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Near-surface seismic refraction tomography and electrical resistivity imaging were used to study the collapse and subsidence of two asphalt roads on the campus of South Valley University in southern Egypt. The roads surround a garden where irrigation water was suspected to be the cause of the damage to the asphalt roads. Two seismic refraction tomography (SRT) lines were measured on the asphalt roads, and a single SRT line and an electric resistivity tomography (ERT) line were measured within the garden. The tomographic inversion of the SRT lines on the road shows several low velocity anomalies indicating areas of weakness beneath the asphalt. The SRT and ERT lines in the garden show a thin surface soil of fine sand and clay overlying a low electric resistivity and low seismic velocity clay layer. Examination of the results suggests that the damage to the asphalt roads could be caused by the presence of loose silt and clay soil that was used as a sub-base for the asphalt. This soil had not been compacted and engineered for use as a strong base layer. Instead, the asphalt was laid directly on top of it, which later led to the

期刊论文 2024-12-01 DOI: 10.4430/bgo00463 ISSN: 2785-339X

This study utilized electrical resistivity imaging (ERI) to investigate subsurface characteristics near Nicolaus Copernicus University Polar Station on the western Spitsbergen-Kaffi & oslash;yra Plain island in the Svalbard archipelago. Surveys along two lines, LN (148 m) collected in 2022 and 2023, and ST (40 m) collected in 2023, were conducted to assess resistivity and its correlation with ground temperatures. The LN line revealed a 1- to 2-m-thick resistive unsaturated outwash sediment layer, potentially indicative of permafrost. Comparing the LN resistivity result between 2022 and 2023, a 600 Ohm.m decrease in the unsaturated active layer in 2023 was observed, attributed to a 5.8 degrees C temperature increase, suggesting a link to global warming. ERI along the ST line depicted resistivity, reaching its minimum at approximately 1.6 m, rising to over 200 Ohm.m at 4 m, and slightly decreasing to around 150 Ohm.m at 7 m. Temperature measurements from the ST line's monitoring strongly confirmed that the active layer extends to around 1.6 m, with permafrost located at greater depths. Additionally, water content distribution in the ST line was estimated after temperature correction, revealing a groundwater depth of approximately 1.06 m, consistent with measurements from the S4 borehole on the ST line. This study provides valuable insights into Arctic subsurface dynamics, emphasizing the sensitivity of resistivity patterns to climate change and offering a comprehensive understanding of permafrost behavior in the region.

期刊论文 2024-10-01 DOI: 10.3390/w16192707
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