Evaluating expressway stability using interferometric synthetic aperture radar and measuring its impact on the occurrence of geohazards: a case study of Shanxi Province, China

Figures & data

Figure 1. Map of Shanxi Province and data coverage. Sentinel-1 frames are delineated with blue boxes; expressway network is shown in grey line; orange and red dots are the location of subsidence/fissure and landslide, respectively; and the purple triangle denotes the location of GNSS station.

Table 1. Detailed data information of SAR acquisitions.

Tile identifier	Acquisition dates*	Total acquisitions
P11F121	20170312 ~ 20211204	58
P11F116	20170312 ~ 20211204	58
P11F111	20170312 ~ 20211204	58
P113F126	20170319 ~ 20211223	58
P113F121	20170319 ~ 20211223	58
P113F116	20170319 ~ 20211223	58
P113F111	20170319 ~ 20211223	58
P40F127	20170314 ~ 20211230	58
P40F122	20170314 ~ 20211230	58
P40F117	20170314 ~ 20211230	58

(Acquisition dates are represented in yyyymmdd format.).

Figure 2. Flow chart of the stacking workflow used in this study. SLC: single-look complex; MCF: minimum cost flow; SCWU: Supercomputing center of Wuhan University.

Figure 3. Comparison of deformation rate before and after mosaicking and adjustment. Left column is the location indicator of the zoom-ins; A.Before and B.Before are the deformation rate before mosaicking and adjustment; A.After and B.After are the deformation rate after mosaicking and adjustment.

Figure 4. Factors of geohazards assessed in the binary logistic regression. a. Random hazard points. b. Deformation rate. c. Elevation. d. Gradient. e. Annual precipitation. f. Bedrock hardness. g. Stream distribution. h. Fault distribution. i. Traffic load.

Table 2. Detailed data information and preparation strategy.

Factor layer	Data type	Source	Data preparation
Elevation	Raster	ALOS DEM	The elevation is the same as the external DEM used in the InSAR process, with a resolution of 12.5m.
Gradient	Raster	ALOS DEM	The gradient was generated using ALOS DEM with the help of ArcGIS software.
Precipitation	Vector	National Tibetan Plateau Data Center	The precipitation is generated by averaging the precipitation of Shanxi Province from 2000 to 2020.
Bedrock hardness	Raster	National Geological Archives of China	The bedrock hardness map is generated based on the lithology extracted from the 1:200000 geological map released in 2017.
Stream distribution	Vector	ALOS DEM	The stream is extracted from ALOS DEM using ArcGIS software, and used to determine the distance between point and nearest stream.
Fault distribution	Vector	National Geological Archives of China	The fault is extracted from the 1:200000 geological map released in 2017, and used to determine the distance between point and nearest fault.
Traffic load	Vector	Department of Transportation of Shanxi	The traffic load data is calculated by averaging the annual data from 2017 to 2020, and assigned to the expressway network shape file using ArcGIS.

Figure 5. Deformation rate map of Shanxi Province. Negative value represents subsiding, positive value represents uplifting.

Figure 6. Deformation rate map of the expressway network in Shanxi Province. Negative value represents subsiding, positive value represents uplifting.

Figure 7. Comparison between InSAR results and GNSS data.

Figure 8. Results of the binary logistic regression analysis for the eight factors. a. Deformation rate. b. Elevation. c. Gradient. d. Annual precipitation. e. Bedrock hardness. f. Distance to stream. g. Distance to fault. h. Traffic load. VIF: variance inflation factor; sig: significance.

Table 3. Statistical table of pixel count and percentage in each deformation rate interval.

Interval (mm/year)	Pixel count	Percentage
<-20	7725	0.03%
[−20, −15]	212331	0.72%
[−15, −10]	825201	2.80%
[−10, −5]	3547684	12.03%
[−5, 0]	11508127	39.03%
[0, 5]	9607595	32.58%
[5, 10]	2898753	9.83%
[10, 15]	708745	2.40%
[15, 20]	167897	0.57%
>20	3184	0.01%

Data availability statement

Sentinel-1 SAR data can be downloaded from https://scihub.copernicus.eu/; Orbit state data can be downloaded from https://s1qc.asf.alaska.edu/aux_poeorb/; And ALOS PRISM DEM data can be downloaded from https://asf.alaska.edu/; The precipitation data is obtained from National Tibetan Plateau Data Center (http://www.ngac.org.cn/); The bedrock hardness and fault map are obtained from the 1:200000 geological map from National geological archives of China (http://www.tpdc.ac.cn/).