JPH07127367A - Core boring method - Google Patents

Abstract

PURPOSE:To recover core efficiently even from bedrock where a big boring torque is applied to a boring rod in boring in a fractured zone. CONSTITUTION:Core is recovered with an inner rod 1 while the bore wall surface is held with an outer rod 2 of a boring machine 20 that is composed of the inner rod 1 equipped with a core tube 4 for recovering the core and the outer rod 2 arranged for surrounding the periphery of the inner rod 1. In the core boring method as mentioned above, the core is recovered from the ground in front of the front end of the outer rod by a preceding boring executed with the inner rod 1 and after recovery of the core, the outer rod 2 is moved forward with strikes applied to the outer rod 2. Such works are repeated alternately and core is recovered from the depth of the bedrock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core boring method using a boring device having an inner rod and an outer rod.

[0002]

2. Description of the Related Art As a geological survey method for investigating the ground condition when constructing a structure such as a tunnel in the ground, sampling by the core boring method has been generally performed. In this core boring method, the ground is drilled, the core is sampled, and the condition of the deep ground is directly observed to confirm the geological distribution, rock quality, groundwater condition, etc.

The core boring method is conventionally carried out by inserting a hollow boring rod having a core sampling mechanism such as a sampler into the ground. That is, a conventional boring device is composed of, for example, a boring rod having a drill bit on the outer circumference of the tip and a drill head connected to the rear part of the rod to give a rotational propulsion motion to the boring rod. And add a rod between the drill head and
Insert the boring rod into the deep ground. Fluid such as compressed water or compressed air is appropriately fed to the inside or outside of the boring rod via a swivel joint, etc., thereby reducing the friction between the boring rod and the surrounding rock and collecting the core. Is facilitated.

[0004]

However, in the core boring method using the above-mentioned conventional boring device, particularly in the case where horizontal boring is carried out in order to investigate the ground ahead, for example, in tunnel construction, the front ground When the mountain is a shatter zone, the boring rod that advances the hole in the shatter zone increases the drilling depth and exerts a large drilling torque to reduce the drilling speed and causes jamming to collect the core. It may be impossible to do so, and it may be possible to hit the boring rod to compensate for the decrease in the drilling speed, but the ground at the tip of the boring rod is disturbed and the core cannot be sampled sufficiently. There is a fear.

It is also possible to use a double pipe composed of an inner rod and an outer rod as the boring rod. However, if the double pipe is simply used, the drilling torque increases due to an increase in the drilling diameter, and rather the drilling is rather performed. There is a risk that the efficiency will decrease.

Therefore, the present invention is intended to solve the above problems, and a core boring method capable of efficiently collecting cores even in natural ground where a large drilling torque is applied to a boring rod such as a crush zone. It is intended to provide.

[0007]

The present invention has been made in order to achieve the above object, and its gist is to cover an inner rod having a core collecting mechanism and an outer circumference of the inner rod. A core boring method of collecting a core with an inner rod while holding a hole wall surface with the outer rod by a boring device having an outer rod to be arranged. Core boring, characterized in that the outer rod is advanced along the inner rod while striking after the core is sampled and the core is sampled while the core is sampled, and the cores are sampled by alternately repeating such work. It is in the construction method.

[0008]

According to the core boring method of the present invention, the inner rod is covered with the outer rod in the drilled hole, and only the tip of the inner rod projects from the outer rod and comes into contact with the outer peripheral ground. Is retained, and the drilling torque when drilling with the inner rod is greatly reduced. Further, when the outer rod is moved forward, it is possible to reduce the drilling torque by striking the outer rod.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a drilling rod constituting a boring device 20 used in this embodiment for core boring on a ground consisting of a crush zone. 1 is an inner rod and 2 is an inner rod. It is an outer rod arranged on the outer periphery of the rod 1.

The inner rod 1 has an internally hollow starting rod 5 having a core bit 3 made of metal, diamond or the like fixed to the tip thereof, and a rear portion of the starting rod 5 which is linearly connected in succession in accordance with the drilling depth. A plurality of relay rods 6 are provided. In the case of a so-called rod collecting method in which rods of all spans are collected and cores are taken out for each drilling of one span, the tip of the starting rod 5 serves as a core collecting mechanism integrated with the core bit 3. Core tube 4 of is connected.
Further, in the case of a so-called wire line recovery method in which only the core tube 4 is recovered via a wire or the like, the core tube 4 having a smaller diameter than this is accommodated inside the starting rod 5 independently of the core bit 3. At the same time, a wire line is connected to the rear end of the wire to extend it to the collection work position at the rear.

The outer rod 2 is set to have an inner diameter capable of covering the inner rod 1 while keeping a predetermined space between the outer rod 2 and the inner rod 1 and an inner hollow starting rod 8 having an outer bit 7 fixed thereto. , A rear part of the starting rod 8 is also provided with a plurality of relay rods 9 which are sequentially added linearly according to the drilling depth,
The rearmost parts of the rods 1 and 2 described above are provided at the recovery work position, and the boring device 21 constituting the boring device 20.
(See FIG. 2).

As shown in FIG. 2, the drilling device 21 is connected to the rods 1 and 2 through a water supply swivel joint 10, and a drill head 11 and a drill head 11 for applying a rotational force to the rods 1 and 2. Impact device 1 arranged at the rear of this
2, a support base 14 for holding these, a guide rail 16 for guiding the support base 14 forward and backward along the longitudinal direction of the rods 1, 2, and a feeding device 17 provided at the rear end of the guide rail 16. , A clamp device 18 arranged on the front side of the guide rail 16 for gripping and fixing the rods 1 and 2, and a detaching device arranged on the rear side of the clamp device 18 for rotating and attaching and detaching the rods 1 and 2. And a device 19.

The working procedure of the core boring method of the present embodiment using the boring device 20 having the above-mentioned structure is as follows: the starting rods 5 and 8 of the inner rod 1 and the outer rod 2 are clamped by the clamping device 18. The starting rod 5, which is fixed in the vicinity of the clamp device 18 while fixing the drill head 11 to the rear part of the guide rail 16 while fixing it toward the natural ground to be drilled.
First, the relay rod 6 of the inner rod 1 is interposed between the rear end of the drilling head 8 and the drill head 11 by using the attaching / detaching device 19. Then, the inner rod 1 is made by the drill head 11.
By driving the advancing device 17 to move it forward while rotating, the natural rod is drilled by the inner rod 1. At this time, the striking device 12 is not driven.

When the drill head 11 advances to the tip of the guide 16, the driving is stopped, the rear end of the inner rod 1 is removed from the drill head 11 by using the attaching / detaching device 19, and the feeding device 17 is driven in the opposite direction. Drill head 11
Then the relay rod 9 is connected between the rear end of the starting rod 8 of the outer rod 2 and the drill head 11. Then, the outer rod 2 is subjected to natural hole drilling while imparting a rotating force by the drill head 11 and a striking force by the striking device 12, that is, a percussion movement.

After that, after the drilling of each span is completed, the relay rods 6 and 9 are located between the rear end of the relay rods 6 and 9 located near the clamp device 18 and the retracted drill head 11, respectively. By repeating the above-described drilling work while alternately adding the holes, drilling is performed by the rods 1 and 2 while maintaining the state in which the inner rod 1 is in advance, and the core provided on the inner rod 1 concurrently with this drilling. The tube 4 will collect the core.

3 (a) to 3 (d) show a procedure for collecting the core in accordance with the drilling work. First, as shown in FIG. 3 (a), the inner rod 1 is projected from the tip of the outer rod 2. By drilling the ground E by rotating motion in the state,
The core E1 is taken inside the inner rod 1, that is, the core tube 4. Further, the inner rod 1 located rearward of the tip portion is covered with the outer rod 2, and the outer rod 2 firmly protects the hole wall surface of the crush zone, and the inner rod 1 contacts the outer ground. In addition, since the space is maintained between the inner rod 1 and the outer rod 2, the drilling torque at the time of drilling the inner rod 1 is greatly reduced and the risk of jamming is eliminated. In addition, it is preferable that the projection length of the tip of the inner rod 1 precedes the tip of the outer rod 2 and is always about 1.5 to 2 m. Further, during the drilling and core collecting work, drilling water supplied from the hollow inside of the inner rod 1 through the swivel joint 10 is ejected from the tip of the inner rod 1 as shown by the arrow in the figure, and then the outer rod. Water is returned to the ground side along with the excavation gap through the gap between the two.

Here, as a method for recovering the core E1 from the inner rod 1 from which the core E1 has been taken by the drilling operation, as shown in (a), the above-mentioned rod recovery method in which the core tube 4 is arranged at the tip of the rod 1 is used. In case (b)
As shown in Fig. 4, the inner rod 1 itself is retracted and the core tube 4 is removed to recover the core E1. To re-drill, set the core tube 4 and then push the inner rod 1 back to its original position. Put in. Further, in the case of the wire line collection method in which the core tube 4 is housed inside the starting rod 5, as shown in (c), the core tube 4 alone is pulled up through the wire line w, The core E1 can be recovered while leaving the rod 1 as it is. In this case, in order to return the core tube 4 to the original position, it is possible to use the pressure water or the like fed into the inner rod 1.

In the former case, it can be easily carried out when the drilling depth is shallow, but the collecting work becomes complicated as the drilling depth becomes deeper. Therefore, the latter method of collecting only the core tube 4 is used. Is preferably used.

After the above recovery work is completed, the outer rod 2 advances as shown in (d). At this time, the drill head 11 and the striking device 12 are driven to apply the striking force together with the rotating force to the outer rod 2 to alleviate the drilling torque, prevent jamming, and perform quick and efficient drilling. You can do the work. The excavation gap at this time is as shown by the arrow, the inner rod 1
And the returned water flowing through the gap between the outer rod 2 and the outer rod 2 are discharged to the surface side.

At the most advanced position of the outer rod 2, the tip of the inner rod 1 is always protruding from the tip of the outer rod 2, and therefore the core for collecting the core is held without being disturbed. After stopping the drilling by the outer rod 2, the core E1 can be easily taken in the tip of the inner rod 1 by rotating the inner rod 1 again as shown in (a).

[0022]

As described above in detail, the core boring method according to the present invention uses the boring device having the inner rod and the outer rod, and when the core is collected by the inner rod, the ground ahead of the tip of the outer rod is used. The inner rod is pre-drilled with the inner rod, and after the core is collected, the outer rod is advanced while striking the core, so that the outer rod firmly protects the wall surface of the hole and the inner rod is used to collect the core. The drilling torque during drilling is greatly reduced, and the drilling torque is mitigated by hitting the outer rod when advancing it, so a large drilling torque is required for boring rods such as crush zones. The core can be efficiently collected even in the case of a rocky ground.

[Brief description of drawings]

FIG. 1 is a perspective view of an inner rod and an outer rod that constitute a boring device used in an embodiment of the present invention.

FIG. 2 is a side view of a boring device that constitutes the boring device.

3A to 3D are explanatory sectional views showing a procedure of drilling and collecting cores using the boring device.

[Explanation of symbols]

 1 Inner rod 2 Outer rod 3 Core bit 4 Core tube 7 Outer bit 11 Drill head 12 Strike device 20 Boring device 21 Drilling device E Ground E1 core

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaoru Fujisawa 2-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo Head Office

Claims (1)

[Claims] 1. A boring device having an inner rod having a core sampling mechanism and an outer rod arranged to cover the outer circumference of the inner rod, whereby the inner rod holds the core while holding the hole wall surface by the outer rod. It is a core boring method to collect, and at the time of collecting the core, the inner rod pre-drills the ground in front of the tip of the outer rod,
A core boring method characterized in that after the core is collected, the outer rod is advanced along the inner rod while being hit, and the core is sampled while alternately repeating such work.