JPH03132588A - Surveying method for bedrock - Google Patents

Abstract

PURPOSE:To make quick and correct survey possible by drilling a bore into a bedrock and inserting, after grinding the surface of the inner wall thereof, a fiberscope incorporating optical fiber illuminators and a CCD image sensor into the bore, and by visualizing the sensed images. CONSTITUTION:To a bedrock of a place where a tunnel is to be excavated or is under excavation, a bore 14 for surveying of bedrock is bored and the surface of the inner wall thereof is ground. Then a guide tube 24 equipped with a fiberscope 22 incorporating optical fibers 22a and 22a and a CCD image sensor 22b is inserted into the bore 14. Optical wave is then projected through the optical fibers 22a and 22a toward the surface of the inner wall of the bore 14, and reflected ray is caught by the CCD image sensor 22b and image sensing and visualization of the surface of the inner wall are made therewith. Thereby the state of the bedrock can be grasped correctly in a short period of time on the spot.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a rock survey method.

(Conventional technology) As is well known, at the site where mountain tunnels are planned to be excavated or at tunnel excavation sites, the rock mass is investigated in advance to prevent disasters such as face collapse and sudden spring water. There is.

The conventional method for investigating this type of rock has been the core sampling method, in which core boring is performed along the planned tunnel route and the soil properties of the collected cores are ascertained.

Although this rock surveying method using core boring allows accurate information on soil properties to be obtained from the collected cores, it also has the technical problems described below.

(Problem to be Solved by the Invention) In other words, in the core sampling method using polling, there is almost no ground where all the cores can be collected in the axial direction, and some cores may be missing, for example, if there are relatively large cracks in the rock. If there is, even if the existence of cracks can be confirmed,
There is a problem in that the size and direction of the width, the condition of intervening soil particles, etc. cannot be accurately determined.

Further, in the core sampling method using polling, it takes time to sample the core, and for example, when performing this during tunnel excavation, there is also a problem that the excavation of the face is interrupted for a long time.

Furthermore, there is also the problem that the preparation and installation of the polling device is complicated and costs increase.

This invention was made in view of these conventional problems, and its purpose is to provide a method for investigating rock mass that can accurately grasp the rock mass properties at the current location in a short time. There is a particular thing.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for investigating rock mass at a planned tunnel excavation site or during tunnel excavation.
After drilling a borehole in the bedrock and polishing the inner wall of the borehole, a fiberscope with a built-in optical fiber illuminator and a CCD camera is inserted into the borehole to image the inner wall of the borehole. It is characterized by becoming

(Operations and Effects of the Invention) According to the rock survey method having the above configuration, the inner wall surface of the rock excavation hole is polished and smoothed, and then a fiberscope having a built-in optical fiber illuminator and a CCD camera is installed inside the rock excavation hole. Since the inner wall surface of the excavated hole is imaged, the properties of the rock mass at the current location can be grasped.

In this case, unlike the core sampling method, there are no missing parts on the inner wall surface of the drill hole, so the width of cracks can be accurately inspected.

To investigate a borehole, simply insert a fiberscope with a built-in optical fiber illuminator and a CCD camera into the borehole, so if you also use a video tape recorder, for example, the investigation can be completed in a short time, and the excavation of the face can be completed quickly. There is no need to interrupt work for long periods of time.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 5 show an embodiment of the rock survey method according to the present invention.

The investigation method shown in the figure is applied to the case of investigating the bedrock of the face 12 of the tunnel 10 that is currently being excavated, and first, an excavation hole 14 is excavated in the face 12.

To excavate the borehole 14, as shown in FIG. 1, a drilling rod 16 with a drilling bit attached to its tip is attached to a drilling machine 18, and the borehole 14 is excavated to a predetermined length.

When the drilling of the borehole 14 is completed, the drilling machine 18 has a second
A polishing rod 20 shown in the figure is attached, and the inner wall surface of the excavated hole 14 is polished.

The polishing rod 20 has a polishing bit 20a attached to its tip.
, a polishing rod main body 20c on which a plurality of polishing diamond bits 20b are fixed at predetermined intervals on the outer periphery, an extension rod 20d and a sleeve joint 20e, and the polishing rod main body 20c has a polishing rod body 20c fixed to the outer circumference at predetermined intervals. is polished to a nearly mirror surface by this polishing rod 20.

When the polishing of the inner wall surface of the excavated hole] 4 is completed, a guide pipe 24 equipped with a fiber cob 22 is attached in place of the polishing rod 20 of the drilling machine 18, and the guide pipe 24
As shown in the figure, it is inserted into the borehole 14.

As shown in FIG. 4, the guide tube 24 is formed into a hollow cylindrical shape, and has a hole 24a through which the fiberscope 22 is inserted in the center thereof, and a plurality of jet water injection nozzles 24b provided on the outer periphery. ing.

Each injection nozzle 24b is opened at its tip so as to be inclined outward with respect to the central axis of the guide tube 24, and one end of the hose 26 is connected to the rear end side. A jet pump 27 is connected to the end, and when the jet pump 27 is driven as necessary, the inner wall surface of the excavation hole 14 can be cleaned with water jetted from the jet nozzle 24b.

On the other hand, the fiber scope 22 has an optical fiber 22a for illumination disposed on the outer periphery and a CC disposed in the center.
D camera 22b, and these parts are inserted into a protective case 22c.

One end is an optical fiber 22a and a CCD camera 2.
The cable 23 of the fiberscope 22, which is connected to the cable reel 2b and whose other end is extended to the outside of the borehole 14, is wound around a cable reel 28, and the end thereof has an optical fiber 22a as shown in FIG. A light source device 30 that sends light waves to
, a TV monitor 32 that visualizes the imaged signal of the CCD camera 22b, a video tape recorder 34 that records the visualized signal, and a video printer 36 that depicts the visualized signal on paper.

Now, in the above configuration, the guide pipe 24 is connected to the excavated hole 14.
When the light source device 30 is driven when the guide tube 24 is inserted into the borehole or when the guide tube 24 inserted to a predetermined position is pulled out, a light wave is projected from the optical fiber 22a toward the inner wall surface of the borehole 14, and the inner wall surface is The reflected light from the CCD camera 22b is received by the CCD camera 22b.

The optical signal received by the CCD camera 22b is converted into an electrical signal and sent to the TV monitor 32 or the like, and the state of the inner wall surface is visualized.

According to the rock investigation method performed as described above, the inner wall surface of the rock excavation hole 14 is polished and smoothed, and then the fiber scope 22 having the optical fiber 22a and the CCD camera 22b built therein is installed. Insert the drilling hole 1
Since the inner wall surface of No. 4 is visualized, the properties of the rock mass at the current location can be grasped.

In this case, the inner wall surface of the borehole 14 is not compressed as in the core sampling method, so it is possible to accurately inspect the width of cracks and at the same time detect changes in the amount of water flowing out.

Rock strength, jamming tendency, Pi-Sochi rock type of cracks,
You can also check the inclination angle and direction of the strata.

In addition, the investigation of the excavation hole 14 is carried out using the optical fiber 22a and CCD.
Since the fiberscope 22 with a built-in camera 22b is simply inserted into the excavation hole 14, if a video tape recorder 34 or the like is also used, the investigation can be completed in a short time, and there is no need to interrupt the excavation work of the face for a long time.

Note that the inner wall surface of the excavated hole 14 was
4 and jet water is ejected from the nozzle 24b, or cleaning may be performed with jet water during the investigation.

FIG. 6 shows another embodiment of a fiberscope 22' for use in the method of the invention.

The fiberscope 22- shown in the same figure has a protective case 2
A mirror 40 that is rotationally driven by a small motor 38 is provided at the tip of the mirror 2c, and the mirror 40 is inclined at an angle of about 45 degrees with respect to the central axis.

When using the fiberscope 22' configured in this way, the light projected from the optical fiber 22a and reflected on the inner wall surface of the borehole 14 is focused by the mirror 40 and incident on the CCD camera 22b, so that a clearer image can be obtained. An image of the inner wall surface can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the excavation state of a borehole in the rock survey method according to the present invention, Fig. 2 is a perspective view of a polishing rod used for polishing the borehole in the same method, and Fig. 3 is an explanatory diagram showing the state of excavation of a borehole in the rock survey method according to the present invention. An explanatory diagram of the guide tube inserted into the excavation hole, Figure 4 is a detailed diagram of the guide tube, Figure 5 is an explanatory diagram of the equipment connected to the fiberscope, and Figure 6 is an illustration of other guide tubes. It is an explanatory diagram showing an example. 10... Tunnel 14... Excavation hole 22... Fiber scope 22a... Optical core inoku 22b... CCD camera 32... TV monitor

Claims (1)

[Claims] In a rock survey method for a planned tunnel excavation site or during tunnel excavation, an excavation hole is excavated in the rock, and after polishing the inner wall surface of the excavation hole, an optical fiber illuminator and a CCD camera are installed in the excavation hole. A rock investigation method characterized by inserting a built-in fiberscope and visualizing the inner wall surface of the excavation hole.