Strength and deformational behaviour of non-persistent jointed rock mass are the most important issues in the field of rock mechanics. In this paper, many slab shaped rock-like blocks containing two pre-existing parallel rough non-persistent joints were subjected to the uniaxial compressive load in order to investigate the effect of joint roughness coefficient, length of bridge, angle of bridge and inclination of joint on its mechanical responses through physical tests. Based on the test results, two models i.e. gene expression programming and linear regression analysis have been developed, and some statistical indexes were adopted to evaluate their performance. The results revealed that the gene expression programming is far superior to linear regression method, and its results are in agreement with the lab tests outcomes; moreover, parametric study of the suggested models indicated that joint inclination and joint roughness coefficient have the highest and lowest effective on the tests outcomes respectively.
