Nitrogen isotope homogenization of dissolved ammonium with depth and 15N enrichment of ammonium during incorporation into expandable layer silicates in organic-rich marine sediment from Guaymas Basin, Gulf of California

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中文题名加利福尼亚湾瓜伊马斯盆地富有机质海相沉积物中溶解铵的氮同位素随深度均匀化以及铵在可膨胀层硅酸盐中的15N富集
作者Toshiro Yamanaka
作者单位School of Marine Resources and Environment, Tokyo University of Marine Science and Technology, 4-5-7 Konann, Minato-ku, Tokyo 108-8477, Japan
刊名Chemical Geology
2024
666
00
摘要
Vibrations induced by hard rock tunnel boring machine (TBM) construction have become an important concern affecting the environmental quality, particularly in urban environments. Herein, the vibration mechanism of TBM construction is studied by synchronously evaluating the three-dimensional vibration acceleration at different positions (such as the TBM cutterhead, rock stratum, and ground surface) based on the TBM construction subway tunnel project in Qingdao, China. At the TBM cutterhead, the acceleration value in the X direction considerably exceeds those in the Y and Z directions. The effective acceleration values in the X, Y, and Z directions are 0.007, 0.005, and 0.004 m/s2, respectively. Because of the presence of structural cracks in rock mass, the vibration influence of strongly weathered rock strata exceeds that of slightly weathered rock strata. On the ground, the acceleration values in the X and Y directions are amplified at 8.5 m away from the tunnel axis and the vibration signals of different frequencies will rebound at different distances from the tunnel axis. Although the vibration induced by TBM construction does not exceed the national specification requirements, the noise exceeds the set limit, thus necessitating noise control measures.

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