Soil suction occur above the water table in unsaturated pores where the space between soil particles is occupied by some water now the surface tension of that water creates meniscus and a force that pull that binds the soil particles together and that creates an apparent cohesion that the soil that goes beyond the attraction between solid particles so the soil has an apparent cohesion and it is due to the negative pore water pressure that exists these droplets of water so the ability for soil to generate soil suction to generate negative pore water pressure is a function or directly proportional to the particle sizes within the soil so clay size particles will have greater soil suction than sand sized particle so this is important by my thinking about stresses within the soils because we take the pore water pressure from the phreatic surface the phreatic surface is where the pore water pressure is zero and we calculate all pore water pressures as a function of depth below that. This is can be complicated when we go to the field to try to measure where the phreatic surface is because the presence of negative pore water pressure above that creates condition within soil can seem almost fully saturated so even several meters above this phreatic surface so where do we take the phreatic surface from measuring high water contents above it and this is even more trickier for soils with fluctuating phreatic surface where we might have ground water conditions that means that we don’t have constant phreatic surface.
I still didn’t get it
Soil suction occur above the water table in unsaturated pores where the space between soil particles is occupied by some water now the surface tension of that water creates meniscus and a force that pull that binds the soil particles together and that creates an apparent cohesion that the soil that goes beyond the attraction between solid particles so the soil has an apparent cohesion and it is due to the negative pore water pressure that exists these droplets of water so the ability for soil to generate soil suction to generate negative pore water pressure is a function or directly proportional to the particle sizes within the soil so clay size particles will have greater soil suction than sand sized particle so this is important by my thinking about stresses within the soils because we take the pore water pressure from the phreatic surface the phreatic surface is where the pore water pressure is zero and we calculate all pore water pressures as a function of depth below that.
This is can be complicated when we go to the field to try to measure where the phreatic surface is because the presence of negative pore water pressure above that creates condition within soil can seem almost fully saturated so even several meters above this phreatic surface so where do we take the phreatic surface from measuring high water contents above it and this is even more trickier for soils with fluctuating phreatic surface where we might have ground water conditions that means that we don’t have constant phreatic surface.
Sir, is water is under tension due to adsorptive forces(electrostatic and Vander wall forces) in unsaturated soil??
Sir please how can I determine the air entry matrix suction value of soil
should repair eyes