What should be the weight of tunnel lining in kN/m/m?

Question

suppose I am using 25 kN/m3 of unit weight of concrete and the unit weight of soil is 19kN/m3 and modelling lining as a plate element. Should i subtract the unit weights and multiply with the thickness?

Kalyani Singh · Answer

Hi Manisha, 
 In PLAXIS 2D, the specific weight is the force per unit length and per unit width in the out of plane direction. So it represents the product of the unit weight of the material and the area of the cross-section i.e. w=&gamma;xbxd. 
 Here are some links which might be useful for you. 
 https://communities.bentley.com/products/geotech-analysis/w/wiki/58294/considerations-for-modelling-a-thick-slab-as-a-plate 
 (+) plate properties (PLAXIS 2d vs PLAXIS 3D) - GeoStudio | PLAXIS Forum - GeoStudio | PLAXIS - Bentley Communities