Groundwater observation device and groundwater observation method

Abstract

To provide a ground water observation device and a ground water observation method enabling hydraulic pressure measurement and water collecting work to be performed at the same time.SOLUTION: A ground water observation device 100 comprises: a tubular casing 12 which is inserted into and arranged in a boring hole 10; a plurality of water-cutoff packers 14 which is arranged around the casing 12 vertically at intervals; hydraulic pressure measurement means 20 for measuring a hydraulic pressure of ground water in a section sectioned by the packer 14; and water collecting means 22 for collecting the ground water in the section, and an inside of the casing 12 is partitioned off along an extension direction of the casing 12 into a region 16 for hydraulic pressure measurement where the hydraulic pressure measurement means 20 is inserted and arranged and a region 18 for water collection where the water collecting means 22 is inserted and arranged.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a groundwater observation device and a groundwater observation method. [Background technology]

[0002] A groundwater investigation system known as the MP system has been known (see, for example, Non-Patent Document 1). This MP system is a system that can measure water pressure and sample groundwater at different depths by installing multiple packers in a geological investigation borehole, and two different sizes of packers are used depending on conditions such as the depth of the borehole.

[0003] There are two types: the MP38 system, which uses an MP casing with an inner diameter of 38 mm, and the MP55 system, which uses an MP casing with an inner diameter of 55 mm. MP casings are usually made of PVC (polyvinyl chloride) pipes, but the MP55 system may also use stainless steel pipes.

[0004] As a guideline for which system to use, the MP38 system is applied when the depth (length) of the survey hole is shallower than 200m, and the MP55 system is applied when it is deeper than 200m, but in recent years there has been a trend to use the MP55 system even when the hole is shallow.

[0005] Figure 5 conceptually illustrates the groundwater pressure measurement and sampling method in the MP system. This MP system consists of a casing pipe called an MP casing 2, which is equipped with multiple packers 3, installed in a survey hole 1. As shown in Figure 5(1), when measuring water pressure, pressure measurement devices (pressure probes) 5 connected to cables 4 are installed at multiple measurement ports in the MP casing 2, and the groundwater pressure at each section is recorded in a data logger 6 on the ground. This allows for continuous monitoring data acquisition. Also, as shown in Figure 5(2), when sampling water, all pressure probes 5 installed in the survey hole 1 are removed, and then the water sampling device (sampler probe 7 and sampler bottle 8) connected to cables 4 is inserted into the MP casing 2 via a winch 9 on the ground. Groundwater sampling is then performed with the device installed at the sampling port at the desired depth.

[0006] The number of days required for the water sampling work may range from several weeks to several months depending on the amount of water sampled and the number of sections from which sampling is performed. During this period, the water pressure cannot be measured because the pressure probe 5 is not installed, and the water pressure monitoring data will be lost.

[0007] In recent years, there has been a need to sample groundwater while maintaining the continuity of water pressure monitoring data. However, with the conventional MP system described above, it is difficult to insert the sampler probe 7 and sampler bottle 8 into the MP casing 2 while the pressure probe 5 is installed inside the MP casing 2, making it difficult to meet this need. For this reason, there has been a demand for a groundwater investigation system that can measure water pressure and sample water simultaneously.

[0008] To address this issue using a conventional MP system, it would be necessary to drill two boreholes, install a pressure probe 5 in one to constantly monitor pressure, and insert a sampler probe 7 and sampler bottle 8 into the other to periodically sample groundwater. In this case, the cost of drilling would double, increasing costs.

[0009] Therefore, the present patent applicant has proposed a method of using optical fiber for pressure observation as a method that allows water pressure measurement and water sampling to be performed simultaneously in a single borehole (see Patent Document 1). With this method, a sampler probe 7 and a sampler bottle 8 can be inserted into the MP casing 2 while pressure is being observed using the optical fiber. Since the optical fiber is laid on the outside of the MP casing from the hole mouth to the hole bottom, its connection to the MP casing, particularly to the packer, is important. An example of such an interface is shown in Figure 6. Figure 6 (1) shows a method in which the optical fiber 9A is sandwiched between the borehole wall 1A and the packer 3; Figure 6 (2) shows a method in which a gap is provided in the packer 3 for the optical fiber 9A to pass through; and Figure 6 (3) shows a method in which only the part of the optical fiber 9A that is connected to the packer 3 is passed through the MP casing 2. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] OYO Corporation homepage, "MP System", [online], [searched July 28, 2020], Internet<URL:http: / / ika638.com / rwd / work / oyo_hp01 / 4-movement / 2-execution / mp_system.html> [Patent documents]

[0011] [Patent Document 1] Patent Application No. 2020-088391 (currently unpublished) Summary of the Invention [Problem to be solved by the invention]

[0012] However, in the conventional method of Patent Document 1, the optical fiber is laid outside the MP casing, which may make maintenance work such as calibration, repair, and replacement of the optical fiber sensor difficult.

[0013] In order to enable continuous monitoring of groundwater pressure and water sampling simultaneously in an MP system for a single borehole, it is necessary to be able to insert a sampler probe and sampler bottle into the MP casing while the pressure probe is installed. The inventor focused on this and came up with the following invention, in which the inside of the casing is further divided into two sections, allowing the insertion of devices for water pressure measurement and water sampling, respectively.

[0014] The present invention has been made in view of the above, and has an object to provide a groundwater observation device and a groundwater observation method that are capable of simultaneously performing water pressure measurement and water sampling work. [Means for solving the problem]

[0015] In order to solve the above-mentioned problems and achieve the object, the groundwater observation device of the present invention is a groundwater observation device comprising a tubular casing inserted into a borehole, a plurality of water-blocking packers arranged at intervals in the vertical direction around the casing, a water pressure measuring means for measuring the water pressure of the groundwater in the section separated by the packers, and a water sampling means for sampling the groundwater in this section, and is characterized in that the inside of the casing is partitioned along the extension direction of the casing into a water pressure measurement area where the water pressure measuring means is inserted and arranged, and a water sampling area where the water sampling means is inserted and arranged.

[0016] In addition, the groundwater observation device of the present invention is characterized in that, in the above-mentioned invention, the casing has a large-diameter tubular outer casing that is placed on the outermost side, and two small-diameter tubular inner casings that are placed parallel inside this outer casing, and the water pressure measuring means and the water sampling means are inserted into these inner casings, respectively.

[0017] In addition, the groundwater observation device of the present invention is a groundwater observation device in the above-mentioned invention, comprising a tubular casing inserted into a borehole, a plurality of water-blocking packers arranged at intervals in the vertical direction around the casing, a water pressure measurement means for measuring the water pressure of the groundwater in the section separated by the packers, and a water sampling means for sampling the groundwater in this section, wherein the casings are a water pressure measurement casing and a water sampling casing arranged parallel to each other along the extension direction of the borehole, the water pressure measurement casing defines a water pressure measurement area into which the water pressure measurement means is inserted and placed, and the water sampling casing defines a water sampling area into which the water sampling means is inserted and placed.

[0018] Furthermore, the groundwater observation method according to the present invention is a method for simultaneously measuring the water pressure of groundwater in a section separated by packers and sampling groundwater from this section using the above-mentioned groundwater observation device, and is characterized in that water pressure is measured using a water pressure measuring means inserted and arranged in the water pressure measurement area, and groundwater is sampled using a water sampling means inserted and arranged in the water sampling area. [Effects of the Invention]

[0019] The groundwater observation device of the present invention comprises a tubular casing that is inserted into a borehole, a plurality of water-blocking packers that are arranged at intervals in the vertical direction around the casing, a water pressure measuring means for measuring the water pressure of the groundwater in the section separated by the packers, and a water sampling means for sampling the groundwater in this section, and the inside of the casing is divided along the extension direction of the casing into a water pressure measurement area where the water pressure measuring means is inserted and arranged, and a water sampling area where the water sampling means is inserted and arranged, thereby achieving the effect of allowing water pressure measurement and water sampling operations to be carried out simultaneously.

[0020] In addition, according to the groundwater observation device of the present invention, the casing has a large-diameter tubular outer casing that is positioned on the outside, and two small-diameter tubular inner casings that are positioned parallel to the inside of this outer casing, and the water pressure measuring means and water sampling means are inserted into these inner casings, respectively, thereby achieving the effect of easily forming areas for water pressure measurement and areas for water sampling inside the casing.

[0021] In addition, the groundwater observation device of the present invention is a groundwater observation device comprising a tubular casing to be inserted into a borehole, a plurality of water-blocking packers arranged at intervals in the vertical direction around the casing, a water pressure measurement means for measuring the water pressure of the groundwater in the section separated by the packers, and a water sampling means for sampling the groundwater in this section, wherein the casings are a water pressure measurement casing and a water sampling casing arranged parallel to each other along the extension direction of the borehole, the water pressure measurement casing defines a water pressure measurement area into which the water pressure measurement means is inserted and arranged, and the water sampling casing defines a water sampling area into which the water sampling means is inserted and arranged, thereby achieving the effect of allowing water pressure measurement and water sampling operations to be carried out simultaneously.

[0022] Furthermore, according to the groundwater observation method of the present invention, the above-mentioned groundwater observation device is used to simultaneously measure the water pressure of groundwater in a section separated by packers and sample groundwater from this section, and since water pressure is measured using a water pressure measurement means inserted and arranged in the water pressure measurement area and groundwater is sampled using a water sampling means inserted and arranged in the water sampling area, it has the effect of being able to measure water pressure and sample water simultaneously. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 shows a first embodiment of a groundwater observation device and a groundwater observation method according to the present invention, where (1) is a plan cross-sectional view and (2) is a side cross-sectional view. [Figure 2]FIG. 2 shows a second embodiment of the groundwater observation device and groundwater observation method according to the present invention, where (1) is a plan cross-sectional view and (2) is a side cross-sectional view. [Figure 3] FIG. 3 is a conceptual diagram showing a groundwater observation device and a groundwater observation method according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a configuration diagram showing a groundwater observation device and a groundwater observation method according to a third embodiment of the present invention, where (1) is a side view and (2) is a partially enlarged perspective view. [Figure 5] Figure 5 shows a conceptual diagram of a conventional MP system, where (1) shows water pressure measurement and (2) shows water sampling. [Figure 6] Figure 6 is an explanatory diagram of conventional methods for connecting optical fibers to MP casings. (1) is a method of sandwiching the optical fiber between the hole wall and the packer, (2) is a method of wrapping the optical fiber around the packer, and (3) is a method of passing the optical fiber through the inside of the MP casing at the packer part. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A groundwater observation device and a groundwater observation method according to embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to these embodiments.

[0025] (Embodiment 1) First, a first embodiment of the present invention will be described. As shown in Figure 1, the groundwater observation device 100 of this embodiment 1 comprises a large-diameter, cylindrical outer casing 12 that is inserted approximately coaxially into a substantially circular borehole (investigation hole) 10, multiple water-blocking packers 14 that are arranged at intervals in the vertical direction around the outer casing 12, two small-diameter, cylindrical inner casings 16, 18 (inner double casings) that are arranged axially parallel inside the outer casing 12, a pressure probe 20 that is arranged inside one of the inner casings 16, and a sampler probe 22 and a sampler bottle 24 that are arranged inside the other inner casing 18.

[0026] This embodiment is intended to be applied to the MP38 system. Specifically, it is assumed that the diameter D1 of the borehole 10 is approximately 200 mm or more, the inner diameter D2 of the outer casing 12 is 130 mm, and the inner diameter D3 of the inner casings 16 and 18 is 38 mm. However, the present invention is not limited to this. Furthermore, the outer casing 12 and the inner casings 16 and 18 can each be constructed using PVC pipes, but the present invention is not limited to this. For example, if the groundwater temperature exceeds 60°C, it is desirable to use stainless steel outer casings 12 and inner casings 16 and 18 instead of PVC.

[0027] The outer casing 12 is connected to a roughly cylindrical stainless steel measurement port coupling 28 provided in each section separated by the packers 14. This measurement port coupling 28 is provided with a water pressure measurement port 30 and a water sampling port 32. A connecting pipe 34 is attached to the water pressure measurement port 30 and the water sampling port 32, respectively, toward the inner casings 16 and 18 on the inside.

[0028] The inner casing 16 is an area for measuring water pressure, and when measuring groundwater pressure, it guides the pressure probe 20, which is lowered from the ground via a cable 26, to the water pressure measurement port 30 of the measurement port coupling 28.

[0029] The pressure probe 20 is a water pressure measurement means that is inserted into the inner casing 16. The pressure probe 20 has a location arm 36, a backing shoe 38, and a measurement port 40, and is fixed to the inner surface of the inner casing 16 via the location arm 36 and the backing shoe 38, with the measurement port 40 in close contact with the inner surface of the inner casing 16 and communicating with the connecting pipe 34. The pressure probe 20 is connected to a data logger on land (not shown) via a cable 26. Water pressure data measured by the pressure probe 20 via the water pressure measurement port 30, the connecting pipe 34, and the measurement port 40 is sent to the data logger and recorded.

[0030] The inner casing 18 is an area for sampling water, and when sampling groundwater, it guides the sampler probe 22 and sampler bottle 24, which are lowered from the ground via a cable 26, to the water sampling port 32 of the measurement port coupling 28.

[0031] The sampler probe 22 and sampler bottle 24 are water sampling devices inserted and positioned within the inner casing 18 so that they can be moved vertically. The sampler probe 22 is connected to a ground-based winch and data logger (not shown) via a cable 26. The sampler probe 22 and sampler bottle 24 are connected via a pipe 48. The sampler probe 22 has a location arm 42, a backing shoe 44, and a water sampling port 46. Under the control of a control device located on the ground, the sampler probe 22 is fixed to the inner surface of the inner casing 18 via the location arm 42 and backing shoe 44 using an air jack or the like. The water sampling port 46 can be tightly attached to the inner surface of the inner casing 18 to communicate with the connecting pipe 34. Groundwater outside the measurement port coupling 28 is sampled by the sampler probe 22 through the water sampling port 32, the connecting pipe 34, and the water sampling port 46, and can then be sampled into the sampler bottle 24.

[0032] Conventionally, as mentioned above, monitoring data for groundwater pressure measurement is lost during water sampling operations. In contrast, according to this embodiment, the inside of the casing is divided into two sections, one for water pressure measurement and one for water sampling, and the water pressure measurement means and the water sampling means can be installed simultaneously in a single borehole 10, making it possible to carry out water pressure measurement and water sampling operations simultaneously. Therefore, in the MP system for a single borehole, water pressure measurement is possible even during water sampling operations, and continuous monitoring data can be obtained.

[0033] (Embodiment 2) Next, a second embodiment of the present invention will be described. As shown in FIG. 2, the groundwater observation device 200 according to the second embodiment is intended to be applied to the MP55 system. Specifically, it is assumed that the diameter D1 of the borehole 10 is approximately 250 mm or more, the inner diameter D2 of the outer casing 12 is 190 mm, and the inner diameter D3 of the inner casings 16 and 18 is 57 mm. The configuration of this embodiment is similar to that of the first embodiment, so detailed descriptions of each component will be omitted. Even with this configuration, the same effects as those described above can be achieved. Note that when the groundwater temperature exceeds 60°C, it is preferable to use stainless steel instead of PVC for the outer casing 12 and the inner casings 16 and 18.

[0034] (Embodiment 3) Next, a third embodiment of the present invention will be described. As shown in Figure 3, the groundwater observation device 300 according to the third embodiment comprises a cylindrical water pressure measurement casing 50 and a water sampling casing 52, which are inserted axially parallel to each other and spaced apart laterally within a single, substantially circular borehole (investigation hole) 10. A plurality of water-blocking packers 14 are arranged around the two casings 50, 52, spaced apart in the vertical direction to encompass the casings 50, 52. A pressure probe 20 is arranged inside the water pressure measurement casing 50, and a sampler probe 22 and a sampler bottle 24 are arranged inside the water sampling casing 52.

[0035] According to this embodiment, by using separate casings for water pressure measurement and water sampling, continuous pressure observation and groundwater sampling can be performed simultaneously. This makes it easy to perform maintenance work such as calibration, repair, and replacement of pressure measurement equipment.

[0036] As shown in Fig. 4, the water pressure measurement casing 50 and the water sampling casing 52 may be fixed together using a plate-shaped module 56 having two through holes 54. It is preferable to arrange a plurality of modules 56 at intervals in the vertical direction.

[0037] As described above, the groundwater observation device of the present invention is a groundwater observation device comprising a tubular casing that is inserted into a borehole, a plurality of water-blocking packers that are arranged at intervals in the vertical direction around the casing, a water pressure measuring means for measuring the water pressure of the groundwater in the section separated by the packers, and a water sampling means for sampling the groundwater in this section, and the inside of the casing is divided along the extension direction of the casing into a water pressure measurement area where the water pressure measuring means is inserted and arranged, and a water sampling area where the water sampling means is inserted and arranged, so that water pressure measurement and water sampling operations can be carried out simultaneously.

[0038] In addition, according to the groundwater observation device of the present invention, the casing has a large-diameter tubular outer casing that is positioned on the outside, and two small-diameter tubular inner casings that are positioned parallel to the inside of this outer casing, and the water pressure measuring means and water sampling means are inserted into these inner casings, respectively, so that areas for water pressure measurement and areas for water sampling can be easily formed inside the casing.

[0039] In addition, the groundwater observation device of the present invention is a groundwater observation device comprising a tubular casing that is inserted into a borehole, a plurality of water-blocking packers that are arranged at intervals in the vertical direction around the casing, a water pressure measurement means for measuring the water pressure of the groundwater in the section separated by the packers, and a water sampling means for sampling the groundwater in this section, and the casings are a water pressure measurement casing and a water sampling casing that are arranged parallel to each other along the extension direction of the borehole, and the water pressure measurement casing defines an area for water pressure measurement into which the water pressure measurement means is inserted and arranged, and the water sampling casing defines an area for water sampling into which the water sampling means is inserted and arranged, so that water pressure measurement and water sampling operations can be carried out simultaneously.

[0040] Furthermore, according to the groundwater observation method of the present invention, the above-mentioned groundwater observation device is used to simultaneously measure the water pressure of groundwater in a section separated by packers and sample groundwater from this section, and since water pressure is measured using a water pressure measurement means inserted and arranged in the water pressure measurement area and groundwater is sampled using a water sampling means inserted and arranged in the water sampling area, water pressure measurement and water sampling can be performed simultaneously. [Industrial Applicability]

[0041] As described above, the groundwater observation device and groundwater observation method of the present invention are useful for MP systems that investigate multiple investigation depths using a single borehole, and are particularly suitable for performing water pressure measurements and water sampling work simultaneously. [Explanation of symbols]

[0042] 10 Boreholes 12 Outer casing (casing) 14. Packer 16,18 Inner casing (area) 20 Pressure probe (water pressure measurement means) 22 Sampler probe (water sampling means) 24 sampler bottles 26 Cable 28 Measurement port coupling 30 Water pressure measurement port 32 Water sampling port 34 Connecting pipe 36,42 Location Arm 38,44 Backing shoe 40 Measurement port 46 Water sampling port 48 tube 50 Water pressure measurement casing 52 Water sampling casing 54 Through hole 56 modules 100,200,300 Groundwater observation device

Claims

1. A groundwater observation device comprising: a tubular casing that is inserted into a borehole and extends in the vertical direction; a plurality of water-blocking packers that are arranged around the casing at intervals in the vertical direction; a water pressure measuring means that measures the water pressure of groundwater in a section separated by the packers through a water pressure measuring port provided in the casing in the section; and a water sampling means that samples groundwater in the section through a water sampling port provided in the casing in the section, the interior of the casing is partitioned along an extension direction of the casing into a water pressure measurement area into which the water pressure measuring means is inserted and disposed, and a water sampling area into which the water sampling means is inserted and disposed, The water pressure measurement area and the water sampling area are two areas extending in the vertical direction similar to the casing, the water pressure measurement means is inserted and disposed at a predetermined depth in the water pressure measurement area, and directly measures the water pressure of the groundwater in the section through the water pressure measurement port in the section corresponding to the depth; A groundwater observation device characterized in that the water sampling means is inserted and positioned at a predetermined depth in the water sampling area, and samples groundwater in the section through the water sampling port in the section corresponding to the depth.

2. The groundwater observation device described in claim 1, characterized in that the casing is a large-diameter tubular outer casing that is positioned on the outside, the area for water pressure measurement and the area for water sampling are areas inside two small-diameter tubular inner casings that are positioned parallel inside the outer casing, and the water pressure measurement means and the water sampling means are inserted into these inner casings, respectively.

3. A groundwater observation device comprising: a tubular casing that is inserted into a borehole and extends in the vertical direction; a plurality of water-blocking packers that are arranged around the casing at intervals in the vertical direction; a water pressure measuring means that measures the water pressure of groundwater in a section separated by the packers through a water pressure measuring port provided in the casing in the section; and a water sampling means that samples groundwater in the section through a water sampling port provided in the casing in the section, the casings are a water pressure measurement casing and a water sampling casing arranged parallel to each other, the water pressure measurement casing defining a water pressure measurement area into which the water pressure measurement means is inserted and arranged, and the water sampling casing defining a water sampling area into which the water sampling means is inserted and arranged, the water pressure measurement means is inserted and disposed at a predetermined depth in the water pressure measurement area, and directly measures the water pressure of the groundwater in the section through the water pressure measurement port provided in the water pressure measurement casing in the section corresponding to the depth; A groundwater observation device characterized in that the water sampling means is inserted and positioned at a predetermined depth in the water sampling area, and samples groundwater in the section through the water sampling port provided in the water sampling casing in the section corresponding to the depth.

4. A groundwater observation method that uses the groundwater observation device described in any one of claims 1 to 3 to simultaneously measure the water pressure of groundwater in a section separated by the packers and sample groundwater from this section, characterized in that the water pressure is measured by the water pressure measurement means inserted and arranged in the water pressure measurement area, and at the same time, groundwater is sampled by the water sampling means inserted and arranged in the water sampling area.

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