Optimization-based model of tunneling-induced distributed loads acting on the shield periphery

This paper presents a new approach to predict the loads acting on the shield periphery during excavation. This approach not only represents the dynamic variation of loads, but also can be used to calculate the rectification loads for moving shield backward to the planned alignment. Firstly, the ground reaction curves are adopted to calculate the earth pressure. Particularly, the ground displacement is considered to be induced by two kinds of motion: tunneling-induced ground loss and snake-like motion of shield movement. Then, optimization criteria for load balance, minimum potential energy, shield behavior, and ground settlement have been considered. Finally, basic example is carried out in a straight alignment for the single layer of homogeneous ground. The validity is discussed by comparing the optimization model with numerical simulation, and the results confirm that the proposed approach is reasonable enough to predict the distributed loads acting on the shield periphery. (C) 2012 Elsevier B.V. All rights reserved.