JP2011021462A - Method and device for collecting direction-indicating core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To conduct continuous core collection without causing ground disturbance in ground-survey boring, and to collect direction-indicating cores simultaneously. <P>SOLUTION: The device for collecting the direction-indicating core includes: an outer pipe 4 having a rotary-cutting bit 5 at the tip; and an inner pipe 6 located coaxially inside the outer pipe 4 and accommodating the core. The outer pipe 4 is coupled to an upper boring rod 2 to be rotated together with the boring rod 2. The inner pipe 6 is coupled to a fixing shaft 3, and the fixing shaft 3 extends inside the boring rod 2 upward to be fixed externally and includes a plurality of vertically connected components. A connecting means for connecting upper components with lower components in a non-rotatable way is provided at the connecting section of the respective components, so as to prevent the rotation of the inner pipe 6 along with the rotation of the boring rod 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method and an apparatus for collecting a core having a known orientation for knowing the strike inclination of a surface structure such as a stratum surface of a formation.

In order to solve problems such as pre-investigation for construction of structures in the field of civil engineering and construction, mining planning in the mining industry, and academic ground research, ground survey boring is conducted. The best way to know the underground ground is the survey tunnel excavation method, which excavates the underground tunnel and directly confirms the ground on the wall. Since this involves a long construction period and a large amount of cost, ground survey boring is considered to be an inexpensive and effective geological survey method. The structure of the ground is confirmed in the cores collected continuously without disturbing the ground. At the same time, the stratum surface of the stratum and the slope of the ground surface structure such as cracks and veins are confirmed in the core where the orientation is known, and the underground ground around the borehole can be determined in both results. Hereinafter, a core collected continuously without disturbing the ground is referred to as a good quality core, and a core whose orientation is known is referred to as an orientation core.

FIG. 6 is a conceptual explanatory diagram of core collection at the tip of a known double-pipe sampler used when collecting a good quality core (for example, see Non-Patent Documents 1, 2, and 3). The tip ground is circumferentially cut by the rotation and thrust of the outer tube (4) to which the bit (5) is attached, and the ground standing in a cylindrical shape on the inner circumference becomes the sampling core (71). The excavation speed at the time of core collection is as slow as about 0.5-2 cm / min, and as the excavation progresses, the collection core is a bag-like or cylindrical polyethylene tube loaded inside the inner pipe (6). (72) is continuously accommodated in the inner pipe while being covered in close contact. When the predetermined core collection (usually 1 m) is completed, the sampler is lifted and collected on the ground. In this lift pipe, the core lifter (73) is gripped and the tip of the core is pulled and broken from the ground. In addition, pumping the excavation water from the ground cools and lubricates each member at the tip, such as a bit, through the gap between the outer pipe and the inner pipe, and discharges cutting waste through the gap between the outer pipe and the hole wall. Is done.

In FIG. 6, when ABC is a stratum plane of the formation and abc is a surface structure such as a crack or a vein, it is possible to collect a high-quality core that holds them and In both achievements of knowing the orientation, the underground ground around the borehole can be determined. When the inner tube is rotated, the orientation of the sampled core = the direction of the surface structure is not known.

Figure 5 shows the core sampling with a well-known double-pipe sampler that is used to collect high-quality cores in the ordinary construction method using a rotary-type boring machine that is widely used in ground surveys with a length of less than 200 m. Law. Hereinafter, it is an implementation explanatory diagram referred to as a conventional core sampling method. This double-tube sampler (fracture front view) is composed of three main members: an outer tube (4) having a bit (5) at the tip, an inner tube (6) that carries the core, and a swivel head (60). Composed. In order to collect the core at this depth, the sampler is lowered to the bottom of the hole by connecting a plurality of boring rods (2), and the rotation and thrust of the ground boring machine (1) are transferred to the outer tube via the boring rod and swivel head (60). Cutting is performed by being transmitted to (4). The inner tube has a freely rotating structure suspended by bearing support in the swivel head, and the boring rod, outer tube, and inner tube need to be detachable for work. Yes. In addition, some small tools (not shown) are mounted at the distal end portion of the inner tube in order to smoothly store the core. (See Non-Patent Documents 1, 2, and 3)

In the first place, the ground is composed of various physical properties ranging from plasticity to brittleness, and for the purpose of collecting good quality cores in these grounds, many methods including patented properties have been devised and put into practical use so far. .

In ground survey boring, of course, a method of simultaneously collecting a good quality core and a bearing core is desired for the above-described reason. The boring rod and the outer tube are screwed together and both rotate for excavation, and the inner tube is a freely rotating structure with bearing support, so the inner tube also rotates each time. For this reason, it is not possible to collect orientation cores with the conventional core sampling method. In addition, when trying to devise a method for collecting the orientation core, the sampler has a cylindrical shape with a small diameter of about several centimeters to 10 cm, and the constituent members of the sampler are made of iron, so the magnetic compass cannot be easily used. There are also mechanical and functional constraints. As a result, several prior arts have been devised in the past 20 or more years for collecting orientation cores. (See Patent Documents 1-8)

All of these prior arts are intended to identify the orientation at the original position (hole bottom) of the inner tube or the sampling core and detect twist by some method on the assumption that the inner tube rotates. Various methods cannot be said to have become widespread and are not practical.

However, since the ground cannot be determined unless the slope of the ground surface structure is known, currently, the slope of the ground surface structure is obtained by an image analysis method (such as patent 2724833) using a borehole wall after core collection. The method of knowing is the mainstream, and it is incorporated into the geological survey plan and accumulated. However, this video analysis method has the problem that it cannot be observed or cannot be measured accurately due to the turbidity of the water in the borehole or the collapse of the pore wall. Although it is considered difficult, they have strong desires.

JP-A 54-2909 Japanese Patent Laid-Open No. 57-40087 Japanese Patent Laid-Open No. 58-168791 Japanese Patent Laid-Open No. 64-2758 JP-A-3-81492 JP-A-9-242458 JP-A-10-61365 JP 2000-104480 A

Boring Handbook (National Geological Survey of Japan) p95 Kristensen Maikai GWS series catalog (Yes) Aijii product catalog N66-50 assembly drawing

    All the above-mentioned prior arts that attempt to know the orientation of the core are all subject to a technique for measuring the orientation and twist of the sampling core on the assumption that the inner tube rotates. Further, the twisting of the sampling core is originally derived from the rotation of the inner tube. Therefore, the fundamental problem in the method of trying to know the orientation of the core is that the inner tube rotates when the core is collected.

    In the present invention, it is possible to understand the azimuth by determining the direction to stop and stop the rotation of the inner pipe so that the inner pipe does not rotate at once even when the outer pipe rotates while the core is collected. The present invention provides a method and an apparatus for collecting a core and has the following configuration.

(Core collection device)
It has an outer tube with a bit for rotating cutting at the tip and an inner tube that is coaxially positioned inside the outer tube and carries the core. The outer tube is connected to the upper boring rod and rotates together with the boring rod. And
The inner tube is connected to a fixed shaft, and the fixed shaft extends upward on the inside of the boring rod, is fixed from the outside, and includes a plurality of components connected in the vertical direction. The connecting portion of each component part is provided with a connecting means that allows the upper component part and the lower component part to be connected to each other so as not to rotate, and the inner rod does not rotate with the rotation of the boring rod. I am doing so.

Providing a projection on the peripheral surface of one of the upper and lower constituent parts at a connecting portion of the constituent parts of the fixed shaft, providing a joint for fitting the end of the one constituent part on the other constituent part; A groove into which the protrusion enters may be formed in the joint.
In addition, at the connection portion of the component parts of the fixed shaft, a joint that makes the cross-sectional shape of the end of one of the upper and lower components non-circular and externally fits the end of the one component to the other component Can be provided.

(How to collect cores with a clear bearing)
By the core collecting device, the rotation of the inner pipe that carries the core is restrained and the direction of the inner pipe is maintained in an arbitrary direction, and in this state, the cutting excavation is performed by the configuration related to the cutting excavation. Yes.

    The present invention makes it possible to collect a core whose orientation is known to be difficult in the ordinary method using a rotary boring machine. Since the orientation of the core can be known at the same time in the general-purpose high quality core sampling method, the ground around the borehole can be determined independently without using other methods, and it is cheaper and more useful ground Information will be provided.

Explanatory diagram of a device that collects cores with a clear bearing Structure explanation of double tube type fixed shaft boring rod Structure explanatory diagram of the sampler head Structure explanatory drawing of fixed axis direction fixed part Implementation diagram of conventional core sampling method Conceptual diagram of core collection

Definitions of words used in the following description will be made here.
a) The fixed shaft is a hollow or solid round bar that is coaxially arranged inside a device connected from the bottom to the ground, such as a sampler, a boring rod, a water swivel, etc., and separated and connected at the device connecting portion Or the rod-shaped member which processed the round bar.
b) The same direction is a positional relationship in which the same rotational phase is maintained with respect to the axial center of the cylinder with respect to the positional relationship between the two points on the cylindrical surface, or both are the axial direction of the cylinder and It means a positional relationship on a single plane upright on the shaft core.
c) The azimuth | direction connection means the connection which becomes the same direction in the direction of the axial rotation direction of the connection of the two pipes or round bars which are coaxially connected long. For example, marks that are in the same direction in the direction of the axial rotation direction are attached to the vicinity of the upper and lower ends of each member to be azimuth-linked, and the two members that are connected by matching these marks are azimuth-linked.

          FIG. 1 is an explanatory view (partially broken front view) of a core collecting apparatus used for carrying out the method for collecting a core with a known orientation according to the present invention. An outer tube (4) having a bit (5) for rotating cutting at its tip and an inner tube (6) that is coaxially positioned inside the outer tube and carries the core are provided, and the outer tube and the inner tube are It has a mechanism that can freely rotate with respect to each other, and the outer tube has a mechanism in which the upper tube is screwed and connected to the upper boring rod and the inner tube is connected in an elongated direction to the upper fixed shaft, A device called a double-tube sampler (A) is placed in the ground to be cored.

    A boring rod (2) and a fixed shaft (3) coaxially positioned inside the rod and having the same connection length as the rod are provided, and the boring rod (2) and the fixed shaft (3) rotate freely with respect to each other. A double tube having a mechanism in which a boring rod is screwed up and down in a long way and a plurality of components of a fixed shaft are connected in a long direction in an up and down direction A device called a type fixed shaft boring rod (A) is arranged.

    Further, on the ground, the rotation of the fixed shaft is stopped at the upper end of the fixed shaft (3) projected from the water swivel (9) attached to the upper end of the boring rod, and the direction of the fixed shaft is fixed in an arbitrary direction. The fixed part body called the fixed axis azimuth | direction fixed part (c) which has the structure mechanism of this is arranged.

    In the above-described double-tube sampler device and a plurality of double-tube fixed-axis boring rod devices that are sequentially connected to the ground in a long manner, the outer tube and the boring rod that is connected to the ground The configuration of is a configuration related to cutting excavation, in which the rotation and thrust of the boring machine (1) are transmitted, and the configuration of the inner tube and the fixed shaft that is connected to the upper end of the fixed shaft on the ground Is a configuration related to the core storage.

    The configuration related to the core storage is characterized in that it has a dual function mechanism that is coaxially inserted freely inside the configuration related to cutting excavation and that is connected in a long direction. . By fixing the orientation of the upper end of the fixed shaft, which is the ground end of the configuration related to the core storage, from the outside in the fixed axis direction fixing portion in an arbitrary direction, the rotation of the inner tube that carries the core storage is restrained and The direction of the inner tube is maintained in an arbitrary direction, and in this state, by performing the cutting excavation with the configuration related to the cutting excavation, a method of collecting a core with a known direction becomes possible.

    The above-mentioned double tube type fixed shaft boring rod (A), which is important in work performance when carrying out the present invention, will be described. A boring rod (2) and a fixed shaft (3) positioned coaxially inside the rod and having the same connection length as the rod. The fixed shaft (3) is composed of a plurality of components connected in the vertical direction.

    Further, the boring rod and the fixed shaft rotate freely with respect to each other. A plurality of constituent parts of the boring rod are screwed up and down by a fixed shaft joint (7) having the same diameter as that of the boring rod. The fixed shaft joint (7) is also one of connecting means at the connecting portion of the components of the fixed shaft (3), and has a fixed shaft joint inner fixed shaft (31) on the inner side, and this fixed shaft joint. The upper and lower end portions of the inner fixed shaft (31) are connected to the constituent parts of the upper and lower fixed shafts (3) via the insertion joints (24) as connecting means, so that the fixed shaft (3) The plurality of constituent parts are connected in a long and downward direction.

    A device in which three members of a boring rod, a fixed shaft, and a fixed shaft joint are integrated is called a double-tube type fixed shaft boring rod (A), which makes the work procedure and work almost equivalent to the conventional core sampling method. Performance is realized.

The method of collecting a core with a known orientation according to the present invention can be implemented as follows.
A) a sampler head (11) connected to the lower end boring rod (2), and an outer tube (4) having a circular cross section having a bit (5) connected to the lower outer edge of the head and performing rotary cutting at the lower end; A fixed shaft (3) which is a freely rotating structure coaxial with the head by bearing support in the head, and is coaxially positioned with a gap through which water can flow inside the outer pipe, and through the inner pipe head (10). A sampler device called a double-pipe sampler (a) having a circular cross-section inner tube (6) that is coaxially connected to the fixed shaft and accommodates the core is disposed in the ground to be core-collected.

    B) A part of the fixed shaft (3) which has a mechanism for connecting the boring rod (2) to the upper and lower portions at the outer periphery and has a free rotating structure coaxial with the rod on the inner side. Three members of a joint portion called a fixed shaft joint (7) having a mechanism for azimuthally connecting in a long direction, a boring rod (2), and a fixed shaft (3) having the same actual connection length as the rod A unit called a double-tube type fixed-shaft boring rod (A) is integrally connected above the sampler head (11) in a plurality of lengths. By this, it becomes arrangement | positioning that the double pipe type fixed axis boring rod connected with the double pipe type sampler is connected to the ground.

    C) To stop the rotation of the fixed shaft at the ground end of the fixed shaft (3) protruding from the water swivel (9) attached to the upper end of the boring rod, and to fix the direction of the fixed shaft in an arbitrary direction. A fixed-axis fixed portion called a fixed-axis azimuth fixing portion (c) having a mechanism is disposed on the ground.

    In the above-described double-tube sampler device and a plurality of double-tube fixed-axis boring rod devices that are sequentially connected to the ground in a long manner, the outer tube and the boring rod that is connected to the ground The structure of the drilling machine transmits the rotation and thrust of the boring machine, and the structure of the fixed shaft that is connected to the inner pipe and the upper end of the fixed shaft on the ground is stored in the core. It becomes the composition concerning. The configuration related to the core storage is characterized in that it has a dual function mechanism that is coaxially inserted freely inside the configuration related to cutting excavation and that is connected in a long direction. .

Means for fixing the orientation of the fixed axis in an arbitrary direction on the ground is as follows.
A fixed rod (55) protruding on one axial plane upright on the axis of the fixed axis in the fixed axis direction fixed section (c) is connected to the upper end of the fixed shaft protruding above the water swivel (9). Let On the other hand, the fixed frame (58) having the fixing groove (59) is engaged and fixed from the outside in parallel to the excavation axis from a rod post or the like in an arbitrary direction as seen from the excavation axis.

    By inserting the fixing rod (55) into the fixing groove (59), the fixing rod can be slid upward and downward in the fixing groove, and the fixing shaft is maintained in an arbitrary direction without rotating. It becomes. In this state, the outer tube (4) to which the rotation and thrust of the boring machine are transmitted is cut and excavated, and the core in which the direction can be recognized in the inner tube (6) that remains in an arbitrary direction without rotating. A sampling method becomes possible. Incidentally, the excavation water reaches the sampler through the water swivel (9) and through the gap between the boring rod and the fixed shaft and the inside of the hollow fixed shaft joint.

Definitions of words used in the following description will be made here.
A) The outer pipe system is a boring rod that is connected to the outer pipe to the ground, and the rotation and thrust of the boring machine are transmitted to the structure related to excavation.
The inner pipe system refers to the inner pipe and a fixed shaft that is a long connection up to the upper end of the fixed shaft of the fixed axis azimuth fixing portion on the ground, and refers to a configuration related to the core accommodation.

    During sampling of cores, so-called sampling abnormalities such as seizure of the tip of the sampler due to malfunctions in the excavation water supply system and clogging of the inner pipe core due to agitation of the tip ground surface in gravelly ground may occur, which causes the inner pipe to And rotate together. Further, even when a mechanical abnormality such as a bearing breakage in which the inner tube system has a freely rotating structure occurs, the inner tube system rotates integrally with the outer tube system.

    If the core is continuously collected while the inner pipe rotates integrally with the outer pipe, a continuous core cannot be obtained = the core is lost, so an inadvertent abnormality that the outer pipe system and the inner pipe system rotate integrally is caused early. It is necessary to interrupt the work. For this reason, the rotation having the function of notifying the above-mentioned inadvertent abnormality between the fixed axis direction fixing nut (54) and the fixed bar (55) for fixing the direction of the fixed axis in the fixed axis direction fixing part (c). An abnormality detection unit (57) is provided.

    The inner tube must not rotate in order to collect the bearing core. On the other hand, if the inner tube system has a freely rotating structure supported by bearings, the inner tube system rotates due to a slight co-rotation force generated in the inner tube system due to the rotation of the outer tube system. By stopping the rotation at the upper end of the fixed shaft of the rotating inner tube system, the fixed shaft connected in a long length from the ground is twisted. Basically, the twist angle of the fixed shaft using a hollow or solid round bar is calculated in terms of material mechanics as a function of the applied torque, the cross-sectional area of the steel material, and the transverse elastic modulus.

    Also, connect a double-tube type fixed shaft boring rod used for core collection in a flat place on the ground to a horizontal length of, for example, 50 m, and grasp in advance the relationship between torque and twist angle on the fixed shaft. Is also possible.

    On the other hand, in the outdoor surface reconnaissance, which is one of the geological survey methods, the surface structure of the ground is the magnetic compass direction (strike) in the horizontal arrangement of the clinometer and the clinocompass measuring instrument attached on the surface and the inclination perpendicular to this. Although it is measured as an angle (tilt), the measurement error is about 3 °. Therefore, the practical range such as the applicable depth of the present technique is subject to restrictions as a condition that the torsion angle of the fixed shaft does not exceed approximately 3 ° in the core sampling.

    In addition, the boring hole always bends due to the installation error of the machine and the reason described later with respect to the drilling direction plan. For this reason, in this method, it is necessary to add consideration to the hole bending. In general, when the tip ground surface is hard or soft in the direction of the reaction force of excavation rotation, the base of the boring hole is bent on the soft side. In the case of a boring hole whose excavation direction is horizontal or gently inclined, the cutting waste concentrates downward so that the hole is bent upward, and as the excavation rotation and the excavation load increase, the hole bending is promoted.

    On the other hand, in order to collect a high-quality core, it is necessary to suppress the digging rotation and the digging load as much as possible, so the degree of hole bending is small and usually within 1 °. However, if there is a concern about hole bending due to the investigation conditions, a known hole bending measurement is performed, and if the hole bending is large, an error has occurred in the orientation of the collected core, or the hole bending This is an evaluation of the core orientation with the measurement result taken into account.

    In the above embodiment, although the practical range is restricted by the twist angle of the fixed shaft and the degree of bending of the boring hole, within this practical range, the rotation of the inner tube responsible for housing the core is restrained and Since the orientation of the inner tube is fixed in an arbitrary orientation, the core that can be seen in the orientation is collected at the same time as the core of good quality.

    FIG. 2 is an example of a structure explanatory view (partially broken front view) of a double tube type fixed shaft boring rod for carrying out the present invention. In order to embody the present invention, it is essential to use a strong member having a large cross-sectional area that suppresses twisting for the fixed shaft, and to have a structure that does not loosen in orientation connection. For example, a boring rod that rotates outside the fixed shaft by buckling due to its own weight when the core sampling direction is vertical, or by bending due to its own weight when the excavating direction is horizontal. There is a concern of contact accidents between the shaft and the fixed shaft.

    Also, as the digging depth increases, the boring rod and the fixed shaft are frequently connected or separated before or after the start of core collection.To reduce this work load, the boring rod and the fixed shaft are simultaneously in the same length and location. A structure that can be connected or disconnected is a requirement.

    For this reason, a fixed shaft joint (7) is arranged at the boring rod connecting part, the fixed shaft has a freely rotating structure with respect to the rod, and an intermediate holding function for dispersing the bearing connection function between the fixed shafts and the weight of the fixed shaft. Have functions together. Usually, a 3 m long boring rod (2) is screwed and connected to separate boring rods at the upper and lower ends of the fixed shaft joint (7) body outer edge.

    Since the normal directional connection cannot be made with screw connection by normal thread processing due to the degree of loosening or tightening, the inner tube system has a fixed shaft such as a special screw connection mechanism or a insertion mechanism using a combination of concave and convex shapes of polygonal columns. Any structure can be used as long as they can be reliably connected in the azimuth direction, but an example structure used in this demonstration test is as follows.

    That is, the fixed shaft joint (7) has a fixed shaft joint internal fixed shaft (31) that supports the bearing inside the body and has a coaxial freely rotating structure, and is fixed inside the boring rod having the same connection length as the boring rod above and below. The bearing is connected to the axis (3). The fixing shaft (3) in the boring rod has insertion joints (24) at both ends, and after both of them are screwed together, a screw fixing pin (26) is used to prevent loosening. 25) is grooved.

    The fixed shaft joint internal fixed shaft (31) has a diameter and a length that are inserted into the insertion joint (24) at both ends, and is provided with a fixed shaft bearing protrusion (32) extending horizontally so as to be in the same direction. Yes. The joint azimuth groove (25) has a groove width that can be inserted into the outer diameter of the fixed axis azimuth protrusion (32) without looseness.

    In order to bring a and a in FIG. 2 into close contact, both are inserted and the boring rod is screwed and connected, so that a boring rod (2), a boring rod fixed shaft (3), and a fixed shaft joint (7) are connected. The member is referred to as a double tube fixed shaft boring rod and is treated as an integral member in the core collection operation. Further, by newly adding another double tube type fixed shaft boring rod (b and b in FIG. 2 are brought into close contact with each other), the rod is elongated. As a result, the fixed shaft inside the double-tube fixed shaft boring rod, which is long from the bottom of the hole to the ground, is azimuthally connected, and the work procedure and work performance almost the same as the conventional core sampling method are realized. .

    FIG. 3 is an example of a structural explanatory view (partially broken front view) of a sampler head portion for carrying out the present invention. The outer pipe system is screwed and connected to the outer pipe (4) at the lower side and the boring rod (2) at the upper side at the outer edge of the body of the sampler head (11). The inner pipe system is a sampler head inner fixed shaft (13) having a coaxial and freely rotating structure by bearing support in the body of the sampler head (11), and the lower part is an inner pipe orientation fixing nut (14) and an inner pipe head (12). Is connected to the inner pipe (6) that bears the core storage through the upper part, and the upper part has the same structure as the double pipe type fixed axis boring rod in the insertion joint part (24) that is the lower end of the boring rod inner fixed axis (3) Connect the direction.

    The inner pipe (6) is screwed and connected to the inner pipe head (12) because it is necessary to separate the inner pipe (6) so that it can be detached and detached each time for operations such as removal of the core and disassembly and inspection. In order to connect the fixed shaft to the inner tube, the inner tube head (12) screwed to the inner tube with the inner tube bearing engraved line (16) is fixed at the threaded portion below the sampler head inner fixed shaft (13). After the rotation adjustment in the same direction as the shaft, the inner pipe head (12) is screwed and fixed by a double nut method using an inner pipe orientation fixing nut (14).

    In addition, at the tip of the inner tube, several small tools (not shown) are arranged to smoothly store the core, and these all have the same direction as the joint azimuth groove and the fixed axis azimuth projection described above. It has a plug-in structure with no looseness shown. As described above, all the inner pipe systems constituted by the inner pipe and the fixed shaft are directionally connected.

    The connecting means for realizing the directional connection of the components of the fixed shaft (3) is such that the upper component and the lower component are coupled to each other so as not to rotate. A fixed axis bearing protrusion (32) provided on the peripheral surface of the component part, an insertion joint part (24) for fitting the end of the upper component part provided on the upper component part, and the insertion joint part It can consist of the joint azimuth | direction groove | channel (25) into which the said fixed-axis azimuth | projection protrusion (32) formed in (24) approachs. The connecting means may be configured with the upper and lower components reversed.

    Although not shown in the drawings, the connecting means includes an end portion having a non-circular cross-sectional shape formed in the constituent part of one of the upper and lower fixed shafts (3) and the one formed in the other constituent part. It can consist of the joint which externally fits the edge part of this component part. The end portion having a non-circular cross-sectional shape may be, for example, a polygon such as a quadrangle or a hexagon, or a circle or an ellipse with a protruding portion in part.

    FIG. 4 is an explanatory diagram of a structure of an example fixed axis azimuth fixing unit having a function of fixing the direction of the inner pipe system. The fixed shaft (43) azimuthally connected to the ground by the double tube fixed shaft boring rod protrudes above the water swivel upper nut (42) for packing the water swivel upper body (41).

    A fixed shaft upper end portion in which the protruding portion of the fixed shaft azimuth fixing nut (54) having a protruding portion protruding on one axial plane standing upright on the axis of the fixed shaft is connected to the inner tube at the bottom of the hole; The rotation is adjusted so as to be in the same direction, and the double nut (56) is screwed and fixed from above and below. The rotation abnormality detector (57) is connected to the protrusion, and the fixing rod (55) is connected to the tip thereof. As a result, the fixed bar becomes a bar-shaped protrusion protruding in the same direction as the direction of the inner tube.

    On the other hand, a fixed frame (58) having a fixing groove (59) is externally fixed in parallel to the excavation axis from a rod post or the like in an arbitrary direction in which the inner tube orientation is to be fixed as seen from the excavation axis. By inserting the fixing rod into the fixing groove, the fixing rod can slide in the fixing groove, and the direction of the inner tube is always fixed in an arbitrary direction during the core sampling.

    A rotation abnormality detector (57) is provided between the fixed axis azimuth fixing nut (54) and the fixing rod (55) for the purpose of detecting the above-mentioned inadvertent abnormality during the core collection at an early stage. The detection unit can be, for example, an electrical detection mechanism that incorporates a tensile load cell in the rotation direction of the fixed rod, but may be any structural mechanism as long as it can detect an inadvertent rotation of the inner tube.

    As an example in the demonstration test, a thin plastic pipe that can be broken and easily repaired at a strength slightly stronger than the co-rotational force grasped in the above-described twisting operation was used. The breaking strength can be freely adjusted by changing the diameter or thickness of the plastic pipe.

    The occurrence of an abnormality in the rotation abnormality detection unit during core collection informs the occurrence of the above-mentioned inadvertent abnormality, and the operation is interrupted because the core is lost. After the excavation stop, the sampler is recovered on the ground by separating the double-tube type fixed-shaft boring rods in order. After disassembling the sampler to check and remove the cause of abnormalities such as clogging, remove the sampled core from the inner tube, assemble the sampler in a normal state, insert the sampler into the hole from the hole, and then double The sampler is lowered again to a predetermined hole bottom by sequentially adding long tube-type fixed shaft boring rods to the long length. After the aforementioned co-rotation test, the rotation abnormality detection unit is set, and when the excavation water supply is sufficient, the core collection is resumed. A high-quality core can be collected by the function of the detection unit that can detect this abnormality at an early stage.

    According to the above embodiment, the rotation of the inner pipe is restrained and the orientation of the inner pipe is fixed at an arbitrary orientation, so that the core having the orientation can be collected simultaneously with the good quality core. Incidentally, the polyethylene tube (Fig. 6) (72), which is tightly coated on the sampling core, is provided with a straight mark in the same direction as the inner tube direction engraved line (Fig. 3) (16). After being taken out of the mark, the mark indicates an arbitrary direction in which the mark is fixed.

    In the present invention, although the practical range is restricted by the twist angle of the fixed shaft and the degree of bending of the borehole, within the practical range, there is a core with a known orientation for knowing the strike inclination of the surface structure in the ground. It will be collected at the same time as a good quality core. This is a useful ground survey method because the underground ground around the borehole can be determined with almost the same equipment and procedure as the ordinary construction method using a general-purpose rotary boring machine.

A Double pipe type sampler B Double pipe type fixed axis boring rod C Fixed axis direction fixing part 1 Boring machine 2 Boring rod (breaking front view)
3 Fixed shaft 4 Outer tube (fracture front view)
5 bits (front view)
6 Inner pipe 7 Fixed shaft joint (fracture front view)
9 Water swivel 10 Inner tube head 11 Sampler head (fracture front view)
14 Inner tube orientation fixed nut 54 Fixed axis orientation fixed nut 55 Fixed rod 57 Rotation abnormality detector 58 Fixed frame 59 Fixed groove

Claims (4)

It has an outer tube with a bit for rotating cutting at the tip and an inner tube that is coaxially positioned inside the outer tube and carries the core. The outer tube is connected to the upper boring rod and rotates together with the boring rod. And
The inner tube is connected to a fixed shaft, and the fixed shaft extends upward on the inside of the boring rod, is fixed from the outside, and includes a plurality of components connected in the vertical direction. The connecting portion of each component part is provided with a connecting means that allows the upper component part and the lower component part to be connected to each other so as not to rotate, and the inner rod does not rotate with the rotation of the boring rod. A core collecting device characterized in that:     A coupling means for connecting the component parts of the fixed shaft includes a protrusion provided on a peripheral surface of one of the upper and lower component parts, and a joint that externally fits an end of the one component part provided on the other component part; The core collecting device according to claim 1, comprising a groove into which the protrusion formed on the joint enters.     The connecting means of the component part of the fixed shaft includes an end part having a non-circular cross-sectional shape formed in one of the upper and lower component parts, and an end part of the one component part formed in the other component part. The core collecting apparatus according to claim 1 or 2, comprising a joint that fits outside. The core collecting device according to claim 1, 2 or 3, wherein the rotation of the inner pipe that bears the core is restrained and the direction of the inner pipe is maintained in an arbitrary orientation, and in this state, the configuration related to cutting excavation A method of collecting a core having an azimuth that is characterized by performing cutting excavation.

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