In order to determine the extent of excavation damaged zone around roadway more reasonably

a new prediction method is proposed based on the dimensional analysis theory. Some physical quantities such as rock uniaxial compressive strength Rc

joint coefficient of rock F

unit weight of rock ?

depth of roadway H

maximum horizontal principal stress ?Hmax and span of roadway B are selected; the dimensionless relations among the thickness of excavation damaged zone L and above mentioned physical quantities are established by means of dimensional analysis. Among them

L/H represented that the thickness of excavation damaged zone is proportional to depth of roadway; F represented structural characteristic of surrounding rock; both ?H/Rc and ?Hmax/Rc represented mechanical characteristics of surrounding rock; B/H represented geometric characteristic of roadway. The quantitative function formula among these dimensionless relations is derived by combining with some field test data

the residual sum of square is 0.003 1

and the correlation coefficient is 0.937 9. Finally

the prediction model of the excavation damaged zone is validated with some testing examples from 3 mines. The results show that the calculation results satisfyingly agree with the measured data at the average relative error of 7.38%

which can be of interest from a practical viewpoint.