JP2002322891A - Excavation method and rock bit used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excavation method for confirming the prescribed fixing layer ground of a rock anchor, and seizing a trend of underground water in the excavation method for waterlessly excavating a hole for burying an anchor tendon and an anchor bolt in an unstable slope (the landslide danger ground). SOLUTION: Excavation is waterlessly performed by discharging high pressure air without using water as a muck discharge fluid by using a compaction bit for arranging a hard blade body, a high pressure air discharge port, and a muck groove being a passage of muck in a head part having a head part outer diameter larger than an outer diameter of a wear sleeve of a down-the-hole drill as a rock bit. Density of an inner wall part of an excavated hole is improved by compacting the muck generated by the excavation to a hole wall in an outer peripheral part of the bit by longitudinally reciprocating the compaction bit in the hole every time when excavating the prescribed length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavation method suitable for excavating a burial hole for burying an anchor material such as an uncurtain don for the purpose of disaster prevention in an unstable slope portion of a mountainous ground including a sediment layer, and a method for the same. This relates to the lock bit to be used.

[0002]

2. Description of the Related Art An anchor material is buried in a hole excavated on a slope, and cement milk is injected and solidified around the hole, as a method of reinforcing an unstable ground having a high rate of occurrence of landslides such as a slope of a mountain area. Reinforcing methods for fixing are widely used.

[0003] A drilling device conventionally used for drilling the hole for burying the anchor material is to mount a guide cell on a vehicle body such as a crawler or a base constructed by combining steel materials, and mount a rock drill on the guide cell. It was a large device. Further, in the above-mentioned conventional excavation method, in order to prevent seizure at the time of excavation of a fixed layer of a bedrock or the like that exerts the effect of a target anchor, water-feeding excavation is performed, and excavation waste is discharged using the water.

[0004]

However, in the above-mentioned conventional excavation method, since a large amount of water is used for excavation, there is a problem that the ground around the excavated hole is loosened. However, there is a problem that the anchor material cannot be buried and cement milk cannot be completely injected. For this reason, it became necessary to embed the casing tube secondarily to hold the hole wall.

Further, if water is used during excavation, it is impossible to grasp the trend of groundwater on the working ground at all. Therefore, when cement milk is injected without confirming the pressurized groundwater, the cement milk is diluted and the anchor body is formed. However, there is a problem that the required strength is not obtained, and as a result, the required tension load is reduced, and the purpose of slope disaster prevention cannot be achieved.

Further, there is another problem that it is difficult to confirm the geological conditions of the anchoring layer which is most important for rock anchors for mountain slope disaster prevention by using water at the time of excavation. Without confirming the geological conditions of this anchorage layer,
If the lock anchor is fixed in a place where the geology is not solid at the time of the initial design, it is naturally dangerous because the necessary tension load cannot be secured. Therefore, the present invention
By performing "waterless drilling", it is possible to confirm the anchored layer (solid geology such as bedrock), which is the life of the permanent anchor, to grasp the trend of groundwater, and to construct a reliable permanent anchor, By reusing the resulting shears to consolidate the hole wall and reduce the void fraction around the borehole,
It is an object to prevent collapse of a hole wall.

[0007]

In order to solve the above problems, the present invention employs the following configuration. That is, the excavation method according to the present invention is an excavation method for excavating a hole for anchor material burying or the like using a down-the-hole type excavator in unstable ground, and a head outer diameter is used as a lock bit of the excavator. Is larger than the outer diameter of the wear sleeve, using a lock bit provided with a hard blade, a high-pressure air discharge port and a slip groove serving as a slip passage in the head, without using water as a slip discharge fluid, While performing anhydrous drilling while discharging high-pressure air, every time a predetermined length of drilling, the rock bit is reciprocated back and forth while rotating the lock bit in the drilled hole, and the slip generated by the drilling is removed at the outer peripheral portion of the bit. It is characterized in that the density of the inner wall portion of the drilled hole is improved by compacting the hole on the hole wall.

Further, a lock bit suitable for use in this excavation method includes a blade of a carbide tip on a head of a steel base, a discharge port for high-pressure air for discharging a shear, and a lock bit for rearward of the shear. In a down-the-hole type lock bit provided with a slip groove serving as a moving passage, a plurality of carbide tips acting to press and fix a slip generated by excavation to a hole wall formed by the excavation are provided on an outer peripheral portion of the head. It is characterized in that it is juxtaposed with its position shifted in the front-rear direction and the circumferential direction.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically based on embodiments of the present invention shown in the drawings.

FIG. 1 illustrates an excavator used in the excavation method of the present invention. In the excavator 1, a guide cell 3 is mounted on a gantry 2, and a rotary drive unit 5 is moved back and forth on the guide cell 3. Mounted freely. A feed device (feed motor in the illustrated example) 10 is provided in the guide cell 3, and the rotary drive device 5 is moved forward and backward by the feed device.

High-pressure air supplied through a hose 21 from a compressor 20 installed at a good location off the excavation site is introduced into a hollow portion of a rotary output shaft 14 of a rotary drive device via a swivel device 15. . 23 in the figure
Is an air controller for adjusting the flow rate of high-pressure air according to the soil. In addition, the rotation drive device 5 uses a generator 25 installed in a good place on the earth as a power source.

The control device 30 remotely controls the rotary drive device 5 and the feed device 10.
2. Operation means such as a feed control knob 33, a rotation direction changeover switch 35, and a rotation control knob 36 are provided, and by appropriately operating these, the rotation direction and rotation speed of the rotation driving device 5 and the feed speed are controlled. The feed direction and feed speed of the device can be freely controlled.

A hollow rod 40 is connected to the output shaft 14 of the rotary driving device 5, and a down-the-hole type drill 50 is connected to the hollow rod 40. These connections are made with screw joints 42.

A down-the-hole (sometimes referred to as "down-hole") drill 50 is known in the art,
As shown in FIG. 4, a cylinder 52 is provided inside a wear sleeve 51, and a piston 53 is provided in the cylinder so as to be movable back and forth (up and down in the figure). A chuck 54 is provided at the front end of the wear sleeve 51, and the lock bit (referred to as a "consolidation bit") 5 is provided by the chuck.
5 is held movably back and forth. 56 is a retaining ring.

A valve 6 is provided at the rear end of the wear sleeve 51.
0 is provided. The base of the valve 60 is held in a concave portion of the distributor 61, and is urged by a spring 62 in a direction to close the air discharge port 64 of the back head 63. When high-pressure air is supplied from the back of the back head 63, the valve 60 is pushed down by the high-pressure air to open the air flow passage. The high-pressure air passes through the passage of the distributor 61, passes between the wear sleeve 51 and the cylinder 52, and is supplied to an air chamber 66 formed on the outer periphery of the piston.
Is supplied to the rear chamber 67 on the rear side and the front chamber 68 on the front side of the piston, and a striking cycle is started.

When the lock bit (consolidation bit) 55 and the piston 53 are lowered to the lowest position, the blow port 69 of the cylinder 52 is opened, and high-pressure air is discharged from the discharge port of the consolidation bit 55 through the blow port through the piston. You. As the drill is lowered, the consolidation bit 55 hits the ground and is pushed up to the shoulder of the chuck 54, and the piston 53 is also pushed up by the bit. Then
The high-pressure air in the air chamber 66 flows into the front chamber 68 through the vertical groove of the piston and the undercut of the wear sleeve 51. This air pressure causes the piston to rise rapidly.

When the piston 53 rises, the inflow port to the front chamber 68 is closed, but the piston continues to rise due to the expansion of the high-pressure air in the air chamber 66 and the inertial force. The air in the rear chamber 67 is compressed by the rise of the piston, and the air chamber 6 is compressed.
The high-pressure air flows into the rear chamber 67 through the undercut portions of the cylinder and the piston. For this reason,
The rise of the piston 53 stops, and the impact energy is accumulated. The air in the front chamber 68 is exhausted through the discharge port of the compaction bit 55.

Next, due to the expansion of the compressed air in the rear chamber 67, the piston 53 suddenly descends (advances) and strikes the compaction bit 55. At this time, when the descending piston comes out of the stem of the distributor, the air in the rear chamber is discharged from the air discharge port at the tip through the passage inside the piston 53 and the inside of the compaction bit. The piston 53 striking the compaction bit retreats slightly by the recoil, and air flows into the front chamber 68. Therefore, the piston moves up, and the same cycle is repeated thereafter.

As shown in FIGS. 2 and 3, the consolidation bit 55 has a tip surface 71 of the head 70 and an inclined surface 7 around the tip surface.
2, a plurality of button tips (hard metal tips) 75,... Are implanted as hard blades. Further, a plurality of forward and backward slip grooves 76,... Are formed in the outer peripheral portion of the head. The slip groove 76 is for moving the slip (milling) generated by excavation from the tip of the bit to the rear. Further, in the head end surface 71, discharge ports 79, 7 of ventilation holes 78, 78 branched from the hollow portion 77 of the consolidation bit.
9 is open. A pair of exhaust grooves 80, 8 extending from the positions of the discharge ports 79, 79 to the diametrically opposed shear grooves 76 (A, B) are formed on the front end face 71 of the compacted bit.
0 is formed.

A spline 81 for transmitting rotation is formed in the outer periphery of the body of the compaction bit 55, and the hollow portion 77 serving as an air passage is formed in the core thereof. An engagement recess 83 formed by cutting out the spline is formed at the rear portion of the body, and an air pipe 84 is inserted at the rear end. A retaining ring for preventing deviation is engaged with the engaging portion 83. The air pipe 84 fits into the through hole 53 a of the piston 53.

Below the inclined surface 72 of the compaction bit 55, a first outer peripheral surface 85 also called a reaming surface is provided.
And a second outer peripheral surface 86 which is inclined below the outer peripheral surface so as to have a slightly smaller diameter on the lower side. It is formed as a surface 87. Then, the first and second outer peripheral surfaces 85,
A plurality (three on one side in the illustrated example) of consolidation chips 90,...
These consolidation chips 90 are arranged at predetermined intervals along the outer peripheral direction of the bit 55 and the vertical (front-back) direction.
As shown in FIG. 3, they are provided in a shape in which the positions are shifted obliquely in a side view. In the illustrated example, the consolidation tip 9
0,... Are three on each side.
Depending on the size of the chip and the size of the chip itself, the number may be two or four or more.

Further, in the illustrated example, the consolidation tip 90 is provided on the outer peripheral portion of the consolidation bit 55 diametrically opposed, and is not provided on the other outer peripheral portion. This is to effectively discharge the powder when the consolidation bit 55 reaches the bedrock, and may be provided so as to be distributed over the entire outer periphery of the consolidation bit 55 depending on conditions. The inclined surface 87 is provided with retracting tips 91 projecting substantially rearward at appropriate intervals. The retracting tip 91 is for crushing rocks or the like that hinder the retraction of the consolidation bit.

Next, a method of reinforcing a slope by using the excavator 1 will be described. First, a scaffold is set at an excavation position, and the excavator 1 is installed thereon. The compressor 20 and the generator 25 for the drilling rig are installed in a well-placed place, and are connected to the motor and the drill of the drilling rig by hoses and electric wires. The drill 50 is connected to the rotary drive device 5 via a relay rod, and presses the consolidation bit 55 to the excavation position while supplying electric power and compressed air to start excavation. While drilling,
The rotational power of the rotary drive device 5, the thrust by the feed device 10, and the striking force by the piston of the drill 50 are transmitted to the compaction bit. At the same time, high-pressure air (for example, 12 to 24 kg / cm ² ) is supplied from the compressor 20 to the drill 50 via a swivel and a rod. This air is used as a pressure fluid for hitting and a cleaning air for discharging the shear, and is discharged from the discharge port 79 of the compaction bit.

Excavation sites requiring reinforcement usually have a considerable thickness of earth and sand layer formed on the bedrock, in which case the earth and sand layer is excavated for a while after the start of excavation. During excavation of soft ground such as a sediment layer, the inner wall of the excavated hole is extremely brittle, so that collapse starts immediately and the excavated hole is often clogged. To prevent this,
In the method of the present invention, the excavation is temporarily stopped every time excavation by the consolidation bit progresses to a certain extent (for example, 100 to 500 mm), and the feed motor of the feeder 10 is rotated forward and reverse to move the consolidation bit 55 a predetermined distance (newly). (The excavated length). The rotation of the consolidation bit 55 and the discharge of air from the discharge port 79 are continued during this back-and-forth reciprocation (referred to as a “consolidation step”), but the air discharge amount and the rotation speed are finely adjusted depending on the soil properties. .

During the above-mentioned consolidation step, the consolidation bit 55 is not seriously hit and the consolidation bit is not strongly pressed against a new excavation surface. Reinforcement is performed. That is, in the process in which the shear (milled) 102 generated by the excavation is sent rearward (upward) from the bottom of the hole by the air discharged from the consolidation bit 55, the outer peripheral portion of the head of the consolidation bit that continues to rotate at a low speed, particularly The pressed chips 90 are pressed against the hole walls. For this reason, the density of the hole wall is significantly increased, and as a result, the strength of the hole wall is improved, so that collapse is less likely to occur. In other words, high-strength inner wall of the hole is formed by recycling the crushed material generated by excavation.

The reciprocating movement of the compacting bit is, for example, 10
The operation may be performed about 0 to 300 mm a plurality of times, for example, about 3 to 5 times, but an optimum condition may be selected in consideration of the properties and efficiency of the ground. The rotation speed of the compaction bit is 6 when excavating.
0 rpm or more, preferably 65-85 rpm (maximum 10
0 rpm or more), but 60 during reciprocating consolidation.
It is preferable to lower it to less than rpm, for example, about 30 to 55 rpm. In the consolidation step, if the number of rotations of the consolidation bit is too high or too low, it is difficult to obtain a desired consolidation effect. On the other hand, if the air discharge amount is too small, the movement of the slip is not sufficiently performed, and if the air discharge amount is too large, the slip is discharged at a stretch backward, so that a sufficient consolidation effect cannot be obtained. Note that the moving speed of the consolidation bit in the consolidation step in the front-rear direction is a speed at which the shear is firmly pressed against the hole wall by the outer peripheral portion, and has a relationship with the rotation speed, but is generally about several tens cm / min. .

When the consolidation step of the predetermined section is completed, the rotation of the consolidation bit 55 is returned again,
A new excavation is performed by giving a thrust of zero. When this excavation has progressed by the predetermined distance as described above, the process proceeds to the consolidation step again. Thus, the excavation process and the consolidation process are repeated to excavate the earth and sand layer. Drilling progresses,
When the consolidation bit 55 reaches the fixing layer such as a bedrock, normal excavation is performed thereafter, and the consolidation step is omitted.

As shown in FIG. 6 (a), when the excavation of a predetermined depth is completed, the consolidation bit 55 and the rod are pulled out (FIG. 6 (b)), and the hole 101 from which the anchor material 100 such as uncurtain don is excavated. (FIG. 3 (c)). Thereafter, as shown in FIG.
To fix the uncurtain don 100 to the ground. This anchor material is used to strengthen the ground. 6 and 7, 101a denotes a hole wall portion reinforced by a consolidation process, and 103 denotes a bedrock.

In this excavation method, excavation is temporarily stopped every time a predetermined depth is excavated, and the consolidation bit 55 is reciprocated.
Since the consolidation process of pressing and fixing the slip 102 to the hole wall is performed,
The density of the pore wall is improved, and it is difficult to collapse. Conventionally, the excavation of the earth and sand layer has been carried out by using a steel pipe casing tube to hold the hole wall. However, according to this method, it is not necessary to use the casing tube. However, if the N value of the sandy soil is 5 or less, the above-mentioned consolidation step becomes difficult. Therefore, a countermeasure such as using a casing tube is necessary.

Since the waterless excavation method does not use water, the properties of the soil can be grasped in detail. Also,
Since water is not used for excavation, it is possible to know immediately when groundwater springs, etc., and to deal with this. Therefore, unlike the conventional method, it is possible to prevent the uncertain anchor body from being formed by injecting the cement milk without confirming the anchoring layer or checking the soil properties such as spring water and pressurized groundwater. be able to.

In the above description, the excavator is
Although the description has been given of the case where the cradle is supported by a gantry, a crawler type or other digging device may be used in some cases. further,
Although an example in which a button-shaped compacting tip 90 is provided on a part of the outer peripheral portion as a compacting bit is illustrated, the compacting tip is capable of pressing a shear (milling) generated by excavation against the excavated hole wall. Any shape may be used, and the shape of the chip is not limited to the button shape, and may be other shapes. Alternatively, the compacted chips may be provided so as to be distributed over the entire outer periphery of the bit head. Further, in the above example, the hollow rod 40 is a simple cylindrical rod, but as shown in FIG. 8, the hollow rod 4 having the consolidation members 40a,.
It is more effective if 0 'is used and the sealing member also performs sealing of the shear against the inner wall of the hole. The shape of the consolidating member 40a is a shape such as a spatula, which can press the slip against the hole wall well.

[0032]

As is clear from the above description, according to the present invention, the anchoring layer can be easily excavated even on unstable ground such as earth and sand, with a hole for burying anchor material having a strong hole wall. You can check the ground. In addition, since water is not used for excavation, it is relatively safe even on the ground that is easily collapsed, and when a groundwater spring is generated, it can be immediately known and a countermeasure can be taken promptly. For this reason, a disaster resulting from spring water or the like can be effectively prevented. Moreover, the excavator used in the excavation method of the present invention can be made compact and inexpensive as compared with the conventional one, and is convenient and economical in handling and transportation.

[Brief description of the drawings]

FIG. 1 is an external view of a drilling rig used for carrying out the present invention.

FIG. 2A is a front view of the lock bit, and FIG.

FIG. 3 is a side view (c) of a main part of the lock bit.

FIG. 4 is a sectional view of a drill.

FIG. 5 is an enlarged sectional view of a main part thereof.

FIG. 6 is an explanatory diagram of a reinforcing method using the present invention.

FIG. 7 is a sectional view of an excavation site and an AA sectional view thereof.

FIG. 8 is an explanatory view of a use state of a hollow rod with a compaction member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drilling apparatus 3 Guide cell 5 Rotation drive device 10 Feeding device 20 Compressor 25 Generator 30 Control device 40 Hollow rod 50 Drill 55 Consolidation bit (lock bit) 76 Grip groove 79 Discharge port 100 Anchor material 101 Drilling hole 101a Consolidation hole wall 103 Bedrock 105 cement milk

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[Procedure amendment]

[Submission date] August 8, 2002 (2002.8.8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

Further, a lock bit suitable for use in this excavation method includes a blade of a carbide tip on a head of a steel base, a discharge port for high-pressure air for discharging a shear, and a lock bit for rearward of the shear. in down-the-hole lock bits formed by providing a shear groove serving as a moving passage, the same circle as the maximum diameter of the lock bit
The tip is protruded to the circumference , and the compacting carbide tip that acts to press and fix the shear generated by excavation to the hole wall formed by the excavation is dispersed over the entire outer peripheral surface of the head.
2 which are diametrically opposed on the outer peripheral surface of the head
Shift the position in the front and rear direction and the circumferential direction respectively
It is characterized in that a plurality of them are juxtaposed.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

In the illustrated example, the consolidation tip 90 is diametrically opposed to the outer peripheral surface of the head of the consolidation bit 55.
It is provided only in two places, and is not provided in other outer peripheral portions. This is Ru der for performing Kukona discharge when the compaction bit 55 reaches the rock effectively. The inclined surface 87
Are provided with retracting tips 91 projecting substantially rearward at appropriate intervals. This retraction chip 9
Numeral 1 is for crushing rocks or the like that hinder the retraction of the compaction bit.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D029 FA03 FB02 FC03 FD01

Claims (3)

[Claims] 1. An excavation method for digging a hole for burying an anchor material or the like using a down-the-hole type excavator on unstable ground, wherein the outer diameter of the head is outside the wear sleeve as a lock bit of the excavator. Using a lock bit larger than the diameter and provided with a hard blade, a high-pressure air discharge port, and a slip groove serving as a slip passage in the head, and discharging high-pressure air without using water as a slip discharge fluid. Waterless excavation, and every time a predetermined length is excavated, the rock bit is rotated back and forth back and forth in the excavated hole, and the slip generated by the excavation is pressed against the hole wall at the outer peripheral portion of the bit. An excavation method wherein the density of the inner wall portion of the excavated hole is improved by doing so. 2. The excavation method according to claim 1, wherein the rotation speed of the lock bit is set to 60 rpm or more in the excavation step, and set to 20 rpm or more and less than 60 rpm in the consolidation step of compacting the shear against the hole wall. 3. A down-the-hole type having a blade of a carbide tip, a discharge port of high-pressure air for discharging a shear, and a shear groove serving as a passage for moving the shear on the head of a steel base. In the lock bit, a plurality of cemented carbide tips acting to press and fix the slip generated by excavation to the hole wall formed by the excavation are juxtaposed in the outer peripheral portion of the head with the positions shifted in the front-rear direction and the circumferential direction. A lock bit characterized by doing.