JP6006138B2 - Vertical hole drilling method and vertical hole drilling apparatus - Google Patents

Description

  The present invention relates to a vertical hole excavation method and a vertical hole excavation apparatus for excavating a vertical hole for inserting a pile or a steel material.

  In recent years, it has been regarded as a problem that in the ground where contaminated soil or contaminated water is present (hereinafter referred to as contaminated layer), the contamination range extends to the lower layer by excavating vertical holes for inserting piles or steel materials. ing. That is, in the ground where the contaminated layer above the impermeable layer and the water permeable layer below the impermeable layer are present, the vertical hole is formed through the impermeable layer vertically. Then, since the insulation state by the impermeable layer is lost during the excavation of the vertical hole, the pollutant in the contaminated layer may move to the lower permeable layer during excavation, and the contamination spreads to the lower permeable layer. There is a fear.

  As countermeasures against this problem, for example, the techniques of Patent Documents 1 and 2 below are known. In the technique of Patent Document 1, an extrapolation tube that reaches an impermeable layer is placed in a contaminated layer, and the hollow portion of the extrapolation tube is soiled and washed, and a pile is installed in the hollow portion of the extrapolation tube, The gap is filled with a filling material. Moreover, in the technique of patent document 2, after replacing the contaminated soil of the area | region where a pile is constructed with the replacement material for preventing infiltration of a pollutant, the pile is installed.

Japanese Patent No. 3572567 Japanese Patent No. 3367042

  However, both the techniques of Patent Documents 1 and 2 have a problem that necessary materials and special processes increase, leading to an increase in work period. In view of this problem, an object of the present invention is to provide a vertical hole excavation method and a vertical hole excavation apparatus that can suppress the diffusion of soil contamination while suppressing an increase in construction period.

  The vertical hole excavation method according to the present invention is a vertical hole excavation in which a vertical hole is formed by excavating the ground having an upper permeable layer located above the impermeable layer and a lower permeable layer located below the impermeable layer. In the method, a first excavation step of excavating a vertical hole to an intermediate portion of the impermeable layer, a replacement step of replacing soil in an area excavated in the first excavation step with an excavating solution, and an upper permeable layer in the excavating solution And a layer forming step of forming a sealing layer by spraying a layer forming material on a region including a boundary portion of the impermeable layer, a second excavating step of excavating a vertical hole from a middle portion of the impermeable layer to the lower permeable layer, It is characterized by providing.

  According to the vertical hole excavation method of the present invention, it is provided with a layer forming step of forming a sealing layer by spraying a layer forming material onto a region including the boundary between the upper permeable layer and the impermeable layer in the drilling liquid. Thus, in the layer formation step, the layer forming material is sprayed onto the region including the boundary portion between the upper water-permeable layer and the impermeable layer, whereby a sealing layer is formed in this region, and the region including the boundary portion, that is, the upper portion The region of the vertical width from the water permeable layer to the water impermeable layer is cured or made highly viscous. Therefore, the contaminated soil of the upper permeable layer located above the impermeable layer is less likely to fall into the impermeable layer, and the contaminated water of the upper permeable layer is less likely to flow out to the region including the boundary portion in the vertical hole. . In this way, since the fall of the contaminated soil into the impermeable layer in the vertical hole and the outflow of the contaminated water to the region including the boundary portion can be suppressed, the upper permeable layer to the uncontaminated lower permeable layer Therefore, the movement of the pollutant is suppressed, and the diffusion of the soil contamination can be suppressed. Further, in the vertical hole excavation method of the present invention, it is not necessary to install an intubation tube or embed a filling material, so that necessary materials and special processes may be extremely increased as compared with conventional vertical hole excavation. Since it can be suppressed, an increase in construction period can be suppressed.

  Moreover, you may provide the pile installation process which installs a pile in a vertical hole after a 2nd excavation process. In this way, even when a method using a cast-in-place pile or a method using a pre-made pile such as a pre-boring method is employed by providing a pile installation step for installing a pile in the vertical hole excavated in the second excavation step The effect is obtained. Moreover, you may provide the steel material installation process which installs the steel materials used by SMW (Soil Mixing Wall) method in a vertical hole after a 2nd excavation process. As described above, by providing the steel material installation step, the same effect as described above can be obtained even when the SMW method, which is a kind of columnar continuous retaining wall method for forming a wall body in the ground, is used.

  Moreover, you may provide the penetration measurement process of measuring the penetration of the sealing layer formed at the layer formation process before the 2nd excavation process. Thus, the hardness of the sealing layer formed by providing a penetration measurement step for measuring the penetration of the sealing layer formed at the boundary between the upper permeable layer and the impermeable layer on the inner surface of the vertical hole. Can be measured. Therefore, since the hardness of the layer forming material is measured before the second excavation process for excavating from the impermeable layer to the lower permeable layer is performed, it is confirmed whether the sealing layer is solidified and the excavation proceeds to the lower permeable layer. It will be possible to determine whether or not it is acceptable. Therefore, the movement of the contaminants from the upper permeable layer to the lower permeable layer is more reliably suppressed, and the contamination diffusion of the ground can be more reliably suppressed.

  A vertical hole excavation apparatus according to the present invention is a vertical hole excavation in which a vertical hole is formed by excavating a ground having an upper permeable layer located above an impermeable layer and a lower permeable layer located below the impermeable layer. In the apparatus, in a state where the vertical hole is excavated to the middle part of the impermeable layer by the excavating part excavating the vertical hole, and the soil in the excavated area is replaced with the excavating liquid, And a spraying part for spraying a layer forming material onto a region including a boundary part between the layer and the impermeable layer to form a sealing layer.

  According to the vertical hole drilling device having such a spraying portion, the layer forming material is sprayed on the region including the boundary portion between the upper permeable layer and the impermeable layer in the drilling liquid, and the region including the boundary portion is cured or hardened. The viscosity is increased to form a sealing layer. Therefore, the fall of the contaminated soil and the outflow of contaminated water to the lower permeable layer can be suppressed, the movement of the contaminant from the upper permeable layer to the lower permeable layer can be suppressed, and the contamination diffusion of the ground can be suppressed. In addition, when the vertical hole drilling device of the present invention is used, it is not necessary to install an extratubation tube or to embed a filling material, so that the necessary materials and special processes are extremely compared with conventional vertical hole drilling. Since the increase is suppressed, an increase in the work period can be suppressed.

  Moreover, the vertical hole excavation device of the present invention may further include a penetration measurement unit that measures the penetration of the sealing layer formed by the spraying unit. In this case, similarly to the vertical hole excavation method described above, it is possible to measure the hardness of the sealing layer made of the layer forming material before excavation from the impermeable layer to the lower permeable layer. Therefore, it is possible to confirm whether or not the sealing layer is solidified and to determine whether or not excavation can proceed to the lower permeable layer, so that the movement of contaminants from the upper permeable layer to the lower permeable layer can be more reliably suppressed. . Accordingly, it is possible to more reliably suppress the soil contamination diffusion.

  ADVANTAGE OF THE INVENTION According to this invention, the vertical hole excavation method and vertical hole excavation apparatus which suppress the spreading | diffusion of the contamination of a ground can be provided, suppressing the increase in a construction period.

(A)-(f) is a figure which shows each process of the vertical hole excavation method which concerns on embodiment of this invention. (A)-(e) is a figure which shows the process of the continuation of FIG. (A) And (b) is a side view which shows the front-end | tip part of the vertical hole excavation apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the sealing layer formed in the inner surface of a vertical hole.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same part or an equivalent part, and the overlapping description is abbreviate | omitted. In the vertical hole excavation method and the vertical hole excavation apparatus of the present embodiment, a vertical hole for inserting a pile or a steel material is formed in the ground. Hereinafter, the vertical hole excavation method and the vertical hole excavation apparatus according to the present embodiment will be described by exemplifying a pre-boring method in which a vertical hole is formed in the ground and the pile body is built by filling the vertical hole with a pile fixing liquid. To do.

  As shown in FIG. 1, the ground 101 to which the pile body is constructed includes an impermeable layer 103 that is clayey and difficult to pass water, an upper permeable layer 105 that is located above the impermeable layer 103, and an impermeable layer. 103 is a ground having a lower water permeable layer 107 located below 103. The upper water permeable layer 105 and the lower water permeable layer 107 each contain ground water.

  The ground constituting the upper permeable layer 105 is contaminated with heavy metals, volatile organic compounds, and the like, and the groundwater contained in the upper permeable layer 105 is also contaminated. The ground constituting the lower permeable layer 107 is not contaminated because the contaminants of the upper permeable layer 105 are blocked by the impermeable layer 103, and the groundwater contained in the lower permeable layer 107 is used for industrial or daily use. It can be used effectively. The lower water permeable layer 107 includes, for example, a relatively soft aquifer and a support layer that is located below the aquifer and is harder than the aquifer.

The impermeable layer 103 is a layer having a water permeability coefficient of 1.0 × 10 ⁻⁴ cm / sec or less and a thickness of 1.0 m or more. The “permeable layer” is applicable. Further, the impermeable layer 103 has a “impermeable layer” (1.0 × 10 ⁻⁵ cm / sec or less) and a thickness of 5.0 m or more as defined in the Soil Contamination Countermeasures Law. Layer).

  Next, the vertical hole excavation method of this embodiment will be described with reference to FIGS. 1 and 2. 1 (a) to 1 (f) and FIGS. 2 (a) to 2 (e) continuously show a series of steps side by side for the construction of a single pile body. The vertical hole excavation method of the present embodiment includes a first excavation process, a replacement process, a layer formation process, a second excavation process, and a pile installation process described below. The vertical hole is excavated by an earth auger (excavation unit) 3 provided in the vertical hole excavator 1 of the present embodiment. The earth auger 3 expands and contracts in the horizontal direction with a hollow rod 3a extending vertically, a drilling bit 3b provided at the tip of the rod 3a, and a spiral blade 3c for earth removal provided on the rod 3a. And an expanded blade 3d. Below, each process of the vertical hole excavation method of this embodiment is demonstrated.

[First excavation process]
In the first excavation process, a pile driving machine is first set on the ground (not shown), the pile core is surveyed, and the machine is installed with high accuracy. Then, as shown in FIG. 1A, the upper permeable layer 105 is excavated by the earth auger 3, and the earth auger 3 has a vertical hole extending to the middle portion 103 a of the impermeable layer 103 so as not to penetrate the impermeable layer 103. 109 is excavated. Here, the soil generated by the excavation of the upper permeable layer 105 and the impermeable layer 103 is entirely discharged.

[Replacement process]
Then, as shown in FIG. 1 (b), bentonite mud water (bentonite mixture liquid) 5 is ejected from the tip of the earth auger 3 inside the vertical hole 109 excavated in the first excavation process. The bentonite mud 5 is a drilling fluid (also referred to as a stabilizing fluid) for maintaining the stability of the soil wall of the vertical hole 109, and the specific gravity of the drilling fluid is greater than the specific gravity of water. Thus, in the replacement process, the soil in the region excavated in the first excavation process is replaced with bentonite mud water 5, and the fall of the contaminated soil into the vertical hole 109 is suppressed by this replacement process.

  The first excavation process and the replacement process may be performed simultaneously. In this case, the earth auger 3 excavates the middle part 103 a of the upper permeable layer 105 and the impermeable layer 103 while ejecting the bentonite mud 5. Do. In the replacement step, another drilling fluid such as water may be used instead of the bentonite mud 5. When water is used as the drilling fluid, it is preferable to set the height H of the drilling fluid higher than the ground surface A in order to reliably suppress the entry of contaminants into the vertical hole 109.

[Layer formation process]
As shown in FIG. 1C, in the layer formation step, the layer forming material 111 is sprayed onto the region S including the boundary portion between the upper permeable layer 105 and the impermeable layer 103 in the bentonite mud water 5. At this time, as shown in FIGS. 3A and 3B, the layer forming material 111 is sprayed from the spraying portion 11 provided on the tip side of the spiral blade 3 c of the earth auger 3. The spray unit 11 includes a nozzle (not shown) for ejecting the layer forming material 111 in a hole formed on the surface of the rod 3a. This nozzle is visible from the outside of the hole of the rod 3a. Further, the nozzle of the spraying part 11 ejects the layer forming material 111 while rotating and moving up and down together with the rod 3 a, and the layer forming material 111 is spirally sprayed on the inner surface of the vertical hole 109. In this way, as shown in FIG. 1C, the layer forming material 111 is sprayed on the vertical width region S extending from the upper water permeable layer 105 to the water impermeable layer 103 on the inner surface of the vertical hole 109.

  By the way, inside the rod 3 a of the earth auger 3, a conduit (not shown) through which the layer forming material 111 flows and a wiring (not shown) for supplying electric power to the spraying part 11 extend. Moreover, the discharge pressure of the layer formation material 111 by the spraying part 11 can be suitably changed according to the soil quality of the upper water-permeable layer 105 and the impermeable layer 103, for example, can be about 5-30 (MPa).

  As shown in FIG. 1 (d), when a certain time (for example, several seconds to several tens of minutes) elapses after the layer forming material 111 is sprayed on the inner surface of the vertical hole 109, the layer forming material 111 hardens or becomes highly viscous. Thus, the sealing layer 113 is formed. As the layer forming material 111 for forming the sealing layer 113, for example, a material having a solidifying property such as mortar, a water glass, or a chemical solution such as active silica colloid, penetrates into the ground and becomes highly viscous. Materials can be used. Here, when mortar is used as the layer forming material 111, the mortar is the same material as the pile (ready-made pile) 7 and the pile periphery fixing liquid 117 shown in FIG. There is no. On the other hand, as water glass and chemicals, those used for ground improvement can be adopted, and further, a two-component mixed material can be used, so the timing of curing the sealing layer 113 can be easily adjusted. It becomes. That is, for example, when the vertical hole 109 is formed on a ground that is relatively easy to collapse, the timing of curing can be advanced, and when the vertical hole 109 having a relatively large diameter is formed, the timing of curing can be delayed. .

  As shown in FIG. 4, the region S in which the sealing layer 113 is formed is a region S having a vertical width extending from the upper water permeable layer 105 to the water impermeable layer 103 on the inner surface of the vertical hole 109. Therefore, the upper end of the sealing layer 113 may be positioned in the upper water permeable layer 105 and the lower end of the sealing layer 113 may be positioned in the impermeable layer 103. Further, when the vertical width of the region S in the upper water permeable layer 105 is defined as the vertical width L1, the vertical width of the region S in the impermeable layer 103 is defined as the vertical width L2, and the vertical width of the water impermeable layer 103 is defined as the vertical width L3. The width L1 = the vertical width L2 = 1.0 (m) and the vertical width L3 = 2.0 (m).

[Penetration measurement process]
As shown in FIG. 1C and FIG. 1D, when forming the sealing layer 113 in the layer forming process, a penetration measurement process for measuring the penetration of the sealing layer 113 is performed. Here, the penetration is an index defined by Japanese Industrial Standard (JIS) K2207 (petroleum asphalt) and K2235 (petroleum wax), and is a value indicating the hardness of asphalt or the like. The penetration is a value indicated by a value (in units of 1/10 mm) ten times the length of the penetrating needle when a specified needle such as a sewing needle penetrates the sample kept at a constant temperature vertically. It is. The smaller the penetration value, the harder the sample, and the higher the penetration value, the softer the sample.

  As shown in FIGS. 3A and 3B, the penetration of the sealing layer 113 is measured by a penetration measurement unit 13 provided at the tip of the earth auger 3. The penetration measuring unit 13 is provided on the tip end side of the spiral blade 3 c of the earth auger 3 and is located above the spraying unit 11. By providing the penetration measuring unit 13 in the upper part of the spraying part 11 in this way, after the spraying part 11 sprays the layer forming material 111 spirally, the needle penetration measuring part 13 spirals the needle penetration. Can be measured. The needle penetration measuring unit 13 includes a needle that moves in a horizontal direction in a hole formed in the rod 3a, and this needle moves by the operation of an actuator such as a hydraulic cylinder. The actuator is actuated by receiving electric power from a wiring extending in the rod 3a. After the layer forming material 111 is sprayed onto the inner surface of the vertical hole 109 by the spraying unit 11, the needle penetration measuring unit 13 projects the needle from the hole of the needle penetration measuring unit 13 in the horizontal direction, and the tip of the needle Is penetrated into the sealing layer 113 and the penetration is measured by measuring the length of the penetrating needle.

[Second excavation process]
As shown in FIG. 1 (e), in the second excavation process, the vertical hole 109 is excavated from the middle portion 103 a of the impermeable layer 103 to the lower permeable layer 107. After the excavation reaches the lower water permeable layer 107, the diameter expanding blade 3d of the earth auger 3 protrudes in the horizontal direction to advance the excavation, and the hole diameter of the vertical hole 109 is increased (FIG. 1 (f)). Then, as shown in FIG. 2 (a), cement milk (water-cement ratio 55 to 60%) as the root hardening liquid 115 is injected into the portion where the pore diameter is enlarged and stirred. After the cement milk injection is finished, the diameter-expanded blade 3d is reduced, and then the cement agglomerated fluid 117 (water cement ratio of 100% or more) is injected into the vertical hole 109 while the earth auger 3 is pulled up. (FIG. 2 (b)). After the earth auger 3 is extracted from the vertical hole 109 (FIG. 2 (c)), the mud in the vertical hole 109 is replaced with cement milk which is substantially the pile circumference fixing liquid 117.

[Pile installation process]
Then, as shown in FIG. 2 (d), the pile 7 is inserted into the vertical hole 109, slowly lowered, and the lower end of the pile 7 is inserted into the cement milk as the root hardening liquid 115 (FIG. 2 (e)). )). Thus, the installation of the pile 7 is completed, and the foundation pile 17 including the pile 7 is completed when the root hardening liquid 115 and the pile periphery fixing liquid 117 are cured.

  Next, the effect of the vertical hole excavation method and the vertical hole excavation apparatus 1 according to the present embodiment will be described.

  As shown in FIGS. 1C and 1D, the vertical hole excavation method according to the present embodiment is formed in a region S including the boundary between the upper permeable layer 105 and the impermeable layer 103 in the bentonite mud 5. A layer forming step of forming the sealing layer 113 by spraying the forming material 111 is provided. In this way, the layer forming material 111 is sprayed onto the region S including the boundary portion between the upper water permeable layer 105 and the impermeable layer 103 in the layer forming step, whereby an upper and lower width region extending from the upper water permeable layer 105 to the impermeable layer 103. The sealing layer 113 is formed by curing or increasing the viscosity of S. Therefore, the contaminated soil of the upper water permeable layer 105 located on the upper part of the water impermeable layer 103 is unlikely to fall on the water impermeable layer 103, and the contaminated water of the upper water permeable layer 105 is less likely to flow out into the region S. As described above, since the contaminated soil can be prevented from falling into the impermeable layer 103 in the vertical hole 109 and the outflow of the contaminated water to the region S, the upper permeable layer 105 can be transferred to the uncontaminated lower permeable layer 107. Therefore, the movement of the pollutant is suppressed, and the diffusion of the soil contamination can be suppressed. In addition, since the vertical hole excavation method of the present embodiment does not require the installation of an extratubation tube, it is possible to suppress the necessary increase in materials and special processes compared to conventional vertical hole excavation, Increase in construction period can be suppressed.

  In addition, the vertical hole excavation method of the present embodiment includes a penetration measurement process for measuring the penetration of the sealing layer 113 formed in the layer formation process before the second excavation process. The hardness of the sealed layer 113 can be measured. Therefore, since the hardness of the sealing layer 113 is measured before the second excavation process for excavating from the impermeable layer 103 to the lower permeable layer 107, it is confirmed whether the sealing layer 113 is solidified and the lower permeable layer 107 is reached. Whether or not excavation can proceed can be determined. Accordingly, the movement of contaminants from the upper permeable layer 105 to the lower permeable layer 107 can be more reliably suppressed, so that the contamination diffusion of the ground can be more reliably suppressed.

  Moreover, the vertical hole excavation apparatus 1 of this embodiment is provided with the spray part 11 which sprays the layer formation material 111 on the area | region S in the bentonite mud water 5, as FIG. 3 (a) and FIG.3 (b) show. Therefore, the sealing layer 113 that is cured or highly viscous can be formed in the region S. Therefore, the fall of contaminated soil and the outflow of contaminated water to the lower permeable layer 107 can be suppressed, the movement of contaminants from the upper permeable layer 105 to the lower permeable layer 107 can be suppressed, and the contamination diffusion of the ground can be suppressed. it can. Moreover, since the vertical hole excavation apparatus 1 includes the penetration measuring unit 13 that measures the penetration of the sealing layer 113, the sealing layer 113 is excavated before excavation from the impermeable layer 103 to the lower permeable layer 107. By measuring the hardness, it can be determined whether or not the sealing layer 113 has hardened and whether or not excavation to the lower water permeable layer 107 can proceed. Therefore, the movement of contaminants from the upper permeable layer 105 to the lower permeable layer 107 can be more reliably suppressed, and the contamination diffusion of the ground can be more reliably suppressed. Further, by adjusting the spray amount of the layer forming material 111 based on the hardness of the sealing layer 113 measured by the penetration measuring unit 13, it is possible to prevent the occurrence of unevenness in the sealing layer 113.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and may be modified without changing the gist described in each claim. For example, the spray unit 11 includes a nozzle in the hole of the rod 3a, and the needle penetration measuring unit 13 includes a needle that passes through the hole of the rod 3a. Is not limited to the above, and can be changed as appropriate. Moreover, it is good also considering the number of the spraying part 11 and the penetration measurement part 13 as multiple.

  Moreover, although the vertical hole excavation method of the said embodiment was provided with the pile installation process which installs the pile 7 in the vertical hole 109, and the penetration measurement process which measures the penetration of the sealing layer 113, the pile installation process And the penetration measuring step may be omitted. Further, the hardness of the sealing layer 113 may be measured by a method different from the penetration test defined by Japanese Industrial Standard (JIS) K2207 (petroleum asphalt) and K2235 (petroleum wax).

  Moreover, in the said embodiment, although the pre-boring construction method which fills the pile periphery fixing liquid 117 in the vertical hole 109 and builds the pile 7 was illustrated, this invention is the construction method by a cast-in-place pile, or SMW construction method etc., for example It can also be applied to wall excavation. In the SMW method, a steel material installation process is executed by installing a steel material such as H-shaped steel in the vertical hole 109. In the steel material installation step, the steel material is inserted and lowered into the vertical hole 109 replaced with the cement milk, and the cement milk in the vertical hole 109 is hardened to complete the installation of the steel material. Thus, even when the present invention is applied to the SMW method, by forming the sealing layer 113 by spraying the layer forming material 111 to each of the excavated vertical holes 109, the same effect as the above embodiment can be obtained. can get.

DESCRIPTION OF SYMBOLS 1 ... Vertical hole drilling device, 3 ... Earth auger (excavation part), 5 ... Bentonite mud (drilling fluid), 7 ... Pile, 11 ... Spraying part, 13 ... Penetration measuring part, 101 ... Ground, 103 ... Impervious water Layer 103a ... midway part 105 105 upper permeable layer 107 lower permeable layer 109 vertical hole 111 layer forming material 113 sealing layer S region

Claims (6)

In the vertical hole excavation method of excavating the ground having an upper permeable layer located at the upper part of the impermeable layer and a lower permeable layer located at the lower part of the impermeable layer to form a vertical hole,
A first excavation step of excavating the vertical hole to an intermediate portion of the impermeable layer;
A replacement step of replacing the soil in the region excavated in the first excavation step with a drilling fluid;
A layer forming step of forming a sealing layer by spraying a layer forming material on a region including a boundary portion between the upper permeable layer and the impermeable layer in the drilling fluid;
A second excavation step of excavating the vertical hole from the middle portion of the impermeable layer to the lower permeable layer;
A vertical hole excavation method comprising:   The vertical hole excavation method according to claim 1, further comprising a pile installation step of installing a pile in the vertical hole after the second excavation step.   The vertical hole excavation method according to claim 1, further comprising a steel material installation step of installing a steel material used in an SMW method in the vertical hole after the second excavation step.   The vertical according to any one of claims 1 to 3, further comprising a penetration measurement step of measuring a penetration of the sealing layer formed in the layer formation step before the second excavation step. Drilling method. In the vertical hole excavation apparatus for excavating the ground having an upper water permeable layer located above the impermeable layer and a lower water permeable layer located below the impermeable layer to form a vertical hole,
An excavation part excavating the vertical hole;
The upper permeable layer and the impermeable layer are excavated in the excavation liquid in a state where the vertical hole is excavated by the excavation part to a middle portion of the impermeable layer, and the soil in the excavated region is replaced with excavation liquid. A spraying part for spraying a layer forming material to a region including the boundary part and forming a sealing layer;
Vertical hole drilling device equipped with.   The vertical hole excavation apparatus according to claim 5, further comprising a penetration measurement unit that measures a penetration of the sealing layer formed by the spray unit.

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