Optimization of Composite Middle Wall in Large Span and Flat Multi-arch Tunnel

Abstract

In order to assuring the safety of construction, reduce the digging span and economize the engineering investment, by using finite element software ADINA in a certain support engineering, the development rules of middle wall stress and strain in different middle wall shapes were simulated and analysed to choose the optimized composite middle wall shape. On this basis, the variation process of displacement and stress of middle walls with different thicknesses and the corresponding displacements of surrounding rock were researched, and the simulation result was compared and verified by field monitoring. Thus the middle wall shape was optimized, the key control factor of reinforcement and the reasonable thickness of middle wall at surrounding rock grade V were put forward.