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This paper presents a novel analytical solution for the consolidation behavior of viscoelastic saturated soft soil subjected to large-scale ground loading. The rheological properties of clay are described using the general Voigt model. Based on the Terzaghi-Rendulic theory, the governing equations for the dissipation of excess pore water pressure in the surrounding soil mass of a tunnel are established under the first and second boundary conditions. The governing equations are solved using the complex variable method. The obtained solutions are verified by reducing them to the forms of three traditional rheological models, demonstrating the reliability of the proposed approach. Finally, based on the established solutions, the dissipation characteristics of excess pore water pressure around the tunnel are analyzed. The case results indicate that the soil permeability coefficient (k), the independent Newtonian viscosity coefficient (K-0) and Hooke's spring modulus (E-0) in the general Voigt model have significant influences on the dissipation of excess pore water pressure and the degree of consolidation. A larger k, K-0, and E-0 lead to faster dissipation and consolidation development, while a greater tunnel buried depth (b) results in slower consolidation process. The influence of k on excess pore water pressure dissipation is more significant than that of K-0 and E-0. For the first boundary type, consolidation is instantaneous when k > 0.1 m/d. For the second type, when k < 0.0001 m/d, excess pore pressure remains unchanged within 100 d. The permeability condition of the tunnel has a considerable impact on the distribution of excess pore water pressure in the soil layer directly above the crown. When the tunnel is fully permeable, the effects of k, K-0, and E-0 on the dissipation of excess pore water pressure are more pronounced in the early stage, with almost complete dissipation of excess pore pressure above the tunnel before 100 d. However, when the tunnel is completely impermeable, their effects are more prominent in the later stage, and by 100 d, the maximum excess pore pressure within the depth range is 25 % of the initial.

期刊论文 2024-02-01 DOI: 10.1016/j.compgeo.2023.105926 ISSN: 0266-352X

The study examines the thermodynamic structure of the marine atmospheric boundary layer (MABL) and its effect on the aerosol dynamics in the Indian Ocean sector of Southern Ocean (ISSO) between 30 degrees S-67 degrees S and 57 degrees E-77 degrees E. It includes observations of aerosols and meteorology collected during the Xth Southern Ocean Expedition conducted in December 2017. The results revealed the effect of frontal-region-specific air-sea coupling on the thermodynamic structure of MABL and its role in regulating aerosols in ISSO. The MABL over the subtropical front was unstable and formed a well-evolved mixed layer ( 2400 m) capped by low-level inversions ( 660 m). Convective activities in the Sub-Antarctic Frontal region were associated with the Agulhas Retroflection Current, which supported the forma-tion of a well-developed mixed layer ( 1860 m). The mean estimates of aerosol optical depth (AOD) and black carbon (BC) mass concentrations were 0.095 +/- 0.006 and 50 +/- 14 ng m-3, respectively, and the resultant clear sky direct shortwave radiative forcing (DARF) and atmospheric heating rate (HR) were 1.32 +/- 0.11 W m-2 and 0.022 +/- 0.002 K day-1, respectively. In the polar front (PF) region, frequent mid-latitude cyclones led to highly stabilized MABL, supported low-level multi-layered clouds (>3-layers) and multiple high-level inversions (strength > 0.5 K m-1 > 3000 m). The clouds were mixed-phased with temperatures less than -12 degrees C at 3000 m altitude. Interestingly, there was higher loading of dust and BC aerosols (276 +/- 24 ng m-3), maximum AOD (0.109 +/- 0.009), clear sky DARF (1.73 +/- 0.02 W m-2), and HR (0.029 +/- 0.005 K day-1). This showed an accumulation of long-range advected anthro-pogenic aerosols within baroclinic-boundaries formed over the PF region. Specifically, in the region south of PF, weak convection caused weakly-unstable MABL with a single low-level inversion followed by no clouds/single-layer clouds. Predominant clean maritime air holding a small fraction of dust and BC accounted for lower estimates of AOD (0.071 +/- 0.004), BC concentrations (90 +/- 55 ng m-3) and associated clear sky DARF and HR were 1.16 +/- 0.06 W m-2 and 0.019 +/- 0.001 K day-1, respectively.

期刊论文 2023-02-01 DOI: 10.1016/j.scitotenv.2022.159770 ISSN: 0048-9697
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