How does negative pore water pressure develop in dense soil?

Negative pore water pressure is due to the capillarity action of water in the soil. When the water in the soil is below the ground level, some parts of soil above water level gets saturated due to capillary rise. Due to an increase in effective stress, shear strength of soil increases.

What is the significance of pore water pressure in triaxial test?

Significance of Triaxial Testing Consolidation will occur if the pore water pressure which develops upon application of confining pressure is allowed to dissipate. Otherwise the effective stress on the soil is the confining pressure (or total stress) minus the pore water pressure which exists in the soil.

What is the difference between positive and negative pore water pressure?

The pressure in the pore is greater than atmospheric pressure. Hence, it is said to be positive pore pressure. Above the water table, soil remains unsaturated and pressure in pore is lower than the atmospheric pressure. Hence, it is said to be negative pore pressure.

What affects pore water pressure?

The measurement of pore pressure during static soundings -the CPTU tests, depend on several factors: soil type, the degree of humidity, its stiffness, stress state, preconsolidation, water flow conditions and the degree of geological medium destruction as a result of mass movements [18] .

What is pore water pressure in soil mechanics?

Pore-water pressure is the pressure (isotropic normal force per unit area) exerted by the fluid phase in a porous medium (soil or rock) composed of a solid framework and pores filled or partially filled with water or other fluid.

In which of the following pairs of soil types would you anticipate negative pore pressure when subjected to shearing?

So dense sand and over-consolidated clay would anticipate negative pore pressure when subjected to shearing.

What is consolidated undrained triaxial test?

The standard consolidated undrained test is compression test, in which the soil specimen is first consolidated under all round pressure in the triaxial cell before failure is brought about by increasing the major principal stress.

Which of the following Cannot be obtained by using undrained test?

Which of the following cannot be obtained by using un-drained test? Explanation: Since only one Mohr circle in terms of effective stresses, is obtained from all un-drained tests, effective stress failure envelope cannot be obtained from this test.

What is pore water pressure in soil?

Why is pore pressure important?

The vertical stress is commonly known as the overburden or lithostatic pressure and is found through modeling the bulk density data with depth. With knowledge of the vertical stress, estimation of the pore pressure requires an accurate interpretation of the vertical effective stress.

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).

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