A method for determining potential landslide areas based on InSAR and borehole imaging technology

Abstract

The present invention discloses a method for determining a potential landslide area based on InSAR and borehole photography technology, which adopts the following technical scheme: S1 selects the scope of a research area and InSAR technical means; S2 obtains historical InSAR image data of different time domains and processes the data; S3 obtains the surface deformation rate of multiple time domains in the research area, extracts the surface deformation displacement time curve in the research area, comprehensively determines the threshold value of the surface deformation rate of landslide risk according to the historical image, topographic data and displacement time curve, and determines the position and scope of the potential landslide body in the research area; S4 arranges boreholes in the potential landslide body area, collects digital image information in the boreholes by means of borehole photography equipment, and S5 determines the joint inclination angle in the rock body by analyzing the digital image of the borehole, outlines the contour line of the potential sliding surface, and determines the depth of the potential landslide body. The present invention can not only accurately and quickly determine the position and scope of the landslide, avoid large-scale and inefficient on-site surveys, but also improve work efficiency and accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of slope engineering, and more particularly to a method for determining a potential landslide area based on InSAR and borehole photography technology. Background Art

[0002] Landslides have always occurred around the world, whether they are natural slopes or artificial slopes. Once they occur, they will pose a huge threat to social public safety and economic development. However, the occurrence of landslides is not only affected by natural factors (such as geological structure, rock mechanical properties, rainfall, earthquakes, etc.), but also related to human engineering activities (engineering excavation, mining, etc.). However, no matter what factors induce landslide geological disasters, if disaster identification can be carried out before the landslide occurs, the deformation and displacement precursor information of the landslide body can be accurately captured, and the location, scope and depth of the potential landslide body can be identified, it will not only provide powerful data for disaster risk assessment, but also provide support information for disaster emergency response and major project site selection.

[0003] The existing methods for determining potential landslide areas include manual survey, remote sensing measurement, and mechanical or mathematical model analysis. Among them, the manual survey method is to conduct geological surveys in the mining area by human means, using equipment such as compasses, steel rulers, and inclinometers to investigate the slope, but this method is inefficient, has a long evaluation cycle, and is costly. In addition, the geological exploration drilling method only focuses on the integrity of the extracted core, ignoring the intrinsic correlation between the occurrence of joints and fissures inside the rock mass and the formation of landslides.

[0004] Remote sensing measurement refers to the use of advanced remote sensing measurement methods, such as synthetic aperture radar interferometry, drones and other technical equipment, to measure and analyze objects within the assessment range to determine the location of potential landslides. The problem with this method is that it can only characterize the deformation of the slope surface and does not provide any information about the interior of the landslide. However, the occurrence of landslides is not only related to the deformation of the slope surface, but more importantly, it is related to the mechanical properties of the rock mass, the occurrence of the structural surface and the state of groundwater in the slope. Ignoring the internal information of the slope will lead to serious errors in the assessment results.

[0005] The mechanical or mathematical model analysis method is to analyze the mechanical state of the slope at a typical location and use mathematical means to calculate and solve. This method requires the evaluator to have professional knowledge and ability. In addition, the mathematical model is often greatly simplified, resulting in poor accuracy of the evaluation results. In addition, the boundary conditions are complex during the calculation, and there will be non-convergence and other situations that make it impossible to perform the calculation.

[0006] Therefore, it is an urgent problem for those skilled in the art to propose a method that can more accurately and quickly determine the location, scope and depth of potential landslides. Summary of the invention

[0007] In view of this, in order to more conveniently and quickly determine the location, range and depth of potential landslides, the present invention provides a method for determining potential landslide areas based on InSAR and borehole imaging technology.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] S1. Select the research area and InSAR technology;

[0010] S2, obtain historical InSAR image data in different time domains and process the data;

[0011] S3. Obtain the multi-time domain surface deformation rate in the study area, and extract the surface deformation displacement time curve in the study area, comprehensively determine the landslide risk surface deformation rate threshold value based on historical images, topographic data and displacement time curve, and determine the location and range of potential landslide bodies in the study area based on the surface deformation threshold value;

[0012] S4. Drill holes are arranged in the potential landslide area, and digital image information inside the boreholes is collected with the help of borehole camera equipment.

[0013] S5. Determine the inclination angle of joints in the rock mass by analyzing the digital images of the borehole, outline the contour of the potential sliding surface, and determine the depth of the potential landslide.

[0014] Preferably, the InSAR technical means in step S1 include, but are not limited to, D-InSAR, GB-InSAR, PSInSAR or SBAS-InSAR.

[0015] Preferably, in step S2, acquiring historical InSAR image data in different time domains refers to providing single-view complex image data for InSAR monitoring.

[0016] Preferably, in step S2, processing the data refers to combining the acquired SAR images into image pairs and selecting the satellite image at the start time as the reference image.

[0017] Preferably, in step S2, the data is processed by performing registration, resampling, interference and flattening, phase unwrapping, trajectory refinement, error removal and geocoding on the basis of the reference image.

[0018] Preferably, in step S3, obtaining multi-time domain surface deformation rates and extracting the surface deformation displacement time curve at a typical location means obtaining the surface cumulative deformation rate in the WGS84 coordinate system from the processed SAR data in step S2, and obtaining the displacement change over time information by analyzing the fringes of InSAR interferometric images in different time domains.

[0019] Preferably, in step S3, the threshold value of the surface deformation rate for landslide risk is comprehensively determined based on historical images, topographic data and displacement time curves, which means that the terrain changes in the assessment area are comprehensively analyzed and evaluated in combination with the InSAR surface deformation rate cloud map and the displacement curve of typical positions to determine the allowable cumulative deformation value, and abnormal deformation data are analyzed and identified, which helps to improve the accuracy of judgment.

[0020] Preferably, in step S3, the location and range of the potential landslide body in the study area is determined based on the surface deformation threshold value, which means that the area with deformation greater than the threshold value after removing abnormal data is determined as the potential landslide body location. Since the landslide area is exactly the area with large surface cumulative deformation, the range of the potential landslide body is delineated according to the InSAR surface cumulative deformation value.

[0021] Preferably, in step S4, drilling holes are arranged in the potential landslide area, which means that the potential landslide position is determined in step S3, and various types of drilling holes are arranged, including but not limited to plum blossom, triangle, diamond and zigzag shapes.

[0022] Preferably, in step S5, the inclination angle of the joint is determined by analyzing the digital image of the borehole, and the contour line of the potential sliding surface is outlined. This means that by analyzing the digital image in the borehole and marking the dominant joints on the map, the contour line of the control structure surface is the contour line of the potential sliding surface, wherein the dominant joint refers to the joint width in the borehole image>10.0mm and the inclination angle is greater than 60°.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] The beneficial effects of the present invention are as follows: the present invention combines InSAR surface deformation with digital borehole photography technology, and applies it to the identification of the position, range and depth of potential landslide bodies, which can not only accurately and quickly determine the position and range of landslides, but also avoid large-scale and inefficient on-site surveys, greatly improve work efficiency and accuracy, and reduce costs; digital borehole photography determines the depth of potential sliding surfaces, effectively making up for the deficiency that InSAR cannot provide information about the inside of the rock mass, and can fully characterize the distribution state of joints inside the rock mass; from the whole to the part, from the surface to the inside, from the macro to the micro, multi-level and multi-angle data comprehensive analysis not only provides powerful data for disaster risk assessment, but also provides supporting information for disaster emergency response and site selection of major projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow chart of the present invention;

[0026] Figure 2 A schematic diagram of a potential sliding surface determined by digital drilling photography of the present invention;

[0027] In the figure, 1 is the slope of the study area, 2 is the computer, 3 is the depth pulse transmitter, 4 is the cable winch, 5 is the panoramic probe, 6 is the borehole, 7 is the joint dip angle, and 8 is the potential sliding surface. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] The embodiment of the present invention discloses a method for determining a potential landslide area based on InSAR and borehole imaging technology, comprising the following steps:

[0031] S1. Select the research area and InSAR technology;

[0032] In a specific embodiment, step S1 selects a 2km×2km rectangular range as the study area, and the target slope is located in the middle of the study area. In view of the advantages of short baseline SBAS-InSAR technology, D-InSAR, GB-InSAR or PSInSAR can also be selected as the InSAR technical means for the implementation example.

[0033] D-InSAR is synthetic aperture radar differential interferometry, GB-InSAR is ground-based radar differential interferometry, PS-InSAR is synthetic aperture radar permanent scatterer interferometry, and SBAS-InSAR is short baseline set interferometry.

[0034] The purpose of selecting the InSAR technical means in step S1 is to select a suitable technical method according to the geological conditions, vegetation conditions and building distribution in the study area, which can not only effectively improve the evaluation accuracy, but also avoid data anomalies caused by terrain, vegetation and buildings.

[0035] S2, obtain historical InSAR image data in different time domains and process the data;

[0036] In a specific embodiment, step S2 obtains 26 radar images of the study area from November 22, 2015 to April 8, 2021 from the European Space Agency's Sentinel satellite by purchasing image data from a data supplier, and selects the 20180908 image as the reference image of the image sequence. On this basis, data alignment, resampling, interference and flattening, phase unwrapping, orbit refinement, error removal and geocoding are performed.

[0037] Image data are collected by spaceborne radar sensors, including but not limited to RadarSAT-2, Cosmo-SkyMed, TerraSAR-X, ALOS-2, Sentinel-1A / 1B or PAZ. Multi-time domain SAR image data in the study area can be obtained by searching relevant websites or purchasing from commercial satellite agents.

[0038] S3. Obtain the surface deformation rate in multiple time domains and extract the surface deformation displacement time curve of key points in the study area. According to the historical images, topographic data and displacement time curve, comprehensively determine the threshold value of the surface deformation rate for landslide risk. Based on the threshold value of the surface deformation, determine the location and range of the potential landslide body in the study area.

[0039] In step S3, obtaining the multi-time domain surface deformation rate in the study area and extracting the surface deformation displacement time curve in the study area refers to converting the processed SAR data in step S2 into the surface cumulative deformation rate in the WGS84 coordinate system, and obtaining the displacement change over time information by analyzing the fringes of the InSAR interferometric images in different time domains;

[0040] In step S3, the location and range of the potential landslide body in the study area are determined based on the threshold value of surface deformation, which means that the area with deformation greater than the threshold value after removing abnormal data is determined as the location of the potential landslide body. Since the landslide area is exactly the area with large surface cumulative deformation, the range of the potential landslide body is delineated according to the InSAR surface cumulative deformation value;

[0041] In a specific embodiment, step S3 obtains a distribution cloud map of the surface cumulative deformation rate in the study area, extracts 12 points as key points of the study area and draws a displacement time curve, and determines that the threshold value of the surface deformation rate for landslide risk is 20 mm / year based on historical images, topographic data and displacement time curves, and determines the range where the InSAR surface cumulative deformation rate is greater than the threshold value as the potential landslide body range, thereby determining the potential landslide area in the northeast of the study area.

[0042] S4. Drill holes are arranged in the potential landslide area, and digital image information inside the boreholes is collected with the help of borehole camera equipment.

[0043] In a specific embodiment, step S4 selects the inclined slope surface to arrange plum blossom-shaped drilling holes, or triangles, or diamonds, or zigzags, and the drilling camera equipment model is BHCTV, such as Figure 2 As shown, a plum blossom-shaped borehole 6 is arranged on the slope surface of the slope 1 in the study area, and a computer 2 and a depth pulse transmitter 3 are connected. At the same time, a cable winch 4 of a BHCTV model drilling camera equipment is laid, and a panoramic probe 5 is slowly lowered into the borehole 6. The collected digital image data of the borehole is observed in real time on the computer 2.

[0044] The cores taken out after drilling can not only be used to evaluate the integrity of the rock mass through the RQD rock quality index, but can also be used as a direct means to determine the lithology of the slope.

[0045] In step S4, the RQD rock quality index can be calculated using the formula:

[0046]

[0047] According to the core quality index, the rock mass is divided into 5 categories, see Table 1 below

[0048] Table 1 Rock quality index table

[0049]

[0050] S5. Determine the inclination angle of joints in the rock mass by analyzing the digital images of the borehole, outline the contour of the potential sliding surface, and determine the depth of the potential landslide.

[0051] In a specific embodiment, the inclination angle 7 of the joints is determined by analyzing the digital image of the borehole 6, and the inclination angle 7 of the joints inside the rock mass is determined to be 66° by comparing multiple groups of joints in the borehole 6. The potential sliding surface 8 is determined by multiple groups of digital images in the borehole 6, and the distance between the joints in the borehole and the ground surface is measured, and the depth of the potential sliding surface is obtained to be 12.7 meters.

[0052] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining potential landslide areas based on InSAR and borehole imaging technology, characterized in that: The following steps are involved: S1. Select the research area and InSAR technology; S2, obtain historical InSAR image data in different time domains and process the data; S3. Obtain the surface deformation rate in multiple time domains and extract the surface deformation displacement time curve in the study area. According to the historical images, topographic data and displacement time curve, comprehensively determine the threshold value of the surface deformation rate for landslide risk. Based on the threshold value of the surface deformation, determine the location and range of the potential landslide body in the study area. S4. Drill holes are arranged in the potential landslide area, and digital image information in the boreholes is collected by means of drilling camera equipment; S5. Determine the inclination angle of the dominant joints in the rock mass by analyzing the digital image of the borehole, outline the contour of the potential sliding surface, and achieve the purpose of determining the depth of the potential landslide body; In step S5, the dip angle of the joints is determined by analyzing the digital image of the borehole and the contour line of the potential sliding surface is outlined, which means that the digital image in the borehole is analyzed and the joints are marked on the map, and the contour line of the control structure surface is the contour line of the potential sliding surface, wherein the dominant joint refers to the joint width in the borehole image>10.0mm and the dip angle is greater than 60°.

2. The method for determining potential landslide areas based on InSAR and borehole imaging technology according to claim 1, characterized in that: The InSAR technology in step S1 is D-InSAR, GB-InSAR, PSInSAR or SBAS-InSAR.

3. The method for determining potential landslide areas based on InSAR and borehole imaging technology according to claim 1, characterized in that: In step S2, acquiring InSAR historical image data in different time domains means providing single-view complex image data for InSAR monitoring; In step S2, processing the data refers to combining the acquired SAR images into image pairs, selecting the start time satellite image as the reference image; and performing registration, resampling, interference and flattening, phase unwrapping, orbit refinement, error removal and geocoding on the basis of the reference image.

4. The method for determining potential landslide areas based on InSAR and borehole imaging technology according to claim 1, characterized in that: In step S3, obtaining the multi-time domain surface deformation rate in the study area and extracting the surface deformation displacement time curve in the study area refers to converting the processed SAR data in step S2 into the surface cumulative deformation rate in the WGS84 coordinate system, and obtaining the displacement change over time information by analyzing the fringes of the InSAR interferometric images in different time domains; In step S3, the threshold value of the landslide risk surface deformation rate is determined comprehensively based on historical images, topographic data and displacement time curves, which means that the terrain changes in the study area are comprehensively analyzed, and the allowable cumulative deformation value is determined in combination with the InSAR surface deformation rate and the displacement curve of the typical position; In step S3, the location and range of the potential landslide body in the study area are determined based on the surface deformation threshold value, which means that the area with deformation greater than the threshold value after removing abnormal data is determined as the location of the potential landslide body. Since the landslide area is exactly the area with large surface cumulative deformation, the range of the potential landslide body is delineated according to the InSAR surface cumulative deformation value.

5. The method for determining potential landslide areas based on InSAR and borehole imaging technology according to claim 1, characterized in that: In the step S4, drilling holes are arranged in the potential landslide area; this means that the potential landslide position is determined in the step S3, and various forms of drilling holes are arranged, including plum blossom, triangle, diamond and zigzag shapes.

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