[Geoqus] On Geostatic Step

[bsaad at po-box.mcgill.ca]

Does any one have some remarks on how can I establish equilibrium and 
get zero displacement out of Geostatic Step. I have avery simple plain 
strain (2D) model and I applied the following initial stress that 
balances the gravity load of g=-10 m/s^2 operating in z direction 
throughout a zone that extends vertically from z=0 to z=100 m

I am estimating the intial vertical stress as follows. I have  the zone 
density of 2066 kg/m^3 and therefore bulk unit weight is (2066 * g=-10) 
=-20060 N/m^3
the stress at depth of 100 is 100*-20060= -2006000 N/M^2

Therefore Initial Geostatic Stress is

*initial conditions, type=STRESS, geostatic
Ground, -2006000, 0, 0, 100, 0.38, 0
Where 0.38 is the coefficient of earth pressure calculated from 
K0=v/1-v  (v is poission ratio).However I am getting ridicules 
displacement : in the order of 0.10 m

Background
In fact (in plain strain) the exact geostatic stresses in the body is 
done through Calculating stress and displacement fields resulted from 
gravity (assuming elastic media) is done through elasticity relations 
Inserting initial stresses based on
\sigma_v = \gamma*h, \sigma_h = K*\sigma_v, where h and K are distance 
of the calculated point from the surface and Coef earth pressure, 
respectively,  is just a very approximate way for the existing stress 
field and hence displacement field. One should play with these 
approximate field until it becomes very close to the above exact stress 
field (calculated based on FE elasticity). This game may regretfully 
last hours and hours.