JP2007108073A - Ground stress measuring device and ground stress measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground stress measuring device and a ground stress measuring method capable of protecting a load cell or the like from getting wet with water and detecting each strain (stress) of a structure. <P>SOLUTION: A tunnel model ground stress measuring device 101 comprises a load cell 10 having a base section 11 attached with a perpendicular strain gauge 15 and a shearing strain gauge 16 and an inside pressure plate 13, a rubber film 61 arranged outside the inside pressure plate 13, an outside pressure plate 20 that is arranged outside the rubber film 61 at an arrangement place of the inside pressure plate 13 and is fixed to the inside pressure plate 13 with a joint screw 50, and a sealing material or sealing agent that is arranged in a clearance or the like around the joint screw 50 and prevents water or the like of external model ground 301 from intruding into a space V1 in the rubber film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus and method for measuring ground stress, which is the stress acting on the outer surface of a structure, and more particularly to ground stress without trouble even when water is present around the outer surface of the structure. The present invention relates to an apparatus and a method that can measure the above.

  Conventionally, a tunnel model test using an apparatus as shown in FIG. 3 is known (for example, see Patent Document 1). In this tunnel model test, a soil container 202 is placed on the vibration table device 201, and a soil model 202 is formed by filling the soil container 202 with soil or sand, and a tunnel model is formed inside the model ground 301. 401 is embedded to simulate a tunnel in the ground, a load cell 501 is attached to the surface of the tunnel model 401, and an electrical output from the load cell 501 is taken out by a lead wire (not shown) or the like. By detecting the electrical output from the tunnel, the stress acting on the outer surface of the tunnel model 401 (hereinafter referred to as “model ground stress”) is detected, and the “similarity” between the model and the actual ground and structure is detected. It is intended to analyze the nature of the ground stress in the actual ground while considering the “law”. Although not shown in the figure, the vibration table device 201 includes a drive source and a vibration generator that generates vibration by the power of the drive source.

  As the above-described load cell 501, various structures are known. FIG. 4 shows an example of the configuration of a load cell that can be used in the conventional tunnel model test described above. The load cell 30 shown in FIG. 4 includes a stress σ (hereinafter referred to as “normal stress”) in a direction perpendicular to the surface S1 of the tunnel model and a stress τ (hereinafter referred to as “shear stress” in a direction parallel to the surface S1 of the tunnel model. It is a type of load cell that can detect both of them simultaneously. FIG. 4A shows a front view of the load cell 30, and FIG. 4B shows a top view of the load cell 30.

  As shown in FIG. 4A, the load cell 30 has two leg portions 31 and the bottom surfaces of the two leg portions 31 are attached to the tunnel model surface S1 with an adhesive (not shown) or the like. Yes. The two legs 31, 31 support a substantially beam-shaped body part 32, and a substantially “inverted U-shaped” support structure is formed by the two legs 31, 31 and the body part 32. ing. A substantially columnar neck 34 stands upright from a substantially central portion of the support structure, and the upper end of the neck 34 supports the vicinity of the substantially central portion of a substantially strip-shaped pressure receiving plate 33.

  Two openings 32a and 32a penetrating the side portion of the body portion 32 are formed on both sides of the attachment portion of the neck portion 34 (substantially central portion of the body portion 32) on the side portion of the body portion 32 described above. . In each of the openings 32a and 32a, a strain gauge 35 is attached to the upper surface of the body part 32 directly above the opening 32a with an adhesive (not shown) or the like (see FIG. 4A). ).

Also,
On the upper surface of the pressure receiving plate 33, two openings 33a and 33a penetrating the upper and lower surfaces of the pressure receiving plate 33 are formed on both sides of the attachment position of the neck portion 34 (substantially central portion of the body portion 32) ( (See FIG. 4A). In each of the openings 33a and 33a, a strain gauge 36 is attached to the side surface of the pressure receiving plate 33 on the side of the opening 33a with an adhesive (not shown) or the like (FIG. 4B). reference).

  FIG. 5 is a diagram showing a detailed configuration of a strain gauge (for example, 35 or 36 in FIG. 4) in the load cell. As shown in FIG. 5, the strain gauge 35 includes a gauge base 41, a resistance portion 42, and lead wires 43 and 44. The gauge base 41 is made of an electrically insulating material such as paper or polyester resin, and is formed in a thin film shape. The resistance portion 42 is made of metal, semiconductor, or the like, and is formed in a linear shape or a foil shape. The length LG of the resistance portion 42 is called a gauge length. The strain gauge 35 is used by being attached to the surface of an object to be measured with an adhesive or the like.

When an external force is applied to the object to be measured, a stress is generated on the surface of the object to be measured at which the strain gauge 35 is attached, and accordingly, an elongation or shrinkage amount ΔL is generated in the gauge length LG of the resistance portion 42. The ratio of ΔL to LG (ΔL / LG) is called “strain” and is equal to “surface strain” generated on the surface of the object to be measured. Resistance of metal or the like changes in proportion to strain. When the resistance value of the strain gauge 35 is R, the strain is ε (= ΔL / LG), and the change in the resistance value of the strain gauge 35 due to the strain ε is ΔR, the relationship of the following equation (1) is established.

ΔR / R = K × ε (1)

Here, K is a proportionality constant and is called a gauge factor.

  The lead wires 43 and 44 are formed of a conductor such as metal and are used for connection to an external electric circuit or the like, and output the above-described resistance change of the gauge as a change in voltage or the like.

  Note that the strain gauges 35 and 36 are rarely used alone as shown in FIG. 5, and four strain gauges are connected so as to have a substantially rhombus shape, so-called “Wheatstone bridge circuit ( The “strain” accompanying the external force acting on the gauge can be measured by the electrical output from the “Wheatstone bridge circuit (not shown)”.

  However, the conventional tunnel model test described above has various problems as described below.

  In the case where water is contained in the ground, when a large external force such as an earthquake acts on the ground, the ground containing water exhibits a property as if it became liquid (hereinafter referred to as “liquefaction”). . In some cases, the tunnel model test apparatus shown in FIG. 3 is used to observe the behavior of the tunnel model 401 in the model ground 301 where liquefaction occurs and to perform data measurement. However, in the case of such liquefaction, the load cell 501 and the strain gauge attached to the tunnel model 401 are in direct contact with the liquefied soil. The strain gauge is a device that obtains a value corresponding to “strain” by taking out an electrical output (for example, a voltage value), and has a problem that a short circuit occurs when it comes into contact with liquid water, which is not preferable. Further, when the load cell 30 shown in FIG. 4 is used as the load cell 501 in FIG. 3, when the liquefied soil enters the space between the lower surface of the pressure receiving plate 33 and the upper surface of the body portion 32, Water applies a force toward the outside (for example, upward in FIG. 4) on the lower surface of the pressure receiving plate 33. In such a state, the infiltrated soil is caused by the stress acting on the outer surface of the tunnel model 401 (for example, the vertical stress σ acting downward from the upper surface of the pressure receiving plate 33 in FIG. 4), which is a value to be originally measured. The problem that the stress acting on the outer surface of the tunnel model 401 cannot be measured because the stress acting on the outer surface of the tunnel model 401 is subtracted from the lower surface of the pressure receiving plate 33 (for example, upward in FIG. 4). There was also.

In order to solve this, a countermeasure has been taken in which the entire tunnel model 401 to which the load cell 501 is attached is covered with a rubber film or the like. However, when the entire tunnel model 401 is covered with a rubber film or the like, there is a problem that the shear stress acting in parallel with the surface of the tunnel model 401 cannot be measured.
Japanese Patent Laid-Open No. 08-029297

  The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to protect each load cell and the like from getting wet, while detecting each strain (stress) of the structure. An object of the present invention is to provide a possible ground stress measuring device and a ground stress measuring method.

In order to solve the above-described problem, a ground stress measurement device according to claim 1 of the present invention includes:
A device for measuring ground stress, which is the stress that the ground acts on the outer surface of the structure,
A first force receiving member supported in parallel with the outer surface of the structure;
A first stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the first stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A normal stress measuring means for measuring a normal stress perpendicular to the outer surface of the structure,
A second stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the second stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A shear stress measuring means for measuring a shear stress parallel to the outer surface of the structure,
A rubber film covering the first force receiving member, the normal stress measuring means, and the shear stress measuring means, and having all edges bonded to the outer surface of the structure;
A second force receiving member disposed outside the rubber film so as to be parallel to the outer surface of the structure;
Force receiving member coupling means for coupling the second force receiving member to the first force receiving member via the rubber film;
A waterproof means for sealing the periphery of the force receiving member coupling means against water;
After the ground stress is received by the second force receiving member, the force receiving member coupling means transmits the ground stress to the first force receiving member, and the vertical stress measuring means measures the vertical stress and the shear stress measuring means. The shear stress is measured, and water is prevented from entering the rubber film from the outside of the second force receiving member through the periphery of the force receiving member coupling means.

In addition, the ground stress measurement method according to claim 2 of the present invention,
A method of measuring ground stress, which is the stress that the ground acts on the outer surface of the structure,
A first force receiving member supported in parallel with the outer surface of the structure;
A first stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the first stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A normal stress measuring means for measuring a normal stress perpendicular to the outer surface of the structure,
A second stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the second stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A shear stress measuring means for measuring a shear stress parallel to the outer surface of the structure,
A rubber film covering the first force receiving member, the normal stress measuring means, and the shear stress measuring means, and having all edges bonded to the outer surface of the structure;
A second force receiving member disposed outside the rubber film so as to be parallel to the outer surface of the structure;
Force receiving member coupling means for coupling the second force receiving member to the first force receiving member via the rubber film;
Using waterproof means for sealing the periphery of the force receiving member coupling means against water,
After the ground stress is received by the second force receiving member, the force receiving member coupling means transmits the ground stress to the first force receiving member, and the vertical stress measuring means measures the vertical stress and the shear stress measuring means. The shear stress is measured, and water is prevented from entering the rubber film from the outside of the second force receiving member through the periphery of the force receiving member coupling means.

  According to the ground stress measurement device and the ground stress measurement method according to the present invention, the vertical stress measurement means to which the first stress detector is attached, the shear stress measurement means to which the second stress detector is attached, and the first receiver. A force member, a rubber film disposed outside the first force receiving member, and an outer surface of the first force receiving member by the force receiving member coupling means and disposed outside the rubber film at a location where the first force receiving member is disposed. Since the second force receiving member fixed to the force receiving member and the waterproofing means disposed in the gap around the force receiving member coupling means and the like to prevent the outside water from entering the inside are provided. After receiving the ground stress acting on the structure from the second force receiving member, it is transmitted to the first force receiving member by the force receiving member coupling means, and the vertical stress is measured by the vertical stress measuring means, and the shear stress is measured. Measure shear stress by means The waterproof means can prevent water from entering from the ground outside the second force receiving member through the periphery of the force receiving member coupling means to the inside of the rubber film. is doing.

  In the first or second embodiment described below, the load cell 10 having a base 11 and an inner pressure plate 13 to which a vertical strain gauge 15 and a shear strain gauge 16 are attached, and the inner pressure plate 13 are arranged outside. A rubber film 61 or 62, an outer pressure receiving plate 20 that is disposed outside the rubber film 61 at a position where the inner pressure receiving plate 13 is disposed, and is fixed to the inner pressure receiving plate 13 by a coupling screw 50; The tunnel model ground stress measuring apparatus 101 is configured to include a sealing material or a sealing agent that is disposed in a gap or the like and prevents water or the like of the external model ground 301 from entering the rubber film space V1 or V2. After the model ground stress acting on the tunnel model 401 from the model ground 301 is received by the outer pressure receiving plate 20, The vertical stress and shear stress can be measured by the base 11 of the load cell 10 and transmitted to the side pressure plate 13, and from the model ground 301 outside the outer pressure plate 20 through the periphery of the coupling screw 50, It is possible to prevent water from entering the internal space V1 with a sealing material or a sealing agent, which is the best mode for realizing the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a tunnel model ground stress measuring apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, the tunnel model ground stress measuring device 101 includes a load cell 10, a rubber film 61, an outer pressure plate 20, a coupling screw 50, and a sealing material or a sealing agent described later. Yes.

  The load cell 10 has a base 11 made of a metal material (for example, an aluminum alloy, a steel, etc.) having a lower end 11a attached to the surface S1 of the tunnel model 401, which is a structure, with an adhesive (not shown), and a base 11 The inner pressure receiving plate 13 is a plate-like member made of a metal material (for example, an aluminum alloy, a steel material, etc.) and is attached to and supported by the upper end 11b, and has a substantially “T-shaped” cross-sectional structure as a whole. Make up body. Here, the inner pressure plate 13 is supported so as to be substantially parallel to the tunnel model surface S1, which is the surface of the structure. The inner pressure plate 13 corresponds to the first force receiving member in the claims. The inner pressure receiving plate 13 is formed with a through hole 13a communicating the upper surface and the lower surface thereof, and a female screw is formed on the inner wall of the through hole 13a. Hereinafter, the through hole 13a is referred to as “female screw hole”. The female screw on the inner wall of the female screw hole 13a is screwed with a male screw formed on the outer peripheral cylindrical surface of a shaft portion 50b of the coupling screw 50 described later.

  A vertical strain gauge 15 and a shear strain gauge 16 are attached to the surface of the base 11 of the load cell 10. The vertical strain gauge 15 detects a strain in a direction perpendicular to the surface of the inner force receiving plate 13, thereby causing a stress σ (hereinafter referred to as “vertical stress”) in a direction perpendicular to the tunnel model surface S 1 to be electric. It can be converted into a quantity (for example, a voltage value) and output, and corresponds to the first stress detector in the claims. Further, the shear strain gauge 16 detects a strain in a direction parallel to the surface of the inner force receiving plate 13, thereby generating a stress τ (hereinafter referred to as “shear stress”) in a direction parallel to the tunnel model surface S 1. It can be converted into a quantity (for example, a voltage value) and output, and corresponds to the second stress detector in the claims.

  The rubber film 61 has a portion that is attached to the surface of the tunnel model 401 that is a structure by an adhesive 71 and covers the tunnel model 401 that is a structure. Further, at the place where the load cell 10 is installed, the rubber film 61 has a rubber film hole 61a. The rubber film hole 61 a is a hole having a substantially circular cross section having an inner diameter smaller than the outer diameter of a shaft portion 50 b of the coupling screw 50 described later, and is a through hole that communicates the outside and the inside of the rubber film 61.

  The rubber film 61 is disposed so as to cover the upper surface of the inner pressure receiving plate 13 at the installation location of the load cell 10. In this case, the upper surface opening position of the female screw hole 13 a of the inner pressure receiving plate 13 and the position of the rubber film hole 61 a of the rubber film 61 are arranged to coincide with each other.

  The outer pressure receiving plate 20 is disposed outside the rubber film 61 at this location. The outer pressure plate 20 is a plate-like member made of a metal material (for example, an aluminum alloy, a steel material, etc.), has a lower surface that is substantially the same as the upper surface of the inner pressure plate 13, and has a female screw hole 13 a in the inner pressure plate 13. A female screw hole 20a having a female screw thread and a female screw valley having the same inner diameter as that of the female screw hole 13a is formed at a position equal to the opening position. In addition, a screw head housing recess 20b, which is a recess (or a hole from the outside) that is larger in diameter than the female screw hole 20a and has no female screw formed, is formed at the external opening position of the female screw hole 20a.

  With such a configuration, as shown in FIG. 1, if the outer pressure plate 20 is brought into contact with the portion where the outer side of the inner pressure plate 13 is covered with the rubber film 61 and the shaft portion 50 b of the coupling screw 50 is screwed, The shaft portion 50b is screwed into the female screw hole 20a, and the lower end of the shaft portion 50b enters the space V1 inside the rubber film 61 from the rubber film hole 61a due to the lowering of the coupling screw 50. And the female screw hole 13a. Thus, the outer pressure plate 20 is fixed to the inner pressure plate 13 by the coupling screw 50 with the rubber film 61 interposed therebetween. For this reason, the external force acting on the outer pressure plate 20 is transmitted to the base 11 of the load cell 10 via the coupling screw 50 and the inner pressure plate 13. The rubber film 61 covers the entire outer surface of the tunnel model 401, and covers the entire inner pressure plate 13 and the base portion 11 at the load cell 10.

  Here, the base 11 of the load cell 10 has a lower end 11a which is a part thereof fixed to the tunnel model surface S1 which is an outer surface of the structure, and an upper end 11b which is another part is a first force receiving member. The surface of the tunnel model which is fixed to the lower surface of the inner pressure receiving plate 13 and is fixed to the outer pressure receiving plate 20 by the coupling screw 50 with the rubber film 61 interposed therebetween. It is configured to measure a normal stress that is a stress perpendicular to S1, and constitutes a normal stress measuring means in the claims.

  Further, the base 11 of the load cell 10 has a lower end 11a which is a part thereof fixed to a tunnel model surface S1 which is an outer surface of the structure, and an upper end 11b which is another part is an inner side which is a first force receiving member. Since it is fixed to the outer pressure plate 20 with the coupling screw 50 in a state of being fixed to the lower surface of the pressure plate 13 and sandwiching the rubber film 61, the tunnel model surface S1 that is the outer surface of the structure out of the ground stress. It is the structure which measures the shear stress which is a stress parallel to this, and comprises the shear stress measurement means in a claim.

  Further, the outer pressure plate 20 is disposed outside the rubber film 61 at the place where the load cell 10 is installed, and is disposed so as to be parallel to the tunnel model outer surface S1, which is the outer surface of the structure. Corresponds to the second force receiving member.

  The coupling screw 50 couples the outer pressure receiving plate 20 as the second force receiving member to the inner pressure receiving plate 13 as the first force receiving member via the rubber film 61. It corresponds to a force member coupling means.

  Further, around the coupling screw 50 as the force receiving member coupling means, for example, around the coupling screw 50 in the vicinity of the rubber film hole 61a, or between the screw head accommodating recess 20b and the coupling screw head 50a in the outer pressure receiving plate 20. In the gap portion 20b1 (hereinafter, referred to as “waterproof seal portion”) or the like, a sealing material (for example, water) included in the external model ground 301 can be prevented from entering the rubber film inner space V1. , O-ring, etc.) and a sealing agent (for example, grease) are disposed. These sealing materials or sealing agents are means for sealing against water and correspond to waterproof means in the claims.

  With the configuration as described above, in this tunnel model ground stress measuring apparatus 101, after receiving the model ground stress acting on the tunnel model 401 from the model ground 301 by the outer pressure receiving plate 20 which is the second force receiving member, the tunnel model ground stress measuring apparatus 101 receives the model ground stress. The force is transmitted to the inner pressure receiving plate 13 as the first force receiving member by the connecting screw 50 as the force member connecting means, and the vertical stress is measured by the base portion 11 of the load cell 10 as the vertical stress measuring means, and the shear stress measuring means is used. The shear stress can be measured by the base 11 of a certain load cell 10. At this time, water enters the space V1 inside the rubber film 61 from the model ground 301 outside the outer pressure receiving plate 20 that is the second force receiving member, through the periphery of the connecting screw 50 that is the force receiving member connecting means. This is prevented by a sealing material or a sealing agent which is a waterproof means. Here, the model ground stress corresponds to the ground stress in the claims.

  The present invention can also be realized by configurations other than the first embodiment described above. FIG. 2 is a diagram showing a configuration of a tunnel model ground stress measuring apparatus according to the second embodiment of the present invention.

  As shown in FIG. 2, the tunnel model ground stress measuring device 102 of the second embodiment is the same as in the case of the load cell 10, the rubber film 62, the outer pressure plate 20, the coupling screw 50, and the first embodiment 101. 2. A sealing material or sealing agent (around the coupling screw 50 in FIG. 2, for example, around the coupling screw 50 in the vicinity of the rubber film hole 62a, or between the screw head receiving recess 20b and the coupling screw head 50a in the outer pressure plate 20). Material provided in a waterproof seal portion 20b1 or the like that is a gap portion between them. In the tunnel model ground stress measuring device 102 of the second embodiment, the rubber film 62 does not cover the entire tunnel model 401, and covers only the vicinity of the installation location of the load cell 10. Is different from the tunnel model ground stress measuring apparatus 101 of the first embodiment in that the edge of the tunnel model is bonded to the tunnel model surface S1 (the outer surface of the structure in the claims) by an adhesive 72. The configuration and operation of the other components are the same as those of the tunnel model ground stress measuring apparatus 101 of the first embodiment.

  With the configuration as described above, also in this tunnel model ground stress measuring apparatus 102, after receiving the model ground stress acting on the tunnel model 401 from the model ground 301 by the outer pressure receiving plate 20 which is the second force receiving member, The force is transmitted to the inner pressure receiving plate 13 as the first force receiving member by the coupling screw 50 as the force receiving member coupling means, and the vertical stress is measured by the base 11 of the load cell 10 as the vertical stress measuring means, and the shear stress measuring means. The shear stress can be measured by the base 11 of the load cell 10. At this time, water enters the space V2 inside the rubber film 61 from the model ground 301 outside the outer pressure receiving plate 20 that is the second force receiving member, through the periphery of the connecting screw 50 that is the force receiving member connecting means. This is prevented by a sealing material or a sealing agent which is a waterproof means.

  In addition, this invention is not limited to each above-mentioned Example. Each of the above-described embodiments is an exemplification, and any device that has substantially the same configuration as the technical idea described in the claims of the present invention and has the same operational effects can be used. It is included in the technical scope of the present invention.

  For example, in each of the above embodiments, a tunnel model ground stress measuring device that can be used for a tunnel model test has been described, but the present invention is applicable not only to a tunnel model ground stress measuring device but also to an actual ground stress measuring device. Is possible.

  The present invention is a measurement service industry that measures ground stress, a measuring instrument manufacturing industry that manufactures measuring instruments that measure ground stress, and a civil engineering / building industry that performs construction and maintenance of ground structures such as tunnels. It can be implemented and used in these industries.

It is a figure which shows the structure of the tunnel model ground stress measuring apparatus which is 1st Example of this invention. It is a figure which shows the structure of the tunnel surrounding ground stress measuring apparatus which is 2nd Example of this invention. It is a figure explaining the conventional tunnel model test. It is a figure which shows the structure of an example of the load cell used for the conventional tunnel model test. It is a figure which shows the detailed structure of the strain gauge in a load cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Load cell 11 Base 11a Lower end 11b Upper end 13 Inner pressure receiving plate 13a Female screw hole 15 Vertical strain gauge 16 Shear strain gauge 20 Outer pressure receiving plate 20a Female screw hole 20b Screw head accommodation recessed part 20b1 Waterproof seal location 30 Load cell 31 Leg part 32 Body part 32a Opening 33 Pressure receiving plate 33a Opening 34 Neck 35, 36 Strain gauge 41 Gauge base 42 Resistor 43, 44 Lead wire 50 Coupling screw 50a Head 50b Shaft 61 Rubber film 61a Rubber film hole 62 Rubber film 62a Rubber film hole 71 , 72 Adhesives 101, 102 Tunnel model ground stress measurement device 201 Shaking table device 202 Earth container 301 Model ground 401 Tunnel model 501 Load cell LG Gauge length S1 Tunnel model surface V1, V2 Rubber film space σ Vertical stress τ Shear stress

Claims (2)

A device for measuring ground stress, which is the stress that the ground acts on the outer surface of the structure,
A first force receiving member supported in parallel with the outer surface of the structure;
A first stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the first stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A normal stress measuring means for measuring a normal stress perpendicular to the outer surface of the structure,
A second stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the second stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A shear stress measuring means for measuring a shear stress parallel to the outer surface of the structure,
A rubber film covering the first force receiving member, the normal stress measuring means, and the shear stress measuring means, and having all edges bonded to the outer surface of the structure;
A second force receiving member disposed outside the rubber film so as to be parallel to the outer surface of the structure;
Force receiving member coupling means for coupling the second force receiving member to the first force receiving member via the rubber film;
A waterproof means for sealing the periphery of the force receiving member coupling means against water;
After the ground stress is received by the second force receiving member, the force receiving member coupling means transmits the ground stress to the first force receiving member, and the vertical stress measuring means measures the vertical stress and the shear stress measuring means. A ground stress measuring device that measures the shear stress and prevents water from entering the rubber film from the outside of the second force receiving member through the periphery of the force receiving member coupling means. . A method of measuring ground stress, which is the stress that the ground acts on the outer surface of the structure,
A first force receiving member supported in parallel with the outer surface of the structure;
A first stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the first stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A normal stress measuring means for measuring a normal stress perpendicular to the outer surface of the structure,
A second stress detector that converts an acting stress into an electrical quantity and outputs the same; a part of the second stress detector is fixed to the outer surface of the structure; the other part is fixed to the first force receiving member; A shear stress measuring means for measuring a shear stress parallel to the outer surface of the structure,
A rubber film covering the first force receiving member, the normal stress measuring means, and the shear stress measuring means, and having all edges bonded to the outer surface of the structure;
A second force receiving member disposed outside the rubber film so as to be parallel to the outer surface of the structure;
Force receiving member coupling means for coupling the second force receiving member to the first force receiving member via the rubber film;
Using waterproof means for sealing the periphery of the force receiving member coupling means against water,
After the ground stress is received by the second force receiving member, the force receiving member coupling means transmits the ground stress to the first force receiving member, and the vertical stress measuring means measures the vertical stress and the shear stress measuring means. The ground stress measurement method characterized by measuring the shear stress and preventing water from entering the rubber film from the outside of the second force receiving member through the periphery of the force receiving member coupling means. .

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