This paper presents numerical modelling of powered supports for analysing the interaction of supports with the strata surrounding them. Finite element analyses were carried out for fourteen types of 2-leg shields, nine types of 4-leg chock shields and nine types of 4-leg shield, allowing us to compare their performances with one another. The main results obtained from the numerical analyses are as follows:
(1) The principal direction of the stiffness of powered support reflects its attitude, and provides a suitable indication of its performance of controlling strata.
(2) The inclination of hydraulic legs determines the principal direction of stiffness of 2-leg shield. Relatively weak roof strata are controlled by 2-leg shields better than by the others.
(3) The principal direction of stiffness of 4-leg chock shield is controlled by an algebraic sum of the inclination angles of the front and rear hydraulic legs. 4-leg chock shields whose front legs tilt forward and rear legs incline backward cope well with the condition of strata that both the roof and floor are moderately strong.
(4) The principal direction of stiffness depends solely on the inclination angle of the front hydraulic legs in 4-leg shields. Relatively weak floor condition is less harmed and better accommodated by 4-leg shields than by the others.
