To determine the reference value of surrounding rock deformation in shallow buried large-span four-track tunnels,a dynamic reference value system for surrounding rock deformation under sequential excavation method(SEM)is established,taking the ultimate safety factor of the initial support structure as the criterion.Taking Xiabeishan four-track tunnel as the research background,the control value of surrounding rock deformation under SEM is determined by using strength reduction method and actual measurement statistical method.The results show that:(1)the deformation reference value when using the three-bench method is-35.5 mm,and the deformation reference value when using the double side drift method is-30.5 mm.The construction method affects the reference value of surrounding rock deformation by varying the degree of disturbance to the surrounding rock.(2)According to the statistical results of settlement monitoring of 52 sections,the stable settlement range of the surrounding rock in the Xiabeishan Tunnel is 20～30 mm,which is basically consistent with the obtained deformation reference control value.The research results can provide reference for the development of monitoring and early warning systems during the construction period of similar tunnels.
维普
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