Objective Question & Answer

Negative pore-water pressure develops during undrained shearing in soils that have a tendency

to dilate (increase in volume).

Dense sand tends to dilate during shearing.

Under undrained conditions, water cannot enter the voids to permit this increase in volume.

Hence:u < 0

So, dense sand develops negative pore-water pressure.

Highly over-consolidated clay also tends to dilate during shearing. Under undrained conditions,

this dilation results in: D u < 0

Therefore, both dense sand and over-consolidated clay can develop negative pore pressure

during shearing.

जब soil को undrained condition में shear किया जाता है, तो जो soil dilate अर्थात अपना volume बढ़ाने की प्रवृत्ति

रखती है, उसमें negative pore-water pressure विकसित होता है।

Dense Sand shearing के दौरान फैलने (dilate) की प्रवृत्ति रखती है। लेकिन undrained condition में पानी अंदर नहीं

आ सकता, इसलिए:u < 0

इसी प्रकार Over-Consolidated Clay भी shearing के दौरान dilate करने की प्रवृत्ति रखती है, जिससे negative pore

pressure उत्पन्न होता है।

Dense Sand + over – consolidated clay  Þ Dilation Þ Negative pore pressure

Loose Sand + Normally Consolidated Clay Þ Contraction Þ Positive Pore Pressure