals on the inner peripheral surface. Excavator for pile construction characterized by being configured. In the pile construction excavation device according to any one of claims 1 to 3,
The inner tube is configured to include a connecting portion that is connected to an upper portion of the inner tube and rotationally supports the inner tube, and a connecting portion crushing means provided in the connecting portion. Drilling equipment for pile construction. In the excavation apparatus for pile construction according to any one of claims 1 to 4,
The inner pipe is configured to have external crushing means for crushing the soil between the inner pipe and the outer pipe,
The pile digging apparatus characterized in that the external crushing means has at least one bit provided on the outer peripheral surface of the inner pipe. In the excavation apparatus for pile construction according to claim 5,
The bits on the outer peripheral surface of the inner tube are configured in a row form of at least one bit row arranged in the circumferential direction on the outer peripheral surface or a spiral bit row arranged in a plurality of spirals on the outer peripheral surface. Excavator for pile construction, characterized by In the pile construction excavation apparatus according to any one of claims 1 to 6,
At least one bit for pulverizing soil between the inner pipe and the inner peripheral surface of the outer pipe is provided,
The bit on the inner peripheral surface of the outer tube is in the form of either a plurality of bit rows arranged in the circumferential direction on the inner peripheral surface, or a spiral bit sequence arranged in a plurality of spirals on the inner peripheral surface. Excavator for pile construction characterized by being configured. In the excavation apparatus for pile construction according to any one of claims 1 to 7,
One of the common drive unit that rotationally drives the outer tube and the inner tube, or the outer tube drive unit and the inner tube drive unit that independently rotate and drive the outer tube and the inner tube,
The excavation apparatus for pile construction, wherein the outer tube and the inner tube are rotationally driven in the same direction or independent directions by the one driving unit or the plurality of driving units. The excavation apparatus for pile construction according to claim 8,
The discharging means includes a screw device that conveys excavated soil upward by rotation of a screw provided on an outer periphery of a rod that connects the inner tube and the common drive unit or the inner tube drive unit, and excavated soil through the inside of the rod. A pile construction drilling device comprising: an air lift device for sucking up excavation soil and a mud lift device for sucking up excavated soil through the inside of the rod together with water supplied to the inside of the outer pipe. A pile construction method for constructing a pile on the ground excavated using the excavation apparatus for pile construction according to any one of claims 1 to 9,
The ground is excavated by the outer pipe and the inner pipe constituting the excavation apparatus for pile construction, the soil inside the inner pipe is crushed by the internal crushing means, and the crushed soil is discharged to the ground by the discharging means. Pile construction method. In the construction method of the pile of Claim 10,
The pile construction excavator includes a common drive unit that rotationally drives the outer tube and the inner tube, or an outer tube drive unit and an inner tube drive that independently rotate and drive the outer tube and the inner tube, respectively. Department,
The outer tube and the inner tube are driven to rotate in the same direction by the one driving unit or the plurality of driving units to excavate the ground, or the outer tube and the inner tube are reversed to each other. A pile construction method characterized by excavating the ground by rotating. In the construction method of the pile of Claim 11,
Pile characterized in that the outer pipe is composed of a steel pipe pile constituting the pile, and the connection with the common drive part or the outer pipe drive part is released after the outer pipe penetrates into the support layer of the ground. Construction method. In the construction method of the pile of Claim 12,
The excavation by the inner pipe is stopped above the support layer, and a depth equal to or larger than the outer diameter of the outer pipe is excavated from the upper surface of the support layer by the outer pipe and penetrated into the support layer. Pile construction method. In the construction method of the pile according to claim 12 or claim 13,
The method for constructing a pile, wherein a penetration dimension of the outer pipe into the support layer is set in a range of 2 to 5 times an outer diameter dimension of the outer pipe. In the construction method of the pile in any one of Claims 12-14,
Before the completion of excavation of the outer pipe, discharging of the excavated soil by the discharging means is stopped, and soil having a depth of three times or more of the outer diameter of the outer pipe is left inside the tip of the outer pipe. Pile construction method. In the construction method of the pile according to claim 10 or claim 11,
After excavating using the excavator for pile construction, the outer pipe and the inner pipe are pulled out from the excavation hole, and a cast-in-place pile is formed by placing concrete in the excavation hole, or an existing concrete pile in the excavation hole Or the construction method of a pile characterized by embedding a steel pipe pile and constructing an embedded pile.

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