equivalent plastic strain works with mohr-coloumb plastity???

can i use the equivalent plastic strain to evalute the state of the elements (yield or elastic) when the i use Mohr-Coloumb plasticity (Abaqus 6.6).

 i am asking this question because i made a model to simulate  the uniaxial compression test using mohr-coloumb plasticity, but i find that the equivalent plastic strain remain constant at all elements, i am sure that the it should change from the edged of the sample to the core of the sample.