Abstract In order to understand the mechanical behaviors of the super-long tunnel in soft and fractured surround?
ing rocks under different construction methods and to find out an efficient and safe construction method suitable for the geological conditions, indoor simulation of tunnel excavation by three construction methods under six working conditions are conducted by means of core sampling at site, measuring of mechanical parameters of surrounding rock and preparations of similar material and primary support material based on a tunnel project, and the characteristics of stress field of surrounding rock and response of internal force of support system under different working conditions are studied. The results show that: when the water cement ratio is 1∶1.6, the initial support of C25 shotcrete can be simulated; the three-bench method is not suitable for tunnel excavation in this geological condition due to the large disturbance to the surrounding rock in front of the tunnel and the large load on the initial support, and other methods can ensure the safety and stability of tunnel construction. Considering the construction progress and construction cost, the method of three-bench with reserved core under case M4 is the best; after the completion of tunnel excavation and support under different working conditions, the maximum internal force of shotcrete initial support occurs at the side wall and follows by the arch foot, and the smallest one occurs at vault.
Abstract：
In order to understand the mechanical behaviors of the super-long tunnel in soft and fractured surround?
ing rocks under different construction methods and to find out an efficient and safe construction method suitable for the geological conditions, indoor simulation of tunnel excavation by three construction methods under six working conditions are conducted by means of core sampling at site, measuring of mechanical parameters of surrounding rock and preparations of similar material and primary support material based on a tunnel project, and the characteristics of stress field of surrounding rock and response of internal force of support system under different working conditions are studied. The results show that: when the water cement ratio is 1∶1.6, the initial support of C25 shotcrete can be simulated; the three-bench method is not suitable for tunnel excavation in this geological condition due to the large disturbance to the surrounding rock in front of the tunnel and the large load on the initial support, and other methods can ensure the safety and stability of tunnel construction. Considering the construction progress and construction cost, the method of three-bench with reserved core under case M4 is the best; after the completion of tunnel excavation and support under different working conditions, the maximum internal force of shotcrete initial support occurs at the side wall and follows by the arch foot, and the smallest one occurs at vault.
TIAN Xingchao LIU Yuanming TAO Tiejun YANG Jiazhao MA Zhili
.Model Test Study on Mechanical Behaviors of Tunnel Construction in Soft and Fractured Surrounding Rocks[J] MODERN TUNNELLING TECHNOLOGY, 2020,V57(5): 200-209
2020, Vol. 57 