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Pore water pressure

About: Pore water pressure is a research topic. Over the lifetime, 11455 publications have been published within this topic receiving 247670 citations. The topic is also known as: pwp.


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Journal ArticleDOI
TL;DR: A large strain theory of one-dimensional consolidation for normally consolidated and overconsolidated or aged clays which considers the changes in compressibility and permeability during the consolidation and includes secondary compression, shows that the consolidation process in clays is controlled by indexes of compression, recompression, secondary compressions, permeability, and critical pressure ratio, load-increment ratio, and the magnitude of total compression as discussed by the authors.
Abstract: A large strain theory of one-dimensional consolidation for normally consolidated and overconsolidated or aged clays which considers the changes in compressibility and permeability during the consolidation and includes secondary compression, shows that the consolidation process in clays is controlled by indexes of compression, recompression, secondary compression, permeability, and the critical pressure ratio, load-increment ratio, and the magnitude of total compression. A decreasing compressibility during the consolidation process accelerates the rates of compression and the excess pore pressure dissipation, whereas a decreasing permeability retards them. The influence of the load-increment ratio on the rate of consolidation depends on the ratio of permeability index to compression index. The secondary compression has a significant influence on the compression curves; however, it does not affect the dissipation of pore-water pressure appreciably. A fraction of the excess pore-water pressure equal to the critical pressure ratio dissipates at a rapid rate; the remaining pore pressure dissipates at a slower rate.

146 citations

Journal ArticleDOI
TL;DR: In this article, an overview of geochemical data from pore waters and solid phases that clarify earliest diagenetic processes affecting modern, shallow marine carbonate sediments is presented.
Abstract: We present an overview of geochemical data from pore waters and solid phases that clarify earliest diagenetic processes affecting modern, shallow marine carbonate sediments. Acids produced by organic matter decomposition react rapidly with metastable carbonate minerals in pore waters to produce extensive syndepositional dissolution and recrystallization. Stoichiometric relations among pore water solutes suggest that dissolution is related to oxidation of H$\_{2}$S which can accumulate in these low-Fe sediments. Sulphide oxidation likely occurs by enhanced diffusion of O$\_{2}$ mediated by sulphide-oxidizing bacteria which colonize oxic/anoxic interfaces invaginating these intensely bioturbated sediments. Buffering of pore water stable isotopic compositions towards values of bulk sediment and rapid $^{45}$Ca exchange rates during sediment incubations demonstrate that carbonate recrystallization is a significant process. Comparison of average biogenic carbonate production rates with estimated rates of dissolution and recrystallization suggests that over half the gross production is dissolved and/or recrystallized. Thus isotopic and elemental composition of carbonate minerals can experience significant alteration during earliest burial driven by chemical exchange among carbonate minerals and decomposing organic matter. Temporal shifts in palaeo-ocean carbon isotope composition inferred from bulk-rocks may be seriously compromised by facies-dependent differences in dissolution and recrystallization rates.

146 citations

Journal ArticleDOI
01 May 2006
TL;DR: In this paper, the radon mass balance was constructed by assuming that radon may be advected via groundwater discharge into all compartments of the boat basin and the mixing outputs from an inner box would be an input into the adjacent box.
Abstract: Estimates of groundwater discharge into a boat basin in Donnalucata, southeastern Sicily, based on radon measurements are reported. A continuous monitor was deployed at several locations that made repeated integrated measurements of radon concentration in the seawater once per hour. We observed large differences in the concentrations (60–2500 Bq m −3 ) and inventories (90–3200 Bq m −2 ) of 222 Rn at various locations within the boat basin. The station closest to shore had the highest concentration by far (up to over 3000 Bq m −3 ), reflecting inputs of radon-rich groundwater into this zone. We constructed a radon mass balance by assuming that radon may be advected via groundwater discharge into all compartments of the boat basin and the mixing outputs from an inner “box” would be an input into the adjacent box. We also made allowances for atmospheric evasion losses that were occasionally very high due to high winds and huge concentration gradients across the air–sea interface. Once the radon fluxes have been estimated, we could calculate groundwater discharge by dividing these fluxes by the radon concentration of the groundwater. Should the groundwater be entering the basin by widely disseminated seepage through bottom sediments, it would be appropriate to use values of pore water derived by sediment equilibration techniques. These values (2700±200 Bq m −3 ) are close to those from several samples from shallow wells collected near the boat basin (1700–2700 Bq m −3 ). However, we measured higher radon levels than this in the waters of the innermost portion of the basin. We thus elected to assume that the main radon entry was either via direct spring input with activities (15 100 Bq m −3 ) similar to those measured from a natural spring on a nearby beach or a blend of spring water with surficial aquifer water. The resulting range in our calculated groundwater discharges into the boat basin is 1200 to 7400 m 3 day −1 . These estimates are higher than those based on seepage meters (range=300–1000 m 3 day −1 ), probably because of the wide spatial variability of the spring and seep inputs.

146 citations

Journal ArticleDOI
TL;DR: In this article, an extensive program of research into the influence of undissolved gas bubbles on the behavior of fine-grained onshore soils is reviewed. But the results are limited by surface tension effects, which limit the difference between gas pressure and pore water pressure.
Abstract: An extensive programme of research into the influence of undissolved gas bubbles on the behaviour of fine-grained onshore soils is reviewed. The programme has been based on the development of a laboratory technique for the preparation of reconstituted soil samples containing a uniform distribution of gas bubbles. The structure of these samples is similar to that observed in sediment recovered from the sea bed, and consists of large gas-filled cavities surrounded by a matrix of saturated soil. It is found that surface tension effects limit the difference between gas pressure and pore water pressure, and that the overall void size is effectively a function of the strength of the matrix, so that changes in void volume may be modelled by cavity expansion and contraction in an ideal plastic medium, leading to limits on the difference between gas pressure and mean total stress. A new parameter, operative stress, is shown to influence both the consolidation and the strength of these gassy soils. Thus, during con...

145 citations

Journal ArticleDOI
TL;DR: A novel high-resolution dialysis technique was developed for rapid sampling of dissolved reactive phosphate (DRP) and ferrous iron in pore water at a vertical resolution of 2mm, verifying the control of P mobilization by Fe in sediments.

145 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023552
2022995
2021572
2020564
2019566
2018566