JP7375156B2 - Measuring system, measuring method and interval determination method - Google Patents

Description

The present invention relates to a measurement system, a measurement method, and an interval determination method.

Conventional measurement management for root cutting and mountain retaining work involves simple measurement of the displacement of the head of the mountain retaining wall using piano wire, and measurement of the depth distribution of horizontal displacement using an inclinometer. However, conventional methods can only obtain point/linear and local measurement data, making it difficult to understand the overall behavior of retaining walls at a glance.

From the above-mentioned background, a three-dimensional measurement system for retaining walls has been proposed as a measurement method that can perform surface evaluation for measurement management of retaining walls (Patent Document 1). This system is characterized by arranging a plurality of sensors (displacement meters or inclinometers) on the surface of the retaining wall and visualizing displacement data in three dimensions. By arranging a combination of an expensive high-sensitivity sensor and an inexpensive low-sensitivity sensor, it is possible to perform measurements at low cost.

Japanese Patent Application Publication No. 2011-94442 JP2019-52467A

FIG. 9 is a side view schematically showing a displacement pattern of the retaining wall. FIG. 9(a) shows a modified example after primary root cutting, and FIG. 9(b) shows a modified example after secondary root cutting. Further, FIG. 9(c) shows a modified example of rotation, and FIG. 9(d) shows a modified example of parallel movement. When the system described in Patent Document 1 is operated independently, the displacement data obtained is the relative displacement of the retaining wall because there is no fixed point, and even if the deformation and rotation of the retaining wall are captured, Behavior such as parallel movement cannot be captured. Furthermore, since the sensor has to be placed on the surface of the retaining wall, that is, after excavation, the measurement is performed on something that has already been displaced, so it is desirable to reconsider the measurement method.

Therefore, the inventor of the present application developed a method for measuring relative displacement in the horizontal (out-of-plane) direction of the wall surface by attaching a MEMS-type acceleration sensor (hereinafter referred to as "sensor") to the core material of the wall retaining wall in measurement management of root cutting and retaining work. (See Patent Document 2).
Here, it is desirable that the installation interval of the sensors can be determined so as to satisfy the accuracy required for peak-holding measurement.

The present invention has been made in view of the above circumstances, and provides a measurement system and measurement system that can monitor the overall behavior of the ground, including the area around the excavation area, with high precision during the entire period of root cutting and mountain retaining work. The present invention aims to provide a method and an interval determination method.

In order to solve the above problems, one aspect of the present invention provides that, in a retaining wall configured using a core material having a longitudinal direction in the excavation direction, which is a vertical direction, the core material is spaced at a predetermined first interval in the longitudinal direction. information representing the inclination angle of the core material measured using a first inclination angle detection unit configured from a plurality of inclination angle detection units attached to the longitudinal direction; The core material is measured using a second inclination angle detection unit configured from a plurality of the inclination angle detection sections attached to the core material at predetermined second intervals in the horizontal direction, which is a direction perpendicular to the core material. an inclination angle information acquisition unit that acquires information representing the inclination angle of from the second inclination angle detection unit ; an absolute position measurement unit that measures the absolute position of a predetermined measurement point of the head of the retaining wall in a non-contact manner; an absolute position information acquisition unit that acquires information representing the absolute position of a predetermined measurement point of the head of the retaining wall in the longitudinal direction from the absolute position measurement unit, the information acquired from the first inclination angle detection unit. information representing a first relative displacement based on the information representing the tilt angle; information representing a second relative displacement based on the information representing the tilt angle acquired from the second tilt angle detection unit ; and the absolute position information acquisition section. The measuring system is characterized by comprising: an output section that outputs information representing an absolute displacement based on the information representing the absolute position acquired by the measuring system.

Further, in one aspect of the present invention, in a retaining wall configured using a core material having a longitudinal direction in the excavation direction, which is a vertical direction , the inclination angle information acquisition unit is configured to Obtaining information representing the inclination angle of the core material measured using a first inclination angle detection unit constituted by a plurality of inclination angle detection sections attached to the core material from the first inclination angle detection unit; The angle of inclination is measured using a second inclination angle detection unit comprising a plurality of inclination angle detection units attached to the core material at predetermined second intervals in the horizontal direction, which is a direction perpendicular to the longitudinal direction. Information representing the inclination angle of the core material is acquired from the second inclination angle detection unit, the absolute position measuring section measures the absolute position of a predetermined measurement point on the head of the retaining wall in a non-contact manner, and the output section , information representing a first relative displacement based on information representing the tilt angle acquired from the first tilt angle detection unit, and second relative displacement based on information representing the tilt angle acquired from the second tilt angle detection unit. This measurement method is characterized by outputting information representing the absolute position and information representing the absolute displacement based on the information representing the absolute position acquired by the absolute position information acquisition unit .

Further, one aspect of the present invention provides that the predetermined first interval and the predetermined second interval in the measurement system described above are the minimum unit of displacement detected by the inclination angle detection unit, and the inclination angle detection unit This interval determination method is characterized in that the interval is determined according to the minimum unit that can be detected.

According to the present invention, the overall behavior of the ground including the area around the excavation area can be monitored with high accuracy during the entire period of root cutting and mountain retaining work.

FIG. 2 is a schematic diagram for explaining a configuration example of a measurement system according to a first reference example. FIG. 2 is a perspective view schematically showing an example of displacement of the retaining wall 2 shown in FIG. 1. FIG. FIG. 7 is a schematic diagram for explaining a configuration example of a measurement system according to a second reference example. 4 is a plan view schematically showing an example of displacement of the retaining wall 2 shown in FIG. 3. FIG. FIG. 7 is a schematic diagram for explaining a configuration example of a measurement system according to a third reference example. 6 is a schematic diagram showing a configuration example of the tape type inclinometer 40 shown in FIG. 5. FIG. 7 is a schematic diagram showing an example of attachment of the tape type inclinometer 40 shown in FIG. 6 to the core material 21. FIG. It is a schematic diagram which shows the calculation example of the displacement of a mountain retaining wall. It is a schematic diagram which shows the example of the displacement of a retaining wall. FIG. 1 is a schematic diagram for explaining a configuration example of a measurement system 100 according to a first embodiment of the present invention. FIG. 2 is a schematic diagram for explaining a configuration example of a three-axis MEMS acceleration sensor (inclination angle detection section 4) according to the first embodiment of the present invention. FIG. 12 is a diagram showing the relationship between the accuracy of the acceleration sensor shown in FIG. 11 and the installation interval in the depth direction (excavation direction). It is a figure which shows typically the example of the relative displacement of the retaining wall 2 in an excavation plane. FIG. 12 is a diagram showing the relationship between the accuracy of the acceleration sensor shown in FIG. 11 and the horizontal installation interval.

Hereinafter, reference examples and embodiments of the present invention will be described with reference to the drawings.

<First reference example>
FIG. 1 is a schematic diagram for explaining a configuration example of a measurement system 1 according to a first reference example. The measurement system 1 shown in FIG. 1 includes an absolute position information acquisition section 11, a tilt angle information acquisition section 12, and an output section 13. The absolute position information acquisition unit 11 is configured to acquire the absolute position information of a predetermined measurement point 3 of a head 2a of a retaining wall 2 (hereinafter also referred to as retaining wall head 2a), which is constructed using a core material 21 having a longitudinal direction in the excavation direction. Get information representing the location. In the example shown in FIG. 1, the absolute position information acquisition unit 11 acquires information representing the absolute position of a predetermined measurement point 3 of the retaining wall head 2a measured in a non-contact manner by the absolute position measurement unit 30. The inclination angle information acquisition section 12 obtains information representing the inclination angle of the core material 21 measured using a plurality of inclination angle detection sections 4 attached to the core material 21 at predetermined intervals in the longitudinal direction of the core material 21. It is acquired for each corner detection unit 4. The plurality of inclination angle detection units 4 are attached to the core material 21 in advance, for example, before construction of the retaining wall 2. The inclination angle detection unit 4 may be attached to all of the plurality of core materials 21 constituting the retaining wall 2, or may be attached to some of the core materials 21 (for example, at predetermined intervals of the core materials 21). The output unit 13 outputs core material based on information representing the absolute displacement of the measurement point 3 based on the information representing the absolute position acquired by the absolute position information acquisition unit 11 and information representing the inclination angle acquired by the inclination angle information acquisition unit 12. Information representing the relative displacement of 21 is also output. The measurement system 1 can be configured by, for example, a combination of a computer such as a notebook personal computer and peripheral devices such as a communication device. The output unit 13 may be a display device of the computer described above, or a display device of another computer such as a mobile terminal.

The absolute position measuring section 30 can be configured using, for example, a total station. A total station is a surveying device that combines a light wave distance meter to measure distance and a theodolite to measure angle. In this case, for example, a reflecting prism is fixedly installed at each measurement point 3 of the retaining wall head 2a, and the reflecting prisms are sequentially measured from a total station installed at a fixed point (or referring to the fixed point). The absolute position information acquisition unit 11 acquires information (angle and distance) representing the absolute position of the measurement point 3 of the retaining wall head 2a from the total station. The output unit 13 (or the absolute position information acquisition unit 11) determines the location of each measurement point 3 by, for example, comparing coordinate values based on the acquired information (angle and distance) with coordinate values based on past measurement results. Calculate the absolute displacement.

Alternatively, the absolute position measurement unit 30 may be a device (or system) that measures the position using a global navigation satellite system (GNSS). In this case, the absolute position measurement unit 30 collects, for example, a GNSS receiver fixedly (or semi-fixably) installed at each measurement point 3 of the retaining wall head 2a, and the position information measured by the GNSS receiver. and a terminal that transmits the information to the absolute position information acquisition unit 11. In this case as well, the output unit 13 (or the absolute position information acquisition unit 11) calculates the absolute Calculate the amount of displacement.

Further, each tilt angle detection section 4 can be configured using, for example, a three-axis MEMS (Micro Electro Mechanical Systems) acceleration sensor. Each inclination angle detection unit 4 detects gravitational acceleration in three orthogonal axes, and outputs information indicating the detection results. The inclination angle information acquisition unit 12 acquires information indicating the detection results output by each inclination angle detection unit 4 as information representing the inclination angle of the core material 21. The output unit 13 (or the tilt angle information acquisition unit 12) converts the detection results of the three-axis gravitational acceleration into a tilt angle, and further calculates the amount of horizontal displacement by multiplying the tilt angle by the distance from a predetermined reference point. do.

FIG. 8 is a side view schematically showing the relationship between the inclination angle and the relative displacement (displacement with respect to the reference line) for the four inclination angle detection units 4. In FIG. 8, the positions of the four inclination angle detection units 4 are shown as measurement points P ₁ to P ₄ , respectively. The reference line is a vertical straight line passing through the measurement point _P1 . θ _n is the inclination angle formed by the survey line connecting measurement points P _n and P _n+1 with respect to the reference line, δ _n is the displacement of measurement point P _n+1 with respect to the reference line, and l is the distance between the measurement points (each inclination angle detection unit 4) (where n=1 to 3). The displacement δ _n of P _n+1 when there are n measurement lines is expressed as δ _n =l×(θ ₁ +θ ₂ +...θ _n-1 +θ _n ).

Note that the tilt angle detection unit 4 is not limited to a 3-axis acceleration sensor, but may also be a pendulum type or a float type that detects the tilt angle by detecting the deviation between a weight suspended in the direction of gravity or a liquid level and a tilted object. It may also be constructed using a tilt sensor such as the following.

In addition, in this reference example and embodiment, "mountain retaining wall" refers to a wall that protects the sides of root cuttings during excavation, prevents soil collapse and spring water, and ensures the safety of other nearby structures. It is a partition for Mountain retaining walls are also called earth retaining walls. Examples of retaining walls include parent pile horizontal sheet pile walls, steel sheet pile walls, steel pipe sheet pile walls, soil cement solidified continuous walls, and underground continuous walls. A main pile horizontal sheet pile wall is a wall constructed by driving main piles (H-shaped steel) into the ground at predetermined intervals and fitting the horizontal sheet piles between the main piles (the space 22 in FIG. 1). In this case, the parent pile is the core material. A steel sheet pile wall is a wall constructed continuously underground by interlocking the joints of multiple steel sheet piles. In this case, the steel sheet pile is the core material. A steel pipe sheet pile wall is a wall constructed continuously underground by interlocking the joints of a plurality of steel pipe sheet piles. In this case, the steel pipe sheet pile is the core material. Moreover, the space 22 in FIG. 1 does not exist. A soil-cement solidified continuous wall or an underground continuous wall is a wall constructed continuously underground from a core material (H-shaped steel or reinforcing cage) and concrete (cement milk). In addition, "root cutting" is the excavation of earth and rock beneath the ground surface in order to create foundations and underground structures. The "core material" is a member that shares the load-bearing strength as part of the retaining wall, and includes, for example, H-shaped steel, steel sheet piles, steel pipe sheet piles, secondary concrete products, and the like.

Further, "information representing the absolute position of a predetermined measurement point on the head of the retaining wall" includes numerical data representing the absolute position of the measurement point and numerical data serving as a reference when calculating the absolute position. For example, when an absolute position is represented by latitude, longitude, and height in a predetermined geodetic system, numerical data representing the absolute position of a measurement point is numerical data representing latitude, longitude, and height. In addition, the numerical data that serves as a reference when calculating the absolute position is numerical data that can be converted into numerical data representing latitude, longitude, and height by a predetermined conversion process, and when calculating the absolute position, This is numerical data that specifies the location of the measurement point. The numerical data used as a reference when calculating the absolute position is, for example, numerical data representing the distance and angle from the fixed point to the measurement point (or with reference to the fixed point).

In addition, "information representing the inclination angle of the core material" refers to each inclination angle attached to the core material 21 based on a predetermined position (a predetermined point, a predetermined line, or a predetermined surface) on the core material 21. It includes information representing the inclination angle detected by the angle detection section 4 and information serving as a reference when calculating the inclination angle corresponding to each inclination angle detection section 4. The information representing the detected tilt angle is digital or analog data representing the angle of one or two axes representing the tilt angle. The information used as a reference when calculating the inclination angle is, for example, digital or analog data representing three-axis gravitational acceleration.

Furthermore, "absolute displacement" refers to a temporal change (over time) in the position of a measurement point in a predetermined geodetic system, or a temporal change in the position of a measurement point with respect to a predetermined fixed point. In addition, "relative displacement" of the core material refers to a change in the position of each measurement point on the core material due to deformation of the core material with respect to a predetermined point on the core material (a predetermined reference line or reference plane). deviation).

The output unit 13 outputs both information representing the absolute displacement AD of the measurement point 3 and information representing the relative displacement RD at each inclination angle detection unit 4 of the core material 21, as shown in FIG. 2, for example. FIG. 2 is a perspective view schematically showing an example of displacement of the retaining wall 2 shown in FIG. In FIG. 2, the same reference numerals are used for the same components as those shown in FIG. In FIG. 2, the absolute displacement AD of the measurement point 3 is shown by a chain arrow, and the relative displacement RD corresponding to each inclination angle detection part 4 is shown by a solid line arrow. Further, the retaining wall 2 and core material 21 during construction (before excavation) are shown by chain lines, the retaining wall 2 when displacement occurs is shown by a broken line, and the core material 21 when displacement occurs is shown by a solid line.

As described above, the measurement system 1 of this reference example includes the absolute position information acquisition section 11, the tilt angle information acquisition section 12, and the output section 13. Then, the absolute position information acquisition unit 11 acquires information representing the absolute position of a predetermined measurement point 3 of the retaining wall head 2a configured using the core material 21 having a longitudinal direction in the excavation direction. Further, the inclination angle information acquisition section 12 detects the inclination angle by detecting information representing the inclination angle of the core material 21 measured using the plurality of inclination angle detection sections 4 attached to the core material 21 at predetermined intervals in the longitudinal direction. Obtained for each part 4. The output unit 13 also displays information representing an absolute displacement based on the information representing the absolute position acquired by the absolute position information acquisition unit 11 and relative displacement based on information representing the tilt angle acquired by the tilt angle information acquisition unit 12. Output the information together. Therefore, the overall behavior of the ground, including the area around the excavated area, can be easily monitored during the entire period of root cutting and mountain retaining work.

<Second reference example>
Next, a measurement system 1a according to a second reference example will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic diagram for explaining a configuration example of a measurement system 1a according to a second reference example. FIG. 4 is a plan view schematically showing an example of displacement of the retaining wall 2 shown in FIG. 3. FIG. Note that in FIGS. 3 and 4, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

The measurement system 1a shown in FIG. 3 includes a data processing device 8 and a notebook personal computer 9. The data processing device 8 shown in FIG. 3 corresponds to the absolute position information acquisition section 11 and the tilt angle information acquisition section 12 of the first reference example shown in FIG. Further, the notebook personal computer 9 shown in FIG. 3 corresponds to the output unit 13 of the first reference example shown in FIG.

The measurement system 1a shown in FIG. 3 measures the absolute displacement in the horizontal and vertical directions of the head part 2a of the retaining wall, and measures the horizontal (out-of-plane) direction of the wall surface using the inclination angle detection unit 4 disposed inside the retaining wall 2. This is a measurement system that combines relative displacement measurements to three-dimensionally visualize the overall behavior of the ground, including the area around the excavation area during root cutting and mountain retaining work.

A non-contact measuring instrument is used to measure the absolute displacement of the retaining wall head 2a. For example, a reflective prism 3a is installed on the head of the retaining wall 2a, and the reflective prism 3a is sequentially measured from a total station 31 installed at a fixed point (or refers to the fixed point), and the absolute displacement amount of each point is calculated. As long as accuracy can be ensured, a method may be used in which a GNSS observation point is provided at the head of the retaining wall 2a and the absolute displacement is measured using the satellite 32 of the Global Navigation Satellite System.

The relative displacement of the retaining wall 2 is measured using an inclination angle detection unit 4 installed in advance (or at the same time as the construction) before constructing the retaining wall. As the inclination angle detection unit 4, a MEMS acceleration sensor, which is cheaper than an inclinometer, can be installed in the heap retaining core material 21 (H-shaped steel). The measurement of relative displacement is intended to capture the surface behavior of the retaining wall 2, and is realized by erecting core members 21 having a plurality of inclination angle detectors 4 arranged at intervals of 2 to 5 core members.

By combining the absolute displacement data and relative displacement data of the retaining wall 2 measured by the above method, the overall behavior of the retaining wall 2 that occurs during excavation can be understood three-dimensionally. A schematic plan view of the obtained measurement results is shown in FIG. In FIG. 4, the mountain retaining wall 2 before mining is shown as a mountain retaining wall 2-1, and the mountain retaining wall 2 after mining is shown as a mountain retaining wall 2-2. In the example shown in FIG. 4, in the retaining wall 2-2, an absolute displacement AD, which is a parallel movement with respect to the retaining wall 2-1, and a relative displacement RD, which is a deformation with respect to the retaining wall 2-1, occur.

The measurement system 1a shown in FIG. 3 imports measurement data into the data processing device 8 via wireless communication, plots the data on a display screen 91 corresponding to the surface of the retaining wall 2, and displays the data as an image of the displaced retaining wall 2. Visualize.

Furthermore, when the structure 5 is close to the periphery of the excavation area, a reflecting prism 301a is installed on the structure 5, and the reflecting prism 301a is sequentially measured from the total station 31 to calculate the absolute displacement amount at each point. By measuring the displacement of the nearby structure 5 using a non-contact measuring instrument, the influence of the displacement of the retaining wall 2 on the surrounding area can be quantitatively evaluated.

According to this reference example, the overall behavior of the ground, including the area around the excavation area, can be easily monitored during the entire period of root cutting and mountain retaining work. This makes it easier to identify events that cause displacement. In other words, this system will be used to ensure safety during construction and to make decisions regarding the selection of countermeasures when defects occur.

<Third reference example>
Next, a measurement system 1b according to a third reference example will be described with reference to FIGS. 5 to 7. FIG. 5 is a schematic diagram for explaining a configuration example of a measurement system 1b according to a third reference example. FIG. 6 is a plan view schematically showing a configuration example of the tape type inclinometer 40 shown in FIG. 5. As shown in FIG. FIG. 7 is a schematic diagram showing an example of how the tape type inclinometer 40 shown in FIG. 6 is attached to the core material 21. Note that in FIGS. 5 to 7, the same reference numerals are used for the same components as those shown in FIGS. 1 and 2.

The measurement system 1b shown in FIG. 5 has the same configuration as the measurement system 1 shown in FIG. 1 or the measurement system 1a shown in FIG. 3. In this case, the measurement system 1b shown in FIG. 5 is installed in the field office 201. In the third reference example, the configuration for measuring the information used by the measurement system 1b, and the configuration for measuring the inclination angle of the core material 21, is different from the first reference example and the second reference example. Note that in FIG. 5, illustration of a configuration related to measurement of absolute displacement is omitted.

The measurement system 1b shown in FIG. 5 measures the inclination angle of the core material 21 using the tape type inclinometer 40 shown in FIG. Furthermore, the measurement system 1b acquires data measured by the tape type inclinometer 40 via the transmitter 101 and the receiver 102. The transmitter 101 includes a power source 401, a data logger 402, and a transmitter 403, as shown in FIG. A power source 401 supplies predetermined power to the tape type inclinometer 40. The data logger 402 records data measured by the tape type inclinometer 40 and sends and receives predetermined control signals to and from the tape type inclinometer 40. The transmitter 403 transmits the data recorded in the data logger 402 to the receiving unit 102. Furthermore, the receiving unit 102 receives data transmitted by the transmitter 403 and transmits it to the measurement system 1b.

The tape type inclinometer 40 shown in FIG. 6 is composed of a tape-shaped flexible substrate 41, a plurality of sensors 42, wiring 51 to 55 that electrically connects the sensors 42, electrode fittings 43 to 47, 63 to 67, etc. There is. The sensor 42 is equipped with a MEMS three-axis acceleration sensor and a CPU (central processing unit). For signal transmission, for example, a communication standard (1-WIRE (registered trademark), SDI (serial digital interface), etc.) is used in which a plurality of sensors 42 are connected to one cable in a sequential manner for measurement. The sensor 42 has a configuration corresponding to the tilt angle detection section 4 in the first reference example and the second reference example. That is, in the tape type inclinometer 40, a sensor 42 corresponding to the inclination angle detection section 4 is continuously connected on a tape-shaped substrate.

In the tape type inclinometer 40, a plurality of units 4a each having one sensor 42 are connected in series, and the sensors 42 are arranged at intervals of, for example, several tens of cm. Further, an identification ID (identification code) is assigned to the sensor 42. To measure the amount of horizontal displacement, the sensor 42 detects changes in gravitational acceleration in three orthogonal axes, converts this into an inclination angle, and further converts the inclination angle into an amount of horizontal displacement by multiplying the distance.

The electrode fittings 63 to 67 that electrically connect the units 4a have a structure that can be cut in the width direction, and electrodes that can be wired from the cut points are formed between the cut units 4a. Power is supplied from electrode fittings 43 and 44 at the end of the tape (end of flexible substrate 41), and measurement data is collected by connecting electrode fittings 45 to 47 at the end of the tape to data logger 402.

The slope data will be collected using the following steps. (1) Specify the ID from the data logger 402 side and issue a measurement request. (2) Only the sensor 42 corresponding to the ID responds and transmits measurement data. (3) Data logger 402 interprets and stores the data.

Next, with reference to FIG. 7, an example of attaching the tape type inclinometer 40 to the core material 21 will be described. The tape-type inclinometer 40 can be installed on the mountain retaining core material 21, as shown in FIG. For example, when the core material 21 is H-shaped steel, the tape-type inclinometer 40 cut to match the length of the core material 21 is attached to the web 21a (FIG. 7(a)) or the flange 21b (FIG. 7(a)) using adhesive or the like. 7(b)).

As shown in FIG. 5, the data measured by the tape type inclinometer 40 installed on the retaining wall 2 is collected by the data logger 402 shown in FIG. 102, and the site office 201 can constantly monitor the detailed displacement of the retaining wall.

According to the third reference example, by using a relatively inexpensive sensor, physical costs can be reduced compared to measurement using a conventional inclinometer. In addition, it becomes possible to obtain high-density and continuous data on the displacement of retaining walls, and a detailed displacement distribution can be obtained.

<First embodiment>
Next, the measurement system 100 according to the first embodiment of the present invention will be described with reference to FIGS. 10, 11, 12, 13, 14, and 8.
FIG. 10 is a schematic diagram for explaining a configuration example of a measurement system 100 according to the first embodiment of the present invention. Further, FIG. 11 is a schematic diagram for explaining a configuration example of a three-axis MEMS acceleration sensor (inclination angle detection section 4) according to the first embodiment of the present invention. Moreover, FIG. 12 is a diagram showing the relationship between the accuracy of the acceleration sensor shown in FIG. 11 and the installation interval in the depth direction (excavation direction). Moreover, FIG. 13 is a diagram schematically showing an example of relative displacement of the retaining wall 2 in the excavation plane. Moreover, FIG. 14 is a diagram showing the relationship between the accuracy of the acceleration sensor shown in FIG. 11 and the installation interval in the horizontal direction.
Note that in FIG. 10, the same components as those shown in FIG. 1 are denoted by the same reference numerals. That is, the measurement system 100 is configured in a manner corresponding to the measurement system 1 shown in FIG. Here, the differences between FIG. 1 and FIG. 10 are as follows.
That is, in FIG. 10 showing the measurement system 100, the inclination angle detection section is composed of a plurality of inclination angle detection sections 4 attached to the core material 21 at a predetermined first interval lv in the longitudinal direction (excavation direction). This is a tilt angle detection unit 4v (first tilt angle detection unit).
That is, in FIG. 1 showing the measurement system 1, five (plural) inclination angle detection units 4 are attached to the core material 21 at predetermined intervals (constant intervals) in the longitudinal direction (excavation direction).
On the other hand, in FIG. 10 showing the measurement system 100, the core material 21 has five (plural) inclination angle detection units 4 constituting the inclination angle detection unit 4v in the longitudinal direction (excavation direction). They are attached at a first interval lv.

In addition, in FIG. 10 showing the measurement system 100, the inclination angle detection unit includes a plurality of inclination angle detection units attached to the core material 21 at predetermined second intervals lh in the horizontal direction, which is a direction perpendicular to the longitudinal direction. The tilt angle detection unit 4h (second tilt angle detection unit) is composed of the section 4.
That is, in FIG. 1 showing the measurement system 1, the core material 21 has two (two) inclination angle detection sections 4 arranged at predetermined intervals (at regular intervals) in the horizontal direction, which is a direction perpendicular to the longitudinal direction. ) is attached.
On the other hand, in FIG. 10 showing the measurement system 100, the core material 21 has two (plural) inclination angles forming the inclination angle detection unit 4h in the horizontal direction that is perpendicular to the longitudinal direction. The detection units 4 are attached at a predetermined second interval lh.

As described above, in the measurement system 100 according to the present embodiment, in the measurement management of the retaining wall 2, a MEMS type acceleration sensor (inclination angle detection unit 4) is attached to the core material 21 of the retaining wall 2, and the wall surface is horizontal (out of plane). When measuring the relative displacement in the direction, the inclination angle detection units 4v, 4h are installed at installation intervals (a predetermined first interval lv, a predetermined second interval lh) determined by a rational sensor installation method based on sensor accuracy. )have.

Further, as shown in FIG. 10, the output unit 13 includes a first interval determining unit 13v that determines a predetermined first interval lv, and a second interval determining unit 13h that determines a predetermined second interval lh. It consists of

[Decision regarding installation interval lv in depth direction]
Therefore, first, a method for determining the installation interval lv (predetermined first interval) in the depth direction will be described.
As shown in FIG. 11, the 3-axis MEMS acceleration sensor (inclination angle detection unit 4) can detect the inclination angle of a measurement point by detecting the direction in which gravity acts. As shown in FIG. 11, when the tilt angle detector 4 rotates by one axis around the y-axis in the three-dimensional orthogonal coordinate system O-xyz, let αx and αz be the accelerations detected by the tilt angle detector 4. The inclination angle θy around the y-axis is calculated using the following equation (1).
θy=sin ^-1 (αx/1G)...(1)
In addition, "1G" represents the gravity applied to the earth = approximately 9.806 m/sec^2.

Here, by multiplying the inclination angle θy by the distance l from the base point, the horizontal displacement amount δx of the measurement point can be obtained as expressed by the following equation (2).
δx=l・sinθy…(2)

Therefore, the correlation between the acceleration αx detected by the inclination angle detection unit 4, the distance l from the base point, and the horizontal displacement amount δx of the measurement point is expressed by the following equation (3) using equation (1) and equation (2). ).
l=δx・(1G/αx)…(3)
Here, if αx in the above equation (3) is substituted with the minimum unit αx_min that the inclination angle detection unit 4 can detect, and δx is substituted with the minimum unit of displacement δx_min required for crest retaining measurement management, the sensor in the depth direction of the crest retaining wall ( Inclination angle detection unit 4) Installation interval lv is expressed by the following equation (4).

lv=δx_min・(1G/αx_min)…(4)
In conventional mountain retaining measurements, displacement measurements in millimeter (mm) units have been carried out using multi-stage inclinometers or insertion-type inclinometers.
Therefore, when δx_min=0.01 mm, the measurement accuracy is excessive, and when δx_min=1 mm, the measurement accuracy is insufficient to guarantee resolution in millimeter units.

Taking these into consideration, it is reasonable for the minimum unit of displacement δx_min required of the sensor (inclination angle detection unit 4) to be 0.05 to 0.5 mm in practice, as expressed by the following equation (5). be.
0.05≦δx_min≦0.5…(5)
Here, when δx_min=0.1 that satisfies the above formula (5), the installation interval lv in the depth direction is estimated using formula (4), as shown in FIG. 12.

That is, as shown in FIG. 12, the relationship between the minimum unit αx that can be detected by the sensor (accuracy of the acceleration sensor) and the installation interval lv in the depth direction (excavation direction) can be seen.
In other words, the first interval determination section 13v in the output section 13 determines the minimum unit of displacement δx_min (minimum unit of displacement detected by the tilt angle detection section) required of the sensor (tilt angle detection section 4), and the minimum unit of displacement that the sensor (tilt angle detection section 4) can detect. The installation interval lv as shown in FIG. 12 is determined according to the minimum unit αx.
As a result, the output unit 13 uses the determined installation interval lv to output the measurement point P1 (base point: the lowest inclination angle detection unit 4 in the excavation direction) when there are n survey lines, as shown in FIG. The amount of horizontal displacement δ1, . The horizontal displacement amount δn of the measuring point Pn+1 (the position of the (n+1)th inclination angle detection unit 4 from the bottom in the excavation direction), that is, the horizontal displacement amount δ1 to the horizontal displacement amount δn (the first relative displacement ) can be obtained with high accuracy.

[Determination of installation interval lh in horizontal direction]
Next, a method for determining the installation interval lh (predetermined second interval) in the horizontal direction will be explained.
Since it is difficult to easily measure the stress state of uprights, which are mountain retaining supports, visual observation is the main method. However, this poses a problem in that it is difficult to visually observe the bulges, as they are often hidden by retaining walls or inspection passages for struts.
Here, ``Haradori'' is a member used to hold down the soil to prevent it from collapsing when excavating the ground. This refers to the member that holds down the retaining wall 2 to prevent it from collapsing. In the present embodiment, the "belly riser" is attached to the core material 21 at a predetermined distance away from the mountain retaining wall head 2a in the depth direction, as described in, for example, Japanese Patent Application Publication No. 2018-188874. ing.

That is, the inclination angle detection unit 4h (second inclination angle detection unit) as a sensor (inclination angle detection unit 4) detects the arrangement position of the belly riser attached to the core material 21 (in the core material 21 shown in FIG. 1, Any of the inclination angle detection units 4h including the first inclination angle detection unit 4 from the retaining wall head 2a to the inclination angle detection unit 4h including the fifth inclination angle detection unit 4 It is assumed that the inclination angle detection unit 4h is installed corresponding to the arrangement position of the inclination angle detection unit 4h.
Therefore, in the present embodiment, the installation interval lh of the inclination angle detection unit 4 constituting the sensor (inclination angle detection unit 4h) in the horizontal direction is proposed for measurement management of sitting up. Note that the proposed installation interval lh is determined by the second interval determination unit 13h as the installation interval lh of the inclination angle detection unit 4 that constitutes the sensor (inclination angle detection unit 4h) in the horizontal direction.

First, the deflection angle θx of the belly rise is expressed by the following equation (6).
θx=δx'/Le...(6)
Here, Le is the effective span length of the sit-up, and δx' is the deflection of the sit-up.

Because the permissible deflection of the bulge differs depending on the installation status of the mount retaining frame, there are no specific deflection limits listed in the mount retaining design guidelines. In the design process, stress checks are performed on the raised beams as beams that receive uniformly distributed loads to ensure safety. The maximum deflection of a beam fixed at both ends (the cut beam between the brace attached to the retaining wall at one end and the brace attached to the retaining wall at the other end) is 1/300 according to the steel structure design standards. It is shown below.

Therefore, it is reasonable to set the allowable deflection angle θx of the belly-up to θx≦1/300.
Since the tuck-up length is designed in units of 0.1 m (100 mm), by substituting Le=100 (mm) into equation (6), the conditions regarding the minimum unit of tuck-up deflection δx_min' (mm) are as follows. It becomes as shown in equation (7).
δx_min'≦1/3...(7)

Here, by substituting l, θx, and δx shown in FIG. 13, which schematically shows an example of the relative displacement of the retaining wall 2 in the excavation plane, into the following equations (11) and (12), the equation ( 13) can be obtained.
θx=sin ^-1 (αx/1G)...(11)
δx=l・sinθx…(12)
l=δx・(1G/αx)…(13)

Here, if αx in the above equation (13) is substituted with the minimum unit αx_min that can be detected by the inclination angle detection unit 4, and δx is substituted with the minimum unit of displacement δx_min' required for mountain retaining measurement management, the sensor in the horizontal direction of the mountain retaining wall (Inclination angle detection unit 4) The installation interval lh is expressed by the following equation (8), which is the same as equation (4).
lh=δx_min'・(1G/αx_min)...(8)
Here, when δx_min'=0.3, which satisfies equation (7), the installation interval lh in the horizontal direction is estimated using equation (8), as shown in FIG. 14.

That is, as shown in FIG. 14, the relationship between the minimum unit αx (accuracy of the acceleration sensor) that can be detected by the sensor and the horizontal installation interval lh can be seen.
In other words, the second interval determination section 13h in the output section 13 determines the minimum unit of displacement δx_min' (minimum unit of displacement detected by the tilt angle detection section) required for the sensor (tilt angle detection section 4) and the minimum unit of displacement that the sensor (tilt angle detection section 4) detects. The installation interval lh as shown in FIG. 14 is determined according to the possible minimum unit αx.
As a result, the output unit 13 uses the determined installation interval lh to output the measurement point P1 (base point: the position closest to the four corners of the excavation plane before deformation) when there are n survey lines, as shown in FIG. The measurement point P2 (the position of the second inclination angle detection unit 4 located at an installation interval lh from the measurement point P1) corresponding to the reference line, which is a horizontal straight line passing through the inclination angle detection unit 4 attached to the horizontal displacement amount δ1, ..., the horizontal displacement amount δn of the measuring point Pn+1 (the position of the (n+1)th inclination angle detection unit 4 separated by the installation interval lh×n from the measuring point P1), that is, the horizontal displacement amount of n pieces. δ1 to horizontal displacement amount δn (information representing the second relative displacement) can be determined with high accuracy.

As described above, in the measurement system 100, the installation interval in the depth direction of the acceleration sensor (inclination angle detection unit 4) used for mountain retaining measurement is designed based on equation (4). As a result, δx_min in equation (4) can practically take the range (0.05 to 0.5 mm) shown in equation (5).
Furthermore, the measurement system 100 can be used to measure and manage the deflection of a sit-up.
Furthermore, in the measurement system 100, the installation interval in the horizontal direction of the acceleration sensor (inclination angle detection unit 4) used for peak-holding measurement is designed based on equation (8). Thereby, δx_min' in equation (8) can practically take the range of equation (7) (1/3 mm or less).

In this way, when using the acceleration sensor (inclination angle detection unit 4) for peak-holding measurement, the measurement system 100 can achieve the accuracy required for peak-holding measurement by using the proposed design formulas (5) and (7). The sensor performance and installation interval (predetermined first interval, predetermined second interval) that satisfies (the minimum unit of displacement δx_min required of the sensor (inclination angle detection unit 4)) can be determined.
That is, in the measurement system 100, in the measurement management of the retaining wall 2, a MEMS type acceleration sensor (inclination angle detection unit 4) is attached to the core material of the retaining wall 2 to measure the relative displacement in the wall surface horizontal (out-of-plane) direction. In this case, the tilt angle detection units 4v and 4h have installation intervals (a predetermined first interval lv, a predetermined second interval lh) determined by a rational sensor installation method based on sensor accuracy.

Therefore, according to the embodiment of the present invention, during the entire period of root cutting and mountain retaining work, the overall behavior of the ground including the surrounding area of the excavation area can be controlled by slope angles arranged at a predetermined first interval lv. The detection unit 4v (first inclination angle detection unit) and the inclination angle detection unit 4h (second inclination angle detection unit) arranged with a predetermined second interval lh enable highly accurate monitoring.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and includes designs within the scope of the gist of the present invention. For example, as shown in FIG. 10, the measurement system 100 acquires absolute position information that acquires information representing the absolute position of a predetermined measurement point 3 of the retaining wall head 2a measured in a non-contact manner by the absolute position measurement unit 30. It may have a section 11. The measurement system 100 can thereby output the information representing the absolute displacement based on the information representing the absolute position, the information representing the first relative displacement, and the information representing the second relative displacement together.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 100...Measurement system, 2...Mountain retaining wall, 2a...Mountain retaining wall head, 3...Measurement point, 4...Inclination angle detection unit, 4v, 4h...Inclination angle detection unit, 11...Absolute position information acquisition Part, 12... Tilt angle information acquisition part, 13... Output part, 21... Core material, 40... Tape type inclinometer, 42... Sensor

Claims (5)

A retaining wall configured using a core material having a longitudinal direction in the excavation direction, which is a vertical direction, including a plurality of inclination angle detection units attached to the core material at predetermined first intervals in the longitudinal direction. Information representing the inclination angle of the core material measured using the first inclination angle detection unit is acquired from the first inclination angle detection unit, and The second inclination angle detection unit transmits information representing the inclination angle of the core material measured using a second inclination angle detection unit composed of a plurality of the inclination angle detection sections attached to the core material at two intervals. an inclination angle information acquisition unit that acquires from the
an absolute position measurement unit that measures the absolute position of a predetermined measurement point on the head of the retaining wall in a non-contact manner;
an absolute position information acquisition unit that acquires information representing the absolute position of a predetermined measurement point of the head of the retaining wall in the longitudinal direction from the absolute position measurement unit;
information representing a first relative displacement based on information representing the tilt angle acquired from the first tilt angle detection unit; and a second relative displacement based on information representing the tilt angle acquired from the second tilt angle detection unit. and an output unit that outputs information representing the absolute position and information representing the absolute displacement based on the information representing the absolute position acquired by the absolute position information acquisition unit. The output unit determines the predetermined first interval and the predetermined second interval according to a minimum unit of displacement detected by the tilt angle detection unit and a minimum unit detectable by the tilt angle detection unit. The measurement system according to claim 1, characterized in that: The measurement system according to claim 1 or 2, wherein the second inclination angle detection unit is attached to correspond to an arrangement position of a belly riser attached to the core material. In a mountain retaining wall configured using a core material having a longitudinal direction in the excavation direction, which is a vertical direction, the inclination angle information acquisition unit is configured to obtain a plurality of inclinations attached to the core material at predetermined first intervals in the longitudinal direction. Information representing the inclination angle of the core material measured using a first inclination angle detection unit including an angle detection section is obtained from the first inclination angle detection unit, and information is obtained from the first inclination angle detection unit, and Information representing the inclination angle of the core material measured using a second inclination angle detection unit constituted by a plurality of the inclination angle detection sections attached to the core material at predetermined second intervals in a certain horizontal direction. obtained from the second tilt angle detection unit,
an absolute position measurement unit that measures the absolute position of a predetermined measurement point on the head of the retaining wall in a non-contact manner;
The output unit includes information representing a first relative displacement based on information representing the tilt angle acquired from the first tilt angle detection unit, and information representing the tilt angle acquired from the second tilt angle detection unit. 2. The absolute position acquired by the absolute position information acquisition unit that acquires information representing relative displacement and information representing the absolute position of a predetermined measurement point of the head of the retaining wall in the longitudinal direction from the absolute position measurement unit. A measurement method characterized by outputting information representing an absolute displacement based on the information represented. In the measurement system according to claim 1 , the predetermined first interval and the predetermined second interval are set as the minimum unit of displacement detected by the tilt angle detection section and the minimum unit detected by the tilt angle detection section. A method for determining an interval, characterized in that the interval is determined according to.

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