In order to quantify the rock damage evolvements in the rock failure event of uniaxial stress state

a micro-heterogeneous physical cellular automata model（MH-PCA model）is introduced based on energy dissipation theory.The macroscopic dynamic process of rock fracture

damage evolution and complete stress-strain curve under uniaxial compression condition are obtained.The results show:1.In the process of loading

for the rock sample with lower homogeneous degree

the crack initiation and propagation are relatively dispersive

the cracks develop completely and the damage grows slowly;while for the rock sample with higher homogeneous degree

the crack initiation and propagation occur in concentrated zone

the cracks develop incompletely and brittle failure occurs eventually.2.The damage evolvements can be described by an S-shaped cumulative model.There is a large proportion of the second stage to the whole curve

large slope

large damage evolution speed and obvious brittle failure for the rock with larger homogeneous degree.3.With the parameter mincreasing

the peak strength

peak strain and softening modulus of this kind of rock increase.It is not only the average strength but also the homogeneous degree and energy dissipation rate that affect the peak strength.4.A parameter for describing the brittle characteristic of rock is given.The parameter can distinguish the failure phenomena of rock with different homogeneous degrees.Meanwhile

we find out that there is a critical value mcrfor the parameter m.When the homogeneous degree is larger than m

the rock has a distinct brittle failure pattern.When the homogeneous degree is lower than m

the rock has a distinct plastic flow failure pattern.The derived results coincide with the practice and it is very helpful for us to understand the relationship between the microscopic damage and macroscopic failure of rock.