Precise Topographic Model Assisted Slope Displacement Retrieval from Small Baseline Subsets Results: Case Study over a High and Steep Mining Slope.

Lianhuan Wei,Tianhong Yang,Cristiano Tolomei,Christian Bignami,Yachun Mao,Feiyue Liu,Lixin Wu,Shanjun Liu,Qiuyue Feng

doi:10.3390/s20226674

Abstract

Due to the intrinsic side-looking geometry of synthetic aperture radar (SAR), time series interferometric SAR is only able to monitor displacements in line-of-sight (LOS) direction, which limits the accuracy of displacement measurement in landslide monitoring. This is because the LOS displacement is only a three dimensional projection of real displacement of a certain ground object. Targeting at this problem, a precise digital elevation model (DEM) assisted slope displacement retrieval method is proposed and applied to a case study over the high and steep slope of the Dagushan open pit mine. In the case study, the precise DEM generated by laser scanning is first used to minimize topographic residuals in small baseline subsets analysis. Then, the LOS displacements are converted to slope direction with assistance of the precise DEM. By comparing with ground measurements, relative root mean square errors (RMSE) of the estimated slope displacements reach approximately 12–13% for the ascending orbit, and 5.4–9.2% for the descending orbit in our study area. In order to validate the experimental results, comparison with microseism monitoring results is also conducted. Moreover, both results have found that the largest slope displacements occur on the slope part, with elevations varying from −138 m to −210 m, which corresponds to the landslide area. Moreover, there is a certain correlation with precipitation, as revealed by the displacement time series. The outcome of this article shows that rock mass structure, lithology, and precipitation are main factors affecting the stability of high and steep mining slopes.

Highlights

Open-pit mining is one of the most widely used methods for ore excavation in China
By setting thresholds on spatial and temporal baselines, which are 1.5% of the critical baseline and 50 days, 86 differential interferograms out of 29 synthetic aperture radar (SAR) images are generated for the descending stack, whereas 92 differential interferograms out of 28 SAR images are generated for the ascending stack
The differential interferograms are unwrapped based on the Delaunay minimum cost flow method, followed by removal of orbital errors and atmospheric phase components based on iterative filtering in spatial-temporal domains

Summary

Introduction

Open-pit mining is one of the most widely used methods for ore excavation in China. With the continuous increase of mining depth, most open-pit mines initiate deep concave mining modes, resulting in increased slope height and slope angles (and, decreased slope stability).Sensors 2020, 20, 6674; doi:10.3390/s20226674 www.mdpi.com/journal/sensorsIn deep open pit mines, stability of the high and steep slopes plays an important role for the safety of mine production. Open-pit mining is one of the most widely used methods for ore excavation in China. With the continuous increase of mining depth, most open-pit mines initiate deep concave mining modes, resulting in increased slope height and slope angles (and, decreased slope stability). In deep open pit mines, stability of the high and steep slopes plays an important role for the safety of mine production. Instead of occurring immediately after ore excavation, most landslides of high and steep slopes occur after a period of time. Under long-term effects of excavation, rock mass loading, and high permeability, the mining slopes usually suffer from gradual displacement, structural failures, e.g., creep, cumulative damage, dynamic load fatigue, and elastic mutation, etc. The measurement of surface displacement is vital for understanding landslide evolution mechanisms and early warning of catastrophic failures [1]

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Discussion

Conclusion