JP2017128962A - Groundwater sampling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a groundwater sampling method which can sample groundwater at an arbitrary place in the horizontal direction of the ground by forming one borehole in the ground.SOLUTION: A groundwater sampling method comprises steps of: drilling the ground by curved boring by using a hollow casing 3 with a drilling bit 2 at the tip to form a borehole 1; removing the drilling bit 2 from the casing 3; inserting a guide pipe 4 into the casing 3; pulling out the casing 3 from the ground in a state that the guide pipe 4 is left in the borehole 1, through the tip opening of the casing 3; expanding a plurality of first packers 5 mounted on the outer peripheral surface of the guide pipe 4 in the longer direction at intervals, and bringing the packers into close contact with the porous wall of the borehole 1; and sucking groundwater from a water absorbing hole 6 located between the first packers 5 on the outer peripheral surface of the guide pipe 4.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a groundwater sampling method for sampling groundwater in a contaminated area in the ground, for example.

  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 pollution investigation method, for example, sampling of groundwater in a contaminated area in the ground has been conventionally performed.

  As a sampling method of this type, a boring hole is formed by excavating a temporary casing into the ground while penetrating vertically. A water sampling casing in which the packer is attached to the outer peripheral surface with an interval in the length direction is arranged in the borehole, and after pulling out the temporary casing, the packer is expanded by nitrogen gas or the like. A method of sampling groundwater at an arbitrary position of the water sampling casing with a water sampling device inserted into the water sampling casing by closing the gap between the bore wall of the borehole and the cylindrical wall of the water sampling casing. It is known (see, for example, Patent Document 1).

JP 9-41869 A

  However, in the method described in Patent Document 1, since a borehole is formed in the vertical direction in the ground, in order to sample groundwater directly under an existing structure such as a factory, a part of the structure penetrates the ground. If a reinforcing bar or the like is disposed on the floor of the structure, the reinforcing bar or the like may have to be cut. In addition, it is necessary to secure a space in the structure for forming the borehole in the ground. However, if the structure is a factory or the like, the factory operation may be hindered. In addition, if there is contaminated liquid with high specific gravity such as organic chlorine compounds in the ground, forming a boring hole in the vertical direction will cause contamination diffusion such as dropping the contaminated liquid deep into the ground by excavation in the ground. Concerned. Therefore, it is necessary to take measures to prevent the diffusion of contamination such as a double casing. Furthermore, the contaminated area is often scattered in a plurality of locations in the horizontal direction in the ground, but in the method described in Patent Document 1, it is necessary to form a plurality of bore holes in the ground for each contaminated location, There is also a problem that a great work period and cost are required.

  The present invention has been made paying attention to the above problems, and provides a groundwater sampling method capable of sampling groundwater at an arbitrary position in the underground horizontal direction by forming one borehole in the ground. The purpose is to do.

  The object of the present invention is to form a borehole by excavating the ground by bending boring using a hollow casing provided with a drill bit at the tip, and removing the drill bit from the casing or of the drill bit. The step of removing the core material inserted into the through hole from the excavation bit, the step of inserting a guide pipe into the casing, and the boring hole through the opening at the front end of the casing or the through hole of the excavation bit A step of pulling out the casing from the ground with the guide pipe remaining, and a plurality of first packers mounted on the outer peripheral surface of the guide pipe with a space in the longitudinal direction are expanded to form a hole wall of the boring hole A process of sucking groundwater from a water absorption hole located between the first packing and the first packer on the outer peripheral surface of the guide pipe; When it is accomplished by groundwater sampling method comprising.

  In the groundwater sampling method configured as described above, a locking member is provided at the tip of the guide pipe so as to be able to protrude and retract outside the guide pipe. In the step of inserting the guide pipe into the casing, the guide pipe It is preferable to fix the distal end portion of the guide pipe to the ground by projecting the distal end portion of the guide pipe into the ground and then projecting the locking member into the ground.

  In the groundwater sampling method having the above-described configuration, it is preferable that the first packer expands by supplying a liquid or a gas into the guide pipe. The first packer may expand by supplying a liquid or a gas to a fluid supply pipe passing through the guide pipe and connected to the first packer.

  In the groundwater sampling method having the above-described configuration, it is preferable that a suction pipe passing through the guide pipe is connected to the water absorption hole.

  Further, in the groundwater sampling method having the above-described configuration, the step of sucking the groundwater has two second packers attached to the outer peripheral surface at intervals in the longitudinal direction, and a suction hole is formed between the second packers. Inserting the water sampling pipe into the guide pipe until the suction hole is located at the ground water sampling point; inflating the second packer to closely contact the inner peripheral surface of the guide pipe; It is preferable to have a step of sucking the groundwater at the water sampling point through the water suction hole with a suction pipe connected to the suction hole.

  According to the present invention, since a boring hole extending in the horizontal direction is formed in the ground by bending boring, even if a contaminated area exists directly under an existing structure such as a factory, it reaches the contaminated area directly under the structure. The drilling hole to be formed can be formed by excavating the ground from the open space around the structure. Therefore, there is no need to dig through the ground through a part of the structure, so there is no need to cut the reinforcing bars arranged on the floor of the structure, and the structure is a factory etc. There is no risk of disturbing the operation of the factory.

  In addition, even when a contaminated liquid having a large specific gravity, such as an organic chlorine compound, exists in the ground, it is possible to excavate the ground without causing contamination diffusion such as dropping of the contaminated liquid vertically downward. Furthermore, even when the contaminated area is scattered in a plurality of locations in the horizontal direction in the ground, the boreholes extend in the horizontal direction, so that only one borehole is formed, and groundwater is sampled for each of the plurality of contaminated locations. be able to. Therefore, the construction period can be shortened and the cost can be reduced.

It is the schematic which shows the procedure of the groundwater sampling method which concerns on one Embodiment of this invention. It is the schematic which shows the procedure of the groundwater sampling method following FIG. It is the schematic which shows the procedure of the groundwater sampling method following FIG. It is the schematic which shows the procedure of the groundwater sampling method following FIG. It is the schematic which shows the procedure of the groundwater sampling method following FIG. It is the schematic which shows the procedure of the groundwater sampling method following FIG. It is the schematic which shows the procedure of the groundwater sampling method following FIG. In the groundwater sampling method which concerns on one Embodiment of this invention, it is sectional drawing which expands and shows the principal part in a boring hole. It is sectional drawing which expands and shows the principal part in the boring hole which showed the procedure of the groundwater sampling method following FIG. It is sectional drawing which expands and shows the principal part in the boring hole which showed the procedure of the groundwater sampling method following FIG. It is sectional drawing which expands and shows the principal part in a boring hole in the groundwater sampling method which concerns on other embodiment of this invention. It is sectional drawing which expands and shows the principal part in the boring hole which showed the procedure of the groundwater sampling method following FIG. It is sectional drawing which expands and shows the principal part in the boring hole which showed the procedure of the groundwater sampling method following FIG. In the groundwater sampling method which concerns on further another embodiment of this invention, it is sectional drawing which expands and shows the principal part in a boring hole. It is sectional drawing which expands and shows the principal part in the boring hole which showed the procedure of the groundwater sampling method following FIG. It is sectional drawing which expands and shows the principal part in the boring hole which showed the procedure of the groundwater sampling method following FIG. It is sectional drawing which expands and shows the principal part in the boring hole which showed the procedure of the groundwater sampling method following FIG. It is a front view of the excavation bit concerning other embodiments of the present invention. It is a front view of the core material with which the excavation bit of FIG. 17 is mounted. It is an exploded view of the core material of 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 excavation 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 excavation bit is shown in a sectional view. It is a front view of the core material with which the excavation bit concerning other embodiments of the present invention is equipped. It is a front view of the state which mounted | wore the drill bit with the core material. The excavation bit is shown in a sectional view. It is the schematic which shows the procedure of the groundwater sampling method which concerns on other embodiment of this invention. It is the schematic which shows the procedure of the groundwater sampling method following FIG. It is the schematic which shows the procedure of the groundwater sampling method following FIG. It is the schematic which shows the procedure of the groundwater sampling method following FIG.

  Hereinafter, one embodiment of the groundwater sampling method of the present invention will be described with reference to FIGS. In the groundwater sampling method of the present invention, for example, in order to sample the groundwater immediately under the existing structure B, the groundwater (horizontal) from the ground surface outside the structure B to the stratum (depth) where the contaminated water directly under the structure B exists. A boring hole 1 extending in the direction is formed, and groundwater is sampled at a plurality of locations of the boring hole 1.

  In the groundwater sampling method according to an embodiment of the present invention, a step ST1 (shown in FIG. 1) of forming a borehole 1 by excavating by bending boring using a casing 3 provided with a drill bit 2 at the tip, and groundwater After excavating to the contaminated area to be sampled, a step ST2 (shown in FIGS. 2 and 3) for removing the excavation bit 2 from the casing 3, and a step ST3 for inserting the guide pipe 4 into the casing 3 (FIGS. 2 to 4). A step ST4 (shown in FIGS. 5 and 6) of pulling out the casing 3 from the ground while leaving the guide pipe 4 in the boring hole 1 through the tip opening of the casing 3, and the outer periphery of the guide pipe 4 Step ST5 in which at least two first packers 5 mounted on the surface with a space in the longitudinal direction are inflated to closely contact the hole wall 10 of the boring hole 1 7 and FIG. 9) and a step ST6 (shown in FIG. 7 and FIG. 10) for sucking groundwater from the water absorption holes 6 located between the first packers 5 on the outer peripheral surface of the guide pipe 4. Yes.

  The detail of each process ST1-ST6 is demonstrated below. In addition, each process ST1-ST6 is not necessarily performed in the order arranged. Moreover, in the following description, the direction which inserts the casing 3 of FIG. This will be described with reference to other drawings.

  First, as shown in FIG. 1, by using a well-known boring machine 10 and performing bending boring that excavates with the excavating bit 2 while pushing the casing 3 into the ground in a non-rotating state or a rotating state, 1 is performed (step ST1).

  The casing 3 is bendable and has a cavity into which the guide pipe 4 can be inserted over the entire inside thereof. The casing 3 can be formed, for example, by connecting a plurality of cylindrical bodies so that they are sequentially added in series according to the depth of insertion into the ground. As a material of the casing 3, a known material such as a metal or a synthetic resin can be used. Further, the inner diameter and the wall thickness of the casing 3 may be appropriately set according to the strength of the ground, the soil quality, and the like, and are not limited. The casing 3 has a drilling bit 2 detachably attached to its tip, but the casing 3 and the drilling bit 2 can be conventionally known ones, and the attachment / detachment method is also a conventionally known method. Can do.

  The excavation bit 2 is made of metal (for example, steel), and the tip end surface thereof is formed on a tapered surface 20 that is inclined so that the thickness decreases from the casing 3 side toward the tip end side. Thereby, curve excavation is enabled by propelling the excavation bit 2 in the non-rotating state. Specifically, when the excavation bit 2 is pushed into the ground obliquely downward from the ground surface in a non-rotating state so that the taper surface 20 faces downward with respect to the propulsion direction X of the excavation bit 2, the tapered surface 20 Due to the earth pressure continuously acting on the excavation bit 2, an upward force with respect to the propulsion direction X is applied to the excavation bit 2 at any time. Then, as a result of the excavation bit 2 being propelled upward from the propulsion direction X, the excavation bit 2 is propelled in a curved shape convex in a diagonally downward direction. On the other hand, when a curved excavation is performed to the formation (depth) where contaminated water exists, the excavation bit 2 is pushed into the ground in a rotating state, so that a specific direction acting on the tapered surface 20 of the excavation bit 2 can be obtained. The earth pressure is canceled by the change around the rotation axis. Therefore, since the excavation bit 2 is propelled linearly along the propulsion direction X, straight excavation is performed so as to proceed in the horizontal direction.

  After excavating the ground to the contaminated region where groundwater should be sampled by bending boring in step ST1, an operation of removing the excavation bit 2 from the casing 3 (step ST2) is performed. The operation of removing the excavation bit 2 from the casing 3 can be performed by a conventionally known method. For example, an elongated rod-shaped inner rod (not shown) set to an outer diameter smaller than the inner diameter of the casing 3 so as to be movable in the casing 3 is inserted into the casing 3, and the tip of the inner rod (not shown) The removal work can be performed by pushing the part into the excavation bit 2. When the excavation bit 2 is removed from the casing 3 using an inner rod (not shown), the inner rod (not shown) is then pulled out from the casing 3 and then the guide pipe 4 is inserted into the casing 3. Work is performed (step ST3).

  In the present embodiment, as shown in FIGS. 2 and 3, the excavation bit 2 is removed by the guide pipe 4 inserted into the casing 3 for sampling the groundwater. The guide pipe 4 has a cylindrical shape with a closed end that is set to an outer diameter smaller than the inner diameter of the casing 3 so as to be movable in the casing 3. The guide pipe 4 has rigidity in the length direction in order to push the excavation bit 2 out of the casing 3, and has flexibility so as to follow the casing 3 bent and inserted in the ground. The guide pipe 4 is made of metal (for example, steel), for example.

  An elongated rod-like portion 40 is provided at the tip of the guide pipe 4. In the present embodiment, the guide pipe 4 is inserted into the casing 3 instead of the inner rod (step ST3), and the excavation bit 2 is pushed in by the rod-shaped portion 40 at the tip of the guide pipe 4, whereby the casing 3 of the excavation bit 2 is obtained. Can be removed (step ST2). A detailed description of the removal work is omitted here.

  When the excavation bit 2 is removed from the casing 3 by the guide pipe 4, the guide pipe 4 is pulled back slightly as shown in FIG. 4, and the rod-like portion 40 at the tip of the guide pipe 4 is protruded from the opening at the tip of the casing 3 into the ground. It is preferable. Further, as described above, when the guide pipe 4 is inserted into the casing 3 after the excavation bit 2 is removed from the casing 3 using an inner rod (not shown), the tip of the guide pipe 4 is connected to the casing 3. It is preferable to protrude from the tip opening into the ground.

  A pair of locking members 41 are provided on the rod-like portion 40 at the tip of the guide pipe 4 so as to be able to go out of the guide pipe 4. The locking member 41 is normally open to the outside of the guide pipe 4, and is folded against the urging force of a spring member (not shown) around the shaft 42 (closes the opened one), so that the guide pipe 4 Can be stored in the tip of When the rod-like portion 41 at the tip of the guide pipe 4 provided with such a locking member 41 is protruded from the opening at the tip of the casing 3 into the ground, the pair of locking members 41 are widely opened and caught in the ground. Therefore, the tip of the guide pipe 4 can be fixed in the ground, and the guide pipe 4 can be prevented from being pulled out by the casing 3 when the casing 3 described later is pulled out from the ground.

  When the excavation bit 2 is removed from the casing 3 and the guide pipe 4 is inserted into the casing 3 in steps ST2 and ST3, the casing 3 is connected to the boring machine 10 again as shown in FIG. The work (ST4) of pulling out from the ground is performed. As a result, as shown in FIG. 6, the guide pipe 4 remains in the boring hole 1.

  When the casing 3 is pulled out from the ground in the step ST4, next, as shown in FIG. 7, the work of expanding the plurality of first packers 5 mounted on the outer peripheral surface of the guide pipe 4 at intervals in the length direction. (ST5) is performed.

  The first packer 5 is a flexible and stretchable ring bag made of, for example, rubber, and both ends thereof are fixed to the guide pipe 4 by fixtures (not shown). . The first packer 5 is always contracted. As shown in FIG. 8, the portion of the outer peripheral surface of the guide pipe 4 covered with each first packer 5 includes an inert gas (for example, nitrogen gas) or air as an expansion fluid in the first packer 5. In order to supply a liquid such as gas or water, a supply hole 43 penetrating the cylindrical wall is formed. In the present embodiment, the fluid is supplied into the first packers 5 through the supply holes 43 by pumping the fluid into the guide pipe 4 from the fluid pump 11 disposed on the ground. As a result, as shown in FIG. 9, each first packer 5 expands and comes into close contact with the hole wall of the boring hole 1, so that a gap between the hole wall of the boring hole 1 and the outer peripheral surface of the guide pipe 4 is formed. Each first packer 5 partitions and a liquid-tight space is formed between adjacent first packers 5.

  If each 1st packer 5 of the outer peripheral surface of the guide pipe 4 is expanded by process ST5, next, as shown in FIG. 10, the water absorption hole located between the 1st packers 5 which the outer peripheral surface of the guide pipe 4 adjoins. The operation | work (process ST6) which attracts | sucks groundwater from 6 is performed.

  Between the 1st packers 5 which the outer peripheral surface of the guide pipe 4 adjoins, as shown in FIG. 9, the water absorption hole 6 which penetrates a cylinder wall is each formed. Each water absorption hole 6 is an inlet for introducing groundwater at a predetermined location in the ground into the guide pipe 4, and a separate suction pipe 12 is connected to each water absorption hole 6. As the suction tube 12, for example, a flexible hose can be used. The upper end of each suction pipe 12 is connected to a suction pump 13 disposed on the ground. On the outer peripheral surface of the guide pipe 4, a filter member 7 (for example, a built-in screen is installed) so as to cover each water absorption hole 6 between the adjacent first packers 5 to remove foreign matters and dust in the groundwater. Installed).

  Then, as shown in FIG. 10, the sampling points in the boring holes 1 are partitioned by the first packers 5 on the left and right sides of the respective water absorption holes 6, so that a predetermined suction pipe 12 is used by driving the suction pump 13. When the groundwater is sucked in the ground, only the groundwater at a predetermined position in the region where the groundwater is to be sampled flows into the suction pipe 12 in the guide pipe 4 through the filter member 7 and the water suction hole 6. Thereby, the groundwater of a desired water sampling location can be sampled with respect to the some water sampling location in the ground.

  In the present embodiment, the fluid is fed into the guide pipe 4 to supply the fluid into the first packers 5 through the supply holes 43 to expand the first packers 5 (FIG. 9). However, as shown in FIG. 11, a fluid supply pipe 14 having a plurality of branch pipes 14A connectable to the supply holes 43 of the guide pipe 4 is inserted into the guide pipe 4, and each first packer 5 is connected to the fluid supply pipe. You may comprise so that it may receive and inflate with supply of the fluid from each 14th branch pipe 14A. The upper end of the fluid supply pipe 14 is connected to a fluid pump 11 disposed on the ground.

  In this embodiment, fluid is supplied into each first packer 5 through each branch pipe 14 </ b> A and each supply hole 43 by pumping the fluid from the fluid pump 11 into the fluid supply pipe 14. As a result, as shown in FIG. 12, each first packer 5 expands and comes into close contact with the hole wall of the boring hole 1, so that a gap between the hole wall of the boring hole 1 and the outer peripheral surface of the guide pipe 4 is formed. Each first packer 5 partitions and a liquid-tight space is formed between adjacent first packers 5. In this state, when suction is performed using the predetermined suction pipe 12 by driving the suction pump 13, as shown in FIG. 13, only the groundwater at a predetermined location in the region where the groundwater is to be sampled is the filter member 7 and the water absorption. It flows into the suction pipe 12 in the guide pipe 4 through the hole 6. Therefore, it is possible to sample groundwater at a desired water sampling point with respect to a plurality of water sampling points in the ground.

  Moreover, in this embodiment, the suction pipe 12 is connected to each water absorption hole 6 of the guide pipe 4, and the groundwater at each sampling point is sucked and sampled by the plurality of suction pipes 12. However, as shown in FIG. 14, the water sampling pipe 8 may be inserted into the guide pipe 4 in the step ST <b> 6 for sucking groundwater.

  The water sampling pipe 8 has a cylindrical shape with a closed end that is set to an outer diameter smaller than the inner diameter of the guide pipe 4 so as to be movable in the guide pipe 4. The water sampling pipe 8 has flexibility so as to be along the guide pipe 4 which is bent and inserted into the ground. The water sampling pipe 8 is made of metal (for example, steel), for example.

  Two second packers 9 are mounted on the outer peripheral surface on the distal end side of the water sampling pipe 8 at intervals in the length direction. Each of the second packers 9 is a flexible and stretchable annular bag made of, for example, rubber, and both ends thereof are fixed to the water sampling pipe 8 by fixtures (not shown). Has been. Each second packer 9 is normally contracted. A portion of the outer peripheral surface of the water sampling pipe 8 covered with each of the second packers 9 includes an inert gas (for example, nitrogen gas) or an air gas such as air or water as an expansion fluid in the second packer 9. In order to supply the liquid, a supply hole 81 penetrating the cylindrical wall is formed. In the present embodiment, fluid is supplied into each second packer 9 via each supply hole 81 by pumping the fluid from the fluid pump 11 arranged on the ground into the water sampling pipe 8, and each second The packer 9 expands.

  A suction hole 80 penetrating the cylindrical wall is formed between the adjacent second packers 9 on the outer peripheral surface of the water sampling pipe 8. A suction pipe 12 connected to the suction pump 13 is connected to the suction hole 80.

  In this embodiment, in the step ST6 for sucking groundwater, first, two second packers 9 are mounted on the outer peripheral surface with a distance in the longitudinal direction, and a suction hole 80 is formed between the two second packers 9. Until the suction hole 80 reaches the ground water sampling point, that is, the water suction hole 6 and the suction hole 80 of the guide pipe 4 located at a predetermined water sampling point in the boring hole 1 A process of inserting into the guide pipe 4 is performed up to the opposing position (FIG. 14).

  Next, the fluid is supplied into the first packers 5 through the supply holes 43 by pumping the fluid from the fluid pump 11 disposed on the ground into the guide pipe 4 excluding the water sampling pipe 8. As a result, as shown in FIG. 15, each first packer 5 expands and comes into close contact with the hole wall of the boring hole 1, so that a gap between the hole wall of the boring hole 1 and the outer peripheral surface of the guide pipe 4 is formed. Each first packer 5 partitions and a liquid-tight space is formed between adjacent first packers 5.

  When each first packer 5 on the outer peripheral surface of the guide pipe 4 is inflated, next, as shown in FIG. 16, by pumping the fluid from the fluid pump 11 arranged on the ground into the water sampling pipe 8, A process of supplying a fluid into each second packer 9 through each supply hole 81 to expand each second packer 9 is performed. Thereby, each 2nd packer 9 closely_contact | adheres to the inner peripheral surface of the guide pipe 4, and the space | gap between the outer peripheral surface of the water sampling pipe 8 and the inner peripheral surface of the guide pipe 4 is made by each 2nd packer 9. A partitioned space is formed between the adjacent second packers 9.

  And the process of attracting | sucking the groundwater of the predetermined water sampling location in the boring hole 1 through the water absorption hole 6 with the suction pipe 12 connected to the suction hole 80 is performed. As shown in FIG. 17, the water sampling location in the borehole 1 is partitioned by the first packers 5 on the left and right of the water suction aperture 6, and the location where the water absorption aperture 6 in the guide pipe 4 is located is the suction aperture 80. Are separated by the left and right second packers 9, so that only the groundwater at a predetermined location in the region where the groundwater is to be sampled passes through the filter member 7, the water suction hole 6 and the suction hole 80, and the suction pipe in the water sampling pipe 8 12 flows in. Thereby, the groundwater of a desired water sampling location can be sampled with respect to the some water sampling location in the ground.

  According to this embodiment, the water sampling pipe 8 is moved in the guide pipe 4, and the suction hole 80 is positioned so as to face the other water absorption holes 6 of the guide pipe 4. It is possible to sample groundwater at a plurality of sampling points. Therefore, since it is not necessary to connect the suction pipe 12 to each of a plurality of water collection points (water absorption holes 6) in the guide pipe 4, the apparatus can be simplified.

  As described above, according to the groundwater sampling method of the present invention, the boring hole 1 extending in the horizontal direction in the ground is formed by bending boring, so that even if a contaminated area exists directly under an existing structure such as a factory. The boring hole 1 that reaches the contaminated area immediately below the structure can be formed by excavating the ground from the open space around the structure. Therefore, there is no need to dig through the ground through a part of the structure, so there is no need to cut the reinforcing bars arranged on the floor of the structure, and the structure is a factory etc. There is no risk of disturbing the operation of the factory.

  Furthermore, even when the contaminated area is scattered in a plurality of locations in the horizontal direction in the ground, the borehole 1 extends in the horizontal direction, so that only one borehole 1 is formed, and groundwater is supplied to each of the plurality of contaminated locations. Sampling is possible. Therefore, the construction period can be shortened and the cost can be reduced.

  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, in the above-described embodiment, in steps ST2 to ST4, after the excavation bit 2 is removed from the casing 3, the guide pipe 4 inserted into the casing 3 is left in the boring hole 1 through the front end opening of the casing 3. The casing 3 is pulled out from the ground. However, instead of removing the excavation bit 2 from the casing 3, a part of the excavation bit 2 is removed from the excavation bit 2, and the guide inserted into the casing 3 through the through hole of the excavation bit 2 into which the excavation bit 2 has been inserted. The casing 3 may be pulled out from the ground with the pipe 4 left in the borehole 1.

  Specifically, for example, as shown in FIGS. 18, 22, and 23, the excavation bit 2 includes a front end side portion 2A into which the core member 22 is inserted and a rear end side portion 2B to which the casing 3 is attached. A through-hole 21 is formed in the inside so as to penetrate both portions 2A and 2B in the axial direction. The front end side opening of the through hole 21 is exposed, and the rear end side opening (opening on the casing 3 side) communicates with the inside of the casing 3. The core member 22 is inserted into the through hole 21 of the distal end side portion 2A in a retaining state, and a lock ball 34, which will be described later, is fitted on the inner peripheral surface of the distal end side portion 2A (the inner surface of the through hole 21). A recessed groove 23 that can be inserted is formed over the entire circumference. The concave groove 23 and the lock ball 34 serve to keep the core material 22 in the through hole 21.

  The core material 22 is made of metal (for example, steel), and 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. The core material 22 is formed so as to match the shape of the through hole 21 of the excavation bit 2 as shown in FIGS. Further, the core material 22 is inclined linearly in a front view in which the distal end surface is inclined obliquely so as to match the shape of the distal end surface (tapered surface 20) of the excavation bit 2 and is continuous with the tapered surface 20 of the excavation bit 2. The left side surface is a substantially elliptical tapered surface 24.

  On the distal end surface (tapered surface 24) of the core member 22, for example, a protrusion 25 having a mountain shape in cross section is provided. The protrusion 25 is made of steel such as cast iron, mild steel, or hard steel, and may be fixed on the tapered surface 24 by welding, a screw, or the like, or may be integrally formed on the tapered surface 24. In addition, the cross-sectional view shape of the protrusion 25 is not particularly limited to a polygonal shape or the like other than the triangular shape as long as the pointed top is linearly extended. Note that the top does not necessarily need to be pointed, and may be a flat surface having a slight width.

  A first hole 28 that can accommodate the coil spring 26 and the sleeve 27 and a second hole 29 that is slightly larger in diameter than the first hole 28 are formed in the rear end portion of the core member 22 in order from the front end side. ing. A female screw 30 is formed on the inner surface of the second hole 29, and a coil spring 26 and a sleeve 27 are connected to the first hole 29 by fitting a nut 32 having a male screw 31 formed on the outer peripheral surface thereof into the second hole 29. It is confined in the hole 28. In addition, a plurality of accommodation holes 33 that penetrate the cylindrical wall in the radial direction are formed in the rear end portion of the core member 22 along the circumferential direction, and a spherical lock ball 34 (movable body) is formed in the accommodation hole 33. Is housed. On the other hand, a concave groove 23 into which a part of the lock ball 34 can be fitted is formed on the inner peripheral surface (the inner surface of the through hole 21) of the tip side portion 2A of the drill bit 2 over the entire circumference. .

  When inserting the core material 22 into the through-hole 21 of the drill bit 2, as shown in FIG. 21A, first, the rod-shaped portion 101 of the adapter 100 having the elongated rod-shaped portion 101 at the tip is the center of the nut 32. The sleeve 27 is pushed toward the distal end side against the spring force of the coil spring 26 through the cavity. Thereby, as shown in FIG. 21B, the lock ball 34 is completely retracted into the accommodation hole 33. When the lock ball 34 is retracted, as shown in FIG. 22, after inserting the core member 22 into the through hole 21 of the drill bit 2, when the adapter 100 is pulled out, the sleeve 27 is pulled by the restoring force of the coil spring 26. At this time, each lock ball 34 is pushed radially outward by the outer peripheral surface of the sleeve 27. As a result, as shown in FIG. 23, each lock ball 34 fits into the concave groove 23 of the drill bit 2. As a result, the core material 22 is prevented from coming out of the through hole 21 of the drill bit 2, so that a retaining state is formed.

  On the other hand, when the core material 22 is pushed out from the through hole 21 of the drill bit 2, the sleeve 27 is moved by the rod-like portion 40 at the tip of the guide rod 4 (or the inner rod (not shown) described above). When the lock ball 34 is pushed toward the tip side against the force, the lock ball 34 is completely retracted into the accommodation hole 33, so that the engagement between the core material 22 and the through hole 21 of the drill bit 2 is released. Thereby, since the retaining state of the core member 22 is released, the core member 22 can be pushed out from the through hole 21 by pushing the guide rod 4 (or the inner rod (not shown)) as it is.

  In the above description, the core material 22 is pushed out from the through hole 21 of the excavation bit 2 to open the through hole 21. However, as shown in FIGS. 24 and 25, the core material 22 is removed from the through hole 21. You may open the through-hole 21 by drawing out. In the excavation bit 2 shown in FIGS. 24 and 25, the same components as those of the excavation bit 2 shown in FIGS.

  In the excavation bit 2 shown in FIGS. 24 and 25, the core member 22 has a length of the second hole 29 in the rear end portion larger than the length of the nut 32, and the nut 22 is fitted in the state where the nut 32 is fitted. Two holes 29 extend beyond the nut 32 to the rear.

  In order to extract the core member 22 inserted into the through hole 21 of the excavation bit 2 from the through hole 21, an adapter 102 as shown in FIG. 25 is used. The adapter 102 includes a long and narrow rod-shaped portion 103 at the tip, and a detachable portion 104 that allows the adapter 102 and the core member 22 to be detached. A male screw 105 that can be fastened to the female screw 30 formed on the inner surface of the second hole 29 of the core member 2 is formed on the outer peripheral surface of the detachable portion 104. The adapter 102 is detachably attached to the distal end portion of the inner rod 106 described above by fastening with a screw or the like. Note that the tip portion of the inner rod 106 may be configured to include a rod-like portion 103 and a detachable portion 104 like the adapter 102.

  The adapter 102 is rotated while the sleeve 27 is pushed toward the tip side against the spring force of the coil spring 26 by the rod-like portion 103 of the adapter 102 configured as described above, and the male screw 105 is turned into the female screw in the second hole 29 of the core member 2. When fastened to 30, the lock ball 34 is completely retracted into the accommodation hole 33, so that the engagement between the core member 22 and the through hole 21 of the excavation bit 2 is released. Thereby, the retaining state of the core member 22 is released. When the inner rod 106 is pulled out, the core member 22 moves together with the adapter 102, so that the core member 22 can be pulled out from the through hole 21.

  In addition, as a structure of the other excavation bit 2 which opens the through-hole 21 by pushing out or pulling out the core material 22 from the through-hole 21, the structure described in the specification of Japanese Patent Application No. 2015-212415 is used. Can do.

  As described above, as shown in FIGS. 26 and 27, the core material 22 is pushed out (or pulled out) from the through-hole 21 of the drill bit 2 to open the through-hole 21, as shown in FIG. 28. , By causing the rod-like portion 40 at the tip of the guide pipe 4 inserted into the casing 3 to protrude from the tip opening of the casing 3 into the ground, the pair of locking members 41 are widely opened and caught in the ground. The tip of the guide pipe 4 can be fixed in the ground. Then, as shown in FIG. 29, the guide pipe 4 can be left in the boring hole 1 by pulling out the casing 3 from the ground through the through hole 21 of the excavation bit 2. Thereafter, groundwater sampling can be performed by performing the same processes ST5 and ST6 as in the above embodiment.

DESCRIPTION OF SYMBOLS 1 Boring hole 2 Drilling bit 3 Casing 4 Guide pipe 5 1st packer 6 Water absorption hole 8 Pipe for water sampling 9 2nd packer 12 Suction pipe 14 Fluid supply pipe 21 Through-hole 22 Core material 80 Suction hole

Claims (6)

Using a hollow casing with a drilling bit at the tip to form a borehole by drilling the ground by bending boring;
Removing the drill bit from the casing or removing the core material inserted into the through hole of the drill bit from the drill bit;
Inserting a guide pipe into the casing;
A step of pulling out the casing from the ground while leaving a guide pipe in the boring hole through the tip opening of the casing or the through hole of the excavation bit;
Inflating a plurality of first packers mounted on the outer peripheral surface of the guide pipe at intervals in the longitudinal direction to closely contact the hole wall of the boring hole;
And a step of sucking groundwater from water-absorbing holes located between the first packers on the outer peripheral surface of the guide pipe. A locking member is provided at the tip of the guide pipe so as to be able to appear and disappear outside the guide pipe,
In the step of inserting the guide pipe into the casing,
The groundwater sampling method according to claim 1, wherein after the front end portion of the guide pipe protrudes into the ground, the front end portion of the guide pipe is fixed in the ground by projecting the locking member into the ground.   The groundwater sampling method according to claim 1 or 2, wherein the first packer expands by supplying a liquid or a gas into the guide pipe.   The groundwater sampling method according to claim 1 or 2, wherein the first packer expands by supplying a liquid or a gas to a fluid supply pipe that passes through the guide pipe and is connected to the first packer.   The groundwater sampling method according to any one of claims 1 to 4, wherein a suction pipe passing through the guide pipe is connected to the water absorption hole. The step of sucking the groundwater includes
A water sampling pipe in which two second packers are attached to the outer peripheral surface with a space in the longitudinal direction and a suction hole is formed between the second packers, and the suction hole is located at a groundwater sampling point. Inserting into the guide pipe until,
Inflating the second packer and closely contacting the inner peripheral surface of the guide pipe;
The groundwater sampling method in any one of Claims 1-4 which has the process of attracting | sucking the groundwater of a water sampling location through the said water absorption hole with the suction pipe connected to the said suction hole.