I would like to know if the definition or the concept "pore water pressure" in unsaturated soil in Geotechnics is the same as "water pressure" in Richards equation in Hydrogeology. If not, which equation can establish the connection with these two parameters? Any comments or replies would be sincerely appreciated.
Both are different. Pore water pressure is groundwater held within a soil or rock.in gap between particles. Water pressure is the force that puses water through pipe . water pressure determined the flow of water from the tap.
Dear Colleague,
Pore water pressure" and "water pressure" are related but not identical concepts, especially when comparing their use in geotechnics (unsaturated soil mechanics) and hydrogeology (Richards equation). In geotechnics, pore water pressure refers to the pressure of water within the pores of a soil. In unsaturated soils, this pressure is typically negative (suction) because the soil is not fully saturated, and the water is held in the pores by capillary forces.In hydrogeology, the Richards equation describes the movement of water in unsaturated porous media. The "water pressure" in this context is the hydraulic pressure head, which is related to the water potential in the soil.
Hello, following previous answers, it arises that 'pressure' due to water presence inside pores (mainly soils or some kind of rocks) or flowing along joints (the majority of fractured rock masses) has to be better defined accordingly to the specific context of the problem. In facts, there are other conditions that request additional consideration (unsaturated soil, velocity of flow for associate modelling, flow direction). For example: it is possible to study 'pore water pressure' for microscopic and lab research, while it is possible to define generically 'water pressure' that applied to bodies for stability analyses (rock blocks along slopes, buoyancy in foundation or excavation). Hope this cam help. Regards
No, pore water pressure and water pressure are not the same. Pore water pressure refers to the pressure exerted by water within the pores of soil or rock, influencing soil strength, stability, and effective stress in geotechnical engineering. It depends on factors like soil permeability, groundwater conditions, and external loads. In contrast, water pressure (or hydrostatic pressure) is the pressure exerted by a static or moving water body, increasing with depth according to Pascal’s Law. Unlike pore water pressure, which affects soil behavior, water pressure applies to free water in lakes, rivers, or pipelines. The major difference is that pore water pressure occurs within soil pores and impacts geotechnical stability, whereas water pressure acts on open water surfaces.
Please see section 4.4 (Archimedes and Terzaghi) in the attached textbook by A. Verruijt, "Soil Mechanics". I think it will help you understand this issue.
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