Disclosure of Invention
The invention aims to provide a landslide disaster emergency monitoring method based on a foundation radar, which aims to solve the technical problems in the prior art, can monitor landslides in real time for a long time, acquire a two-dimensional deformation map of a landslide area and provide data support for landslide geological disaster early warning and treatment.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a landslide hazard emergency monitoring method based on a foundation radar, which comprises the following steps:
surveying and selecting points: selecting a foundation radar erection point;
field laying: pouring an observation mound, erecting a tent and observing a landslide;
data acquisition: setting observation parameters of a foundation radar, and determining observation time and observation range for acquiring landslide data;
data transmission: building a data transmission network, and remotely transmitting the landslide data collected in the field to a working end through the data transmission network;
interference treatment: performing interference processing on the adjacent two-scene image data by using GAMMA software to obtain an interference pattern of an adjacent image pair;
phase unwrapping: filtering interferograms of adjacent image pairs, selecting a stable point from the interferograms as a starting point of phase unwrapping, and unwrapping the filtered interferograms based on the starting point of the phase unwrapping to obtain phase unwrapping graphs in a rectangular coordinate system;
single deformation map generation: converting the phase unwrapping graph under the rectangular coordinate system into a polar coordinate system, converting the phase value of the phase unwrapping graph under the polar coordinate system into a deformation value, and generating a single deformation graph;
generating a total deformation graph: and sequentially accumulating the deformation values of the two adjacent scene image pairs to generate a total deformation graph of each time period, dividing the total deformation graph of each time period by the accumulated observation time to obtain a rate graph, and analyzing the region of interest based on the total deformation graph and the rate graph.
Preferably, the observation parameters of the ground radar are optimized and adjusted according to the range of an observation site, climate and environmental factors and the type of ground surface and ground objects; the selection of the observation time comprises the time interval of image acquisition and the total continuous observation time, and the observation time is selected according to the quality and the size of the image; the observation range is determined according to the landslide area, the data storage and the data processing conditions.
Preferably, the observation parameters of the ground-based radar include a radar antenna rotation start-stop angle, a radar antenna rotation speed, and a radar antenna pitch angle.
Preferably, the data transmission network adopts one of a wireless network card, a wireless network and a wired broadband; the ground radar is connected with the notebook, and the notebook passes through data transmission network remote connection to work end, with data real-time transmission to long-range work end that ground radar gathered, the work end can carry out remote operation to the ground radar through data transmission network, and the work end still is used for handling the data that ground radar gathered.
Preferably, the phase unwrapping of the interferograms of the selected adjacent image pairs specifically includes:
firstly, selecting stable points from interference images of adjacent image pairs;
secondly, selecting the azimuth direction and the distance direction of the stable point in the interference image of the adjacent image pair;
thirdly, a coherence threshold of phase unwrapping is selected based on the quality of the image.
Preferably, the single deformation map is a deformation map of two adjacent moments of the observation area; the total deformation graph is a deformation accumulation graph of an observation time period.
Preferably, the GAMMA software and the Matlab program are combined to process the phase unwrapping map to obtain a total deformation map.
The invention discloses the following technical effects:
(1) the landslide area two-dimensional deformation map is obtained based on the ground-based radar, and the method has the advantages of all-weather time, wide observation range, high correlation, capability of continuous observation and the like, and has important significance for early warning and treatment of large-scale landslide geological disasters;
(2) according to the invention, through survey point selection, field arrangement and observation parameter setting, the ground radar can carry out long-time continuous observation in the field, remote operation can be carried out, and field data can be timely transmitted back for processing;
(3) according to the method, through interference processing, phase unwrapping and deformation graph generation, a deformation time sequence of an interested point on a landslide can be independently extracted, so that the monitoring precision is effectively improved and can reach a submillimeter level;
(4) the invention has the advantages that the installation and erection of the foundation radar are more flexible for different landslides, the foundation radar can be directly installed at the periphery of an observation area, the data acquisition time interval is short, the self-control is realized, and the real-time monitoring capability on a rapid deformation area is realized.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Referring to fig. 1, in the present embodiment, a lazin ancient landslide is taken as an example to describe in detail the landslide hazard emergency monitoring method based on the ground-based radar, and the lazin ancient landslide is located in yanmen county village zang village in germany county, Yunnan province and is a landslide intersecting the middle section of a mountain and the right bank of the upstream of a yangtangjiang river; from 6 months and 7 days in 2019, the rear edge of a landslide body of the Lajinshen landslide cracks, and the rear edge cracks continuously develop from top to bottom towards two sides; by 7, 9 and 9 months in 2019, the deformation of the rear edge and the boundaries on the two sides of the landslide is stronger, the transverse width of the crack is 15-80 cm, the crack is staggered up and down by 5-380 cm, the length of the crack is about 1200m, the rear edge and the cracks on the north side of the landslide are completely communicated, and the cracks on the south side of the landslide are also extended to the middle-lower part; lajinshen ancient landslide is in a deformation development stage, the stability is poor, and instability can enter the river if the Lajinshen ancient landslide is continuously developed.
The embodiment provides a landslide hazard emergency monitoring method based on a foundation radar, which specifically comprises the following steps:
s1, survey point selection: and selecting a proper foundation radar erection point.
The selection of the foundation radar erection points needs to comprehensively consider the following points:
1) the foundation radar instrument is convenient to erect;
2) facilitating power supply and network signaling;
3) the visual field is wide without the interference of a shelter;
4) the instrument can be erected for a long time for observation without interference of other activities;
5) the sight direction of the radar is approximately parallel to the landslide displacement direction, and the depression angle or the lift angle of the radar is set to be smaller than 15 degrees in the embodiment.
S2, field layout: and pouring in advance to observe the landslide, and erecting a tent for observing the landslide for a long time.
In the embodiment, after surveying, an observation pier is poured on a mountain opposite to a landslide, and the distance between the observation pier and the landslide body is 1-3 kilometers; the landslide mass site is shown in FIG. 2 and the landslide mass position is shown in FIG. 3.
S3, data acquisition: and (3) setting observation parameters of the foundation radar, determining observation time and observation range for acquiring landslide data, and facilitating long-term observation.
Optimizing and adjusting observation parameters of the ground radar according to the range of an observation site (namely a landslide area), climate and environmental factors and the type of ground surface ground objects; the selection of the observation time comprises the time interval of image acquisition and the total continuous observation time, the observation time is selected according to the quality and the size of the image, the condition that the image coherence is greater than a preset threshold value and is convenient for machine storage and subsequent data processing is required to be met, and the image coherence of the embodiment is greater than 0.75; the determination of the observation range requires consideration of landslide area, data storage and data processing issues.
The observation parameters of the foundation radar of the embodiment comprise a radar antenna rotation starting and stopping angle, a radar antenna rotation speed and a radar antenna pitch angle.
In this embodiment, a swiss GAMMA portable interferometric radar is used for data acquisition, a ground-based radar working diagram is shown in fig. 4, after a previous network and power supply preparation is completed, a landslide body is monitored by the ground-based radar, the data acquisition time is from 7 months and 14 days in 2019 to 8 months and 13 days in 2019, the acquisition mode is sweep, the rotation angle is 120 degrees, the acquisition frequency is 20 minutes, and a 2100 view of data is acquired in total, wherein the ground-based radar parameter setting is shown in table 1:
TABLE 1
S4, data transmission: and a data transmission network is built, and the landslide data collected in the field is remotely transmitted to a working end through the data transmission network, so that the collected landslide data can be processed in time.
The data transmission network adopts one of wireless network card, wireless network, wired broadband, and the ground radar is connected with the notebook, and the notebook passes through data transmission network remote connection to work end, with data real-time transmission to long-range work end that ground radar gathered, carries out remote operation to the ground radar through the work end to and handle the data that ground radar gathered, thereby can observe the dynamic change of landslide in real time.
S5, interference processing:
and performing interference processing on the adjacent two-scene image data by using GAMMA software to obtain an interference pattern of the adjacent image pair.
S6, phase unwrapping: filtering the interference patterns of adjacent image pairs to generate a mask pattern with coherence greater than 0.75; and selecting a stable point with coherence greater than 0.9 from the interference pattern as a phase unwrapping starting point by combining field site topography, and unwrapping the filtered interference pattern by using GAMMA software based on the phase unwrapping starting point to obtain a phase unwrapping pattern in a rectangular coordinate system.
Performing phase unwrapping on the interference pattern of the selected adjacent image pair by using GAMMA software, specifically comprising:
firstly, selecting a stable point with coherence larger than 0.9 from interference patterns of adjacent image pairs;
secondly, selecting the azimuth direction and the distance direction of the stable point in the interference images of the adjacent image pairs, wherein the selection of the azimuth direction and the distance direction enables the stable point to be easily interpreted from the interference images of the adjacent image pairs;
and thirdly, selecting a coherence threshold value of the phase unwrapping based on the quality of the image to ensure the accuracy of a phase unwrapping result, wherein the coherence threshold value is set according to the actual situation.
S7, generating a single deformation graph: converting the phase unwrapping graph in the rectangular coordinate system into a polar coordinate system by using GAMMA software, and converting the phase unwrapping graph into a data format which can be processed by Matlab; in Matlab software, the phase values of the phase unwrapping map under the polar coordinate system are converted into deformation values, and a single deformation map is generated.
The single deformation graph is a deformation quantity graph of two adjacent moments of the observation area.
S8, generating a total deformation graph: and sequentially accumulating the deformation values of a plurality of groups of adjacent two-scene image pairs to generate a total deformation graph of each time period, dividing the total deformation graph of each time period by the accumulated observation time to obtain a rate graph, and analyzing the region of interest based on the total deformation graph and the rate graph.
The total deformation graph is a deformation accumulation graph of an observation time period, and a single deformation graph is accumulated by writing a program.
And in the steps S7 and S8, the GAMMA software and the Matlab program are combined to process the phase unwrapping map together to obtain a total deformation map, and the interesting region of the landslide is analyzed and researched based on the total deformation map.
In the embodiment, interference processing and phase unwrapping operation are carried out on adjacent two scene influence data acquired by a ground radar by utilizing GAMMA software to obtain a deformation graph and a velocity graph of a landslide body in the sight line direction; the deformation graph is shown in fig. 5, and the velocity graph is shown in fig. 6; the interpretation of fig. 5 and 6 shows that the deformation inside the landslide is uneven, the tension and the extrusion are carried out at multiple positions on the trailing edge and the sliding body, the accumulated deformation of the crack is continuously increased, the maximum displacement reaches 88cm in the observation period, and the deformation rate reaches 40 mm/day at most.
Based on fig. 5, the deformation time series of the point of interest on the landslide can be extracted separately, as shown in fig. 7, it can be known from fig. 7 that the deformation value of the selected point of interest steadily increases, and the deformation rate does not show obvious changes.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.