JP3181247U - Impervious device, interval water pressure measuring device using this - Google Patents

Abstract

[PROBLEMS] To reduce the time required for the formation of a water-impervious layer in a borehole despite the simple structure, and to ensure that groundwater from the aquifer is blocked (stopped) by forming the water-impervious layer. Provide a water shield capable of water).
Using a sheet that breaks when a predetermined pressure is applied in a state where water has permeated, the axial direction is aligned with the vertical direction of the boring hole, and the elongate has a size that fits in a region corresponding to the impermeable layer in the boring hole. A hollow cylinder 2 is formed, and a predetermined amount of a water shielding material 3 that expands when water is absorbed is filled in the cylinder 2, and both ends 2 a and 2 b of the cylinder 2 are sealed.
[Selection] Figure 1

Description

  The present invention relates to a water shielding device and an interval water pressure measuring device using the same, and in particular, despite the simple configuration, the time required for forming the water shielding layer in the borehole is shortened, and The present invention relates to a water shielding device capable of reliably shielding (stopping water) groundwater from an aquifer by forming a water layer, and an interval water pressure measuring device using the water shielding device.

  In order to understand the strength and deformation characteristics of the ground, it is extremely important to measure the distribution of pore water pressure under the ground in investigations such as foundations for dams, stability of cut slopes, prevention of landslides, and installation of wells. It is an important matter. Here, the ground is usually a multi-layer aquifer in which an aquifer having water permeability and saturated groundwater, and an impermeable layer that is difficult or impermeable to groundwater are alternately laminated in the vertical direction. The water pressure in the groundwater flowing out from each aquifer is the measurement target.

  In order to measure the pore water pressure of the multilayer aquifer, the following method has been conventionally employed. First, a single borehole is drilled in the multi-layer aquifer whose interval water pressure is to be measured, and the pore water pressure is measured in the region (depth position, depth space) corresponding to the aquifer within the borehole. In addition to installing a pore water pressure meter, filter materials such as cobblestones, crushed stones, and pebbles are filled to form a filter layer. Next, the area corresponding to the impermeable layer in the borehole is filled with a water shielding material (sealing material) such as bentonite, mortar, cement milk, etc. to form a water shielding layer (water blocking layer, sealing layer). Let By repeating these operations, the filter layer and the water-impervious layer are alternately stacked in the borehole so as to correspond to the aquifer layer and the impermeable layer of the ground. Further, the lead wire (measurement cable) of the pore water pressure gauge installed for each filter layer is led out to the ground, and the lead wire is connected to a computer (device) for measuring the pore water pressure. Then, the computer measures the water pressure (measured value) of the pore water pressure gauge for each filter layer. Thereby, pore water pressure measurement is implemented.

  However, in the above-described conventional technology, the filter material and the water shielding material are alternately filled (injected) into the borehole so as to correspond to the aquifer and impermeable layer of the ground. If the filling amount of the filter material or the filling amount of the impermeable material is slightly inaccurate, the impermeable layer is not properly formed in the region corresponding to the impermeable layer, and the groundwater in the aquifer becomes unaffected. There is a problem that the water pressure of the pore water pressure gauge fluctuates due to leakage from the water layer. Further, when the water shielding material penetrates into a crack or the like in the boring hole, there is a problem that a filling amount of the water shielding material is insufficient and a water shielding layer is not properly formed up to a predetermined depth. Furthermore, the lead wires of the pore water pressure gauges embedded in each filter layer form a “water path” in the vertical direction, and the “water path” breaks the water-blocking state (water-stopping state) of each water-blocking layer. Therefore, there is a problem that the water pressure of each filter layer cannot be measured accurately. When filling (embedding) a filter material or a water shielding material, there is a problem in that the exposed pore water pressure gauge or lead wire may be damaged.

  In order to solve the problem, for example, in Japanese Patent Laid-Open No. 3-279510 (Patent Document 1), a water pressure measuring tube incorporating a (gap) water pressure gauge is provided at appropriate intervals, and a filter material is provided on the outer surface. There is disclosed a pore water pressure measurement method in which cloth bags are alternately attached and a measurement tube formed by covering the outer surface of the water pressure measurement tube with the filter material is prepared in advance. And the said measurement pipe | tube is inserted in the said measurement hole, and the said bag body is filled with a sealing material, and is expanded and water-blocked in multistage form. Thereby, it is said that many effects, such as being able to install a sealing material and a filter material correctly to a measurement depth, are acquired.

  Japanese Patent Application Laid-Open No. 3-279511 (Patent Document 2) discloses a water pressure measuring tube in which a water pressure meter communicating with a water inlet is appropriately incorporated at every interval, and a lead wire of the water pressure meter is led to the ground side. A method for measuring pore water pressure in the ground used is disclosed. In the measurement method, the water pressure measurement tube is inserted into the borehole, the filter material is filled into the borehole, the filter material layer is measured at the place where the water inlet is covered by measuring the filling depth of the filter material. Form. Further, the sealing material is filled with cement or synthetic resin, and the sealing material layer is laminated by measuring the filling depth of the sealing material, and the lamination of the filter material layer and the sealing material layer is repeated a plurality of times, The measured value of each water pressure gauge at each depth is measured by a ground-side measuring instrument connected to a lead wire. Thereby, it is said that many effects, such as being able to obtain | require the filling depth of a filter material and a sealing material correctly for every filling work, are acquired.

  Japanese Patent Laid-Open No. 4-97009 (Patent Document 3) uses a granular solid material layer made of gravel and a synthetic resin for curing in the seal layer, thereby reducing the amount of the synthetic resin used. The amount of heat generated by curing the synthetic resin can be reduced.

  JP-A-4-97010 (Patent Document 4) discloses that each granular solid material layer formed in a number of stages by using a specific vertical communication single pipe and a sealing material injection pipe. It is said that it is possible to supply the sealing material to the inside at once.

  JP-A-4-97094 (Patent Document 5) discloses a specific synthetic resin (a main agent such as an epoxy resin and a curing agent) having a specific gravity greater than water, a viscosity within a specific range, and thixotropy. ) As a sealing material, it is possible to achieve both quick curability and low heat build-up, shortening the construction time and improving water stoppage.

  JP-A-9-13866 (Patent Document 6) discloses a kneaded product obtained by adding a polymer admixture such as a polymer water-soluble ether compound and a water reducing agent to one or both of cement and bentonite. A water shielding material is disclosed which is formed, dried and solidified, expands due to water absorption, and has a property of condensing in the expanded state. Thereby, it is said that highly rigid water shielding can be performed over a long period of time.

  Japanese Patent Laid-Open No. 2000-94764 (Patent Document 7) discloses impervious water that sandwiches a groundwater layer or a landslide surface obtained in advance by a support pipe having a required length inserted into a borehole drilled in the ground. A water shielding tool for a bored hole in which a water-swellable water shielding member is attached for each layer position is disclosed. In the water shield, the expansion rate of the water-absorbing expandable rubber layer is set to be larger than the expansion rate of the water-absorbing expandable water-insulating material, and the expansion rate of the lower water-absorbing expandable rubber layer is set to the expansion of the upper water-absorbing expandable rubber layer It is set larger than the speed. As a result, even when the groundwater necessary for the expansion of the water shielding material is insufficient, such as the borehole of the unsaturated aquifer, spring water falling from above the water shielding position is received by the lower rubber layer and received. Using the spring water, make a puddle, and then expand the upper rubber layer. For this reason, even if it is a saturated aquifer where there is sufficient groundwater or an unsaturated aquifer where there is a shortage of groundwater, reliable water shielding can be performed.

  Japanese Patent Laying-Open No. 2010-243337 (Patent Document 8) discloses a method for measuring the interval water pressure of a multilayer aquifer using an interval water pressure meter and a groundwater flow direction meter. In the interval water pressure measurement method, first, the borehole is drilled through the multilayer aquifer through the multilayer aquifer, and the depth position of each aquifer in the multilayer aquifer is measured after drilling. Next, a pore water pressure gauge is disposed in the borehole, and a groundwater flow direction meter is disposed at the corresponding location of each measured aquifer depth position. Then, after performing the water level lowering operation in the borehole, during the process of recovering the water level in the borehole, the groundwater of each aquifer is measured by the groundwater flowmeter installed corresponding to each aquifer. The flow direction change time is measured, and the water level surface in the borehole is measured by the pore water pressure gauge at the change time, whereby the pore water pressure of each aquifer is measured based on the measured value. This makes it possible to simultaneously and accurately measure the pore water pressure (pressure head) of each aquifer in a multilayer aquifer without installing a seal layer or a water shielding layer at one borehole. .

JP-A-3-279510 JP-A-3-279511 Japanese Patent Laid-Open No. 4-97009 Japanese Patent Laid-Open No. 4-97010 JP-A-4-97094 Japanese Patent Laid-Open No. 9-13866 JP 2000-94764 A JP 2010-243337 A

  However, in the technique described in Patent Document 1, it is unclear whether or not the water shielding material exudes easily from the cloth when the water shielding material is expanded because the water shielding material is filled in the cloth bag. There is a problem that it may take time for the seepage water blocking material to come into close contact with the borehole wall. In some cases, it is also assumed that the water-impervious material soaked in water does not ooze from the cloth.

  In addition, the technique described in Patent Documents 2-5 has a problem that costs are increased because a special synthetic resin or the like is used as a special water pressure measuring tube or a water shielding material. In addition, there is a problem that a pipe for injecting a sealing material for filling the boring hole with a water shielding material is separately required. Furthermore, it takes several hours to cure the synthetic resin or the like, and there is a problem that the construction time before the pore water pressure measurement tends to be prolonged.

  Furthermore, in the techniques described in Patent Documents 6 and 7, it is necessary to prepare a special water shielding material and a water shielding tool in advance, and in the technique described in Patent Document 8, groundwater other than the pore water pressure gauge is required. It is necessary to separately use a flow direction meter, and in any technique, it is necessary to separately prepare an instrument or apparatus different from the conventional technique, and there is a problem that costs are increased.

  By the way, as a conventional method for forming a water shielding layer in the borehole, there is a method in which an operator gently puts a predetermined amount of a water shielding material manually from the opening of the borehole or a grout having a long pipe. There is a method in which a predetermined amount of a water shielding material is vigorously charged into a desired region using a pump. However, in any method, filling of the water shielding material may be insufficient or non-uniform, and accordingly, the water shielding performance of the formed water shielding layer is inferior, and an accurate pore water pressure is measured. There is a problem that it cannot be done.

  Therefore, the present invention has been made to solve the above problems, and despite the simple configuration, the time required for forming the water shielding layer in the borehole is reduced, and the water shielding layer is also provided. An object of the present invention is to provide a water shielding device capable of reliably shielding (stopping water) groundwater from an aquifer by forming a gap, and an interval water pressure measuring device using the same.

  In order to solve the above-mentioned problems and achieve the object, the present invention is designed to measure the pore water pressure of each aquifer in the ground of a multi-layer aquifer in which aquifers and impermeable layers are alternately laminated. And a water shielding tool for forming a water shielding layer in a region corresponding to the water impermeable layer in the borehole drilled in the ground.

  The water shielding device fits in a region corresponding to the impermeable layer in the borehole when the axial direction is aligned with the vertical direction of the borehole using a sheet that breaks when a predetermined pressure is applied in a state where water has permeated. An elongated hollow cylinder having a size is formed, and a predetermined amount of a water shielding material that expands when water is absorbed is filled in the cylinder, and both ends of the cylinder are sealed.

  This reduces the time required to form the water-impervious layer in the borehole despite the simple structure, and also ensures that the groundwater from the aquifer is blocked (stopped) by forming the water-impervious layer. Water).

  That is, when forming the water-impervious layer in the borehole, the operator can remove the water shield from the upper surface of the borehole with the axial direction of the water shield and the vertical direction of the borehole aligned. If it falls (throws in), the water shield is wet with the water (for example, groundwater) in the borehole, and the lower surface (the bottom surface, the upper surface of the filter layer) corresponding to the impermeable layer in the borehole To fall.

  Here, the water shielding material conveys the water shielding material to the lower surface until a sheet constituting the water shielding material is broken by expansion (swelling) of the water shielding material inside. Therefore, before the internal water shielding material reaches the region corresponding to the impermeable layer, it is dispersed in the boring hole and is different from the region (for example, the region corresponding to the aquifer). It is possible to prevent stagnating or adhering to the hole wall. As a result, it is possible to sufficiently (appropriately) fill the region with a predetermined amount of the water shielding material without reducing the water shielding material in spite of simple work.

  Further, in the water shield that has reached the region, when the water in the boring hole is sufficiently permeated into the inside, the water shielding material inside expands and pushes and breaks through the external sheet with a predetermined pressure. Then, the water-impervious material is appropriately dispersed in the region where the impermeable layer is to be formed, and is in close contact with the adjacent water-impervious material or attached to the borehole wall in the region corresponding to the impermeable layer. Thus, a water shielding layer is formed.

  Here, since the shape of the water shield itself is an elongated shape that fits (adapts) in the region corresponding to the impermeable layer, the internal water shielding material is not dispersed in other regions, and the region A water-impervious layer is formed so as to fit (match) uniformly. As a result, the formed water shielding layer can surely shield (stop water) the groundwater from the aquifer located above and below.

  Furthermore, the water shielding device according to the present invention has a remarkable effect of being excellent in cost performance because it has a few components and an extremely simple configuration.

  In addition, it is possible to adopt a configuration in which the sheet is any one of newspaper, Japanese paper, calligraphy paper, half paper, shoji paper, cocoon half paper, paper made of natural fiber, and paper made of semi-synthetic fiber.

  In addition, the present invention can be provided as a pore water pressure measuring device that measures the pore water pressure of each aquifer in the ground of a multilayer aquifer in which aquifers and impermeable layers are alternately laminated. That is, the pore water pressure promoting device corresponds to an impermeable layer in the borehole when the axial direction is aligned with the vertical direction of the borehole using a sheet that breaks when a predetermined pressure is applied in a state where water has permeated. Forming a thin and long hollow cylinder having a size that can be accommodated in the region, filling the cylinder with a predetermined amount of a water shielding material that expands when water is absorbed, and further sealing the both ends of the cylinder, In addition, a predetermined number of the water shielding tools are disposed in a region corresponding to the water-impermeable layer so as to form a water shielding layer in the region. Even with this configuration, the same effects as described above can be obtained.

  According to the water shielding device according to the present invention and the pore water pressure measuring device using the same, the time required for forming the water shielding layer in the borehole is shortened, and the water shielding material is used despite the simple configuration. Formation of the layer makes it possible to reliably shield (stop water) the groundwater from the aquifer.

It is a perspective view which shows the water shielding tool and storage box which concern on this invention. It is a 1st perspective view which shows the preparation method of the water shield based on this invention. It is a 2nd perspective view which shows the preparation method of the water shield based on this invention. It is a flowchart for showing the execution procedure of the pore water pressure measuring method using the water shield according to the present invention. It is a 1st figure which shows the outline of the pore water pressure measuring method using the water shielding tool which concerns on this invention. It is a 2nd figure which shows the outline of the pore water pressure measuring method using the water shielding tool which concerns on this invention. It is the 3rd figure which shows the outline of the pore water pressure measuring method and the pore water pressure measuring apparatus using the water shielding tool which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

<Water shielding device according to the present invention>
FIG. 1 is a perspective view showing a water shielding device and a storage box according to the present invention.

  The water shielding device 1 according to the present invention has a hole formed in the ground when measuring the pore water pressure of each aquifer in the ground of a multilayer aquifer in which aquifers and impermeable layers are alternately laminated. It is the water shielding tool 1 for forming a water shielding layer in the area | region corresponding to the said impermeable layer in a boring hole.

  As shown in FIG. 1, the water shield 1 uses a sheet that breaks when a predetermined pressure is applied in a state where water has permeated, and aligns the axial direction with the vertical direction of the boring hole. An elongated hollow cylinder 2 having a size that fits in a region corresponding to the water permeable layer is formed, and the cylinder 2 is filled with a predetermined amount of a water shielding material 3 that expands when water is absorbed. The portions 2a and 2b are sealed.

  Thereby, when forming a predetermined | prescribed water shielding layer in the area | region corresponding to the impermeable layer in the said boring hole, the axial direction of the said water shielding tool 1 is match | combined with the up-down direction of the said boring, and the said water shielding tool 1 is used. If it is thrown into (dropped into) the borehole, the inner water shielding material 3 can be sufficiently filled in the region without being dispersed in the middle of the borehole. Moreover, if the internal water-impervious material 3 absorbs water and expands, the external sheet is automatically broken to form a water-impervious layer. Here, since the shape of the water shielding tool 1 itself is an elongated shape having a size that can be accommodated in the region, the water shielding layer is formed so as to uniformly fit (match) the region. Therefore, the formed water-impervious layer can reliably block (stop water) groundwater from the aquifer positioned above and below the impermeable layer (described later).

  Here, the size of the cylinder 2 may be any size as long as it fits in the region corresponding to the impermeable layer in the borehole when the axial direction is aligned with the vertical direction of the boring. Depending on the type of the impermeable layer, etc., it may be much larger or smaller than the region corresponding to the impermeable layer. Ideally, the length 2c in the axial direction is set to be equal to or less than the length (thickness) in the vertical direction of the impermeable layer, and the length 2d in the width direction is set to be equal to or less than the diameter of the boring hole. With this configuration, although it depends on the type of the impermeable layer and the length in the vertical direction, the operator can easily carry the water shield 1 as a whole and easily put the water shield 1 into the boring hole ( Easy to fall).

  Further, the length 2d in the width direction of the cylinder 2 may be any length as long as it is equal to or smaller than the diameter of the boring hole. Usually, the diameter of the boring hole is the length of the boring hole, Although it varies depending on the size and the type of multilayer aquifer to be investigated, it is in the range of 66 mm (φ66), 86 mm (φ86), 116 mm (φ116), 150 mm (φ150). Therefore, the length 2d in the width direction of the cylinder 2 is set to, for example, a range of ¼ to ½ of the diameter of the boring hole, specifically, 25 mm (2.5 cm) -100 mm (10 cm). If it is within the range of 40 mm (4 cm) -60 mm (6 cm), it is possible to obtain a highly versatile water shielding device 1 applicable to any boring hole, and for the operator to The water tool 1 can be held and carried with one hand, and the handleability of the water shield 1 is improved.

  On the other hand, when the length 2d in the width direction of the cylinder 2 is larger than the above-described range (100 mm), the water shield may not be applicable to a bore hole having a relatively small diameter. The water shield cannot be held with one hand, which is not preferable. Further, when the length 2d in the width direction of the cylinder 2 is smaller than the above-described range (25 mm), an operator can attach a large number of water shields 1 to the bore holes in order to form a water shield layer. It is not preferable because it is necessary to throw in, and the labor of the worker increases.

  Further, the length 2c in the axial direction of the cylinder 2 may be any length as long as it is equal to or less than the length in the vertical direction of the impermeable layer, but usually the length in the vertical direction of the impermeable layer. The height is in the range of 100 cm (1 m) to 500 cm (5 m), although it varies depending on the type of ground of the multilayer aquifer, the depth at which the impermeable layer exists, and the like. Therefore, the length of the cylinder 2 in the axial direction is, for example, in the range from one third to the length of the impermeable layer in the vertical direction, specifically 20 cm to 150 cm, preferably 30 cm to 100 cm. Then, while it can be set as the water shielding tool 1 which can form the water-impervious layer corresponding to any impermeable layer, even if it fills the said water-impervious material 1 with a rather heavy water shielding material 3 The operator can carry the water shield 1 alone, thereby improving the convenience for the operator.

  When the length of the impermeable layer in the vertical direction is remarkably large (for example, 5 m), a plurality of (for example, five) water shields 1 having a predetermined axial length (for example, 1 m) are provided in the vertical direction. By arranging so as to be stacked, a desired water shielding layer corresponding to the impermeable layer is formed.

  On the other hand, when the length 2c in the axial direction of the cylinder 2 is smaller than the above-described range (20 cm), an operator must throw a large number of water shielding tools into the boring holes in order to form the water shielding layer. This is undesirable because it increases the labor of the operator. Further, when the length 2c in the axial direction of the cylinder 2 is larger than the above-described range (150 cm), when the operator lifts the water shield, the water shield itself is bent, and the boring is performed. There is a possibility that it cannot be put into the hole, which is not preferable.

  The cylinder 2 may have any shape as long as it is an elongated shape. However, since the boring hole is generally a cylindrical shape, the cylinder 2 has a substantially cylindrical shape or a substantially cylindrical shape. When the polygonal cylindrical shape is adopted, when the water shielding material 3 filled in a substantially cylindrical shape expands in a region corresponding to the impermeable layer of the boring hole, the whole water shielding material 3 fits in the region without a gap. Include. Therefore, the water-impervious layer formed by the water-impervious material 3 sufficiently and uniformly adheres to the inner wall of the region, and reliably exerts the water-impervious performance.

  Here, the substantially cylindrical shape includes, for example, a cylindrical shape whose bottom surface is a perfect circle and an elliptic cylinder shape whose bottom surface is an ellipse. In addition, the substantially polygonal column shape includes, for example, a polygon whose bottom is triangular, square, pentagon, hexagon, heptagon, octagon, nine-angle, ten-angle, twelve-angle, fourteen-sided, ten-hexagon, eighteen-sided Is included.

  The sheet constituting the exterior (outer peripheral part) of the water shield 1 may be any sheet as long as it is torn when a predetermined pressure is applied in a state where water has permeated (wet water). Although not available, for example, commercially available sheets such as newspaper, Japanese paper, calligraphy paper, semi-paper, shoji paper, cocoon semi-paper, paper made of natural fiber, paper made of semi-synthetic fiber are used. Is done.

  In particular, when newspaper is used as the sheet, it can be easily obtained, and the length of the newspaper in the spread state is about 100 cm (the length in the longitudinal direction of the newspaper in the single-open state is about 50 cm). The length 2c in the axial direction of the water shield 1 (cylinder 2) described above is satisfied, and the sheet size adjustment in the production of the water shield 1 is not necessary. Moreover, since the newspaper does not cause a big problem even if it remains in the ground (underground), it is optimal as an external material for the water shield 1. The same applies to Japanese paper and calligraphy paper.

  Here, the predetermined pressure is, for example, a pressure that allows the water-permeable material 3 expanded by water absorption to press (press) the outside, or the operator presses (impacts) the water-permeable device 1 using a predetermined rod or weight. The pressure is about.

  Further, the water shielding material 3 may be any water shielding material as long as it is a water shielding material that expands when absorbing water, that is, a normal water shielding material used in the pore water pressure measurement method. Bentonite, mortar, cement milk, a mixture of these with a predetermined synthetic resin, or the like is employed.

  In addition, the predetermined amount (filling amount) of the water shielding material 3 is usually an amount corresponding to the entire inner volume of the water shielding device 1, but the length of the impermeable layer confirmed in the field in the vertical direction You may adjust suitably according to the magnitude | size etc. of a boring hole. For example, if the volume of the region corresponding to the impermeable layer in the borehole is a half of the volume of the water shield 1, four water shields 1 are prepared, and any one water shield The filling amount of the water shielding material 3 in 1 is halved to correspond to the volume of the region. Thus, the filling amount of the water shielding material 3 can be appropriately adjusted at the site.

  Further, any method may be used for sealing the both end portions 2a, 2b of the cylinder 2 as long as the inner water shielding material 3 does not fall from the both end portions 2a, 2b of the cylinder 2. For example, after filling the water shielding material 3, a method in which the one end portion 2 a of the cylinder 2 is simply bent inward from the outside toward the center so as to be a bottom surface, after filling the water shielding material 3, Examples include a method in which the other end 2b is bent to the inside from the outside toward the center with the other end 2b being the bottom surface, and the state is fixed with the construction tape 4.

  1 has one end 2a sealed without the construction tape 4 and the other end 2b sealed with the construction tape 4, but both ends are sealed. It may be sealed without the construction tape 4, and both ends may be sealed with the construction tape 4. Further, when sealing the both end portions 2a, 2b of the cylinder 2, a gap through which water can flow from the outside to the inside is provided in advance so as to promote the intrusion of water into the water shield 1 It may be configured.

  In addition, as shown in FIG. 1, a plurality of water shields according to the present invention are prepared in advance from the stage before the pore water pressure measurement is performed, and a predetermined number of the water shields 1 can be accommodated. Store in box 5. If the water shield 1 is stored in the box 5, the box 5 protects the internal water shield 1 from external pressure (impact), and the pressure prevents the sheet of the water shield 1 from being torn. To prevent. Even if the sheet of the water shielding tool 1 is torn for some reason during the conveyance of the box 5, the box 5 can prevent the internal water shielding material 3 from being dispersed to the outside.

<How to make a water shield according to the present invention>
Next, a method for creating a water shield according to the present invention will be described.

  Any method may be used as a method of creating the water shielding device according to the present invention, but for example, the following method is adopted.

  2 and 3 are perspective views showing a method for producing a water shielding device according to the present invention.

  First, the water shielding device 1 is formed with an elongated cylinder 6 (for example, a cylindrical pipe) having a diameter (here, 60 mm) corresponding to about a half of a predetermined bore diameter, for example, 116 mm (φ116). A sheet 7 (for example, newspaper) is prepared.

  Next, with the newspaper 7 in a spread state, as shown in FIG. 2, the side in the longitudinal direction (long side) is applied to the cylindrical pipe 6, the newspaper 7 is wound around the cylindrical pipe 6, and the newspaper 7 An elongated cylindrical tube 2 having a substantially cylindrical shape is formed.

  Here, since the length in the longitudinal direction of the newspaper 7 in a spread state is about 100 cm, the length in the axial direction of the produced cylinder 2 is equal to or less than the length in the vertical direction of the normal impermeable layer described above. The cylinder 2 has a size that fits in a region corresponding to the impermeable layer in the borehole when the axial direction is aligned with the vertical direction of the borehole.

  Further, the number of times of winding the newspaper 7 around the cylindrical pipe 6 may be any number as long as the newspaper 7 is a long and narrow hollow cylinder 2, but if the number of winding is 2 to 10 times, the cylinder 2 Since moderate strength can be imparted to itself, for example, it is possible to prevent the water shielding device 1 from being bent and the newspaper 7 from being broken due to the weight of the filled water shielding material 3. In addition, about the surrounding surface of the elongate hollow cylinder 2, it fastens with the construction tape 4 as needed.

  Furthermore, one end 2a (for example, one end 2a in the right direction shown in FIG. 2) of the produced cylinder 2 is folded inward from the outside toward the center so as to be a bottom surface, and the state is taped for construction. 4 and the one end 2a is sealed.

  Next, the water shielding material 3 is filled from the other end 2b (for example, one end 2b in the left direction shown in FIG. 2) of the opened cylinder 2 with the one end 2a of the sealed cylinder 2 as a substantially cylindrical bottom surface. To do. The water shielding material 3 is, for example, a commercially available pelletized bentonite. Although the filling amount of the water shielding material 3 is adjusted as appropriate, it is herein assumed to be the entire volume inside the created cylinder 2.

  When the inside of the cylinder 2 is filled with a predetermined amount of the water shielding material 3, the other end 2b of the cylinder 2 is bent inward from the outside toward the center so as to be a bottom surface and lightly fixed. Thereby, it becomes possible to adjust the filling amount by appropriately extracting the inner water shielding material 3 from the other end 2b of the cylinder 2. In this way, as shown in FIG. 3, the water shielding device 1 according to the present invention is completed. The time required to create the water shield 1 according to the present invention is about 5 to 10 minutes per water shield, although it varies depending on the operator's familiarity.

  In the above-described method for creating the water shield 1, the water shield 1 is created using the newspaper 7 in the spread state. For example, the water shield 1 is formed using the newspaper 7 in the single-open state (half-open state). You may create it. This point is appropriately adjusted according to the vertical length of the impermeable layer on site.

<Measurement method of pore water pressure using the water shield according to the present invention>
Next, a pore water pressure measuring method using the water shield 1 according to the present invention will be described.

  FIG. 4 is a flowchart for illustrating an execution procedure of the pore water pressure measuring method using the water shield according to the present invention. 5-7 is a figure which shows the outline of the pore water pressure measuring method using the water shield based on this invention.

  First, the position of the ground of the multi-layer aquifer to be subjected to pore water pressure measurement is confirmed, and a predetermined boring machine is moved downward by a predetermined depth (for example, 4.0 m) from the upper surface GL (work floor) of the position. Drilling using a rotary drill (not shown). Then, a mouth pipe (not shown) having a predetermined outer diameter (for example, φ125) is installed in the drilled hole to prepare for pore water pressure measurement.

  Next, as shown in FIG. 5 (A), using a rotary drill having a predetermined inner diameter (for example, φ116), the boring hole 8 is drilled to a predetermined depth along the mouth tube (FIG. 4: S101, FIG. 5 (A)).

  Here, when the boring hole 8 is drilled, for example, a predetermined pipe 9 (a casing pipe having an outer diameter equivalent to the outer diameter of the boring) is appropriately installed on the hole wall of the boring hole 8, and the hole Casing digging to protect the walls is adopted.

  Further, the predetermined depth of the boring hole 8 is a depth that has been investigated (determined) in advance so that the deepest portion (lowermost surface) becomes the aquifer 10, and in the ground shown in FIG. Of the ground where the layers 10 and the two impermeable layers 11 are alternately stacked, the depth is from the bottom until reaching the deepest aquifer 10a in the first stage.

  When the drilling of the boring hole 8 is completed, the inside of the boring hole 8 is washed with fresh water, and the muddy water and the like in the hole are replaced with the fresh water W.

  Further, as shown in FIG. 5B, the length is cut in advance from the work floor GL to a specific depth (for example, the deepest aquifer 10a) at which the water pressure of the predetermined aquifer 10 is to be measured. A commercially available pore water pressure meter 12 is installed at the tip of the steel tension manganese wire 12a, and the pore water pressure meter 12 is inserted into the boring hole 8 and installed in the vicinity of the specific depth (FIG. 4: S102, FIG. 5 (B)). In addition, the measurement cable of the pore water pressure gauge 12 is placed along the manganese wire 12a in advance so that the measurement cable is led out to the ground.

  Then, an amount of filter material 13 (cobblestone, crushed stone, etc.) to be filled is prepared from the volume of the region 101 corresponding to the aquifer 10 in the borehole 8 at the location where the pore water pressure gauge 12 is installed. Then, while pulling out the casing pipe 9, the filter material 13 is gently put into the predetermined amount from the opening 8a (upper surface) of the boring hole 8 (FIG. 4: S103, FIG. 5 (B)). The filter material 13 is gently put around the pore water pressure gauge 12 to form a filter layer 14 in which the pore water pressure gauge 12 is installed.

  Here, whether or not the filter material 13 is appropriately filled in the region 101 corresponding to the aquifer 10 in the borehole 8 is determined by a predetermined instrument (for example, a filling depth measuring device for filter material). It is confirmed. When the filling amount of the filter material 13 is insufficient, for example, when the uppermost surface of the filter layer 14 does not reach an appropriate filling depth (FIG. 4: S104 NO), the filter material 13 is filled again. (FIG. 4: S103).

  On the other hand, as shown in FIG. 5C, when the filter material 13 is appropriately filled in the region 101 corresponding to the aquifer 10 in the boring hole 8, that is, the uppermost surface of the filter layer 14 is appropriate. When a sufficient filling depth has been reached (FIG. 4: S104 YES, FIG. 5C), it is confirmed whether or not the filling operation should be terminated (FIG. 4: S105).

  Here, in the ground shown in FIG. 5, it is necessary to form a water-impervious layer directly above the formed filter layer 14 corresponding to the impermeable layer 11a immediately above the aquifer 10a. The work is continued (FIG. 4: S105 NO).

  As shown in FIG. 5C, the water-impervious layer to be formed immediately above the filter layer 14 in the borehole 8 is not formed in the borehole 8 (located directly above the aquifer 10a). Since it is the volume of the area | region 111 corresponding to the water permeable layer 11a, an operator is a specific number of specific water shielding (for example, 2-4 pieces) which should be thrown in into the said boring hole 8 based on the said volume. Prepare tool 1.

  Here, in the pore water pressure measurement method according to the present embodiment, the size of the specific water shield 1 is accommodated in the region 111 corresponding to the impermeable layer 11 in the boring hole 8 in order to simplify the description. Magnitude. Specifically, the water shield 1 has an axial length 2c equal to the vertical length of the impermeable layer 11 (for example, 100 cm) and a width length 2d of the boring hole 8. The diameter is about one half of the diameter (for example, 60 mm).

  Next, as shown in FIG. 6 (D), a predetermined number of prepared water shields 1 are gently introduced from the opening 8a of the boring hole 8 while the casing pipe 9 is pulled out. 1 is disposed in a region 111 corresponding to the impermeable layer 11 (FIG. 4: S106, FIG. 6D).

  Here, when the water shield 1 is put into the boring hole 8, the operator can make sure that the water shield 1 fills the entire inner diameter of the boring hole 8. Are aligned, the water shield 1 is placed in the width direction (radial direction) of the bore hole 8 and the water shield 1 is inserted. Depending on the length of the water shield 1 in the width direction, for example, the length of the water shield 1 in the width direction is different from that of the water shield 1 arranged on the inner diameter of the bore hole 8. If it is about one half of the diameter of the hole 8, as shown in FIG. 6 (E), the two water shields 1 are arranged adjacent to each other in the width direction of the opening 8a of the boring hole 8, Inscribed in the opening 8a. Further, if the length in the width direction of the water shield 1 is about one third of the diameter of the boring hole 8, the three water shields 1 are drawn so that the centers of the three water shields 1 are substantially triangular. The water tools 1 are arranged adjacent to each other in the radial direction, and are inscribed in the opening 8a. Further, if the length in the width direction of the water shield 1 is about one-fourth of the diameter of the borehole 8, the four water shields 1 are drawn so that the centers of the four water shields 1 draw a substantially square shape. The water tools 1 are arranged adjacent to each other in the radial direction and are inscribed in the opening 8a. It should be noted that the water shield 1 has the bore hole so that the manganese wire 12a extending from the pore water pressure gauge 12 exists in the gap formed between the water shield 1 and the opening 8a of the bore hole 8. 8 openings 8a are arranged and arranged.

  Now, when the water shield 1 is inserted into the boring hole 8, the sheet 7 constituting the outside of the water shield 1 prevents the dispersion of the water shield 3 inside. 3 can be filled (arrived) in a desired region 111 (depth position) corresponding to the impermeable layer 11 without being dispersed in the middle of the borehole 8.

  Here, as in the prior art, for example, when the water shielding material 3 is put into the boring hole 8 as it is, the water shielding material 3 is in the middle of the boring hole 8 before reaching the desired region 111. In some cases, the groundwater W was absorbed while being dispersed to expand and adhere to the wall of the borehole 8. In that case, the water shielding material 3 is clogged in the middle of the boring hole 8, and the water shielding layer 15 cannot be formed in the appropriate region 111, and it is necessary to redo a new boring hole 8. was there. The water shielding device 1 according to the present invention sufficiently fills the desired region 111 with the water shielding material 3 in order to significantly reduce the possibility that the water shielding material 3 is dispersed in the middle of the boring hole 8. Is possible.

  In addition, as shown in FIG. 6 (F), when the inserted water-impervious device 1 falls to the uppermost part of the filter layer 14 due to its own weight, the sheet 7 constituting the outside of the water-impermeable device 1 is removed. Thus, the groundwater W in the borehole 8 penetrates into the interior, and the water shielding material 3 in the interior causes water expansion. Then, the water shielding material 3 pushes and breaks through the sheet 7 with a predetermined pressure, and the water shielding layer 15 is formed in the region 111 corresponding to the impermeable layer 11.

  Here, since the shape of the water shield 1 itself is an elongated shape that matches the region 111 corresponding to the impermeable layer 11, if the water shield 3 of the water shield 1 is expanded as it is. As shown in FIG. 7G, a water shielding layer 15 that exactly matches (matches) the region 111 corresponding to the impermeable layer 11 is formed by combining with other water shielding materials 3. . Thereby, the said water-impervious layer 15 can reliably water-block (stop water) the groundwater W from the aquifer 10 positioned above and below the impermeable layer 11.

  When the water shield 1 reaches the uppermost part of the filter layer 14, the water W in the boring hole 8 does not permeate the water shield 1 for some reason, and the water shield When the water shielding material 3 inside 1 does not cause expansion, a string (or long bar) having a predetermined length with a predetermined weight is prepared, and the weight is put into the boring hole 8. If it is dropped and collided with the water shield 1, the outer sheet 7 of the water shield 1 is broken by the collision with the weight, and the water impermeable material 3 is impermeable to the boring hole 8. 11 is dispersed in a desired region 111 corresponding to 11 to forcibly form the water shielding layer 15.

  Further, since the water shielding material 3 has a substantially elongated shape and expands substantially uniformly, the water shielding layer 15 made of the water shielding material 3 is substantially evenly applied to the measurement cable extending from the pore water pressure gauge 12 located immediately below. Contact (abut). Therefore, the measurement cable is less likely to be damaged as compared with the case where the water shielding layer 15 contacts non-uniformly.

  Next, the operator determines whether or not the water-impervious material 3 is appropriately filled in the region 111 corresponding to the impermeable layer 11 in the boring hole 8 in the same manner as the filter material 13. (For example, a filling depth measuring device for a water shielding material, a measuring tape, etc.) When the filling amount of the water shielding material 3 is insufficient, for example, when the uppermost surface of the water shielding layer 15 does not reach an appropriate filling depth (FIG. 4: S107 NO), the necessary amount of the water shielding material 3 Accordingly, the size and shape of the other water shield 1 are adjusted (FIG. 4: S108), and the adjusted other water shield 1 is inserted from the opening 8a in the boring hole 8 (FIG. 4: S106). Adjustment of the size and shape of the other water shield 1 can be achieved, for example, by appropriately shortening the axial length of the other water shield 1 or by filling the water inside the other water shield 1 with water. This is done by appropriately reducing the amount of the material 3.

  On the other hand, when the impermeable material 3 is appropriately filled in the region 111 corresponding to the impermeable layer 11 in the borehole 8, that is, when the uppermost surface of the impermeable layer 15 reaches an appropriate filling depth ( FIG. 4: S107 YES, FIG. 7G), it is confirmed whether or not the filling operation should be terminated (FIG. 4: S109).

  Here, in the ground shown in FIG. 7, since it is necessary to further form the filter layer 14 immediately above the water-impervious layer 15, the filling operation is continued (FIG. 4: S109 NO), the process returns to S102, and the boring is performed. A pore water pressure gauge 12 is installed in a region 101 corresponding to the aquifer 10 in the hole 8 (FIG. 4: S102), and the filter material 13 is filled into the region 101 by a predetermined filling amount (FIG. 4). 4: S103). This is the same as described above.

  On the other hand, after alternately filling the filter material 13 and charging the water shield 1, in other words, three filter layers 14 and two water shield layers 15 are alternately placed in the borehole 8. After the lamination, in S105 or S109, when the filling operation is completed (FIG. 4: S105 YES, S109 YES), as shown in FIG. It connects to the computer 16 for water pressure measurement, and the pore water pressure for each aquifer 10 is measured (FIG. 4: S110). Thereby, pore water pressure measurement is implemented.

<Examples, comparative examples, etc.>
Now, if the results differ slightly depending on the type of ground of the multilayer aquifer, the depth of the impermeable layer 11, the length (thickness) of the impermeable layer 11 in the vertical direction, the size of the inner diameter of the boring hole 8, and the like. However, in order to show the operation and effect of the present invention, in the pore water pressure measuring method (Example) using the water shield 1 according to the present invention and the conventional pore water pressure measuring method (Comparative Example) An example of the time required for forming the water shielding layer 15 in the borehole 8 and the evaluation of the water shielding performance of the water shielding layer 15 is shown below.

  In the embodiment, when forming the water shielding layer 15 in the region 111 corresponding to the impermeable layer 11 in the boring hole 8, as shown in FIGS. 4 and 6, the operator has a predetermined number (for example, two, The top surfaces of the three water shields 1 are aligned, and the water shields 1 are arranged in the width direction of the boring hole 8 and put into the boring hole 8, so the time required for the pouring is several seconds. It was. Further, when the sheet 7 of the water shield 1 is made of newspaper, the time required for the water shield 3 inside the water shield 1 to absorb the water W and expand to become the water shield layer 15. Was several minutes (for example, about 5 minutes). Therefore, the time required for forming one water shielding layer 15 is about several minutes.

  Next, in the examples, in order to confirm whether the formed impermeable layer 15 reliably impedes groundwater from the aquifer 10 positioned above and below, the impermeable performance evaluation shown below is performed. Carried out.

  First, as shown in FIG. 7 (H), a borehole 8 for measuring pore water pressure, that is, two water shielding layers 15 (from the bottom to the first water shielding layer 15a and the second water shielding layer 15b). And three filter layers 14 (with the first filter layer 14a, the second filter layer 14b, and the third filter layer 14c from the bottom) in which the pore water pressure gauge 12 is installed are formed alternately. Boring holes 8 are created in advance. Next, in the vicinity of the boring hole 8, a first boring hole for a pumping test is drilled to the depth of the aquifer 10a corresponding to the first filter layer 14a, and water is pumped from the aquifer 10a. .

  Here, if the pore water pressure of the first filter layer 14a and the pore water pressure of the second filter layer 14b are equivalent despite pumping from the aquifer 10a, the first filter It indicates that groundwater is leaking from the first water shielding layer 15a formed immediately above the layer 14a, and it is determined that the water shielding performance of the first water shielding layer 15a is inferior. On the other hand, if the pore water pressure of the first filter layer 14a is different from the pore water pressure of the second filter layer 14b, it is confirmed that the first water shielding layer 15a is appropriately impermeable (water blocking). It is determined that the water shielding performance of the first water shielding layer 15a is excellent.

  After carrying out pumping from the aquifer 10a, the pore water pressure of the first filter layer 14a and the pore water pressure of the second filter layer 14b were compared. As a result, they showed completely different values. It was confirmed that the water shielding performance of the first water shielding layer 15a was excellent.

  Further, in order to investigate the water shielding performance of the second water shielding layer 15b, the second boring hole for the pumping test is drilled to the depth of the aquifer 10b corresponding to the second filter layer 14b. Then, water was pumped from the aquifer 10b, and the water shielding performance of the second water shielding layer 15b was confirmed. As a result, the pore water pressure of the second filter layer 14b and the pore water pressure of the third filter layer 14c are completely different from each other. It was confirmed that the water performance was excellent.

  When the water shielding performance of the water shielding layer 15 is confirmed for a predetermined number (for example, 10) of boreholes 8 for measuring the pore water pressure, groundwater is collected for the water shielding layers 15 of all the boreholes 8. Leakage could not be confirmed, and the water shielding performance of the water shielding layers 15 of all the boring holes 8 was excellent.

  On the other hand, in Comparative Example 1, when the operator quietly puts the water shielding material 3 from the center of the opening 8a of the boring hole 8 by a predetermined filling amount, it was as follows. That is, when the operator manually inputs the water shielding material 3 into the boring hole 8, the operator must carefully input the water shielding material 3 so as not to clog in the middle of the boring hole 8. Therefore, it took several minutes to several tens of minutes for the input. Further, the time required for the introduced water shielding material 3 to become the water shielding layer 15 is mainly combined with the water shielding material 3 that has been introduced last and the water shielding material 15 that has been introduced last. Therefore, the time required for forming one water shielding layer 15 is about several tens of minutes in total.

  Here, in Comparative Example 1, the introduced water shielding material 3 may adhere to a hole wall in the middle of the boring hole 8. In addition, since the operator inputs the water shielding material 3 from the center of the opening 8a of the boring hole 8, the water shielding material 3 is uniformly in the region 111 corresponding to the impermeable layer 11 in the boring hole 8. May not be filled.

  Next, in Comparative Example 1, when the water shielding performance of the formed water shielding layer 15 was confirmed for a predetermined number (for example, 10) of boreholes 8 for pore water pressure measurement as described above, the water shielding performance was confirmed. Due to insufficient or uneven filling of the water material 15, leakage of groundwater was confirmed in several water shielding layers 15, and the water shielding performance of 30 to 50% of the water shielding layers as a whole was inferior.

  As another comparative example, in Comparative Example 2, when the operator employed a commercially available grout pump for introducing the water shielding material 3, the following was obtained. That is, an operator must first install a pipe attached to the grout pump for leading out the water shielding material 3 in a region 111 corresponding to the impermeable layer 11 in the boring hole 8. Therefore, it took about several minutes for the installation. In addition, when a predetermined amount of the water-impervious material 3 is charged from the pipe, in order to uniformly (evenly) fill the region 111 with the water-impermeable material 3, Speed) could not be accelerated so much, and it took several minutes. Therefore, the time required for forming one water shielding layer 15 is about several tens of minutes in total.

  Here, in Comparative Example 2, in order to uniformly fill the region 111 with the water shielding material 3, it is necessary for an operator to appropriately swing the grout pump pipe in the boring hole 8. Depending on the case, there is a possibility that the water shielding material 3 is not uniformly filled in the region 111. Further, when the water in the borehole 8 penetrates into the pipe, the water-impervious material 3 being injected may expand due to the water and may be clogged with the pipe.

  Next, in Comparative Example 2, in the same manner as described above, the water shielding performance of the formed water shielding layer 15 was confirmed for a predetermined number (for example, 10) of boreholes 8 for pore water pressure measurement. Similar to 1, the water shielding performance of 30 to 50% of the water shielding layer as a whole was inferior.

  Therefore, although the water shielding tool 1 according to the present invention has a simple configuration as compared with the prior art, the time required for forming the water shielding layer 15 can be reduced by several minutes. It is understood. Moreover, in the water shielding tool 1 which concerns on this invention, it is understood that the water shielding performance of all the formed water shielding layers 15 is excellent, and it can be surely water-shielded.

  As described above, in the water shield 1 according to the present invention, when the axial direction is matched to the vertical direction of the boring hole 8 using the sheet 7 that is torn when a predetermined pressure is applied in a state where water has permeated, the boring hole 8 An elongated hollow cylinder 2 having a size that fits in a region 111 corresponding to the inner impermeable layer 11 is formed, and the inside of the cylinder 2 is filled with a predetermined amount of a water shielding material 3 that expands when water is absorbed, Both ends 2a and 2b of the cylinder are sealed.

  Thereby, when the predetermined water shielding layer 15 is formed in the region 111 corresponding to the impermeable layer 11 in the boring hole 8, the axial direction of the water shielding tool 1 is matched with the vertical direction of the boring 8. If the water shield 1 is put (dropped) into the boring hole 8, the internal water shielding material 3 is sufficiently filled in the desired region 111 without being dispersed in the boring hole 8. It becomes possible. Further, when the inner water-impervious material 3 absorbs water and expands, the outer sheet 7 is automatically broken to form a water-impervious layer 15. Here, since the shape of the water shielding tool 1 itself is an elongated shape having a size that can be accommodated in the region 111, the water shielding layer 15 is formed so as to uniformly fit (match) the region 111. Therefore, the formed water shielding layer 15 can surely shield (stop water) the groundwater from the aquifer 10 positioned above and below the impermeable layer 11.

  In the present invention, newspaper is used as the sheet 7 constituting the water shielding device 1, but the same applies to other sheets such as Japanese paper, calligraphy paper, half paper, shoji paper, and half paper. The same applies to a sheet that is torn when a predetermined pressure is applied in a state where water has permeated, for example, a sheet made of natural fibers or a sheet made of semi-synthetic fibers.

  Further, in the embodiment of the present invention, the length 2c in the axial direction of the water shield 1 is made equal to the vertical length of the impermeable layer 11 (100 cm), and the width in the width direction of the water shield 1 is set. Although 2d was set to about one half (60 mm) with respect to the diameter of the boring hole 8, for example, without changing the length 2 d in the width direction of the water shield 1, The same is true if the axial length 2c is set to 20 cm or 150 cm. The same applies even if the length 2c in the axial direction of the water shield 1 is 100 cm and the length 2d in the width direction of the water shield 1 is 25 mm or 100 mm.

  In the embodiment of the present invention, one pore water pressure gauge 12 is installed in one filter layer 14, but other configurations may be used. That is, in place of the pore water pressure gauge 12, a pore water pressure meter 12 communicating with a predetermined water inlet is divided and incorporated at a predetermined interval, and a measurement cable of the pore water pressure gauge 12 is led to the ground side. A simple water pressure measuring tube may be used. With this configuration, it is possible to reduce the time required to install the pore water pressure gauge 12 for each filter layer 14.

  Further, in the embodiment of the present invention, it is configured such that the worker puts the water shield 1 into the boring hole 8, but for example, the water shield 1 is automatically thrown into the boring hole 8. You may comprise an apparatus. That is, in the present invention, as shown in FIG. 7 (I), the pore water pressure of each aquifer 10 is measured in the ground of a multilayer aquifer in which aquifers 10 and impermeable layers 11 are alternately laminated. The pore water pressure measuring device 17 may be configured. The pore water pressure measuring device 17 uses the sheet 7 that breaks when a predetermined pressure is applied in a state where water has permeated, and aligns the axial direction with the vertical direction of the boring hole 8, and the impermeable layer 11 in the boring hole 8. A long and narrow hollow cylinder 2 having a size that can be accommodated in a region 111 corresponding to is formed, and a predetermined amount of a water shielding material 3 that expands when water is absorbed is filled in the cylinder 2, and both ends 2 a of the cylinder are further filled. An arrangement means for forming a water shielding layer 15 in the region 111 by arranging a predetermined number of the water shielding device 1 sealing 2b and the water shielding device 1 in the region 111 corresponding to the impermeable layer 11. It is characterized by providing. Even with this configuration, the same effects as described above can be obtained.

  Note that when the predetermined number of the water shields 1 are arranged in the region 111, the arrangement means is configured so that, for example, the predetermined number of the water shields 1 are filled in the entire inner diameter of the boring hole 8. The tool 1 is arranged in the width direction (radial direction) of the boring hole 8 and then inserted into the boring hole 8. Thereby, the formed water shielding layer 15 is formed so as to be in close contact with the region 111 corresponding to the impermeable layer 11 of the boring hole 8. The pore water pressure measuring device 17 and the arrangement means are prepared by a known technique.

  In the embodiment of the present invention, for example, there is a pore water pressure measuring method for measuring the pore water pressure of each aquifer 10 in the ground of a multilayer aquifer where the aquifer 10 and the impermeable layer 11 are alternately laminated. You may comprise. The pore water pressure measuring method uses a sheet 7 that breaks when a predetermined pressure is applied in a state where water has permeated, and aligns the axial direction with the vertical direction of the boring hole 8 to form an impermeable layer 11 in the boring hole 8. A long and narrow hollow cylinder 2 having a size that can be accommodated in a corresponding region 111 is formed, and a predetermined amount of a water shielding material 3 that expands when water is absorbed is filled in the cylinder 2, and both ends 2a of the cylinder are further filled. A step (arrangement step) of forming a water shielding layer 15 in the region 111 by disposing a predetermined number of the water shielding device 1 sealing 2b in the region 111 corresponding to the impermeable layer 11 is provided. And Even with this configuration, the same effects as described above can be obtained.

  As described above, the water shielding device according to the present invention and the interval water pressure measuring device using the same are technical fields in which a water shielding layer needs to be formed in the borehole, for example, civil engineering technical field, surveying technical field, measurement. Although it is useful in technical fields and has a simple structure, it reduces the time required to form a water-impervious layer in the borehole and ensures the groundwater from the aquifer by forming the water-impervious layer. It is effective as a water shielding device capable of water shielding (water stopping), and an interval water pressure measuring device using the same.

DESCRIPTION OF SYMBOLS 1 Water shielding tool 2 Cylinder 3 Water shielding material 4 Construction tape 5 Box 6 Cylindrical pipe 7 Newspaper 8 Boring hole 9 Casing pipe 10 Aquifer 11 Impermeable layer 12 Pore pressure gauge 13 Filter material 14 Filter layer 15 Impermeable layer 16 Computer 17 Pore water pressure measuring device

Claims (3)

Corresponding to the impermeable layer in the borehole drilled in the ground when measuring the pore water pressure of each aquifer in the ground of the multilayer aquifer where the aquifer and the impermeable layer are alternately laminated A water shielding device for forming a water shielding layer in the area to be
Using a sheet that breaks when a predetermined pressure is applied in a state where water has permeated, and aligning the axial direction with the vertical direction of the borehole, an elongated hollow body having a size that fits in a region corresponding to the impermeable layer in the borehole. A water-impervious device, wherein a tube is formed, a predetermined amount of a water-blocking material that expands when water is absorbed is filled in the tube, and both ends of the tube are sealed. The water shielding device according to claim 1, wherein the sheet is any one of newspaper, Japanese paper, calligraphy paper, half paper, shoji paper, straw half paper, paper made of natural fiber, and paper made of semi-synthetic fiber. A pore water pressure measuring device for measuring the pore water pressure of each aquifer in the ground of a multilayer aquifer where alternating aquifers and impermeable layers are laminated,
Using a sheet that breaks when a predetermined pressure is applied in a state where water has permeated, and aligning the axial direction with the vertical direction of the borehole, an elongated hollow body having a size that fits in a region corresponding to the impermeable layer in the borehole. Forming a cylinder, filling the cylinder with a predetermined amount of a water shielding material that expands when water is absorbed, and further, a water shielding tool that seals both ends of the cylinder,
A pore water pressure measuring device comprising: a disposing means for forming a water shielding layer in the region by arranging a predetermined number of the water shielding tools in the region corresponding to the impermeable layer.