In this paper, a scaled-down physical model of circular tunnel experiment was carried out to investigate the strata and mechanical deformational behavior of unsupported tunnel periphery in soft groundmass. The authors developed and performed a three-dimensional physical model experiment to understand these phenomena. In spite of having highly advanced computational techniques, researchers still heavily depend on physical model tests before constructing any underground excavation to understand the phenomenon’s like tunnel damage process, deformation pattern, subsidence and caving mechanism etc. A variety of distinct physical modelling techniques has already been developed and proposed by several researchers all over the world to study the ground response around the tunnel opening and monitoring the surface settlement. These techniques range from simple “base friction models” to highly advanced “manually controlled centrifuge models” that simulates the failure mechanism and distortion behavior of tunnel under variable engineering and geomechanical conditions. The present study shows a laboratory model conducted under the effect of gravity to study the deformational behavior, tunnel mechanical features, failure mode and ground settlement profile. The ground deformation was observed with the help of normal measuring tape attached on transparent acrylic wall and video recording of events. The outcome of these tests were then compared with empirical equations and well-established mathematical models.

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