Analysis > Options > Zero Strain Placement

Use zero strain support placement – during Map3D BEM analysis.

This option enables simulation of ground support elements. When simulating stiff support systems such as arches, steel sets, props, thick liners, chalks, strong backfill etc., it is necessary to model the ground movement up to the point of support placement, then insert the support elements either in a stress/strain free state, or with a prescribed pre-stressing. This feature is particularly useful for simulation of structural support elements and can accommodate placement, modification of properties and subsequent removal if desired. This option has been enabled for use with 3D FF blocks and/or DD planes.

To enable this feature you must first excavate the desired support element (either a 3D FF block or DD plane) to the desired pre-stressed state (use a zero material code for zero stresses or a negative material number for a prescribed stress state), then in a subsequent mining step insert the support material (use a positive material number to do this). With the Analysis > Options > Zero Strain Support Placement option checked, Map3D conducts the necessary calculations to place support elements in a stress/strain free state or with a prescribed pre-stressing at the current mining step. The action of excavation to a zero or prescribed stress state followed by insertion of an alternate material signals Map3D to conduct the required calculations.

Without this option, all materials are placed at the pre-mining deformation state. This can cause erroneous large stresses particularly in stiff support elements.

Notes:

This function must be checked before conducting the Map3D BEM analysis

Analysis > BEM Analysis

This option requires additional calculations and hence increases analysis time.