A highway crossing deep loose soil layer goaf settlement prediction method based on InSAR

Abstract

The application discloses a highway crossing deep loose soil layer goaf settlement prediction method based on InSAR, belongs to the technical field of road engineering, and discloses the main control factor of the highway construction site settlement above the high water level thick loose layer goaf based on InSAR ground surface deformation monitoring data, and discloses the space-time evolution law of the settlement basin settlement; the highway surface residual deformation prediction method crossing the goaf is proposed, which can not only be used for highway route selection, but also be used for route selection of other grades of roads, and can also be applied to railway route selection and other engineering site selection; can significantly reduce the large resource consumption caused by the common treatment measures, obviously reduce the field work load and the labor intensity of the staff in the goaf stability evaluation, and avoid the adverse effects of deep drilling on the site environment and underground water.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, specifically to an InSAR-based method for predicting settlement in mining subsidence areas where highways cross deep, loose soil layers. Background Technology

[0002] The development and utilization of mineral resources is an indispensable part of my country's economic development. Excessive underground coal mining easily leads to surface subsidence, resulting in deformation of buildings and railways, damage to land and water conservancy projects, and reduced agricultural yields. It is estimated that every 10,000 tons of coal mined causes 0.3 hectares of land subsidence, posing a serious threat to the safety of the nation and its people. Highways often have long routes, especially when they pass through areas with deep, loose soil layers above mined-out areas. Not only do these mined-out areas cause surface impacts, but groundwater extraction from these deep, loose soil layers also causes subsidence at the highway construction site. Current subsidence analysis mainly focuses on subsidence caused by mined-out areas. However, highways are typical linear projects with long lengths and wide construction areas. The inherent characteristics of highways make it difficult to accurately identify the main controlling factors of subsidence when highway construction crosses areas with deep, loose soil layers from coal mine mined-out areas.

[0003] Due to the lack of historical data monitoring of sites along highways, the stability of these sites can currently only be evaluated through empirical estimation and on-site investigation, which is no longer sufficient for engineering practice. In contrast, the InSAR (Interferometric Radar) technology, which has emerged in recent years, can quickly obtain the extent and deformation field of large-area subsidence basins and has been well applied in surface deformation monitoring.

[0004] Inverting settlement parameters based on SBAS-InSAR monitoring results, identifying risk points along highways, and constructing surface subsidence prediction models for these risk points are of significant practical importance for assessing the stability of highway construction sites. Therefore, this paper proposes an InSAR-based method for predicting settlement in mining subsidence areas where highways cross deep, loose soil layers. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to more effectively and accurately assess the stability of highway construction sites, and provides an InSAR-based method for predicting settlement of highways crossing deep loose soil layers and mining subsidence areas.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution, and the present invention includes the following steps:

[0007] S1: Extract historical topographic deformation data of highway construction sites based on SBAS-InSAR technology to generate a settlement distribution map of highway construction sites;

[0008] S2: Conduct on-site investigations and verifications of the basic conditions of highway construction sites, and collect geological and hydrological parameters of the highway construction sites;

[0009] S3: Select a function to fit the historical settlement data curve, invert the settlement characteristic parameters of the settlement basin, and analyze the settlement factors;

[0010] S4: Combine historical settlement data curves to construct a two-dimensional settlement prediction model and solve for the settlement prediction model parameters;

[0011] S5: Generate a three-dimensional spatial geological model of the subsidence basin using a two-dimensional subsidence prediction model;

[0012] S6: Based on the settlement factors, the size of the settlement basin area, the development direction, and the nearest distance to the highway, conduct a site evaluation for highway construction and design a treatment plan.

[0013] Furthermore, in step S1, when extracting historical topographic deformation data of highway construction sites based on SBAS-InSAR technology, time-series SAR images and satellite precise orbit files are obtained within the study area. All images are combined according to their time baseline and spatial baseline, and an interferogram is generated by selecting a set short temporal and spatial baseline pair. Then, deformation data of the study area is generated based on coherent point targets.

[0014] Furthermore, step S1 specifically includes the following processing procedures:

[0015] S11: Download SAR imagery of highway construction site targets and simultaneously obtain satellite precise orbit parameter files for the corresponding date SAR imagery;

[0016] S12: Register the input SAR images, combine and network the interferometric pairs with the set time and space baseline-threshold, generate the connection map, and perform differential interferometry on each image pair using the reference numerical elevation model.

[0017] S13: After the differential interferogram is generated, it undergoes 3D phase unwrapping processing. For each pair of interferometers, the corresponding interferometric filtering result and unwrapping map are generated. At the same time, the differential interferogram is transformed from the SAR coordinate system to the geographic coordinate system to confirm the location of suspected deformation points and realize a preliminary estimate of the deformation rate of the study area.

[0018] S14: After removing phase disturbances caused by factors such as noise, atmospheric phase error, and flat ground effect, geometric relationships are used to transform them to obtain the historical deformation of the entire area and generate a settlement distribution map of the highway construction site.

[0019] Furthermore, in step S11, the target SAR image history is no less than one year, and no less than two SAR images are acquired each month.

[0020] Furthermore, in step S2, the on-site investigation and verification of the basic conditions of the highway construction site, and the collection of geological and hydrological parameters of the highway construction site specifically include: investigating the settlement site of the deep loose soil goaf according to the settlement distribution map; and collecting information on the distribution of coal seams, mining conditions, physical properties of rock and soil layers, and distribution of groundwater levels around the deep loose soil goaf.

[0021] Furthermore, step S3 specifically includes the following processing procedures:

[0022] S31: Based on the settlement distribution map, areas where the degree of surface deformation reaches a set threshold are designated as key settlement risk areas. Taking the settlement center of the key settlement risk area as the origin, xyz coordinate axes are set, where the x-axis is perpendicular to the direction of the highway line, the y-axis is parallel to the direction of the highway line, and the z-axis represents ground settlement.

[0023] S32: Using historical topographic deformation data of highway construction sites extracted by SBAS-InSAR technology, draw two-dimensional curves of the subsidence basin surface in the plane perpendicular to the highway line along the xz coordinate axis, and draw two-dimensional curves of the subsidence basin surface in the plane parallel to the highway line along the yz coordinate axis.

[0024] S33: Based on the funnel shape of the surface subsidence basin, select Z x =b x +A x *exp(-0.5*((x-X0) / W x Equation )^2) and Z y =b y +A y *exp(-0.5*((y-Y0) / W y )^2) Fit the surface settlement curves of the xz plane and the yz axis respectively, where A x A y X0 and Y0 are used to determine the extreme values ​​of the equation, and W is used to determine the axes of symmetry of the equation. x W y Used to determine the opening amplitude of the equation, b x b y It is a correction of the equation value;

[0025] S34: Determine the factors related to coal mine goaf and groundwater irrigation extraction based on field investigation data; the determination criteria are as follows: (a) For Z x =b x +A x *exp(-0.5*((x-X0) / W x(a) If the extreme values ​​of the equation curve are consistent with the depth of the groundwater extraction irrigation well, the settlement boundary is consistent with the normal groundwater level, and the slope of the surface settlement curve is consistent with the slope of the additional stress settlement caused by the groundwater drop, then it can be preliminarily determined that the settlement is caused by groundwater extraction; (b) If the three conditions are not met simultaneously, but the unmet conditions are consistent with the results of the settlement extreme values, settlement boundaries, and curve slopes of the goaf calculated according to the technical document requirements, and the settlement area is located within the coal mining face of the coal mine, then it can be preliminarily determined that the settlement is caused by the goaf; (c) If the three conditions are not met simultaneously, and the characteristic values ​​of the goaf calculated according to the technical document requirements are not met, then another on-site investigation and analysis of other settlement factors should be conducted; (d) Taking Z y =b y +A y *exp(-0.5*((y-Y0) / W y The equation curve parameter values ​​are used to verify the initial judgment results. If the verification results are the same, the settlement factors are considered to be the same as the initial judgment results. If the verification results are different, other settlement factors are investigated and analyzed on site again.

[0026] Furthermore, in step S4, settlement prediction for key settlement risk areas is carried out based on the equation Z=b0+A*exp(-0.5*((x-X0) / W1)^2). Combined with historical settlement data curves, the development boundary of the settlement basin and the central settlement point are determined. The parameters of the settlement prediction model are solved, and a two-dimensional settlement prediction model is constructed. Specifically, the following processing steps are included:

[0027] S41: Suppose that the historical topographic deformation data of a highway construction site extracted based on SBAS-InSAR technology spans n months to the present. Fit the settlement curve Z of the settlement basin in the xz plane from n months ago to the present according to the equation Z=b0+A*exp(-0.5*((x-X0) / W1)^2). x-1 Settlement curve Z from n-1 months ago to present x-2 Settlement curve Z from n-2 months ago to present x-3 ..., Settlement curve Z from 1 month ago to present x-n -1, and statistically determine the settlement boundaries X1, X1', X2, X2', X3, X3'...X on both sides of each settlement curve. n-1 X n-1 ';

[0028] The settlement curves of the settlement basin from n months ago to the present are fitted to the equation Z = b0 + A*exp(-0.5*((x-X0) / W1)^2) on the yz plane. y-1 Settlement curve Z from n-1 months ago to present y-2 Settlement curve Z from n-2 months ago to present y-3 ..., Settlement curve Z from 1 month ago to presenty-n -1, and statistically determine the settlement boundaries Y1, Y1', Y2, Y2', Y3, Y3'...Y on both sides of each settlement curve. n-1 Y n- 1';

[0029] The central settlement C1, C2, C3...C is determined based on actual measured data. n-1 With the location of the settlement center as the axis of symmetry X 0f / Y 0f X 0f With Y 0f equal;

[0030] S42: Determine the subsidence basin boundary by fitting the surface subsidence curve. If the subsidence basin no longer develops, i.e., X1, X1', X2, X2', X3, X3'...X n-1 X n-1 If the value of X1, X2, X3...X remains unchanged, the boundary of the settlement basin can be determined; if the settlement basin is still developing, then the boundaries of X1, X2, X3...X can be determined. n-1 ,X1',X2',X3'......X n-1 The fitting process is performed to analyze the development trend of the settlement basin and determine the boundary X of the settlement basin m years after the highway is built. m With X m Similarly, determine the settlement basin boundary Y m years after the highway is completed. m With Y m ';

[0031] S43: Based on the statistical data of the central settlement of key settlement risk areas, C1, C2, C3...C n-1 By fitting the central settlement point, the settlement C at the central settlement point is predicted m years after the highway is built. m ;

[0032] S44: Let the equation of the settlement curve for the key settlement risk area be Z. x-f =b 0xf +A xf *exp(-0.5*((xX 0f ) / W xf )^2), Zy-f=b 0yf +A yf *exp(-0.5*((yY 0f ) / W yf )^2), based on the settlement basin boundary X m years after the highway is built m With X m ', The settlement C after m years from the completion of the highway m Solve the simultaneous equations to find A. xf A yf X 0f Y0f W xf W yf b 0xf b 0yf .

[0033] Furthermore, in step S5, the same height in the xz and yz plane surface subsidence curves is connected to form a three-dimensional spatial subsidence basin geological model to predict m years after the highway is built.

[0034] Furthermore, in step S6, if the predicted area and direction of the three-dimensional settlement basin intersect with the highway after m years, then the settlement factor is considered and the highway is treated in advance during the construction period; if the predicted area and direction of the three-dimensional settlement basin do not intersect with the highway after m years, then the highway is not treated.

[0035] Furthermore, in step S6, the specific handling plan is as follows:

[0036] When settlement is caused by coal mining and the expected impact of settlement on the highway construction site exceeds the set threshold, the highway alignment will be adjusted or the goaf will be grouted.

[0037] When the settlement is caused by coal mining and the expected impact of the settlement on the highway construction site is less than the set threshold, it is necessary to compact the site of the expected affected road section and reinforce the embankment.

[0038] If the subsidence is caused by groundwater extraction for irrigation or other factors, the highway construction site shall be dealt with according to the actual situation.

[0039] Compared with existing technologies, this invention has the following advantages: Based on InSAR surface deformation monitoring data, it summarizes the main controlling factors of settlement at highway construction sites above high groundwater level, thick loose layer goaf areas, and reveals the spatiotemporal evolution law of settlement basin settlement; it proposes a method for predicting residual surface deformation of highways across goaf areas, which can be used not only for highway route selection, but also for route selection of other road grades, as well as railway route selection and other engineering site selection; it can significantly reduce the large amount of resource consumption caused by commonly used treatment measures, significantly reduce the workload of field work for goaf stability evaluation and the labor intensity of staff, and at the same time avoid the adverse effects of deep drilling on the site environment and groundwater. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating the InSAR-based method for predicting settlement in mining subsidence areas where highways cross deep, loose soil layers, according to an embodiment of the present invention.

[0041] Figure 2 This is a flowchart illustrating step two in an embodiment of the present invention;

[0042] Figure 3This is a flowchart illustrating step three in an embodiment of the present invention;

[0043] Figure 4 This is a flowchart illustrating step four in an embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram (top view) showing the relative position of the settlement basin and the highway construction site in an embodiment of the present invention. Detailed Implementation

[0045] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0046] like Figure 1 As shown, this embodiment provides a technical solution: a method for predicting settlement of highways crossing deep loose soil layers and mining subsidence areas based on InSAR, including the following steps:

[0047] Step 1: Extract historical topographic deformation data of the highway construction site based on SBAS-InSAR technology and generate a settlement distribution map of the highway construction site;

[0048] Step 2: Conduct on-site investigation and verification of the basic conditions of the highway construction site, and collect geological and hydrological parameters of the highway construction site;

[0049] Step 3: Select a function to fit the historical settlement data curve, invert the settlement characteristic parameters of the settlement basin, and analyze the settlement factors;

[0050] Step 4: Combine historical settlement data curves to construct a two-dimensional settlement prediction model and solve for the settlement prediction model parameters;

[0051] Step 5: Generate a three-dimensional spatial geological model of the subsidence basin;

[0052] Step Six: Based on the settlement factors, the size of the settlement basin area, the development direction, and the nearest distance to the highway, conduct a site evaluation for highway construction and design a treatment plan.

[0053] In this embodiment, step one involves extracting historical topographic deformation data of the highway construction site based on SBAS-InSAR technology. The core of this step is acquiring time-series SAR images and precise satellite orbit files within the study area. All images are combined according to their temporal and spatial baselines, and shortest spatiotemporal baselines are selected to generate interferograms. Then, deformation data of the study area is generated based on coherent point targets, such as... Figure 2 As shown, the specific steps are as follows:

[0054] (1) Download SAR images of highway construction site targets. The historical period of the target SAR images should be no less than 1 year. To ensure accuracy, no less than 2 SAR images should be acquired each month. At the same time, obtain the satellite precise orbit parameter files of the SAR images for the corresponding dates.

[0055] (2) Register the input SAR images, combine and network the interferometric pairs with the set time and space baseline-threshold, generate the connection map, and use the reference numerical elevation model (DEM) to perform differential interferometric processing on each image pair.

[0056] (3) After the differential interferogram is generated, it is processed by 3D phase unwrapping. Each pair of interferograms generates an interferometric filtering result and an unwrapped map. At the same time, the differential interferogram is transformed from the SAR coordinate system to the geographic coordinate system to confirm the location of suspected deformation points and realize a preliminary estimate of the deformation rate of the study area.

[0057] (4) Further, after removing phase disturbances caused by factors such as noise, atmospheric phase error, and flat ground effect, geometric relationships are used to transform them to obtain the historical deformation of the entire area and generate a settlement distribution map of the highway construction site.

[0058] In this embodiment, step two involves conducting on-site investigations and verifications of the basic conditions of the highway construction site, and collecting geological and hydrological parameters of the highway construction site. Specifically, this includes investigating the settlement site of the deep loose soil goaf based on the settlement distribution map; and collecting relevant data such as the distribution of coal seams and mining conditions around the deep loose soil goaf, physical properties of the rock and soil layers, and the distribution of groundwater levels.

[0059] In this embodiment, as Figure 3 As shown, the specific steps of step three are as follows:

[0060] (1) Based on the settlement distribution map, areas where the surface has undergone significant deformation are designated as key settlement risk areas. The settlement center of the key settlement risk area is taken as the origin, and xyz coordinate axes are set, where the x-axis is perpendicular to the direction of the highway line, the y-axis is parallel to the direction of the highway line, and the z-axis represents the ground settlement.

[0061] (2) Using historical topographic data of highway construction sites extracted by SBAS-InSAR technology, draw two-dimensional curves of the surface of the subsidence basin in the plane perpendicular to the highway line along the xz coordinate axis, and draw two-dimensional curves of the surface of the subsidence basin in the plane where the highway line is located along the yz coordinate axis.

[0062] (3) Based on the funnel shape of the surface subsidence basin, select Z x =b x +A x *exp(-0.5*((x-X0) / W x Equation )^2) and Z y=b y +A y *exp(-0.5*((y-Y0) / W y )^2) Fit the surface settlement curves of the xz plane and the yz axis respectively, where A x A y X0 and Y0 are used to determine the extreme values ​​of the equation, and W is used to determine the axes of symmetry of the equation. x W y Used to determine the opening amplitude of the equation, b x b y It is a correction to the equation value, and its value is closely related to the settlement slope, settlement extreme value, and settlement boundary caused by settlement factors; "^2" means the square power.

[0063] (4) Determine the factors related to coal mine goaf and groundwater irrigation extraction based on field survey data; determination criteria: (a) Z x =b x +A x *exp(-0.5*((x-X0) / W x (a) Taking the equation curve as an example, if the extreme value is consistent with the depth of the groundwater extraction irrigation well, the settlement boundary is consistent with the normal groundwater level, and the slope of the surface settlement curve is consistent with the slope of the additional stress settlement caused by the groundwater drop, then it can be preliminarily determined that the settlement is caused by groundwater extraction; (b) If the three conditions cannot be met simultaneously, but the unmet conditions are consistent with the results of the settlement extreme value, settlement boundary, and curve slope of the goaf area calculated according to the requirements of the "Technical Specifications for Design and Construction of Highways in Goaf Areas", and the settlement area is located within the coal mining face of the coal mine, then it can be preliminarily determined that the settlement is caused by the goaf area; (c) If the three conditions cannot be met simultaneously, and the goaf area characteristic value calculated according to the requirements of the "Technical Specifications for Design and Construction of Highways in Goaf Areas" is not met, then another on-site investigation and analysis of other settlement factors should be conducted; (d) Taking Z y =b y +A y *exp(-0.5*((y-Y0) / W y The equation curve parameter values ​​are used to verify the initial judgment results. If the verification results are the same, the settlement factors are considered to be the same as the initial judgment results. If the verification results are different, other settlement factors are investigated and analyzed on site again.

[0064] In this embodiment, in step four, settlement prediction for key settlement risk areas is carried out based on the equation Z=b0+A*exp(-0.5*((x-X0) / W1)^2). Combined with historical settlement data curves, the development boundary of the settlement basin and the central settlement point are determined. The parameters of the settlement prediction model are solved, and a two-dimensional settlement prediction model is constructed, as follows: Figure 4 As shown, the specific steps are as follows:

[0065] (1) Suppose that the time span from the extraction of historical topographic deformation data of highway construction sites based on SBAS-InSAR technology to the present is n months. Fit the settlement curve Z of the settlement basin in the xz plane from n months ago to the present according to the equation Z=b0+A*exp(-0.5*((x-X0) / W1)^2). x-1 Settlement curve Z from n-1 months ago to present x-2 Settlement curve Z from n-2 months ago to present x-3 ..., Settlement curve Z from 1 month ago to present x-n-1 And the settlement boundaries X1, X1', X2, X2', X3, X3'...X on both sides of each settlement curve were statistically determined. n-1 X n-1 ';

[0066] The settlement curves of the settlement basin from n months ago to the present are fitted to the equation Z = b0 + A*exp(-0.5*((x-X0) / W1)^2) on the yz plane. y-1 Settlement curve Z from n-1 months ago to present y-2 Settlement curve Z from n-2 months ago to present y-3 ..., Settlement curve Z from 1 month ago to present y-n -1, and statistically determine the settlement boundaries Y1, Y1', Y2, Y2', Y3, Y3'...Y on both sides of each settlement curve. n-1 Y n- 1';

[0067] The central settlement C1, C2, C3...C is determined based on actual measured data. n-1 ;

[0068] (2) The boundary of the subsidence basin is determined by the fitted surface subsidence curve. If the subsidence basin no longer develops, i.e., X1, X1', X2, X2', X3, X3'...X n-1 X n-1 If the value of X1, X2, X3...X remains unchanged, the boundary of the settlement basin can be determined; if the settlement basin is still developing, then the boundaries of X1, X2, X3...X can be determined. n-1 ,X1',X2',X3'......X n-1 The fitting process is performed to analyze the development trend of the settlement basin and determine the boundary X of the settlement basin m years after the highway is built. m With X m Similarly, determine the settlement basin boundary Y m years after the highway is completed. m With Y m ’ ;

[0069] (3) Based on the statistical data of the central settlement of key settlement risk areas C1, C2, C3...C n-1By fitting the central settlement point, the settlement C at the central settlement point is predicted m years after the highway is built. m With the location of the settlement center as the axis of symmetry X 0f / Y 0f X 0f With Y 0f equal;

[0070] (4) Let the equation of the settlement curve for the key settlement risk area be Z. x-f =b 0xf +A xf *exp(-0.5*((xX 0f ) / W xf )^2)Z y-f =b 0yf +A yf *exp(-0.5*((yY 0f ) / W yf )^2), based on the settlement basin boundary X m years after the highway is built m With X m ', The settlement C after m years from the completion of the highway m Solve the simultaneous equations to find A. xf A yf X 0f Y 0f W xf W yf b 0xf b 0yf .

[0071] In this embodiment, in step five, as Figure 4 As shown, the same height in the xz and yz plane surface settlement curves is connected to form a three-dimensional spatial settlement basin geological model m years after the highway is built.

[0072] In this embodiment, in step six, if the predicted area and direction of the three-dimensional settlement basin after m years intersect with the highway, then the settlement factor is considered and the highway is treated in advance during the construction period; if the predicted area and direction of the three-dimensional settlement basin after m years do not intersect with the highway, then the highway does not need to be treated.

[0073] In this embodiment, the specific handling scheme for step six is ​​as follows:

[0074] If the settlement is caused by coal mining and is expected to have a significant impact on the highway construction site, the highway alignment needs to be adjusted or the goaf needs to be grouted.

[0075] If the settlement is caused by coal mining and the impact on the highway construction site is expected to be small, the site of the expected affected road section needs to be compacted and the embankment needs to be reinforced.

[0076] If the subsidence is caused by groundwater extraction for irrigation or other factors, the highway construction site should be dealt with according to the actual situation.

[0077] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for predicting settlement of highways crossing deep loose soil layers and mining subsidence areas based on InSAR, characterized in that, Includes the following steps: S1: Extract historical topographic deformation data of highway construction sites based on SBAS-InSAR technology to generate a settlement distribution map of highway construction sites; S2: Conduct on-site investigations and verifications of the basic conditions of highway construction sites, and collect geological and hydrological parameters of the highway construction sites; S3: Select a function to fit the historical settlement data curve, invert the settlement characteristic parameters of the settlement basin, and analyze the settlement factors; S4: Combine historical settlement data curves to construct a two-dimensional settlement prediction model and solve for the settlement prediction model parameters; S5: Generate a three-dimensional spatial geological model of the subsidence basin using a two-dimensional subsidence prediction model; S6: Based on settlement factors, the size of the settlement basin area, the development direction, and the nearest distance to the highway, conduct a site evaluation for highway construction and design a treatment plan; Step S3 specifically includes the following processing procedures: S31: Based on the settlement distribution map, areas where the degree of surface deformation reaches a set threshold are designated as key settlement risk areas. Taking the settlement center of the key settlement risk area as the origin, xyz coordinate axes are set, where the x-axis is perpendicular to the direction of the highway line, the y-axis is parallel to the direction of the highway line, and the z-axis represents ground settlement. S32: Using historical topographic deformation data of highway construction sites extracted by SBAS-InSAR technology, draw two-dimensional curves of the subsidence basin surface in the plane perpendicular to the highway line along the xz coordinate axis, and draw two-dimensional curves of the subsidence basin surface in the plane parallel to the highway line along the yz coordinate axis. S33: Based on the funnel shape of the surface subsidence basin, select Z x =b x +A x *exp(-0.5*((x-X0) / W x Equation )^2) and Z y =b y +A y *exp(-0.5*((y-Y0) / W y )^2) Fit the surface settlement curves of the xz plane and the yz axis respectively, where A x A y X0 and Y0 are used to determine the extreme values ​​of the equation, and W is used to determine the axes of symmetry of the equation. x W y Used to determine the opening amplitude of the equation, b x b y It is a correction of the equation value; S34: Determine the factors related to coal mine goaf and groundwater irrigation extraction based on field investigation data; the determination criteria are as follows: (a) For Z x =b x +A x *exp(-0.5*((x-X0) / W x (a) If the extreme value of the equation curve is consistent with the depth of the groundwater extraction irrigation well, the settlement boundary is consistent with the normal groundwater level, and the slope of the surface settlement curve is consistent with the slope of the additional stress settlement caused by the groundwater drop, then it can be preliminarily determined that the settlement is caused by groundwater extraction; (b) If the three conditions cannot be met simultaneously, but the unmet conditions are consistent with the results of the settlement extreme value, settlement boundary, and curve slope of the goaf calculated according to the technical document requirements, and the settlement area is located within the coal mining face of the coal mine, then it can be preliminarily determined that the settlement is caused by the goaf; (c) If the three conditions cannot be met simultaneously, and the characteristic value of the goaf calculated according to the technical document requirements is not met, then another on-site investigation and analysis of other settlement factors should be conducted; (d) Taking Z y =b y +A y *exp(-0.5*((y-Y0) / W y The equation curve parameter values ​​are used to verify the initial judgment results. If the verification results are the same, the settlement factors are considered to be the same as the initial judgment results. If the verification results are different, other settlement factors are investigated and analyzed on site again.

2. The method for predicting settlement of highways crossing deep loose soil layers in mining subsidence areas based on InSAR according to claim 1, characterized in that: In step S1, when extracting historical topographic deformation data of highway construction sites based on SBAS-InSAR technology, time-series SAR images and satellite precise orbit files are obtained within the study area. All images are combined according to their time baseline and spatial baseline, and an interferogram is generated by selecting the shortest possible time-space baseline pair. Then, deformation data of the study area is generated based on coherent point targets.

3. The InSAR-based method for predicting settlement in mining subsidence areas where highways cross deep loose soil layers, as described in claim 2, is characterized in that: Step S1 specifically includes the following processing procedures: S11: Download SAR imagery of highway construction site targets and simultaneously obtain satellite precise orbit parameter files for the corresponding date SAR imagery; S12: Register the input SAR images, combine and network the interferometric pairs with the set time and space baseline-threshold, generate the connection map, and perform differential interferometry on each image pair using the reference numerical elevation model. S13: After the differential interferogram is generated, it undergoes 3D phase unwrapping processing. For each pair of interferometers, the corresponding interferometric filtering result and unwrapping map are generated. At the same time, the differential interferogram is transformed from the SAR coordinate system to the geographic coordinate system to confirm the location of suspected deformation points and realize a preliminary estimate of the deformation rate of the study area. S14: After removing phase disturbances caused by factors such as noise, atmospheric phase error, and flat ground effect, geometric relationships are used to transform them to obtain the historical deformation of the entire area and generate a settlement distribution map of the highway construction site.

4. The InSAR-based method for predicting settlement in mining subsidence areas where highways cross deep loose soil layers, as described in claim 3, is characterized in that: In step S11, the target SAR image history is no less than 1 year, and no less than 2 SAR images are acquired each month.

5. A method for predicting settlement of highways crossing deep loose soil layers in mining subsidence areas based on InSAR, as described in claim 3, characterized in that: In step S2, the on-site investigation and verification of the basic conditions of the highway construction site and the collection of geological and hydrological parameters of the highway construction site specifically include: investigating the settlement site of the deep loose soil goaf according to the settlement distribution map; and collecting information on the distribution of coal seams, mining conditions, physical properties of rock and soil layers and distribution of groundwater levels around the deep loose soil goaf.

6. A method for predicting settlement of highways crossing deep loose soil layers and mining subsidence areas based on InSAR, as described in claim 5, is characterized in that: In step S4, settlement prediction for key settlement risk areas is carried out based on the equation Z=b0+A*exp(-0.5*((x-X0) / W1)^2). Combined with historical settlement data curves, the development boundary of the settlement basin and the central settlement point are determined. The parameters of the settlement prediction model are solved, and a two-dimensional settlement prediction model is constructed. Specifically, the following processing steps are included: S41: Suppose that the historical topographic deformation data of the highway construction site extracted based on SBAS-InSAR technology spans n months to the present. Fit the settlement curve Z of the settlement basin in the xz plane from n months ago to the present according to the equation Z=b0+A*exp(-0.5*((x-X0) / W1)^2). x-1 Settlement curve Z from n-1 months ago to present x-2 Settlement curve Z from n-2 months ago to present x-3 ..., Settlement curve Z from 1 month ago to present x-n-1 And the settlement boundaries X1 and X1' on both sides of each settlement curve were calculated. ＇ X2, X2 ＇ X3, X3 ＇ ...X n-1 X n-1 ＇ ; The settlement curves of the settlement basin from n months ago to the present are fitted to the yz plane according to the equation Z=b0+A*exp(-0.5*((x-X0) / W1)^2). y-1 Settlement curve Z from n-1 months ago to present y-2 Settlement curve Z from n-2 months ago to present y-3 ..., Settlement curve Z from 1 month ago to present y-n -1, and statistically determine the settlement boundaries Y1, Y1', Y2, Y2', Y3, Y3'...Y on both sides of each settlement curve. n-1 Y n-1 '; The central settlement C1, C2, C3...C is determined based on actual measured data. n-1 With the location of the settlement center as the axis of symmetry X 0f / Y 0f X 0f With Y 0f equal; S42: Determine the subsidence basin boundary by fitting the surface subsidence curve. If the subsidence basin no longer develops, i.e., X1, X1 ＇ X2, X2 ＇ X3, X3 ＇ ...X n-1 X n-1 ＇ If the boundary of the settlement basin no longer changes, then the boundary can be determined; if the settlement basin is still developing, then for X1, X2, X3...X n-1 X1 ＇ X2 ＇ X3 ＇ ...X n-1 ＇ By performing fitting analysis, the development trend of the settlement basin is analyzed, and the boundary X of the settlement basin is determined m years after the highway is built. m With X m ＇ Similarly, determine the settlement basin boundary Y m years after the highway is completed. m With Y m ’ ; S43: Based on the statistical data of the central settlement of key settlement risk areas, C1, C2, C3...C n-1 By fitting the central settlement point, the settlement C at the central settlement point is predicted m years after the highway is built. m ; S44: Let the equation of the settlement curve for the key settlement risk area be Z. x-f =b 0xf +A xf *exp(-0.5*((xX 0f ) / W xf )^2)Z y-f =b 0yf +A yf *exp(-0.5*((yY 0f ) / W yf )^2), based on the settlement basin boundary X m years after the highway is built m With X m ＇ The settlement C after m years from the completion of the highway m Solve the simultaneous equations to find A. xf A yf X 0f Y 0f W xf W yf b 0xf b 0yf .

7. A method for predicting settlement of highways crossing deep loose soil layers and mining subsidence areas based on InSAR according to claim 6, characterized in that: In step S5, the same height in the xz and yz plane surface subsidence curves is connected to form a three-dimensional spatial subsidence basin geological model to predict m years after the highway is built.

8. A method for predicting settlement of highways crossing deep loose soil layers and mining subsidence areas based on InSAR, as described in claim 7, characterized in that: In step S6, if the predicted area and direction of the three-dimensional settlement basin after m years intersect with the highway, then the settlement factor is considered and the highway is treated in advance during the construction period; if the predicted area and direction of the three-dimensional settlement basin after m years do not intersect with the highway, then the highway is not treated.

9. A method for predicting settlement of highways crossing deep loose soil layers and mining subsidence areas based on InSAR, as described in claim 8, characterized in that: In step S6, the specific handling plan is as follows: When settlement is caused by coal mining and the expected impact of settlement on the highway construction site exceeds the set threshold, the highway alignment will be adjusted or the goaf will be grouted. When the settlement is caused by coal mining and the expected impact of the settlement on the highway construction site is less than the set threshold, the site of the expected affected road section will be compacted and the embankment will be reinforced. If the subsidence is caused by groundwater extraction for irrigation or other factors, the highway construction site shall be dealt with according to the actual situation.

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