Filed model tests on bearing behavior of mudstone tunnel anchorage

To study the deformation, failure and long-term stability of soft surrounding rock (mudstone) tunnel anchorage under heavy loads, the Changjiang River Bridge under construction is taken as an example, in which 1∶30 reduced-scale models are used for field tests on the mudstone tunnel anchorage in natural state (moisture content of 5.36%) and soaked state (moisture content of 7.39%). According to the research, it is easy to know that the tunnel anchorage is applicable to soft surrounding rock. The soft surrounding rock (mudstone) tunnel anchorage can withstand higher drawing loads and has a certain safety margin when working in the design load conditions. When subjected to yield loads, the contact surfaces of the anchorage and the surrounding rock are sheared into failure first, which will cause large deformation of the surrounding rock. When subjected to high drawing loads, the mudstone tunnel anchorage with higher moisture content undergoes larger deformation of the surrounding rock than the mudstone tunnel anchorage with lower moisture content. Considering the influence of changes of the river water level, the long-term safety factor of mudstone tunnel anchorage for Changjiang River Bridge is suggested to be 3.5. The research results may provide reference for the design and construction of similar projects.