JP2017089263A - Soil sampling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil sampling method that enables soil sampling work to be easily carried out and prevents slurry from being mixed into the sampled soil.SOLUTION: A soil sampling method is used to sample underground soil by drilling the ground up to a predetermined position. A hollow drilling pipe 3 has an open hole 21, which penetrates in an axial direction and has a dimension enabling a soil sampling equipment 8 to be inserted in the hole, and a drilling bit 2 at a tip, which has a core material 4 inserted in the open hole 21. The soil sampling method comprises at least: a process to insert the drilling pipe into underground by drilling the ground by the drilling bit 2; a process to pull out the core material 4 from the open hole 21 of the drilling bit 2 by an inner rod 6 inserted in the drilling pipe 3; and a process to take the soil into the soil sampling equipment 8 by inserting the soil sampling equipment 8 into the drilling pipe 3 and making the soil sampling equipment project underground from the open hole 21 of the drilling bit 2.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a soil sampling method for sampling soil in a contaminated area in the ground.

  In recent years, the diffusion of pollutants into the ground has been regarded as a problem, and contamination surveys are being conducted in contaminated areas where the probability of contamination is high. As this contamination investigation method, for example, Patent Document 1 discloses a method of injecting muddy water from a drill bit and sampling the excavated soil together with the muddy water when excavating with the drill bit. In this method, soil can be sampled continuously while excavating.

  Patent Document 2 discloses a method of sampling after sampling to a predetermined position to be sampled by a drilling bit, inserting a sampler into the drilling pipe, and further excavating with the drilling bit to sample the soil into the sampler. It is disclosed.

JP 2007-155495 A JP 2010-180581 A

  However, in the method described in Patent Document 1, since the soil is sampled in a state in which muddy water is jetted, the mud is also sampled together with the soil. It contains chemicals to prevent it. Therefore, in order to analyze the sampled soil, it is necessary to separate the mud from the soil, but the operation is extremely difficult. Further, when the soil is contaminated, the collected mud is also contaminated, so that the pollutants increase and the processing cost increases. Further, when the soil is contaminated, if the soil is sampled while spraying mud from the drilling bit, the contaminated mud diffuses to the periphery, and the contaminated area is expanded.

  On the other hand, in the method of Patent Document 2, when soil is sampled while excavating with a drill bit, since the hole is covered with soil, friction resistance is generated in the drill tube during excavation. Therefore, if the length of the drilling tube is increased to sample the soil deep in the ground, the frictional resistance also increases. Therefore, a large force is required for drilling the drilling bit, and the drilling bit is brought into the ground. Since the resistance when pushing in is large, sampling work becomes difficult.

  The present invention has been made paying attention to the above-described problems, and an object of the present invention is to provide a soil sampling method that facilitates soil sampling work and prevents muddy water and the like from being mixed into the sampled soil.

  The above object of the present invention is a soil sampling method for excavating to a predetermined position and sampling soil in the ground, and has a through-hole having a size capable of penetrating in the axial direction and inserting a soil sampling device. And a step of inserting a hollow drilling tube having a drilling bit having a core inserted into the through-hole into the ground while excavating with the drilling bit, and being inserted into the drilling tube. A step of pulling out the core material from the through hole by an inner rod; and inserting the soil sampling device into the drilling pipe and projecting the soil from the through hole of the drilling bit into the ground. And the step of taking in the device.

  In the soil sampling method having the above-described configuration, after the soil is taken into the soil sampling device, the step of collecting the soil sampling device, and the core material is inserted into the through hole of the drilling bit and again by the drilling bit. And a step of excavating.

  Further, in the soil sampling method having the above-described configuration, the core material is inserted into the through hole in a state of being retained by a retaining means, and the retaining state of the core material by the retaining means is released by the inner rod. Then, it is preferable to pull out the core material from the through hole.

  In this case, the retaining means is provided on the inner surface of the through hole of the drilling bit, and the movable body provided on the core member so that a part of the core member can appear from the outer peripheral surface of the core member. A concave groove that can be engaged with a part of the movable body that has emerged from the outer peripheral surface of the core material, and a part of the movable body that can be projected and retracted from the outer peripheral surface of the core material. It is preferable that a part of the movable body is retracted from the outer peripheral surface of the core member into the core member by pressing the switching mechanism with the inner rod.

  Further, in the soil sampling method of the above configuration, the core material is inserted into the through hole in a state of being connected to the inner rod, and the inner rod is inserted into the ground together with the drilling tube, It is preferable to pull out the core material from the through hole by pulling it out from the hole drilling tube.

  In the soil sampling method having the above configuration, the soil sampling device includes a cylindrical sampling tube filled with soil, a cylindrical casing that houses the sampling tube, and a cylinder attached to one end of the casing. It is preferable to provide a shape-like tip shoe.

  Moreover, in the soil sampling method of the said structure, it is preferable that the front end surface of the said front end shoe is formed in the taper surface which inclines linearly by front view.

  Moreover, in the soil sampling method of the said structure, it is preferable that the said sampling tube is formed by closing two openable and closable members.

  ADVANTAGE OF THE INVENTION According to this invention, it is easy to perform soil sampling operation | work, and it can prevent that muddy water etc. mix in the sampled soil.

It is the schematic which shows the procedure of the soil sampling method which concerns on one Embodiment of this invention. It is a front view of a drill bit. It is a front view of a core material. It is an exploded view of a core material. It is the schematic which shows the procedure of the soil sampling method following FIG. It is the schematic which shows the procedure of the soil sampling method following FIG. It is a front view which shows the state with which a drill bit is mounted | worn with a core material. It is a front view of the state which attaches a core material to a drill bit. The drill bit is shown in a sectional view. It is a front view of the state which mounted | wore the drill bit with the core material. The drill bit is shown in a sectional view. It is the schematic which shows the procedure of the soil sampling method following FIG. It is the schematic which shows the procedure of the soil sampling method following FIG. (A) is sectional drawing of the state which decomposed | disassembled the soil sampling apparatus, (b) is sectional drawing of a soil sampling apparatus. It is the schematic which shows the procedure of the soil sampling method following FIG. It is the schematic which shows the procedure of the soil sampling method following FIG.

  Hereinafter, the actual form of the soil sampling method according to the present invention will be described with reference to FIGS. In the soil sampling method according to the present invention, a step of inserting a hollow drilling tube 3 having a drilling bit 2 having a core material 4 inserted into a through-hole 21 at the tip thereof into the ground while excavating with the drilling bit 2. S1 (shown in FIG. 1) and the inner rod 6 inserted into the drilling tube 3 after excavating to a predetermined position to be sampled by the drilling bit 2, the core material 4 is inserted into the through-hole 21 of the drilling bit 2. Step S2 (shown in FIG. 5 and FIG. 6), and a soil sampling device (hereinafter, also referred to as “sampler”) 8 is inserted into the drilling pipe 3 and the through hole 21 of the drilling bit 2 is inserted into the ground. Step S3 (shown in FIG. 10 and FIG. 11) for taking in the soil into the sampler 8 by projecting to at least. Further, in the soil sampling method of the present embodiment, after the soil is taken into the soil sampling device 8, the step S4 (shown in FIG. 13) of extracting the soil sampling device 8 from the bore tube 3 and the penetration of the bore bit 2 Step S5 (shown in FIG. 14) for inserting the core material 4 into the hole 21 and excavating again with the drill bit 2 is further provided. In the following description, the direction in which the drilled tube 3 of FIG. 1 is inserted into the ground is the tip side. This will be described with reference to other drawings.

  First, in step S1, as shown in FIG. 1, using a boring machine 10 installed on the ground, excavating with a drill bit 2 while pushing the drill pipe 3 into the ground in a non-rotating state or a rotating state. Thus, the work of inserting the drilling tube 3 into the ground is performed.

  The drilling tube 3 can be bent, and has a cavity into which various instruments for soil sampling can be inserted in the entire tube. This drilled tube 3 can be formed, for example, by connecting a plurality of cylindrical bodies so as to be sequentially added in series according to the depth of insertion into the ground. As the material of the drilling tube 3, a known material such as a metal or a resin can be used. Further, the inner diameter and the wall thickness of the hole drilling tube 3 may be appropriately set according to the strength of the ground, the soil quality, etc., and are not limited.

  The drill bit 2 is made of metal (for example, steel), and as shown in FIG. 2, a front end portion 2A into which the core material 4 is inserted, and a rear end portion 2B to which the drill tube 3 is attached. It has. The front end surface of the drill bit 2 is a tapered surface 20 having a substantially elliptical shape in a left side view that is inclined in a straight line when viewed from the front, and the front end portion 2A is formed in a tapered shape.

  For example, by pushing the drill bit 2 into the ground obliquely downward in a non-rotating state so that the taper surface 20 faces downward with respect to the propulsion direction X of the drill bit 2, the taper surface 20 is continued. The upward force with respect to the propulsion direction X acts on the drill bit 2 at any time due to the earth pressure acting on the earth. As a result, the drill bit 2 is propelled upward from the propulsion direction X, and as a result, is propelled in a convex curve in a diagonally downward direction. On the other hand, when the drill bit 2 is pushed into the ground in a rotating state, the earth pressure from a specific direction acting on the tapered surface 20 of the drill bit 2 is canceled by the change around the rotation axis. Therefore, the drill bit 2 is propelled linearly along the propulsion direction X.

  In the drill bit 2, a through hole 21 penetrating in the axial direction is formed inside. The opening on the front end side of the through hole 21 is exposed, and the opening on the rear end side (opening on the drilling tube 3 side) communicates with the inside of the drilling tube 3. A female screw 22 is formed on the inner peripheral surface of the rear end side portion 2B of the drill bit 2 and is fastened with a male screw (not shown) formed on the outer peripheral surface of the tip portion of the drill tube 3. The drill bit 2 is fixed to the drill tube 3. Although details will be described later, the sampler 8 is inserted into the through hole 21. Therefore, the through hole 21 is formed in a size that allows the sampler 8 to be inserted. In addition, the core material 4 is normally inserted in the through-hole 21.

  On the inner peripheral surface (the inner surface of the through hole 21) of the portion 2A on the distal end side of the drill bit 2, a concave groove 23 into which a part of a lock ball 52 described later can be fitted is formed over the entire circumference. . The concave groove 23 constitutes a retaining means 5 for inserting the core material 4 into the through hole 21 in a retaining state.

  The core member 4 may be made of, for example, hard plastic or FRP (fiber reinforced plastic) as long as it has a certain degree of hardness and wear resistance, in addition to being made of metal (for example, steel). As shown in FIGS. 3 and 4, the core material 4 is formed so as to match the shape of the through hole 21 of the drill bit 2. Further, the core material 4 is linear in a front view in which the tip surface is inclined obliquely so as to match the shape of the tip surface (tapered surface 20) of the drill bit 2 and is continuous with the tapered surface 20 of the drill bit 2. The left side surface is inclined with a substantially elliptical tapered surface 40.

  On the distal end surface (tapered surface 40) of the core member 4, for example, a protrusion 41 having a mountain shape in cross section is provided. The protrusion 41 is made of steel such as cast iron, mild steel, or hard steel, and may be fixed on the tapered surface 40 by welding, a screw, or the like, or may be integrally formed on the tapered surface 40. In addition, the cross-sectional view shape of the protrusion 41 is not particularly limited to a polygonal shape other than the triangular shape as long as the pointed sharp top portion 42 extends linearly. Note that the top portion 42 is not necessarily sharp, and may be a flat surface having a certain width.

  When excavating to a predetermined position to be sampled using the drill bit 2 having the above-described configuration, in the next step S2, as shown in FIGS. 5 and 6, the inner rod 6 is inserted into the drill tube 3 and inserted. The operation of pulling out the core material 4 from the through hole 21 of the drill bit 2 is performed using the inner rod 6.

  The inner rod 6 is in the shape of a long and narrow bar that is set to have an outer diameter smaller than the inner diameter of the hole drilling tube 3 so as to be movable in the hole drilling tube 3. The inner rod 6 has rigidity in the length direction in order to pull out the core material 4 from the through hole 21 of the drill bit 2 and can be along the drill tube 3 bent and inserted in the ground. It has flexibility. The inner rod 6 is made of metal (for example, steel), for example.

  The core material 4 is normally inserted into the through-hole 21 of the drill bit 2 in a retained state by the retaining means 5. In the present embodiment, the retaining member 5 is provided with a movable body that can partially emerge from the outer peripheral surface of the core member 4, and the inner surface of the through hole 21 of the drill bit 2 (inside of the drill bit 2). The peripheral surface is provided with a concave groove 23 to which a part of the movable body appearing from the outer peripheral surface of the core member 4 can be engaged, and the movable body is engaged with the concave groove 23 so that the through-hole 21 is engaged. The inserted core material 4 is in a state of being prevented from being removed. A coil spring 70 and a sleeve 71 are provided in the core member 4 as a switching mechanism 7 that allows a part of the movable body to protrude from the outer peripheral surface of the core member 4. 4 is configured such that a part of the movable body is withdrawn from the outer peripheral surface of the core material 4 into the core material 4 by pressing the switching mechanism 7 to release the retaining state of the core material 4. Yes.

  As shown in FIGS. 3 and 4, the core member 4 has a first hole 44 capable of accommodating the coil spring 70 and the sleeve 71 in order from the front end side, and a diameter slightly larger than that of the first hole 44. A large second hole 45 is formed. A female screw 46 is formed on the inner surface of the second hole 45, and a coil spring 70 and a sleeve 71 are connected to the first hole 45 by fitting a nut 48 having a male screw 47 formed on the outer peripheral surface thereof into the second hole 45. It is confined in the hole 44. At this time, the length of the second hole 45 of the core member 4 is larger than the length of the nut 48, and the second hole 45 extends rearward beyond the nut 48 in a state where the nut 48 is fitted. . In addition, a plurality of accommodation holes 49 that penetrate the cylindrical wall in the radial direction are formed at the rear end portion of the core member 4 along the circumferential direction. A spherical lock ball 52 is accommodated in the accommodation hole 49. Yes. The lock ball 52 constitutes the movable body of the retaining means 5.

  In order to insert the core material 4 into the through hole 21 of the drill bit 2, an adapter 60 as shown in FIG. The adapter 60 includes an elongated rod-like portion 61 at the tip, and the rod-like portion 61 pushes the sleeve 71 toward the tip against the spring force of the coil spring 70 through the cavity at the center of the nut 48. As shown in FIG. 7B, the lock ball 52 is completely retracted into the accommodation hole 49. When the lock ball 52 is retracted, as shown in FIG. 8, when the core member 4 is inserted into the through hole 21 of the drill bit 2 and then the adapter 60 is pulled out, the sleeve 71 is pulled by the restoring force of the coil spring 70. At this time, the lock balls 52 are pushed radially outward by the outer peripheral surface of the sleeve 71. As a result, as shown in FIG. 9, each lock ball 52 fits into the concave groove 23 of the drill bit 2. Thereby, since the core material 4 is prevented from coming out of the through hole 21 of the drill bit 2, a retaining state is formed. The adapter 60 is detachably attached to the tip of the inner rod 6 by fastening with screws or the like.

  On the other hand, in order to extract the core material 4 inserted into the through hole 21 of the drill bit 2 from the through hole 21, the sleeve 71 is directed toward the distal end side against the spring force of the coil spring 70 by the rod-like portion 61 of the adapter 60. Push in. As a result, the lock ball 52 is completely retracted into the accommodation hole 49, so that the engagement between the core material 4 and the through-hole 21 of the drill bit 2 is released, and the retaining state of the core member 4 by the retaining means 5 is prevented. Canceled.

  Here, the adapter 60 includes a detachable portion 62 that enables the adapter 60 and the core material 4 to be detachable at the base end of the rod-shaped portion 61. A male screw 63 that can be fastened with a female screw 46 formed on the inner surface of the second hole 45 of the core member 4 is formed on the outer peripheral surface of the detachable portion 62.

  When the adapter 60 is rotated while the sleeve 71 is pushed toward the distal end side with the rod-shaped portion 61 of the adapter 60, the male screw 63 of the detachable portion 62 is fastened to the female screw 46 of the second hole 45 of the core member 4. Since the core material 4 and the core material 4 are integrated, the core material 4 moves together with the adapter 60 when the adapter 60 is pulled out. Therefore, the core material 4 can be pulled out from the through hole 21.

  In this embodiment, the adapter 60 is detachably attached to the distal end portion of the inner rod 6, but the distal end portion of the inner rod 6 includes a rod-shaped portion 61 and a detachable portion 62 like the adapter 60. It is also possible to adopt a configuration.

  When the core material 4 is pulled out from the through hole 21 of the drill bit 2 using the inner rod 6 having the above-described configuration, in the next step S3, the sampler 8 is inserted into the drill tube 3 as shown in FIGS. Then, by allowing the sampler 8 to protrude from the through hole 21 of the drill bit 2 into the ground, an operation of taking the soil in the ground into the sampler 8 is performed. The sampler 8 is attached to the tip of the inner rod 6 so as to be detachable by fastening with screws or the like. Led up to.

  As long as the sampler 8 is configured so that the size of the outer shape is smaller than the inner diameter of the hole drilling tube 3 and can move smoothly in the hole drilling tube 3, a conventionally known one can be used. In this embodiment, as shown in FIGS. 12A and 12B, a cylindrical sampling tube 80 into which soil is taken in, and a cylindrical casing 81 that forms the outer shell of the sampler 8 and accommodates the sampling tube 80 therein. And a cylindrical tip shoe 82 attached to one end of the casing 81 is used.

  The casing 81 is made of, for example, metal (for example, steel), and has a cylindrical shape having an accommodation space for the sampling tube 80 therein. A male screw 83A is formed on the outer peripheral surface of the front end portion of the casing 81, and is fastened together with a female screw 83B formed on the inner peripheral surface of the front shoe 82 (the inner surface of the third hole 86C), thereby 82 is fixed to the casing 81. A female screw 84B is formed on the inner peripheral surface of the rear end portion of the casing 81, and the casing 81 is fastened together with a male screw (not shown) formed on the outer peripheral surface of the front end portion of the inner rod 6. Is fixed to the inner rod 6. In the present embodiment, the casing 81 has an internal thread in which a first portion 81A to which the tip shoe 82 is fixed and a second portion 81B to which the inner rod 6 is fixed are formed at the rear end portion and the tip portion, respectively. They are integrated by fastening 85B and male screw 85A.

  The sampling tube 80 is made of, for example, metal (for example, steel), and has a length that extends to the vicinity of the distal end portion of the inner rod 6 fixed to the casing 81 in a state of being accommodated in the casing 81. Accordingly, the position of the sampling tube 80 in the casing 81 is fixed, and when the casing 81 is divided into the first part 81A and the second part 81B, a part of the sampling tube 80 is the first part. Since it is exposed from 81A, the sampling tube 80 can be easily taken out from the casing 80. The sampling tube 80 may be a simple tube, or may be formed by closing two openable / closable half members (not shown). By connecting the two half members with a hinge (not shown) or the like so as to be opened and closed, the soil taken into the sampling tube 80 can be easily taken out.

  The tip shoe 82 is made of, for example, metal (for example, steel), and a through-hole 86 that penetrates in the axial direction is formed inside. The tip shoe 82 is, for example, a tapered surface 87 having a substantially elliptical shape when viewed from the left side, with the tip surface inclined linearly when viewed from the front, and the tip side portion is formed in a tapered shape. The tip shoe 82 does not necessarily have to be formed in a tapered shape on the tip side. The through hole 86 has a first hole 86A, a second hole 86B having a slightly larger diameter than the first hole 86A, and a third hole 86C having a slightly larger diameter than the second hole 86B from the front end side. It consists of and. A female screw 83B is formed on the inner surface of the third hole 86C. The distal end portion of the sampling tube 80 is fitted into the second hole 86B, and the distal end portion of the sampling tube 80 abuts on a step at the boundary between the first hole 86A and the second hole 86B. The sampling tube 80 takes in soil from the first hole 86 </ b> A of the tip shoe 82.

  When the soil at the desired position in the ground is sampled using the sampler 8 having the above-described configuration, in the next step S4, the sampler 8 is recovered by pulling out the inner rod 6 from the drilled tube 3 as shown in FIG. Work is done. Then, after the sampler 8 is collected, in the next step S5, as shown in FIG. 14, the core material 4 is attached to the tip of the inner rod 6, and the inner rod 6 is inserted into the drilled tube 3. Then, after the core material 4 is inserted into the through hole 21 of the drill bit 2 using the inner rod 6, another drilling operation with the drill bit 2 to a predetermined position where the soil should be sampled is performed. In addition, soil sampling work is performed.

  According to the present invention, excavation is performed by pushing the drill bit 2 and drill pipe 3 into the ground, and sampling of the soil is performed by pushing the sampler 8 into the ground using the inner rod 6. Here, when sampling the soil, when the sampler 8 is pushed into the ground, frictional resistance is generated between the sampler 8 and the surrounding soil and between the inner rod 6 and the drilled tube 3. However, since these samplers 8 have a smaller outer shape than the drill bit 2 and the drill tube 3 and the friction resistance between the inner rod 6 and the drill tube 3 is smaller than that of the conventional example, In addition, when the soil is sampled while excavating with the drill bit 2 and the drill tube 3, the frictional resistance generated between the soil and the surrounding soil is small. Therefore, since a large force is not required to push the sampler 8 into the ground, the sampling work can be facilitated, and even if the soil is hard or rubble exists in the soil, it can be pushed away. The soil can be sampled. In particular, when the tip shoe 82 is formed in a tapered shape, the soil can be sampled by effectively pushing away debris and the like.

  In addition, according to the present invention, the soil is sampled by pushing the sampler 8 into the ground in front of the drilling bit 2 and the drilling pipe 3 from the position where the excavation has been completed. No water or muddy water is mixed in the sampled soil. Therefore, as in the conventional example, when analyzing the sampled soil, it is not necessary to separate the mud from the soil, so that the analysis work of the soil can be facilitated, and when the soil is contaminated, There is no increase in pollutants. Furthermore, when the soil is contaminated, the contaminated mud does not diffuse to the surroundings, so that the contaminated area is not enlarged.

  Furthermore, after sampling the soil with the sampler 8, the core material 4 is again inserted into the through hole 21 of the drill bit 2 so that the excavation can be repeatedly performed and the soil can be sampled at another location.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning of this invention.

  For example, as a retaining means for retaining the core material 4 in the through hole 21 of the drill bit 2, a male screw is formed on the outer peripheral surface of the core material 4 and on the inner surface of the through hole 21 of the drill bit 2. The core material 4 may be retained in the through hole 21 by forming a female screw and screwing the core material 4 into the through hole 21. In this case, if the inner rod 6 is connected to the core member 4 so as to be integrally rotatable, and the core member 4 is rotated in a direction in which the screw connection between the male screw and the female screw is released, the core member 4 is moved to the inner rod 6. At the same time, it can be pulled out from the through hole 21 of the drill bit 2.

  Further, it is not always necessary to insert the core material 4 into the through-hole 21 of the drill bit 2 in a retaining state. The core material 4 is simply fitted into the through-hole 21 of the drill bit 2 and the core material 4 and the inner rod 6 are attached. In an always connected state, the inner rod 6 is inserted into the drilling tube 3 from the time of excavation in step S1, and after excavating to a predetermined position to be sampled by the drilling bit 2 in step S2, the inner rod 6 is cut. The core material 4 may be pulled out from the through hole 21 of the drill bit 2 by pulling out from the hole tube 3.

2 drilling bit 3 drilling tube 4 core material 5 retaining means 6 inner rod 7 switching mechanism 8 soil sampling device (sampler)
21 Through-hole 23 Concave groove 52 Rock ball 80 Sampling tube 81 Casing 82 Tip shoe

Claims (8)

A soil sampling method for excavating to a predetermined position and sampling soil in the ground,
A hollow drilling tube having a drilling bit penetrating in the axial direction and having a through-hole of a size capable of inserting a soil sampling device and having a core material inserted into the through-hole is provided at the tip. Inserting into the ground while drilling with a bit;
A step of pulling out the core material from the through hole by an inner rod inserted into the hole drilling tube;
A soil sampling method comprising at least a step of inserting the soil sampling device into the drilling tube and projecting the soil into the soil sampling device by projecting the soil sampling device into the ground from the through hole of the drilling bit. Recovering the soil sampling device after taking the soil into the soil sampling device;
The soil sampling method according to claim 1, further comprising a step of inserting the core material into the through hole of the drill bit and excavating again with the drill bit. The core material is inserted into the through hole in a state of being retained by retaining means,
The soil sampling method according to claim 1 or 2, wherein the core member is pulled out from the through hole by releasing the core member from being retained by the retaining means with the inner rod. The retaining means includes
A movable body provided on the core material such that a part can appear from the outer peripheral surface of the core material;
A concave groove provided on the inner surface of the through hole of the drill bit and engageable with a part of the movable body that emerges from the outer peripheral surface of the core member;
A switching mechanism that is provided in the core material, and that allows a part of the movable body to appear and disappear from an outer peripheral surface of the core material,
The soil sampling method according to claim 3, wherein a part of the movable body is retreated from the outer peripheral surface of the core material into the core material by pressing the switching mechanism with the inner rod. The core material is inserted into the through hole in a state of being connected to the inner rod,
The soil sampling method according to claim 1 or 2, wherein the inner rod is inserted into the ground together with the hole drilling tube, and the core material is pulled out from the through hole by pulling out from the hole drilling tube. The soil sampling device is:
A cylindrical sampling tube filled with soil;
A cylindrical casing that houses the sampling tube therein;
A soil sampling method according to any one of claims 1 to 5, comprising a cylindrical tip shoe attached to one end of the casing.   The soil sampling method according to claim 6, wherein the tip shoe is formed in a tapered surface whose tip surface is linearly inclined in a front view.   The soil sampling method according to claim 6 or 7, wherein the sampling tube is formed by closing two openable and closable half members.

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