JPH0552082A - Boring method for conical hole bottom, conical strain gauge, and inserting tool for conical strain gauge - Google Patents

Abstract

PURPOSE:To bore a boring hole bottom into a conical shape at the concentric position of a boring hole with a combination tool of a double-tube barrel bit. CONSTITUTION:A cylindrical core barrel bit 3 with a required outer diameter is fitted at the tip of a core tube 1, and boring is performed to the preset position. The core barrel bit 3 and a core barrel bit 4 with a diameter smaller than that of the core barrel bit 3 are concentrically protruded via a coupling 2 to form a combination bit, and a boring hole bottom is bored to the preset position. A pilot bit with the same diameter as that of the small-diameter core barrel bit 4 is used in place of the small-diameter core barrel bit 4, and it is concentrically protruded and fitted to the coupling 2 to form a coupling bit, and the hole bottom is bored to the preset position. A taper bit 6 with the same diameter as that of the small-diameter core barrel bit at the large- diameter portion is used in place of the pilot bit, it is concentrically protruded and fitted to the coupling 2 to form a combination bit, the hole bottom is bored to the preset position, and the hole bottom is bored into a conical shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conical hole bottom boring method for boring a conical hole bottom in a rock mass, a conical strain gauge, and a conical strain gauge insertion tool.

[0002]

2. Description of the Related Art Originally, in rock drilling, rock cores are sampled to check the geological condition, and bored holes are used as grouting holes, rock anchor holes, drain holes or various test holes. Since the bedrock boring is used for the above-mentioned thing, it is not necessary to make the bottom of the boring hole into a conical shape, and there is no method for boring the bottom of the hole into a conical shape.

By the way, in recent years, various measuring methods have been proposed in order to investigate the initial stress state of rock mass. Among them, by drilling in the ground where the initial stress exists, after adhering the strain gauge to the bottom of the hole, by measuring the release strain that occurs when the natural stress is released by performing overcoring, On the contrary, the stress release method, which estimates the initial stress of natural ground, is used as a reliable method. However, the door stopper type hole bottom strain gauge method has the drawback that the strain sensitivity in the hole axis direction is poor and that holes in at least three directions are required.

[0004]

The initial stress measurement using the conical strain gauge was released by improving the door stopper type and adhering the strain gauge to the bottom of the conical hole and performing overcoring. It is a method to estimate the initial stress state with high accuracy using only one hole from strain (release strain).

In this case, it is necessary to drill the tip of the boring hole into a conical shape, and it is also necessary to accurately bond a 12-component strain gauge to a predetermined position on this conical surface.

[0006]

Therefore, the present invention has solved the above problems. The first invention is
This is a method of drilling the bottom of a conical hole at the tip of a boring hole in rock. This is a method of combining a rock drilling bit, developing a tip cutting tool for a pilot bit and a taper bit, and sequentially using the tip cutting tool in a boring machine to form the bottom of a conical hole into a boring hole.

The second invention is to develop a conical strain gauge for precisely adhering a 12-component strain gauge to a predetermined position on the bottom surface of a conical hole formed by boring. This is a truncated cone with the same shape as the bottom of the conical hole and a material smaller than the elastic modulus of the rock mass. The third aspect of the invention is to insert the conical strain gauge from the center of the boring hole while detecting the rotation angle in order to accurately bond the conical strain gauge to the relevant place. After the conical strain gauge is bonded, this insertion tool is collected. Is.

[0008]

The present invention will now be described in detail with reference to specific examples shown in the accompanying drawings. First, FIG. 1 shows an outline of boring. The boring machine 66 is provided with a rod 68 via a spindle 67, a core tube head 69 is attached to the tip of the rod 68, and a diamond core barrel bit 3 having an outer diameter of 76 mm is provided via the core tube 1. On the other hand, a water swivel 70 is interposed at the other end of the spindle 67 to connect a hose 71 so that water can be supplied to the perforated portion. Rock 68 by rotating rod 68
To form a hole bottom 10 and retreat to collect the core C in the core tube 1.

2 to 5 show a tip cutting tool and a conical hole bottom boring method of the first invention. As shown in FIG. 2, a cylindrical diamond core barrel 3 having an outer diameter of 76 mm is attached to the tip of the core tube 1, and the rock R is drilled to a predetermined position. In addition, the hole bottom of the hole is shown by reference numeral 10. Next, as shown in FIG. 3, a diamond core barrel bit 4 having an outer diameter of 56 mm, which is smaller than the diamond core barrel bit 3 having an outer diameter of 76 mm, is attached to the tip of the core tube 1 via a coupling 2 and a diamond core barrel bit. 3 is placed inside 3 and concentrically and projectingly attached to the coupling 2 as a combined bit, the hole bottom 10 of said hole is further drilled by 1.8 cm. The newly formed hole bottom is designated by the reference numeral 20.

Subsequently, as shown in FIG. 4, a diamond core barrel bit 4 having an outer diameter of 56 mm is replaced with a pilot bit 5 having an outer diameter equal to that of the diamond core barrel bit 4 inside the diamond core barrel bit 3. Arranged concentrically and projectingly attached to the coupling 3 as a combined bit, the hole bottom 20 of said hole is drilled a further 3.2 cm. The newly formed hole bottom is shown at 30.

Subsequently, as shown in FIG.
In place of the 56mm pilot bit 5, a pilot bit 5 with an outer diameter of 60 ° and a taper bit 6 of the same diameter with an apex angle of 60 ° are placed inside the diamond core barrel bit 3 and are concentrically projected to form the coupling 2. As a mounting combination bit, the hole bottom 30 of said hole is drilled an additional 0.5 cm. The bottom of the newly formed hole is shown at 40. In this way, the bottom of the hole is formed into a cone.

6 to 8 show a conical strain gauge of the present invention and a tool for inserting the same. The front of the conical strain gauge is
It is a truncated cone 51 made of epoxy resin, and the rear part is formed by uniting a cylindrical tube 52 made of the same material. Six strain gauges 53 are fixed to the outer peripheral surface of the truncated cone 51 at equal intervals, and the apex angle of the truncated cone 51 is 60 °, which is the same as the cone shape of the hole bottom drilled by boring, and the outer diameter. Has a hole diameter of 54 mm, which is smaller than 56 mm, and is provided with an air bleeding hole 54 extending from the distal end portion to the base end of the cylindrical body 52.

Inside the cylindrical body 52, the lead wire 55 of the strain gauge 53 is a 36-core cord, and a socket 57 that is jointed with the insertion tool 56 is embedded on the base end face side. The conical strain gauge insertion tool 56 is the insertion tool after the conical strain gauge is inserted to the bottom of the conical hole at the tip of the boring hole and further bonded.
A socket 58 is provided at the tip for collecting 56.

A rotation angle sensor 60 is provided in a waterproof iron container 59 to confirm that the conical strain gauge is properly inserted. The conical strain gauge must not touch the borehole wall during insertion to apply adhesive around the conical strain gauge. Further, in order to smoothly insert into the bottom of the conical hole formed in the concentric circle at the tip of the boring hole, center hole holding blades 61 in the lower left and right three directions are provided as a center hole holding mechanism.

[0015]

According to the first aspect of the present invention, the conical shape at the bottom of the boring hole can be bored at the concentric position of the boring hole by the combination tool with the double tube core bar rail bit. is there. The second aspect of the present invention is capable of measuring strains of a total of 12 components in two directions in the generatrix direction and the circumferential direction by using strain gauges attached at six positions in the circumferential direction at equal intervals on the outer surface of the truncated cone shape made of epoxy resin. Further, the air and the adhesive can be discharged through the air vent hole from the tip of the truncated cone, and the conical strain gauge can be bonded to a predetermined position on the bottom of the conical hole.

A third aspect of the present invention comprises a rotation angle sensor, a center hole holding blade, and an insertion tool. A conical strain gauge can be inserted while detecting the rotation angle of the gauge from the center position of the boring hole. After bonding the strain gauge to the bottom of the conical hole, the insertion tool can be collected by the socket mechanism.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view illustrating the outline of boring.

FIG. 2 is a view showing a tip cutting tool and a conical hole bottom drilling method of the present invention, and is a vertical cross-sectional view showing a state where a rock is drilled with a cylindrical diamond core barrel bit.

FIG. 3 is a view showing a tip cutting tool and a conical hole bottom drilling method of the present invention, and is a vertical cross-sectional view showing a state where a rock is drilled by a combination bit of a diamond core barrel bit and a small diameter diamond core barrel bit.

FIG. 4 is a view showing a tip cutting tool and a conical hole bottom drilling method of the present invention, and is a vertical cross-sectional view showing a state where a rock is drilled by a combination bit of a diamond core barrel bit and a pilot bit.

FIG. 5 is a view showing a tip cutting tool and a conical hole bottom drilling method of the present invention, and is a vertical cross-sectional view showing a state where a rock is drilled by a combination bit of a diamond core barrel bit and a taper bit.

FIG. 6 is a right side view of the conical strain gauge of the present invention.

FIG. 7 is a front view of FIG.

FIG. 8 is a vertical sectional view of the insertion tool of the present invention.

[Explanation of symbols]

 1 ... Core tube 2 ... Coupling 3 ... Core barrel bit 4 ... Small core barrel bit 5 ... Pilot bit 6 ... Conical taper bit 10/20/30/40 ... Hole bottom R ... Rock C ... Core 66 ... Boring machine 67… Spindle 68… Rod 69… Core tube head 70… Water swivel 71… Hose 51… Cone trap 52… Cylindrical body (cylinder) 53… Strain gauge 54… Air vent hole 55… Lead wire 56… Insert tool (baby rod) ) 57… Socket 58… Socket 59… Iron container 60… Rotation angle sensor 61… Center hole holding blade

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsunori Morishita 2-9-18 Honjo Higashi, Kita-ku, Osaka City KANDEN Kogyo Co., Ltd. (72) Inventor Takashi Kariyama 2-9 Honjo Higashi, Kita-ku, Osaka No. 18 inside KANDEN Kogyo Co., Ltd.

Claims (3)

[Claims] 1. A cylindrical core barrel bit having a required outer diameter is attached to the tip of a core tube and is drilled to a predetermined position, and the core barrel bit and a core barrel bit having a diameter smaller than that of the core barrel bit are concentrically projected. As a combination bit via a coupling, the hole bottom of the hole is drilled to a predetermined position, and a small-diameter core barrel bit is replaced with a small-diameter core barrel bit and a pilot bit of the same diameter so as to project concentrically with each other. As a combination bit, drill the bottom of the hole to a predetermined position, replace the pilot bit and attach a taper bit concentric and protruding with a large-diameter portion to the core barrel bit of the small diameter to the coupling. A conical hole bottom boring method for boring the hole bottom to a predetermined position as a combination bit and conically boring the hole bottom. 2. A conical strain gauge in which a cross gauge having two components of a generatrix direction and a circumferential direction is molded at a position where the circumferential direction of the outer surface of the truncated cone is divided into six equal parts. 3. A conical strain gauge insertion tool for inserting a conical strain gauge molded with a gauge into the bottom of a conical hole of a boring hole, the tip of which can be engaged with or disengaged from the conical strain gauge. In addition, a conical strain gauge insertion tool equipped with a center hole holding blade that holds the center hole of the boring hole in the middle and equipped with a rotation angle sensor.