JP2017125684A - Geological survey method in front of working face - Google Patents

Abstract

PROBLEM TO BE SOLVED: To survey even an inferior natural ground having a hole wall prone to collapse and acquire a favorable observation waveform of an elastic wave.SOLUTION: A geological survey method includes: drilling a natural ground in front of a working face S from the inside of a tunnel space by a drilling machine 2 with a drilling bit 4 at a tip of a rod 3; at an arbitrary drilling length position, attaching a hammering tool 6 that has a hammering face projecting in a radial direction of the rod 3, to the rod 3 in the tunnel space and installing a geophone 8 at the working face S; in a state of stopping to drive the drilling machine 2, hammering the hammering face 7 in the axial direction of the rod 3 by a hammer 10 to generate an elastic wave from the tip of the drilling bit 4 to the natural ground; and measuring the elastic wave by the geophone 8 to acquire a velocity of the elastic wave.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for exploring geology in front of a face beforehand when excavating a tunnel or the like.

  In tunnel excavation, there is an increasing need for ground surveys in front of the face from the viewpoint of preventing troubles such as face collapse disasters and evaluating the validity of the support pattern during tunnel excavation in advance.

  As one of the geological exploration methods in front of the face done from the tunnel pit, a drilling hole is formed in front of the face by a drill jumbo, and velocity logging is established to measure the velocity of elastic waves propagating in the ground using this hole. ing.

  There are various methods for the speed logging depending on the vibration generating position and the vibration receiving position. As shown in FIG. 13, a vibration receiver 51 is installed in the bore 50 and the face surface S is struck with a hammer 52. Downhole method for measuring the velocity of elastic waves when oscillated (Patent Document 1 below), as shown in FIG. 14, a geophone 51 is installed on the face S, and a drifter 54 mounted on a drill jumbo 53. There is known an uphaul method (such as Patent Document 2 below) that measures the velocity of an elastic wave when the drilling bit 55 vibrates the tip end surface of the drilling 50 by operating.

JP-A-11-182171 JP 2011-102706 A

  The downhole method is generally used as a geological exploration method in front of the face, but there are problems such as being unable to apply because the geophone is bad and the hole is rough and the geophone cannot be inserted / recovered. .

  On the other hand, the uphole method is a method expected to be put into practical use as a technology that can solve the problem of the downhole method, but to excite the natural ground by operating a drifter mounted on a drill jumbo, There are problems such as (1) vibration (noise) due to the operation of the hydraulic unit, (2) difficult to control the hit, and continuous hitting. It was difficult.

  Therefore, a main object of the present invention is to provide a geological exploration method in front of a face which can be carried out even on a bad ground where the hole wall is easy to collapse and can obtain a good observation waveform of elastic waves.

In order to solve the above-mentioned problem, as the present invention according to claim 1, a drilling machine provided with a drilling bit at the tip of a rod is drilled from a tunnel space to a natural ground in front of the face, and an arbitrary drilling length is achieved. At the position, mounting a striking jig having a striking surface protruding in the radial direction of the rod with respect to the rod in the tunnel space, and installing a geophone on the face surface,
With the drilling machine stopped, the hammer hits the striking surface in the axial direction of the rod to generate an elastic wave from the tip of the drilling bit to the ground, and the elastic wave is measured by the geophone. Thus, a geological exploration method in front of the face is provided, characterized in that the elastic wave velocity of the natural ground is obtained.

  Since the invention according to claim 1 is speed logging by the uphole method in which a geophone is installed on the face surface and an elastic wave is generated in the ground at the tip surface of the drilling, there is a problem in the downhole method. In addition, it is possible to solve the problem that the geophone cannot be inserted and collected when the ground is bad and the hole is rough.

  Particularly, in this method, by attaching a striking jig having a striking surface protruding in the radial direction of the rod to the rod in the tunnel space, and striking the striking surface of the striking jig with a hammer. It is characterized in that a striking force is applied in the axial direction of the rod. Here, as a method of applying a striking force in the axial direction of the rod, a method of disassembling the connecting portion of the rod in the tunnel space and directly striking the exposed end surface of the rod with a hammer can be considered. The work of disassembling the work and the work of assembling the rod again are required, and there is a problem that extra labor and time are required. On the other hand, in the geological exploration method according to the present invention, as described above, the impact jig is attached to the rod, and the impact surface of the impact jig is hit with a hammer. Since it is possible to perform speed logging without disassembling / assembling the rod in the state in which the bit and the rod are being drilled, the labor of the measurement work can be greatly reduced.

  Moreover, since it is not necessary to install a geophone in the perforation, measurement is possible even when the ground is bad and the hole is rough.

  Furthermore, in this geological exploration method, since the elastic wave is measured by the geophone in a quiet environment in which the operation of the drilling machine is stopped, the elastic wave velocity of the natural ground is obtained. An observation waveform of an elastic wave can be obtained. In addition, when generating elastic waves in the natural ground, since the hitting surface is hit with a hammer that is easy to control, continuous hitting can be easily avoided, and a good elastic wave observation waveform can be obtained. become able to.

  According to a second aspect of the present invention, there is provided the geological exploration method in front of the working face according to the first aspect, wherein the striking surface is struck by a hammer in a state where the bit for piercing is pressed against the tip end surface of the perforation by a drifter of the perforator. Provided.

  In the invention according to the second aspect, the striking surface is struck by a hammer while the perforating bit is pressed against the tip end surface of the perforation by the drifter of the perforator, so that the rod and the hole wall are brought into contact with each other. The accompanying noise can be reduced, and an elastic wave can be reliably generated on the tip surface of the perforation.

  According to a third aspect of the present invention, in the rod according to the first aspect of the present invention, at least a portion of the outer peripheral surface facing away from the outer peripheral surface is cut out at a portion where the hammering jig is attached, and a parallel flat surface is formed. 2. A geological exploration method in front of the face according to any one of 2 is provided.

  According to the third aspect of the present invention, the opposite side surfaces of the outer peripheral surface are notched in the portion of the rod to which the striking jig is attached, thereby forming a parallel flat surface. The hitting jig can be easily fixed, and the hitting jig can be reliably prevented from being displaced when hitting with a hammer.

  According to a fourth aspect of the present invention, there is provided a geological exploration method in front of the face according to any one of the first to third aspects, wherein a plurality of the geophones are installed at intervals with respect to the face.

  In the invention described in claim 4, since a plurality of the geophones are installed at intervals with respect to the face, a certain amount of noise is eliminated by performing mutual complementation of observation data observed by each geophone. It is possible to improve the accuracy of reading the initial wave.

  As described above in detail, according to the present invention, it is possible to solve the problem that it becomes impossible to insert and recover the geophone in a defective ground where the hole wall easily collapses, and a good observation waveform of the elastic wave can be obtained.

1 is a longitudinal sectional view of a geological exploration system 1. FIG. The striking jig 6 is shown, (A) is a front view and (B) is a side view. It is a front view of the jig | tool 6 for impact which shows the modification of the rod 3. FIG. It is a front view of the tunnel face surface S which shows the installation position of the perforation 5 and the geophone 8. It is a time series waveform figure by the conventional method (the 1). It is a time-sequential waveform figure (the 1) by this geological exploration method. It is a time series waveform figure by the conventional geological exploration method (the 2). It is a time series waveform figure (the 2) by this geological exploration method. It is a travel time curve by this geological exploration method. It is a travel time curve by a conventional geological exploration method (downhole method). It is a figure which shows the elastic wave velocity by this geological exploration method. It is a figure which shows the elastic wave velocity by the conventional geological exploration method (downhole method). It is a longitudinal cross-sectional view which shows the geological exploration system by the conventional downhole method. It is a longitudinal cross-sectional view which shows the geological exploration system by the conventional uphaul method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a geological exploration system 1 according to the present invention includes a drilling bit 4 at the tip of a rod 3 that performs a drilling operation to form a drilling 5 in a natural mountain in front of a face S from inside a tunnel space. A drilling machine 6 having a striking surface 7 attached to the rod 3 in the tunnel space and projecting in the radial direction of the rod 3, and a face surface. The vibration receiving device 8 installed in S, the vibration signal generating sensor (not shown) attached to the hammer 10 for striking the striking jig 6, the vibration receiving device 8 and the vibration signal generating sensor It is connected via a cable, and is composed of a measuring device 9 that transmits and records data measured by the vibration receiving device 8 and the vibration generating signal generating sensor.

  The punching machine 2 is connected to a travelable carriage (not shown) so that it can be moved forward and backward in a guide cell 11 and connected to the drifter 12 via a shank rod 13 and drilled at the tip. This is a heavy machine for drilling such as a drill jumbo equipped with a drilling rod 3 provided with a working bit 4.

  As shown in detail in FIG. 2, the striking jig 6 projects outward in the radial direction with respect to the rod 3 and strikes the striking surface 7 facing the drifter 12 side perpendicular to the axial direction of the rod 3. And a pair of leg portions 15 and 15 which are fixed to the rod 3 so as to sandwich both sides of the rod 3 and extend downward on both sides of the lower end of the striking portion 14. It is comprised from. The hitting jig 6 is detachably attached to the rod 3 in a state where the drilling operation is performed by the drilling machine 2 without disassembling the rod 3 in the tunnel space.

  The striking jig 6 is fixed to the rod 3 by providing one or a plurality of screw holes 16 in at least one of the pair of leg portions 15, 15. This is done by tightening the rod 3 between the front end of the fastening bolt 17 screwed from the outside and the inside of the leg 15 on the other side.

  The tightening bolts 17 are separated from each other in the axial direction of the rod 3 in order to prevent displacement of the striking jig 6 during hammering and to easily transmit the striking force to the rod 3. It is preferable to provide a location. Accordingly, as shown in FIG. 2B, the leg portion 15 is preferably formed so that the member length along the axial direction of the rod 3 protrudes longer than the member length of the striking portion 14. .

  In addition, it is preferable to prevent slipping with the rod 3 by applying a knurling process or the like to the tip surface of the tightening bolt 17 to form a fine unevenness.

  It is preferable that the rod 3 is formed such that a parallel flat surface is formed by cutting away both opposing side surfaces of the outer peripheral surface at least in a portion where the hammering jig 6 is attached. Accordingly, the hitting jig 6 can be easily fixed by sandwiching the parallel flat surface between the tip of the tightening bolt 17 and the inside of the leg portion 15, and the hitting jig 6 at the time of hitting with a hammer. It is possible to reliably prevent the deviation. In the example shown in FIG. 2, the rod 3 having a hexagonal cross section is used, so that both opposite side surfaces of the outer peripheral surface are the flat surfaces. Also, as shown in FIG. 3, a rod 3 having a circular cross section is used, and notching is performed so that both opposing side surfaces of the outer peripheral surface of the portion to which the hitting jig 6 is attached become the flat surface. May be applied. Of course, the rod 3 may have the cross-sectional shape shown in FIG.

  In order to fix the hitting jig 6 to the rod 3 more firmly, the upper end surface of the hitting portion 14 and the lower end surface of the rod 3 may be fixed by a clamp such as a Bullman (registered trademark). Good.

  The geophone 8 is installed at a predetermined position of the face S, and strikes the striking surface 7 of the striking jig 6 with a hammer 10 to receive elastic waves generated in the ground from the tip of the drilling bit 4. It is.

  As shown in FIG. 4, it is preferable that a plurality of the geophones 8 are installed at predetermined intervals in a certain direction of the face S with reference to the installation position of the perforations 5. By installing a plurality of the geophones 8, the observation data observed by the geophones 8 are mutually complemented, so that a certain amount of noise can be removed and the accuracy of reading the initial motion wave can be improved. In the illustrated example, eight are installed in the vicinity of the perforation 5 and in the horizontal direction therefrom. More specifically, in the vicinity of the perforation 5, a geophone 8 (1 channel (ch)) that receives an elastic wave having a component perpendicular to the face S and a geophone 8 that receives an elastic wave having a component parallel to the face S ( 2ch) and two geophones 8 (3ch, 4ch) that receive elastic waves of components perpendicular to the face S at intervals of 2m from the bore 5, and a second geophone 8 (4ch) 6 geophones 8 that receive elastic waves of a component perpendicular to the face S at intervals of 1 m from each other, and geophones 8 that receive elastic waves of components parallel to the face S at the fourth and sixth points (5ch to 12ch) is installed.

  On the other hand, the vibration signal generating sensor installed on the hammer 10 is a device for measuring vibration data when the hammer 10 strikes the striking surface 7 of the striking jig 6.

  The hammer 10 used for hitting may be any of metal, plastic, wood, rubber, etc., but it is preferable to use a large iron hammer.

  In order to perform geological exploration using the geological exploration system 1 having the above configuration, the following procedure is used. First, a perforating operation is performed by the perforator 2 to form a perforation 5 in the ground in front of the face S from the tunnel space. Then, the hitting jig 6 is attached to the rod 3 in the tunnel space at an arbitrary drilling length position. The perforating operation is performed by a joint flea method in which short rods are sequentially added and extended. The face receiving surface S is provided with the geophones 8, 8... And the hammer 10 is provided with the vibration signal generating sensor.

  Next, with the operation of the punching machine 2 stopped, the hammer 10 strikes the striking surface 7 of the striking jig 6 toward the drilling bit 4 side in the axial direction of the rod 3 for drilling. An elastic wave is generated from the tip of the bit 4 to the natural ground, and the elastic wave is measured by the geophones 8 to obtain the elastic wave velocity of the natural ground.

  As described above, this geological exploration method is the speed logging by the uphole method in which the geophone 8 is installed on the face S and the elastic wave is generated in the natural ground at the tip surface of the bore 5, so the downhole method is used. This solves the problem that the geophone cannot be inserted and collected when the ground is bad and the hole is rough, and the labor of measurement can be greatly reduced.

  In particular, in this geological exploration method, a striking jig 6 is attached to the rod 3 in a tunnel space, and a striking surface 7 of the striking jig 6 is hit with a hammer 10 so that the axial direction of the rod 3 is increased. It has a feature in that a striking force is applied. Here, as a method of applying a striking force in the axial direction of the rod, a method of disassembling the connecting portion of the rod in the tunnel space and directly striking the exposed end surface of the rod with a hammer can be considered. The work of disassembling the work and the work of assembling the rod again are required, and there is a problem that extra labor and time are required. On the other hand, in the geological exploration method, as described above, the speed detection is performed without disassembling / assembling the rod 3 in the state where the drilling bit 4 and the rod 3 are inserted into the drilling 5 as they are. Since layers are possible, the labor of measurement can be greatly reduced.

  Further, since it is not necessary to install a geophone in the perforation 5, measurement is possible even when the ground is bad and the hole is rough.

  Furthermore, in this geological exploration method, since the elastic wave is measured by the geophone 8 in a quiet environment in which the operation of the drilling machine 2 is stopped, the elastic wave velocity of the natural ground is obtained, so there is little noise, It is possible to obtain a good observation waveform of elastic waves. Further, when hitting the striking surface 7, hammering is performed with human power that is easy to control, so that continuous striking can be avoided and a good elastic wave observation waveform can be obtained.

  When striking the striking surface 7 with the hammer 10, it is preferable that the perforating bit 4 is pressed against the tip end surface (bottom surface) of the perforation 5 by the drifter 12 of the perforating machine 2. This makes it difficult for the rod 3 to come into contact with the hole wall, and noise associated with the contact can be reduced, and the elastic wave is surely applied to the tip surface of the drilling 5 via the rod 3 and the drilling bit 4 by the hammer 10. Can be generated.

  Hereinafter, an outline of a comparative survey of data observed using the geological exploration method according to the present invention and the conventional geological exploration method at an actual tunnel construction site will be described.

  As a first comparative investigation, as shown in FIGS. 5 and 6, the influence of the operation of the drilling machine during the elastic wave measurement on the observation data was examined. FIG. 5 shows a conventional geological exploration method. As shown in FIG. 14, a geophone is installed on the face and a drifter mounted on a drill jumbo is operated to excite the tip surface of the drill with a drill bit. It is the time series waveform of the elastic wave observed using the conventional uphaul method which measures the elastic wave at the time. FIG. 6 shows time-series waveforms of elastic waves observed using this geological exploration method. In FIGS. 5 and 6, 1ch to 12ch are data observed by the respective number of the geophones 8 shown in FIG. 4, and 13ch is excitation data.

  As shown in FIG. 5, in the conventional geological exploration method, there was a lot of noise due to the operation of the drilling machine, and it was difficult to interpret the rising position of the initial wave due to the impact. On the other hand, in this geological exploration method, as shown in FIG. 6, since elastic waves are measured in a state where the operation of the drilling machine 2 is stopped, there is little noise, and elastic waves are measured at each measurement point. The rising position of becomes clear. Thus, by measuring in a quiet environment in which the operation of the drilling machine 2 is stopped, noise can be reduced and a good observation waveform of elastic waves can be obtained.

  Next, as a second comparative investigation, as shown in FIGS. 7 and 8, the influence of the vibration method on the observation data was examined. FIG. 7 shows time series waveforms of elastic waves observed using the conventional uphole method shown in FIG. 14 in the same manner as described above. FIG. 8 shows time-series waveforms of elastic waves observed using this geological exploration method. As shown in FIG. 7, in the conventional geological exploration method, since the tip end surface of the drilling is vibrated by the drilling bit by operating the drifter, the hitting is controlled as shown in the 13ch vibration waveform. It is difficult to do so and it becomes a continuous hit in which a plurality of shot marks appear, and it is not easy to specify the rising position of the initial wave. On the other hand, as shown in FIG. 8, in this geological exploration method, the tip of the piercing 5 is passed through the rod 3 and the piercing bit 4 by hitting the striking surface 7 of the striking jig 6 with the hammer 10. Since the surface is oscillated, only the observed waveform corresponding to one hit is obtained as shown in the 13ch oscillating waveform, and the rising position of the initial motion wave is easily specified. Nevertheless, small noise that cannot be avoided can be removed by mutual complementation using a plurality of geophones 8, 8. Specifically, as shown in FIG. 8, when the other receivers are seen with reference to the arrival time of the initial wave in the vicinity of 22 ms of 11ch and 12ch where the rising position of the initial wave is relatively clear, Although noise is recognized, it can be seen that the initial wave arrival times are aligned on the same time (6 ch to 12 ch). Thus, it is difficult to read the initial wave arrival time and the analysis of the elastic wave velocity value with only the geophones (1ch to 5ch) close to the perforation 5, but other vibrations that are considered to have relatively little noise. The rising position of the initial wave can be specified by complementing the vessel data.

  As a third comparative survey, the geological exploration method was compared with the downhole method (Fig. 13) in which a geophone was installed in the borehole and the face was hit with a hammer. FIG. 9 is a travel time curve according to the geological exploration method, and FIG. 10 is a travel time curve according to the downhole method. The slope of the travel time curve corresponds to the section speed value, and the elastic wave average speed obtained based on this is shown in FIGS. 11 and 12, respectively. As shown in FIGS. 9 to 12, the travel time curve has a similar shape for both methods. Moreover, although the average velocity of elastic waves is somewhat low in this geological exploration method, almost the same velocity value is obtained in both methods. Therefore, the consistency between the geological exploration method and the downhole speed structure is generally consistent, and it can be said that this geological exploration method is an effective method for exploring the ground ahead of the face.

  DESCRIPTION OF SYMBOLS 1 ... Geological exploration system, 2 ... Drilling machine, 3 ... Rod, 4 ... Drilling bit, 5 ... Drilling, 6 ... Impact tool, 7 ... Impact surface, 8 ... Vibration receiver, 9 ... Measuring instrument, 10 ... Hammer

Claims (4)

From inside the tunnel space, a drilling machine equipped with a drilling bit at the tip of the rod is used to drill a natural ground in front of the face, and at any drilling length position, the rod is in the tunnel space with respect to the rod. Attach a striking jig with a striking surface projecting in the radial direction, and install a geophone on the face.
With the drilling machine stopped, the hammer hits the striking surface in the axial direction of the rod to generate an elastic wave from the tip of the drilling bit to the ground, and the elastic wave is measured by the geophone. The geological exploration method ahead of the face is characterized by calculating the elastic wave velocity of the natural ground.   The geological exploration method in front of the face according to claim 1, wherein the striking surface is hit with a hammer in a state where the drilling bit is pressed against the tip end surface of the drilling by a drifter of the drilling machine.   The front surface of the face according to any one of claims 1 and 2, wherein the rod is formed with a parallel flat surface by cutting away both opposing side surfaces of the outer peripheral surface at least on a portion to which the hitting jig is attached. Geological exploration method.   The geological exploration method in front of the face according to any one of claims 1 to 3, wherein a plurality of the geophones are installed at intervals with respect to the face.

Images