Application of a Constitutive Model for Swelling Rock to Tunnelling

Swelling due to chemical processes is a well-known problem in tunnelling in anhydritic rocks and certain types of claystone. If the swelling rock mass is exposed to water due to tunnel excavation or natural water influx, in anhydritic rocks large deformations of more than 1 m can be observed, which are typically concentrated at the tunnel invert. Estimating swelling deformations and swelling pressures is of paramount importance for the design of durable underground structures in such materials. This paper presents the results of a numerical back analysis of measured swelling deformations with a simple constitutive model, using swelling parameters derived from laboratory swelling tests.