Water pressure measurement device, installation jig, and water pressure measurement method

Abstract

To provide a water pressure measurement device for accurately measuring water pressure at a position where the device is disposed, an installation jig, and a water pressure measurement method.SOLUTION: A water pressure measurement device 20 for measuring water pressure at a plurality of places in the vertical direction of a borehole 11 comprises: a water pressure gage for each layer 30 for measuring water pressure; and a cylindrical installation jig 21 to which the water pressure gage for each layer 30 is fixed. The installation jig 21 is provided with water cut-off members 25 and 26 expandable after arrangement on axial both sides of the installation jig 21 with respect to the water pressure measurement position of the water pressure gage for each layer 30. The water pressure measurement device 20 expands through water suction of the water cut-off members 25 and 26 after arrangement at the measurement position of the borehole 11. Thus, a space S1 of the borehole 11 is separated from above and below, and the water pressure measurement device 20 performs measurement in this state.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a water pressure measuring device, an installation jig, and a water pressure measuring method for measuring water pressure at multiple points in a vertical direction. [Background technology]

[0002] Excavation work is sometimes carried out in a low-permeability layer above a confined aquifer. In this case, the cause of vertical displacement at the bottom of the excavation (the bottom of the excavation) may be not only rebound due to stress release during excavation, but also ground swelling due to groundwater. In contrast to vertical displacement due to rebound, vertical displacement due to ground swelling may lead to the destruction of the ground at the bottom of the excavation, so it is necessary to lower the pressurized head.

[0003] Therefore, a method for managing displacement at the bottom of an excavation and a measuring device have been studied to distinguish and manage the causes of vertical displacement behavior occurring at the bottom of an excavation (see, for example, Patent Document 1). The measuring device described in Patent Document 1 includes a settlement gauge that measures the amount of vertical displacement, and a pore water pressure gauge that measures pore water pressure. The measuring device measures the amount of vertical displacement and pore water pressure below the bottom of the excavation at least in the upper part of the confined aquifer, and in the lower and upper parts of the impermeable layer located above the confined aquifer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-125818 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, a measuring device is placed that includes a settlement gauge that measures vertical displacement and a pore water pressure gauge that measures pore water pressure. In this case, because groundwater mixes in the borehole, it is difficult for the multiple pore water pressure gauges placed in the borehole to accurately measure the water pressure at the installation position (depth). [Means for solving the problem]

[0006] The water pressure measuring device that solves the above problem is a water pressure measuring device for measuring water pressure at multiple locations in the vertical direction, and comprises a stratified water pressure gauge that measures the water pressure, and a cylindrical installation jig to which the stratified water pressure gauge is fixed, and the installation jig is provided with expansion sections that are expandable from a contracted state on both axial sides of the installation jig relative to the water pressure measurement position of the stratified water pressure gauge. In addition, an installation jig that solves the above problem is an installation jig for fixing a stratified water pressure gauge that measures water pressure at multiple locations in the vertical direction, and is provided with a cylindrical main body for fixing the stratified water pressure gauge, and the main body is provided with expansion sections that can expand from a contracted state on both axial sides of the water pressure measurement position of the stratified water pressure gauge.

[0007] Furthermore, a water pressure measurement method that solves the above problem is a water pressure measurement method for measuring water pressure at multiple locations in a vertically extending hole, in which a water pressure measurement device that measures the water pressure is placed at an installation position of the hole, and then expansion sections provided above and below the water pressure measurement position of the water pressure measurement device are inflated to isolate the space of the water pressure measurement position in the hole from above and below, and measurement is performed in this state using the water pressure measurement device. Effect of the Invention

[0008] According to the present invention, the water pressure at the installed position can be measured with high accuracy. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram illustrating a configuration of a water pressure measurement system according to an embodiment. [Diagram 2] FIG. 1 is a perspective view illustrating a water pressure measuring device according to an embodiment. [Diagram 3] FIG. 2 is a front view illustrating the water pressure measuring device according to the embodiment. [Figure 4]FIG. 2 is a cross-sectional view illustrating the water pressure measuring device according to the embodiment. [Diagram 5] FIG. 2 is a perspective view of a pore water pressure gauge of the water pressure measuring device according to the embodiment. [Figure 6] FIG. 1 is an explanatory diagram illustrating a water pressure measurement method in an embodiment, where (a) shows a rod placed in a borehole, and (b) shows a water pressure measurement device placed at the lower end of the borehole. [Figure 7] FIG. 1 is an explanatory diagram illustrating a water pressure measurement method in an embodiment, in which (a) shows the state immediately after placing the water pressure measurement device in a borehole, and (b) shows the state after the water-stopping material of the water pressure measurement device has expanded. [Figure 8] FIG. 11 is an explanatory diagram for explaining a water pressure measurement method in an embodiment, showing a state in which a subsidence measurement device is lowered to directly above the water pressure measurement device and fixed in place. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the water pressure measuring device, the installation jig, and the water pressure measuring method will be described with reference to Figures 1 to 8. Here, water pressure is measured to determine whether or not an excavation bottom formed in an aquifer-impermeable layer above a confined aquifer by excavation work has swelled due to ground swelling.

[0011] As shown in Fig. 1, the excavation bottom B1 generated during excavation work is located in an impermeable layer L1 above a confined aquifer L2. A borehole 11 is formed by excavation with the excavation bottom B1 as the surface. A measurement system A1 is placed in the borehole 11.

[0012] The measurement values ​​measured by the measurement system A1 are transmitted to the management system 50. The management system 50 determines whether or not there is a swelling based on the measurement position and the measurement value, using the method described in Patent Document 1.

[0013] (Configuration of measurement system A1) The measurement system A1 shown in Fig. 1 includes a rod 15, a data transmission unit 17, a plurality of water pressure measuring devices 20, and a plurality of subsidence gauge devices 40. Here, the components of the measurement system A1 arranged in the borehole 11 (the rod 15, the water pressure measuring devices 20, and the subsidence gauge devices 40) are embedded in grout in the borehole 11. Note that the grout is omitted in the figure.

[0014] The rod 15 is erected in the borehole 11 so as to extend in the vertical direction, which is the extension direction of the borehole 11. Specifically, an anchor 15a is fixed to the tip (lower end) of the rod 15. The anchor 15a is fixed to the confined aquifer L2, which is the bottom of the borehole 11, so that the rod 15 is fixed so as to extend along the central axis of the borehole 11. In this embodiment, the central axis of the rod 15 is fixed in a state closer to the wall side than the central axis of the borehole 11. The rod 15 functions as a guide rod for identifying the arrangement (depth) of the water pressure measuring device 20 and the subsidence gauge device 40.

[0015] The data transmission unit 17 is connected via cables to the water pressure measuring devices 20 and the subsidence gauge devices 40 arranged in the borehole 11. The data transmission unit 17 transmits the measurement value data acquired from each of the water pressure measuring devices 20 and the subsidence gauge devices 40 to the management system 50. In this case, the data transmission unit 17 transmits the measurement value data together with identification information for identifying the water pressure measuring devices 20 and the subsidence gauge devices 40 from which the measurement value data was acquired.

[0016] The multiple water pressure measuring devices 20 are arranged at predetermined positions (depths) spaced apart from each other with the rods 15 penetrating them. In this embodiment, the water pressure measuring devices 20 are arranged at the top of the confined aquifer L2 and at the bottom and top of the low permeability layer L1. The configuration of the water pressure measuring devices 20 will be described later.

[0017] A sinking gauge device 40 is disposed directly above each water pressure measuring device 20 in correspondence with the respective water pressure measuring device 20. The sinking gauge device 40 includes a main body 41 and a hydraulic anchor device 45. The main body 41 is configured by fixing a layer-by-layer subsidence meter 41g to the inner circumferential surface of a cylinder. This layer-by-layer subsidence meter 41g measures the vertical displacement of the stratum (ground) at the installation position. A known layer-by-layer subsidence meter equipped with a subsidence element can be used as this layer-by-layer subsidence meter 41g. This layer-by-layer subsidence meter 41g supplies the measured vertical displacement to the data transmission unit 17 via a cable (not shown).

[0018] A generally columnar hydraulic anchor device 45 is fixed to the lower part of the cylindrical body of the main body 41 via a plurality of connecting members 43 . The hydraulic anchor device 45 is configured by attaching a hydraulically operated device 46 to the inner circumferential surface of a cylinder. A hydraulic connection part 46c is provided at the upper end part of the hydraulically operated device 46. A pressurizing tube (not shown) for applying hydraulic pressure is connected to the hydraulic connection part 46c.

[0019] A plurality of anchors 47 are provided at the bottom of the cylinder of the hydraulic anchor device 45. The plurality of anchors 47 are made of leaf springs, and their upper ends (base ends) are rotatably fixed to the lower peripheral edge of the hydraulic anchor device 45. Each anchor 47 extends vertically in a non-operated state. In an operating state in which hydraulic pressure is applied by the hydraulic operating device 46, each anchor 47 rises so that its tip, which faces downward in a non-operated state, rotates around its base end. Thus, the tip of each anchor 47 is stuck from bottom to top into the wall of the borehole 11, and the sinking gauge device 40 is supported by the wall of the borehole 11.

[0020] (Configuration of water pressure measuring device 20) Next, the configuration of the above-mentioned water pressure measuring device 20 will be described in detail with reference to Figs. As shown in FIGS. 2 to 4, the water pressure measuring device 20 includes an installation jig 21 and a pore water pressure gauge 30.

[0021] The installation jig 21 has a generally cylindrical main body 21b with a hollow section, and is used to place the pore water pressure gauge 30 in the borehole 11. This installation jig 21 fixes the pore water pressure gauge 30 with the lower end of the pore water pressure gauge 30 inserted. The main body 21b of the installation jig 21 has a circular hole 22 formed at one location on the central outer circumferential surface.

[0022] 4, annular recesses 23, 24 are formed on the outer circumferential surface in the axial direction (upper and lower) of the hole 22 of the installation jig 21. Water-stopping members 25, 26 that serve as expansion portions are disposed in the recesses 23, 24.

[0023] The waterproofing member 25 (26) is fixed to the main body 21b of the installation jig 21 by wrapping the outer periphery thereof with adhesive tape and further wrapping wire 27 thereon. The water-stopping members 25, 26 have the same configuration and are capable of expanding by absorbing water.

[0024] The waterproof member 25 (26) is composed of two types of waterproof packers 25a, 25b (26a, 26b). The waterproof packers 25a, 25b (26a, 26b) have the property of expanding when they absorb water, and they perform waterproofing by expanding. The waterproof packers 25a, 25b (26a, 26b) are composed of a material containing a water-absorbing polymer and synthetic rubber.

[0025] The waterproof packer 25a (26a) arranged on the recess 23 (24) side can be a member having a flat inner circumferential surface side and an uneven outer circumferential surface side, for example, a product name "Nice Seal Type B" by Applied Measurement Service Co., Ltd. Also, the waterproof packer 25b (26b) arranged on the outside can be a member having uneven inner and outer circumferential surface sides, for example, a product name "Nice Seal Type E" by Applied Measurement Service Co., Ltd. Note that in this embodiment, the uneven shape of the waterproof packer 25a (26a) and the uneven shape of the waterproof packer 25b (26b) are fitted together to be integrated, and arranged as the waterproof member 25 (26).

[0026] Furthermore, a plurality of (four) hanging bolts 28 are fixed at a distance from each other on the periphery of the upper end of the main body 21b of the installation jig 21. Wires are hung on the hanging bolts 28. These wires are used when lowering the water pressure measuring device 20 into the borehole 11 in a suspended state. As shown in FIGS. 2 and 3, four fixing holes are formed in the main body portion 21b of the installation jig 21 at positions surrounding the hole 22 between the water-stopping members 25 and 26.

[0027] (Configuration of pore water pressure gauge 30) Next, the configuration of the pore water pressure gauge 30 will be described in detail with reference to FIGS.

[0028] 4 and 5, the pore water pressure gauge 30 includes a measurement unit body 31 and a cap unit 32. The measurement unit body 31 has a size smaller than the radius of the body unit 21b of the installation jig 21. As a result, the measurement unit body 31 is attached to the installation jig 21 at a position closer to one side area than the center of the body unit 21b.

[0029] 4, the cap part 32 is attached to the lower end of the measurement part main body 31. This cap part 32 supplies water taken in from the outer periphery of the installation jig 21 to the measurement part main body 31. The measurement unit main body 31 supplies the measured values ​​to the data transmission unit 17 via a cable 30K connected to the upper end portion.

[0030] A cylindrical protruding member 35 that protrudes horizontally is fixed to the cap portion 32. A filter that removes dirt and other contaminants from the taken-in water is provided on the protruding member 35. This filter prevents dirt and other contaminants from entering the measuring unit main body 31. The horizontal plane passing through the center of the protruding member 35 is the water pressure measurement position (depth) where the pore water pressure gauge 30 measures water pressure.

[0031] Furthermore, as shown in FIG. 5, the cap portion 32 is formed with a bolt hole hb1 for fixing the measurement portion main body 31 to the installation jig 21. 2 and 3, the bolts 29 are screwed into the bolt holes hb1 of the pore water pressure gauge 30 with the fixing holes of the installation jig 21 aligned, thereby fixing the pore water pressure gauge 30 to the main body 21b of the installation jig 21. In this case, the pore water pressure gauge 30 is fixed to the installation jig 21 with the protruding members 35 protruding from the holes 22 of the installation jig 21.

[0032] (Measuring device installation method) Next, a method for installing the measurement system A1 having the above-mentioned configuration will be described with reference to FIGS.

[0033] First, as shown in Fig. 6(a), a root cutting base B1 is formed by root cutting work. Then, a borehole 11 is formed by drilling at this root cutting base B1 using a boring machine. This borehole 11 is drilled to a depth at which the water pressure measuring device 20 and the settlement gauge device 40 can be placed above the confined aquifer L2.

[0034] Next, the rod 15 is erected in the borehole 11. Specifically, the anchor 15a at the tip of the rod 15 is driven into the bottom of the borehole 11 to fix the rod 15. In this case, the rod 15 is positioned slightly outside the center of the borehole 11. This makes the gap between the pore water pressure gauge 30 of the water pressure measuring device 20 to be lowered and the rod 15 slightly larger.

[0035] Next, as shown in FIG. 6(b), the water pressure measuring device 20 is placed at the bottom of the borehole 11, which is the upper part of the confined aquifer L2. Specifically, a wire 60 is connected to each of the hanging bolts 28 of the water pressure measuring device 20. Then, the wire 60 is paid out with the rod 15 inserted through the hollow part of the main body 21b of the installation jig 21 of the water pressure measuring device 20. This causes the water pressure measuring device 20 to gradually descend in the borehole 11. Then, the water pressure measuring device 20 reaches the bottom of the borehole 11.

[0036] In this case, as shown in Figure 7(a), immediately after being lowered into the borehole 11, the water-stopping members 25, 26 of the water pressure measuring device 20 are in a contracted state and not yet expanded, and a gap is generated between them and the borehole 11.

[0037] 7(b), the water-stopping members 25, 26 of the water pressure measuring device 20 expand by absorbing groundwater seeping out from the surrounding ground (here, the confined aquifer L2). The expanded water-stopping members 25, 26 come into close contact with the inner wall of the borehole 11 at the upper and lower outer peripheries of the protruding member 35 of the cap portion 32 of the pore water pressure gauge 30. As a result, the space S1 including the water pressure measuring position in the borehole 11 is isolated from the spaces above and below it by the water-stopping members 25, 26.

[0038] Thereafter, as shown in Fig. 8, the subsidence gauge device 40 is lowered in a suspended state to be positioned directly above the water pressure measuring device 20 placed in the borehole 11. Specifically, as shown by the two-dot chain line in Fig. 8, the rod 15 is inserted through the cylindrical body of the hydraulic anchor device 45 and the cylindrical body 41 of the subsidence gauge device 40 with the tip of the anchor 47 facing downward (with the anchor 47 extending vertically). Then, with the rod 15 inserted, the subsidence gauge device 40 is lowered in the borehole 11. In this case, a pressurizing tube is connected to the hydraulic connection part 46c of the subsidence gauge device 40.

[0039] When the subsidence gauge device 40 reaches a position directly above the water pressure measuring device 20 already placed in the borehole 11, hydraulic pressure is supplied to the hydraulic operating device 46 via the pressurizing tube. This causes the tip of the anchor 47 of the hydraulic anchor device 45 of the subsidence gauge device 40 to rotate around the base end and rise, penetrating the wall of the borehole 11. Thus, the subsidence gauge device 40 is fixed at that position (depth) in the borehole 11.

[0040] Thereafter, the water pressure measuring device 20 and the subsidence gauge device 40 in the borehole 11 are buried with grout. In this case, a hose (not shown) is placed with its tip reaching near the water pressure measuring device 20 located at the bottom. Then, grout is supplied from this hose to bury the water pressure measuring device 20 and the subsidence gauge device 40 with grout. This grout is then filled up to the height (depth) where the water pressure measuring device 20 will be placed. Here, it is filled up to the height (depth) near the boundary between the impermeable layer L1 and the confined aquifer L2.

[0041] Then, the next water pressure measuring device 20 is placed. Specifically, the water pressure measuring device 20 is lowered to above the grout filled in the borehole 11 as described above. Then, after the waterstop members 25, 26 of the lowered water pressure measuring device 20 are expanded, the subsidence gauge device 40 paired with this water pressure measuring device 20 is lowered as described above. Then, the water pressure measuring device 20 and the subsidence gauge device 40 are buried with grout. In this case as well, grout is filled up to the top of the impermeable layer L1 where the next water pressure measuring device 20 is to be placed.

[0042] Next, in a similar manner, the water pressure measuring device 20 and the subsidence gauge device 40 are placed in the borehole 11 and buried with grout. Then, the cable 30K of each water pressure measuring device 20 placed in the borehole 11 and the cable of the layer-by-layer subsidence gauge 41g of each subsidence gauge device 40 are connected to the data transmission unit 17. After that, the data transmission unit 17 is attached to the rod 15. As a result of the above, the measurement system A1 is positioned below the excavation bottom B1.

[0043] (Water pressure measurement method) Next, a method for determining and measuring ground swelling, including a water pressure measurement method, will be described. The water pressure measuring device 20 measures the water pressure at the depth at which it is placed. Specifically, as shown in Fig. 7(b), water in the space S1 at the water pressure measurement position of the water pressure measuring device 20 is supplied to the measuring unit main body 31 through the hollow part of the protruding member 35 of the cap part 32. The measuring unit main body 31 measures the pressure of the supplied water. The water pressure measured by the measuring unit main body 31 of the water pressure measuring device 20 is supplied to the data transmission unit 17 via the cable 30K.

[0044] The vertical displacement measured by the subsidence gauge device 40 is also supplied to the data transmission unit 17 via a cable (not shown). The data transmission unit 17 supplies the measurement value (water pressure) measured by the water pressure measuring device 20 and the measurement value (vertical displacement) measured by the subsidence gauge device 40 to the management system 50 together with device identification information.

[0045] The management system 50 stores identification information of the devices (water pressure measuring device 20 and subsidence gauge device 40) from which the measurement values ​​were acquired, and location information (information regarding depth and positional relationship with each layer) associated with this identification information. Therefore, the management system 50 determines whether or not there is ground swelling using the acquired measurement values ​​(water pressure and vertical displacement) and the location information associated with the identification information of the device acquired together with the measurement values.

[0046] (Action of this embodiment) The installation jig 21 of the water pressure measuring device 20 is provided with water stop members 25, 26 above and below the water pressure measuring position. After being placed in the borehole 11, the water stop members 25, 26 absorb the surrounding water and expand. Therefore, the space S1 including the water pressure measuring position is isolated from the spaces above and below the borehole 11 by the expanded water stop members 25, 26.

[0047] According to this embodiment, the following effects can be obtained. (1) In the water pressure measuring device 20 of this embodiment, water-stopping members 25, 26 that expand by absorbing water are disposed above and below the protruding member 35. As a result, the space S1 including the water pressure measuring position of the water pressure measuring device 20 is isolated from the spaces above and below by the expanded water-stopping members 25, 26, and water is stopped. Therefore, the groundwater at the water pressure measuring position in the borehole 11 does not mix with other spaces, and the water pressure in the space S1 can be measured with high accuracy.

[0048] (2) In this embodiment, the water-stopping members 25, 26 are disposed in the recesses 23, 24 of the installation jig 21. As a result, even if the water-stopping members 25, 26 expand, they are unlikely to come off the installation jig 21, and the space S1 can be isolated from above and below.

[0049] (3) In this embodiment, the water-stopping member 25 (26) is composed of two layers of water-blocking packers 25a, 25b (26a, 26b) whose concave and convex shapes fit together. This makes it difficult for the water-stopping member 25 (26) to fall off from its position even if it expands, making it easier to more reliably isolate the space S1 from the spaces above and below.

[0050] (4) In this embodiment, the measuring unit body 31 of the pore water pressure gauge 30 is disposed at a position closer to one side than the center of the installation jig 21. This allows the water pressure measuring device 20 to be lowered into the borehole 11 with the rod 15 inserted through the installation jig 21, so that the water pressure measuring device 20 can be smoothly disposed in the vertical direction of the borehole 11.

[0051] (5) In this embodiment, the pore water pressure gauge 30 is fixed to the installation jig 21 by the bolts 29. This makes it possible to easily attach the pore water pressure gauge 30 or the installation jig 21.

[0052] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction. In the water pressure measuring device 20 of the above embodiment, water-stopping members 25, 26 that expand by absorbing water are used. The expansion section that expands from a contracted state to separate from the spaces above and below after being placed in the borehole 11 is not limited to this configuration. For example, a member that expands by supplying compressed air or the like may be used. In this case, after the water pressure measuring device is placed at a predetermined position (depth) in the borehole 11, compressed air may be supplied through a hose or the like to cause it to expand. The contracted state may be a state in which it can expand from now on, and may be a slightly expanded state.

[0053] In the above embodiment, the water-stopping members 25, 26 as the expanding parts are configured with the uneven water-blocking packers 25a, 25b, 26a, 26b. The shape, arrangement and configuration of the expanding parts are not limited to this. For example, they may be members without uneven shapes, or multiple (two or more rows) of water-stopping members 25, 26 may be provided above and below the protruding members.

[0054] In the above embodiment, the water pressure measuring device 20 is lowered by suspending it from above the borehole 11. The method of arranging the water pressure measuring device 20 is not limited to this, and the water pressure measuring device 20 may be lowered and arranged in a state integrated with the subsidence gauge device 40.

[0055] In the above embodiment, the water pressure measuring device 20 is used when a plurality of water pressure measuring devices 20 and a plurality of subsidence gauge devices 40 are arranged alternately in the borehole 11 for measurement. However, the present invention is not limited to this, and a plurality of water pressure measuring devices 20 alone may be arranged in the borehole without providing a subsidence gauge device to measure water pressure at a plurality of points in the vertical direction. In this case, the water pressure measuring device 20 is used in combination with a configuration in which a plurality of subsidence gauge devices are arranged vertically in another borehole 11 as in the conventional case to measure the vertical displacement.

[0056] In the above embodiment, the cables 30K of each water pressure measuring device 20 arranged in the borehole 11 are connected to the data transmission unit 17. Alternatively, a repeater that bundles the cables 30K of a plurality of water pressure measuring devices 20 may be arranged in the borehole 11, and the repeater and the data transmission unit 17 may be connected.

[0057] Next, the technical ideas that can be understood from the above embodiment and other examples will be described below. (a) The water pressure measuring device according to claim 1, characterized in that the expansion portion expands from the contracted state by absorbing water.

[0058] (b) The installation jig is characterized in that it has a cap portion that horizontally guides the water pressure from the water pressure measurement position to the pressure-receiving portion where the stratified water pressure gauge measures the water pressure.

[0059] (c) A water pressure measurement method as described in claim 3 or 4, characterized in that the water pressure measurement device is placed in at least one location above a confined aquifer, below and above a low-permeability layer located above the confined aquifer.

[0060] (d) A water pressure measurement method as described in claim 3, 4 or (c), characterized in that a settlement meter device for measuring the vertical displacement of the ground at that location is arranged directly above the water pressure measurement device in a pair with the water pressure measurement device. [Explanation of symbols]

[0061] A1...measurement system, B1...root cut bottom, L1...low-permeability layer, L2...confined aquifer, S1...space, hb1...bolt hole, 11...borehole, 15...rod, 15a, 47...anchor, 17...data transmission unit, 20...water pressure measurement device, 21...installation jig, 21b, 41...main body, 22...hole, 23, 24...recess, 25, 26...water-stopping member, 25a, 25b, 26a ,26b...watertight packer, 27...wire, 28...suspension bolt, 29...bolt, 30...pore water pressure gauge, 30K...cable, 31...measuring unit main body, 32...cap part, 35...protrusion member, 40...settlement meter device, 41g...layer-specific settlement meter, 43...connecting member, 45...hydraulic anchor device, 46...hydraulic operating device, 46c...hydraulic connection part, 50...management system, 60...wire.

Claims

1. A water pressure measuring device for measuring water pressure at multiple points in a vertical direction, A layered water pressure gauge for measuring the water pressure; A cylindrical installation jig to which the stratified water pressure gauge is fixed, A water pressure measuring device characterized in that the installation jig has an expansion portion capable of expanding from a contracted state on both axial sides of the installation jig relative to the water pressure measurement position of the stratification water pressure gauge.

2. An installation jig for fixing a stratified water pressure gauge that measures water pressure at multiple points in the vertical direction, A cylindrical body portion for fixing the stratified water pressure gauge is provided, An installation jig characterized in that the main body is provided with expansion sections capable of expanding from a contracted state on both axial sides of the water pressure measurement position of the stratification water pressure gauge.

3. A water pressure measurement method for measuring water pressure at a plurality of locations in a vertically extending hole, comprising: A water pressure measurement method characterized by placing a water pressure measuring device for measuring the water pressure at an installation position of the hole, and then inflating expansion sections provided above and below the water pressure measurement position of the water pressure measuring device to isolate the space of the water pressure measurement position within the hole from above and below, and performing measurement using the water pressure measuring device in this state.

4. A plurality of water pressure measuring devices are provided within the hole; A rod is fixed in the hole so as to extend in the vertical direction, 4. The water pressure measuring method according to claim 3, wherein the water pressure measuring device is disposed vertically spaced apart from the other water pressure measuring devices with the cylindrical main body portion inserted through the rod.

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