please show steps and asnwer the following 1 Describe the yi

please show steps> and asnwer the following.

1- Describe the yield surface in the context of critical state soil mechanics; what parameter determines its size? Describe differences in soil behavior for stresses inside and outside the yield surface. Is the yield surface fixed for a given soil or can it expand; if so, under what conditions?

2- A clay sample was isotropically consolidated under a cell pressure of 250 kPa in a triaxial test and then unloaded isotropically to a mean effective stress of 100 kPa. A standard CD test is to be conducted on the clay sample by keeping the cell pressure constant and increasing the axial stress. Predict the yield stresses, p’y and qy (Cambridge notation), if M = 0.94.

Solution

(1) Answer:-

Yield surface:- yield surface is a five dimensional surface in the six dimensional space of stress. The state stress of inside the yield surface is elastic.

Parameters for size determination:-

(a) Effective mean size

(b) Shear stress

(c ) Specific volume

The stress states that lie outside the yield surface are non- permissible in rate independent plasticity . The state of stress inside the yield surface is elastic.

Yield surface for elastic soil is fix but yield surface for plastic soil is not fixed due to plastic behavior of soil.