Abstract: Taking the rock porosity as the focal point of rock damage analysis, this study is to develop a capillary infiltration technique for non-destructive quantitative analysis of the geotechnical damage. Moreover, variations of the capillary infiltration rate, infiltration area and depth of infiltration are investigated by changing the porosity in capillary infiltration tests. The capillary bundle model is proposed and the mechanism of capillary infiltration technique is also analysed in depth. Compared with the existing damage and non-repeatable measurement technologies, this technology is easy to operate and low cost. In particular, for a rock with specific damage, we can establish a relationship between titration parameters and mechanical parameters. In addition, the capillary model 1, the cylindrical model 2 and the spherical model are put forward, respectively, by considering the effect of capillary infiltration on the lower part of the capillary body in the capillary bundle model. The depth of the liquid infiltration in the lower porosity L is estimated from the upper liquid column descending height and the surface of infiltration radius a. According to the infiltration parameters of the actual pore soil, the validation of the above model is verified. In addition, the result indicates that the spherical infiltration model can better simulate the infiltration depth of the liquid during the process of capillary infiltration. Based on the capillary bundle model, the porosity calculation formulas of three models are separately deduced by the infiltration rate, which is the relationship between the infiltration depth and the infiltration rate. The calculated porosity of the spherical cap model is examined with the measured porosity, and its error is less than 10%. Therefore, the results calculated by this porosity formula are reasonable and effective for general accuracy requirements.

Key words: capillary infiltration technique, porosity: capillary bundle model, columnar model, spherical model