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Soil texture prediction through stratification of a regional soil spectral library

Pedosphere 2022年第2期32卷 294-306页

作者： José Janderson Ferreira COSTA élvio GIASSON Elisangela Benedet DA SILVA Tales TIECHER Antonny Francisco Sampaio DE SENA Ryshardson Geovane Pereira de Oliveira E SILVA Department of Soil Science Faculty of AgronomyUniversity of Rio Grande do SulBento Gonçalves Avenue 7712Porto Alegre 91540-000Brazil Agricultural Research and Rural Extension Corporation of Santa Catarina Rodovia Admar Gonzaga 1347FlorianópolisSanta Catarina 88034-901Brazil

Knowing the spatial distribution of soil texture,which is a physical property,is essential to support agricultural and environmental decision *** texture can be estimated using visible,near infrared,and shortwave infrared(Vis-NIR-SWIR)***,the performance of spectroscopic models is variable because of soil ***,few studies address the effects of soil sample variability on the performance of the models,especially for larger spectral libraries that include soils that are more ***,the objectives of this study were to:i)apply Vis-based color parameters on the stratification of a regional soil spectral library;ii)evaluate the performance of the predictive models generated from the spectral library stratification;iii)compare the performance of stratified models(SMs)and the model without stratification(WSM),and iv)explain possible changes in prediction accuracy based on the ***,a regional soil spectral library with 1535 samples from the State of Santa Catarina,Brazil was *** reflectance data were obtained by Vis-NIR-SWIR spectroscopy in the laboratory using a spectroradiometer covering the 350–2500 nm spectral ***,silt,and clay fractions were determined using the pipette ***-two components of color parameters were derived from the Vis spectrum using the colorimetric models.A cubist regression algorithm was used to assess the accuracy of the applicability of the initial models(SMs and WSM)and of the validation between the *** order derivatives(FODs)at 0.5,1.5,and 2 intervals were used to explain possible changes in the performance of the *** SMs with higher contents of clay and iron oxides obtained the highest accuracy,and the most important spectral bands were identified,mainly in the 480–550 and 850–900 nm ranges and the 1400,1900,and 2200 nm ***,stratification of soil spectral libraries is a good strategy to improve regional assessments of soil resou

关键词： color parameters cubist regression fractional order derivatives soil spectroscopy spectroscopic model stratified model Vis-NIR-SWIR

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Rock characteristics and dynamic fragmentation process of the 2018 Daanshan rockslide in Beijing,China

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Journal of Mountain Science 2023年第2期20卷 448-465页

作者： FAN Tian-zhen AN Hui-cong OUYANG Chao-jun WANG Dong-po State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China Key laboratory of Mountain Hazards and Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China

This study investigated the failure mechanism associated with the rock mass structure and the dynamic fragmentation process of blocky rocks of the 2018 Daanshan rockslide that occurred on 11 August,*** was found that the initially collapsed rock of this rockslide was partitioned along the unconformity and strata *** analyzed how the unique rock mass structure,coupled with the road cut and the antecedent rainfall,jointly resulted in its *** on the rock types and geological structures,the initial stratified configuration of a discrete element model was setup to reveal the influences of the local *** numerical model was divided into three *** 1 is the basalt of the Nandaling Formation,the normal and shear stiffnesses of the basalt particles are set as 80 MPa and 40 *** 2 and 3 are the sandstones interbedded with mudstone and sandstone of the Shihezi Formation,and the normal and shear stiffnesses of these parts were set as 6 MPa and 10 MPa,*** dynamic process of the rockslide,particularly the rock fragmentation process,was numerically analyzed using a 3D discrete element *** numerical results were compared with real-time videos and field *** results show that the rock fragmentation and the final deposition range match well with the real disaster phenomenon,and the calculation accuracy of the rockslide reaches 82.41%.Moreover,a parameter sensitivity analysis was conducted,and classical uniform models under different bonding forces were established;the stratified model can better restore the true state of the fragmentation,movement,and deposition processes of ***,for complicated rocks with significant differences in lithology,clarifying the rock mass stratigraphy is essential for an accurate reconstruction of the dynamic process of rockslides.

关键词： Discrete element method Rockslide stratified model Numerical modeling Fragmentation Daanshan rockslide

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