Consider shrinkage or simulate a volume loss around a lining of TBM tunnel. It can be applied by selecting beam/shell elements in 2D/3D model.

The ‘Contraction’ is for the shrinkage in the circumferential direction of tunnel and the ‘Contraction Inc.’ is for the shrinkage in the excavation direction of 3D tunnel. The ‘Rep. Depth’ is for the reference depth to calculate the shrinkage in the excavation direction of 3D tunnel. To specify this contraction, a contraction value is defined as a strain value in percentage.

Modeling Precautions

1. Contraction can only be applied to circular tunnels (bores tunnels) with an active continuous homogeneous lining. (If the selected elements are closure, contraction can be applied even though non-circular tunnels, but it is unable to get the correct results.)

2. In case of shell elements in 3D model, the coordinate system needs to be aligned that the excavation direction is the Element CSys-X to calculate the excavation length automatically.