Optimum analysis of construction sequences in super large section and span tunnel
Recently, in order to suit for multiply-lane highway construction, many four-lane super large section tunnels have been built all over China. There are some developments about the stress, deformation and stability research on rockmass and lining in four-lane super large section tunnels. As to theory analysis aspect, Qu Haifeng proposed a new loadmode for large crosssection and low flat-ratio tunnel. Some researchers such as Sun Xiang, Huang Lunhai, Wu Mengjun, Xu Chongbang and LI Zhigang have done some work on numerical analysis and model test. Those researches are mainly about model test and numerical analysis of dynamic construction process and the mechanical characteristics. Except that,YuanYong proposed a prebuilt and prestressed innovative support method for four-lane super large section tunnel and made a validation about the pre-built and prestressed structure. Huang Chengzao proposed cross anchor to control the deformation of core rock in four-lane tunnel.As for insitu test on four-lane tunnel, Chen Gengye analyzed the stress characteristics of four-lane tunnel based on stress monitoring. And Zhou Dingheng made a
detailed analysis of rock deformation based on in-situ test of super large section and span tunnel. Based on one four-lane tunnel, Liu Heng finished some research about on the durability of tunnel structure. At present, the design and construction standard of four-lane super large section tunnels has not been formed and the related research is limited. Therefore, it is essential to do further research about four-lane tunnels. Except that, due to the characteristics of large excavation span and low flat-ratio, the construction sequences conversion is complicated and multiply blast has multiply disturbance to the surrounding rock. Especially, the core rock stress is very complicated. Thus, there tends to bemany stability problems such as large section and tunnel collapse. Therefore, further research on super large section and span tunnel is an important content of rock tunnels.