Abstract: When the construction of underground projects in alpine and gorge region is being conducted, different mountain slopes will have important effects on initial geostress distribution. In this paper, the initial geostress distribution of mountain at vertical and horizontal typical profiles were studied in the gravity field by numerical analysis, with conditions of slopes being 30°, 45° and 60°, respectively. After the comparison, it can be known that the calculated values of the vertical geostress which were obtained from direct depth of the mountains varied from the actual values greatly. The steeper the slope is, the greater the differences are. Then two caverns at different positions were set to excavation in the mountain, with slope of 45°in the computation models and the damage - fracture model of joint rock was adopted to analyze the rock stability for the two conditions. The results show that the damage degree of surrounding rock is very asymmetric; and the more close to the slope surface (or slope toe), then the more serious the damage degree is. Finally, the corresponding conclusions and recommendations are proposed.

Key words: mountain slope, geostress, joint-rock mass constitutive model, damage evolution equations, numerical analysis, underground cavern