Deformation Instability Characteristics of Expansive Soil Slope Based on SBAS-InSAR Technique
Aiming at the shortcomings of traditional field monitoring means,which are costly,easy to damage and difficult to recover the overall regional deformation history of slopes,the new remote sensing ground observation technique SBAS-InSAR was used in this study to obtain the overall time-series deformation results of a large area of experimental slopes.The deformation and instability patterns of expansive soil slopes under rainfall infiltration conditions were explored.The expansion soil cutting slope of Zhaotong West Ring Expressway was selected as the experimental area,in which 31 Sintinel-1A SAR images were dealt with pre-differential interference processing,high coherence point selection,phase unwrapping,time-series deformation modeling and final deformation generation.The deformation results before and after the slope collapse were obtained.The whole deformation process of expansive soil cutting high slope from support to collapse was reconstructed.The characteristics and mechanism of the instability deformation were analyzed.The result indicates that the maximum cumulative settlement at slope area is 198 mm.The time-series subsidence curves of characteristic points of slope top,middle and foot can be divided into 4 stages.The accuracy validation is carried out by using leveling result.The inner and external accuracies are estimated as±2.9 mm and±1.5 mm respectively.Combined with the rainfall data analysis,the slope deformation and failure are characterized by shallow,phased,creep,hysteresis and seasonality.When the daily rainfall is less than 15 mm,the subsidence rates of feature points show the slow or slightly uplift characteristics.In this study,the SBAS-InSAR technique is used for post-disaster reconstruction of landslide deformation on expansive soil highway slopes,broadening the application field of InSAR technique,and providing new types of remote sensing monitoring means for the early identification of expansive soil slope instability.
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