Abstract:

At present, the Q system supporting design method based on Norwegian tunneling method is widely used in single layer lining, but this method involving 6 parameters, which can’t be tested accuracy before or during cnstruction and the testing cost is high. So the Q system supporting design method is not suit for China’s single layer lining design. At this background, the design principle and design methodology for single layer lining based on yield approach index and the support theory based on broken rock zone are put forward; and the engineering practice combining with Dabieshan tunnel inclined shafts No.2 on the Hefei-Wuhan railway is executive too. During the research, engineering condition, hydrogeology condition and physico-mechanical indices of surrounding rock where the tunnel located must be got by geological prospecting at first; then the supporting parameters of single layer lining and mechanical index for shotcrete is presented which will form the structure’s pre-design. During the actual process of construction, according to the broken rock zone range which is field tested and then use support theory based on broken rock zone to modify the design, a complete single layer lining design system will form. The practice shows that the design method of single layer lining proposed is economical and applicable; and the interference for construction is low which suits information construction. On the other hand, the single layer lining structure completed is safe and reliable, and it will make notable economic and social benefits in engineering application; it is worthwhile to be popularized.

Key words: tunnel, single layer lining, design methodology, yield approach index, broken rock zone