Abstract: Swelling pressure is an important parameter for the design and construction of geotechnical engineering in swelling rock and soil regions. The swell and load method, the no-swell method, and the load-swell method are the three most commonly used methods for determining swelling pressure. Swelling pressure depends significantly on test method. To explore the effect of testing method on swelling pressure, swelling pressure tests of Yanji swelling rock specimens with different initial water contents were carried out using the above-mentioned three methods; and characteristics of three methods and their application scopes were analyzed and compared. The results indicate that three methods show different values in swelling pressure; and there is a clear effect of hydro-mechanical path on swelling pressure. The swell and load method provides the highest value of swelling pressure; while the load-swell method provides the lowest. There is a significant negative linear relationship between the swelling pressure and the initial water content. Relationships between the swelling pressure and the initial water content obtained by three methods tend to be close to each other with the increasing initial water content, which illustrates that the effect of hydro-mechanical path on swelling pressure is weakened. Every method has its respective characteristic and specific application scope; so testing method of swelling pressure should be determined by practical engineering conditions.

Key words: swelling pressure, swell and load method, no-swell method, load-swell method, hydro-mechanical path, suitability