Evaluation of ground convergence and squeezing potential in the TBM driven Ghomroud tunnel project

One of the new components of water conveyance system in central Iran is the Ghomroud water conveyance tunnel that is being excavated by a double shield TBM. The 36 km long tunnel mainly passes through the metamorphic weak rocks of Jurassic age. Key geotechnical design issues for the tunnel, which has up to 650 m of overburden, include the potential for high ground pressure due to high in situ stress. In order to prevent the shield jamming in these weak rocks, it was necessary to evaluate the amount of ground pressure on the outer surface of TBM shield in the vicinity of the tunnel face. The stress and strain condition in the vicinity of the tunnel face has a 3D nature and it is not realistic to assume a two-dimensional stress state at the tunnel face area. In the convergence-confinement method, it is possible to simulate the tunnel face effect with an internal fictitious pressure that is imposed on the tunnel perimeter. In this study, based on the convergence-confinement method, a new method was introduced to calculate the tunnel face effect on ground pressure distribution around the tunnel face region. Then by using this method, critical areas with potential for shield jamming was predicted along the Ghomroud water conveyance tunnel. The obtained results by this method are in good agreement with the current TBM jamming situations along the Ghomroud tunnel.     

Iran in the Regional Context

For much of its history, Iran was part of an extensive empire with far-reaching trade and cultural networks. The current political situation, however, has often led to a misplaced patriotism that has emphasised the heritage of the nation state over its connections across the region. Farrokh Derakhshani flags up the danger of appropriating a wider common heritage from a local rather than a global perspective, and looks at Iran in the wider context of its immediate neighbours.     

A second-order conic optimization-based method for visual servoing

This work presents a novel method for the visual servoing control problem based on second-order conic optimization. Special cases of the proposed method provide similar results as those obtained by the position-based and image-based visual servoing methods. The goal in our approach is to minimize both the end-effector trajectory in the Cartesian space and image feature trajectories simultaneously. For this purpose, a series of second-order conic optimization problems is solved. Each problem starts from the current camera pose and finds the camera velocity as well as the next camera pose such that (1) the next camera pose is as close as possible to the line connecting the initial and desired camera poses, and (2) the next feature points are as close as possible to the corresponding lines connecting the initial and desired feature points. To validate our approach, we provide simulations and experimental results for several different camera configurations.