Experimental study on swelling characteristics of mudstone in Baotaishan tunnel

In order to clarify the basic physical characteristics and swelling characteristics of mudstone along Yinlan high speed railway, the basic physical characteristics test and swelling test of mudstone were carried out based on the mudstone of Baotaishan tunnel. The test results show that: (1) the mudstone of Baotaishan tunnel is mainly composed of quartz, calcite and illite, and the content of viscous minerals is low;(2) The swelling deformation of mudstone changes with time in three typical stages: rapid growth stage, deceleration growth stage and stable stage. The mudstone swellings rapidly after encountering water, and the swelling deformation at 1h reaches more than 85% of the total deformation; (3) The swelling deformation of mudstone in Baotaishan tunnel is small, but the swelling force is 250.8kPa. The swelling load is considered in the tunnel design. The test results can provide basic data for the design and construction of swelling mudstone tunnel along Yinlan high speed railway.