How does pore pressure affect shear strength?
The reduction in the shear strength will increase gradually as the shaking continues due to the gradual increase in the buildup of the excess pore water pressure. At a certain level of shaking, the soil mass will liquefy and could be considered as a viscous fluid.
Does water affect shear strength?
Highlights. Shear strength decreased with increasing profile depth at low water content. The spatial variation of shear strength varied slightly at saturation. The peak shear properties occurred at water content in a range of 14 ∼ 21%.
Is pore pressure the same as pore water pressure?
In general, the water in the voids of an element of saturated soil will be under pressure, either due to the physical location of the soil or as a result of external forces. This pressure is the pore water pressure or pore pressure u.
What is the shear strength of water?
Over the range of low strain rates the water behaves like a medium with very low shear strength and a shear modulus of the order of 10−6 Pa.
What effect does adding water have on the shear strength of the soil?
The conclusion is that water pressure reduces the shearing force between particles, reducing overall soil strength. In the second demonstration, Professor Burland uses the example of building sandcastles at the beach to show how a small amount of water can increase soil strength.
What is pore water pressure ratio?
1. Dimensionless coefficient defined as a ratio of the pore pressure and normal stress at a certain point within a slope. When slope is dry, r u =0; when the groundwater is at the surface of the slope – r u =0.5.
What is the role of pore water pressure in controlling the stability of the slope?
In general, the presence of pore-water pressure reduces the soil resistance and also increases the stimulus loads, thus reducing the stability coefficients against stability (Wang and Sassa, 2003).
How does shear stress affect the pore pressure in water?
Water, however, cannot withstand shear stress, so the pore-water pressure is acting in all directions of the void. A portion of the pressure can than exert in the opposite direction of the normal stress, which results in a reduction of the normal stress.
Do peak shear properties depend on water content and cementation?
The peak shear properties occurred at water content in a range of 14 ∼ 21%. The unsaturated shear strength was determined by the cementations and porosity. Shear strength is crucial for slope stability and soil erosion measurement, and shearing deformation is one of the most harmful processes for land and environment degradation.
How does pore water pressure affect slope frictional resistance?
Terzaghi (1936) first recognized that pore-water pressure controls the frictional resistance of slopes, which has remained the most important concept in understanding landslide behavior. A founding principle of slope stability is that a rise in pore-water pressure reduces the shear strength of the soil ( Skempton, 1960 ).
How does pressure affect shear strength?
A portion of the pressure can than exert in the opposite direction of the normal stress, which results in a reduction of the normal stress. A change of the pore-water pressure (caused, e.g., by hydrostatic pressure or compression) in the void system therefore can affect the shear strength behavior of the soil and rock material.