JP7246046B2 - Ground deformation evaluation method - Google Patents

Description

The present invention relates to a ground deformation evaluation method that performs laser surveying and analysis for monitoring and inspection of slope disasters after heavy rains and earthquakes, or periodic inspection of slope conditions.

When heavy rains or earthquakes occur, administrators of public infrastructure such as roads need to inspect slopes to confirm safety. For this inspection, methods such as visual observation from patrol vehicles and inspections by specialist engineers who actually walk on the slope are used. In particular, the inspection (reconnaissance) that engineers actually walk on the slope is a hindrance to speeding up the inspection because a skilled professional engineer walks on the site and judges the situation.

On the other hand, when a large-scale landslide disaster occurs, conventionally, aerial photographs have been used to identify ground deformation sites such as collapses and landslides. Recently, in addition to aerial photographs, there is also known a method of extracting ground deformation by performing microtopographic interpretation based on a detailed topographical map obtained by laser surveying (LP) mounted on an aircraft (Patent Document 1).

Laser surveying has the advantage of being able to grasp the shape of the ground under vegetation to some extent, which was not possible with conventional aerial photography. It had the drawback of requiring

In addition, for slopes where landslides and collapses have been confirmed, it is common to install borehole inclinometers, ground inclinometers, ground surface extensometers (landslide gauges), GPS terminals, etc. to observe the dynamics. The method requires the installation of equipment on-site, and in the case of a large-scale disaster, equipment can only be installed in typical deformation locations, and the problem is that it is not possible to grasp the entire disaster area. there were.

Japanese Patent No. 4545219

In view of the conventional drawbacks as described above, the present invention is capable of quickly and objectively judging the presence or absence of ground deformation on a slope when heavy rain or an earthquake occurs, and is capable of quickly and objectively determining signs of deformation. On the other hand, it is an object of the present invention to provide a ground deformation evaluation method capable of monitoring even a slope that cannot be fully observed due to the distance from a security property.

In order to achieve the above object, the ground deformation evaluation method according to claim 1 of the present invention includes a laser surveying step of measuring trees growing on the ground to be surveyed by laser surveying, and a surveying performed in the laser surveying step and a trait evaluation step of evaluating ground deformation from the results, wherein the laser surveying step acquires at least the vertex coordinates of the tree, and the trait evaluation step includes the vertex coordinates of the tree. Characterized by evaluating the deformation or dynamics of the surveyed ground from the state or change of

The property evaluation step of the ground deformation evaluation method according to claim 2 includes at least geometric features of individual trees including vertex coordinates of the trees, geometric features of tree arrangement, the number of trees, or inclination of trees. It is characterized by evaluating the deformation or dynamics of the surveyed ground from any state or change.

The property evaluation step of the ground deformation evaluation method according to claim 3 includes the state or change in the number of trees per unit area, the state or change in arrangement, the state or change in vertex coordinates of the trees, the state of inclination or At least one of the changes is statistically processed to evaluate the deformation or dynamics of the surveyed ground.

The ground deformation evaluation method according to claim 4 is characterized in that, in the trait evaluation step, when evaluating the tilt of the tree, the evaluation is performed assuming the influence of the wind.
The laser surveying step of the ground deformation evaluation method according to claim 5 is characterized in that the laser surveying of trees growing on the ground to be surveyed is performed multiple times from a predetermined position.

As is clear from the above description, the present invention has the following effects.
(1) In the invention described in claim 1, _Hlk125105216, in order to measure the trees growing on the ground to be surveyed, minute ground displacements in millimeters are measured for trees of several centimeters to several tens of centimeters that greatly exceed the measurement error. By grasping it as a state or change, it is possible to quickly output information on the presence or absence of ground deformation_Hlk125105216.
(2) In addition, since it is possible to capture the ground deformation or dynamics as the state or change of trees, even if signs of deformation are recognized, full-scale dynamic observation cannot be performed due to the distance from the security property. It is also possible to monitor ground that is
(3) In order to capture changes in trees and evaluate ground deformation, create secondary data by filtering out the survey point cloud data corresponding to trees, which is used to extract the ground surface shape in normal aviation LP. you don't have to.
Therefore, ground deformation can be evaluated in the process of filtering the tree-equivalent data, so the data can be output more quickly than before.
(4) The inventions described in claims 2 and 3 can also obtain the same effects as the above (1) to (3), and by evaluating the inclination and arrangement of trees by statistical processing per unit area , it is possible to quickly and objectively evaluate ground deformation without the need for interpretation by expert engineers.
(5) In addition, by grasping the slopes and coordinates of trees planarly and periodically measuring and comparing them, it is possible to planarly evaluate the condition of slopes, which could only be evaluated at locations where conventional measuring instruments were installed. .
(6) The invention described in claim 4 has the same effect as the above (1) to (5), and assumes the deviation width of the apex due to the wind using the tree species, tree height, and wind direction and wind speed at the time of survey as parameters. , can be evaluated by excluding measurement errors due to wind.
Therefore, ground deformation evaluation can be performed with higher accuracy.
(7) The invention described in claim 5 has the same effect as the above (1) to (6), and changes can be grasped by surveying multiple times, so it is possible to extract places where changes are active. .
In addition, it is possible to organize the analysis results in chronological order by performing surveying multiple times and evaluating traits each time.

1 to 5 are schematic diagrams showing the first embodiment of the present invention.
6 to 11 are schematic diagrams showing a second embodiment of the present invention.
Process drawing of the ground deformation evaluation method of 1st Embodiment. Schematic diagram of the laser survey process. Schematic diagram showing the focal point of dynamic observation of the surveyed ground. A schematic diagram showing the inclination of the ground and the inclination of trees. Schematic diagram showing ground deformation (landslide) and changes in tree inclination and coordinates. Process drawing of the ground deformation evaluation method of 2nd Embodiment. Schematic diagram showing the disorder of the arrangement of trees per unit area due to the inclination of the trees. Schematic illustration of changes in tree coordinates per unit area. Table showing statistics of changes in tree coordinates per unit area. Schematic diagram of the LP data of a tilted tree projected onto a plane. Schematic diagram showing survey point clouds of upright trees and slanted trees.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail by means of embodiments for carrying out the present invention shown in the drawings.

In the first embodiment of the present invention shown in FIGS. 1 to 5, 1 is a ground deformation evaluation method that can evaluate the characteristics of the surveyed ground by performing laser surveying (LP) on the surveyed ground. is.

This ground deformation evaluation method 1, as shown in FIG. It is composed of a trait evaluation step 3 for evaluating.

In the laser surveying process 2, a tree 6 growing on the survey target ground 5 is surveyed from a low altitude using an unmanned aerial vehicle 4 (drone). At this time, not only the trees 6 but also the surveyed ground 5 can be surveyed.

In conventional laser surveying using manned aircraft, the accuracy of grasping the tree trunk shape was low because it was surveying from a high altitude. It is possible to grasp the tree trunk shape with high accuracy.

Specifically, as shown in FIG. 2, an aerial laser survey using an unmanned aerial vehicle 4 equipped with a laser rangefinder 7 is suitable for surveying both the ground 5 to be surveyed and the trees 6. In particular, in order to survey the trunk of the tree 6 in detail, it is suitable to survey using the unmanned aerial vehicle 4 capable of emitting a range-finding laser at a low angle from a low altitude.

It is desirable that the laser surveying process 2 be periodically performed a plurality of times on the surveyed ground 5 and the like. In such a case, it is possible to find places where changes are active and predict the occurrence of landslides, etc., and to organize the analysis results in chronological order by performing the trait evaluation step 3 each time. can.

In addition, this laser surveying process 2 can evaluate the state of the tree 6, for example, a location where the tree 6 is greatly tilted, as having a high possibility of being dangerous, even in a single survey. However, it is possible to make a certain evaluation of ground deformation.

In the case of surveying using the unmanned aerial vehicle 4, by hovering periodically or at specific coordinates and measuring the wind speed at the site during surveying, the error and reliability of the obtained results can be used for evaluation.

It is necessary to set the flight route so that trees can be measured without loss, but in order to clarify the XYZ coordinates, the route should include structures that will be fixed points and reference points with clear coordinates. is essential. In addition, it is desirable to conduct surveying using GPS or the like.

Note that the laser surveying process 2 may be performed without using the unmanned aerial vehicle 4 .
FIG. 3 shows the state of the trees on the slope (ground 5 to be surveyed) obtained by laser surveying. On slopes where significant slope deformation is observed, a method is generally used to monitor the behavior of ground deformation by installing landslide dynamics observation devices such as ground surface extensometers, borehole inclinometers, and ground tiltmeters on the slopes. .

Here, the survey target ground 5 includes a slope on which trees 6 grow. For example, it includes mountain slopes where landslides and landslides are likely to occur.

However, monitoring using these dynamic observation devices is often limited to places where they can be installed due to the high initial cost of installing the devices. often replaced with On the other hand, in the present invention, if the LP that can obtain the cross section as shown in FIG. 3 is used, the ground surface By measuring the inclination of the tree core as an alternative to the extensometer, it is possible to evaluate the stability of the slope shown in the cross section as an alternative to the ground inclinometer. Since there is no need to install equipment on the ground surface, it is possible to evaluate the progress of ground deformation in a chronological order by performing multiple aerial surveys along a specified route.

In the analysis, after carrying out an aerial survey based on the set position information, each tree on the cross section is compared for each survey. If the activity of slope deformation becomes active, if the coordinates of the trees are greatly different from the previous survey and it becomes difficult to compare, it is necessary to set up markers such as piles and boxes on the ground surface for comparison. can be facilitated.

The trait evaluation step 3 is a step of evaluating the traits of the investigation target ground 4 based on the state or change of the trees 6 surveyed and analyzed in the laser surveying step 2 .

For example, as shown in Fig. 4, in the case of a _Hlk125104777 tree 6 with a height of 10m, if the ground tilts by 1°, the tree core apex will be displaced by about 17cm or more, so the effect will be more pronounced than the deformation of the ground. appears _Hlk125104777. In addition, when a fallen tree occurs due to a slope failure, the coordinates and tree heights of 6 trees (geometric features) in a predetermined range, the decrease in the number of 6 trees, the arrangement of 6 trees (geometric features of the tree arrangement) changes such as disturbances appear.

As described above, even if the change in the surveyed ground 5 itself is slight, the changes in the trees 6 growing on the ground 5 appear greatly. can be appropriately evaluated.

In addition, it is possible to evaluate the location where the tree 6 is greatly tilted as having a high possibility of being dangerous, and by analyzing the state of the tree 6 in this way, it is possible to appropriately evaluate the characteristics of the surveyed ground 5. can.

In this embodiment, laser surveying is used in the laser surveying step 2 to determine the inclination and number of trees 6, the arrangement of trees 6 (geometric features of the tree arrangement), the coordinates and heights of 6 trees (geometric features), and the ground. However, regarding the influence of the wind, which is a concern for the measurement of the inclination of the tree 6, the deviation width of the vertex due to the wind is calculated using the wind speed information, the tree species, the height of the tree, and the wind speed and direction at the time of survey as parameters. It is possible to evaluate the error range, reliability, etc. by making assumptions and organizing the acquired data.

The form shown in FIG. 5 is a schematic diagram showing the inclination of the tree 6 at the time of a disaster, which is the grasping target of the present invention. The left side of the figure shows the arrangement of upright trees 6 before the occurrence of the disaster. The right side of the figure shows a state in which a ground deformation represented by a landslide occurs on the slope 5 . As shown in FIG. 5, at the landslide site, trees 6 often tilt upward on the slope 5 at the top of the landslide, and trees 6 tilt downward on the slope 5 at the bottom of the landslide.

In an aerial photograph using the unmanned aerial vehicle 4, although the tree 6 can be photographed in detail, the characteristic tilt of the optical lens cannot be accurately grasped. On the other hand, laser surveying can accurately grasp the inclination of trees 6 and even the shape of the ground. can. In the present invention, focusing on the relationship between the inclination of the tree 6 and the ground deformation, the vertex coordinates of the tree 6 and the inclination of the tree 6 are extracted, and the position and range of the ground deformation of the surveyed ground 5 can be assumed. can.

[Different Modes for Carrying Out the Invention]
Next, different modes for carrying out the invention shown in FIGS. 6 to 11 will be described. In describing these different modes for carrying out the present invention, the same components as those in the first mode for carrying out the present invention are denoted by the same reference numerals, and duplicate descriptions are omitted.

In the second mode for carrying out the present invention shown in FIGS. 6 to 11, the main differences from the first mode for carrying out the present invention are the change in the number of trees per unit area, the coordinate In that the trait evaluation step 3A for evaluating the ground deformation is performed by statistically processing the change in or the change in inclination, etc., even if the ground deformation evaluation method 1A that performs such a trait evaluation step 3A, the first It is possible to obtain the same effects as those of the embodiment.

In this embodiment, the trait evaluation step 3A is performed by statistically processing the state or change of the trees 6 per unit area. Arrangement of the vertex coordinates of the tree 6 after the occurrence of the disaster is disturbed.

FIG. 7 schematically shows a situation in which the arrangement of vertices of trees 6 per arbitrary unit area is disturbed due to ground deformation. By quantifying and statistically processing the disturbance of the vertex coordinates per unit area, it is possible to evaluate the presence or absence of ground deformation per unit area without comparing each tree.

As another element, the trait evaluation step 3A can be performed by statistically processing changes in vertex coordinates of trees. For example, FIG. 8 schematically shows case a when a displacement of about 0 to 22 cm occurs scattered in a 20 m square range, and case b when a displacement of about 34 cm to 4.7 m occurs. FIG. 9 shows a table of the statistical results of the tree vertex coordinates within a 20 m square for each of the initial state A, the post-variation case a, and the case b shown in FIG. In FIG. 9, each analysis value such as the total value, median value, average value, standard deviation, etc. of tree vertex coordinates within a unit area can clearly show the difference between case a and case b. This method is suitable for checking the presence or absence of ground deformation on a wide range of slopes on a regular basis, and slope inspections related to the lifting of road traffic restrictions during heavy rain. It can also be applied to quickly extract a deformation occurrence range from a wide range of slopes when a large-scale slope disaster occurs.

6 to 9 can be substituted by using the coordinates of the root of the tree 6 instead of the apex of the tree 6 for broad-leaved trees in which the apex of the tree 6 is difficult to determine.
FIG. 10 is a schematic diagram of a state in which tree measurement data obtained by laser surveying is projected onto a plane. Since the projected data has height data in addition to plane coordinate data, the difference between the point coordinates of the trunk portion of the tree 6 and the point coordinates of the vertices of the tree 6 is obtained. You can find the slope and direction.

FIG. 11 is a schematic diagram of a plane projection of the inclination of the tree 6 per unit area. In conventional laser surveying, the plane-projected point coordinates are removed as noise, but in the present invention, the plane-projected points are sorted out, and as shown in FIGS. By statistically processing the slope distribution per unit area, the slope becomes an index for evaluating the ground deformation in that range.

Since there is a high possibility that ground deformation has occurred in areas where trees are tilted, even if there is no data from before the disaster occurred, narrowing down the area with many tilted trees will increase the possibility of ground deformation. It is possible to extract as a region. This method is suitable for quickly extracting the possibility of deformation from a wide range of slopes for which there is no past survey data, such as when a large-scale slope disaster occurs.

In the ground deformation evaluation method of the present invention, extensometers, ground inclinometers, etc. are installed on slopes that are subject to visual inspection even if damage to protected properties is not imminent, or on slopes after a disaster has occurred. It can be applied to preliminary surveys up to

Further, in the embodiment of the present invention, an aircraft (especially an unmanned aircraft) is used to perform the laser survey process, but any device that can survey changes in trees may be used. You can take a survey.

INDUSTRIAL APPLICABILITY The present invention is used in industries that evaluate the presence or absence of ground deformation such as changes in ground characteristics such as slopes.

1, 1A: ground deformation evaluation method,
2: laser surveying process, 3, 3A: trait evaluation process,
4: unmanned aerial vehicle, 5: survey ground,
6: trees, 7: laser rangefinder.

Claims (5)

It consists of a laser surveying process of measuring trees growing on the ground to be surveyed by laser surveying, and a trait evaluation process of evaluating ground deformation from the survey results measured in the laser surveying process,
At least the vertex coordinates of the tree are obtained in the laser surveying step,
The property evaluation step is a ground deformation evaluation method for evaluating the deformation or dynamics of the surveyed ground from the state or change of the tree including the vertex coordinates of the tree . In the trait evaluation step, the state or change of at least one of the geometric features of individual trees including the vertex coordinates of the trees, the geometric features of the arrangement of trees, the number of trees, or the inclination of trees is used to evaluate the ground under investigation. The ground deformation evaluation method according to claim 1, wherein deformation or dynamics is evaluated. The trait evaluation step statistically processes at least one of the state or change in the number of trees per unit area, the state or change in arrangement, the state or change in vertex coordinates or the state or change in inclination of the trees , and performs the survey. 2. The ground deformation evaluation method according to claim 1, wherein the deformation or dynamics of the target ground is evaluated. 4. The ground deformation evaluation method according to claim 2 or 3, wherein, in said character evaluation step, the inclination of a tree is evaluated by assuming the influence of wind. 1 to 4, wherein the laser surveying step performs laser surveying of trees growing on the investigation ground a plurality of times, and the character evaluation step evaluates the deformation of the investigation ground from changes in the trees. The ground deformation evaluation method according to claim 4.

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