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Combined portable free fall penetrometer and chirp sonar measurements of three texas river sections post hurricane harvey
Engineering Geology ( IF 7.4 ) Pub Date : 2021-08-11 , DOI: 10.1016/j.enggeo.2021.106324
Reem Jaber , Nina Stark , Navid Jafari , Nadarajah Ravichandran

The US Gulf of Mexico coastal region has repeatedly been subjected to major flood events. Local geotechnical site characteristics and geomorphology can change due to sediment transport processes during such events. However, field measurements during extreme conditions are challenging. This paper discusses initial attempts at a combined geotechnical and geophysical site investigation of the uppermost layers of riverbeds following severe flooding events at three different rivers in Texas: the Guadalupe, Brazos, and Colorado Rivers in terms of sediment strength derived from a portable free fall penetrometer, backscatter intensity recorded by a chirp sonar, and soil sample characterization. Results show low strength sediments (<40 kPa) along the investigated sections of the Guadalupe and Brazos riverbanks. Although sediments in the center of the Brazos River were characterized with higher strength (>50 kPa) and larger grain sizes (d50 ∼ 0.3 mm), sediment strength of the Guadalupe and Colorado Rivers displayed more variations around bridge piers. The spatial variations likely resulted from sediment remobilization processes and local scour under severe hydrodynamic conditions. Both, geotechnical and geophysical results, reflected the observed variations in the riverbed sediments; nonetheless, a quantitative correlation among the rivers was impeded by challenges primarily related to limitations of spatial accuracy and the significant riverbed heterogeneity, as well as shallow water limitations of the chirp sonar.



中文翻译:

飓风哈维后德克萨斯州三个河流段的组合便携式自由落体穿入仪和线性调频声纳测量

美国墨西哥湾沿海地区多次遭受重大洪水事件。由于此类事件期间的沉积物输送过程,当地的岩土工程场地特征和地貌可能会发生变化。然而,极端条件下的现场测量具有挑战性。本文讨论了在得克萨斯州三个不同河流(瓜达卢佩河、布拉索斯河和科罗拉多河)发生严重洪水事件后,对河床最上层进行岩土工程和地球物理联合现场调查的初步尝试,从便携式自由落体渗透仪得出的沉积物强度来看,由啁啾声纳记录的反向散射强度和土壤样品表征。结果显示沿瓜达卢佩河和布拉索斯河岸的调查部分存在低强度沉积物 (<40 kPa)。d 50  ∼ 0.3 mm),瓜达卢佩河和科罗拉多河的泥沙强度在桥墩周围表现出更多的变化。空间变化可能是由于严重水动力条件下的沉积物再动员过程和局部冲刷造成的。岩土工程和地球物理结果都反映了观察到的河床沉积物的变化;尽管如此,河流之间的定量相关性受到主要与空间精度限制和河床异质性显着以及chirp声纳的浅水限制有关的挑战的阻碍。

更新日期:2021-10-13
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