Study of the Indoor Model Test and CEL Simulation of Jacking Force in the Vertical Tunnelling Method

The jacking force is one of the important parameters affecting the construction process in the vertical tunnelling method. To study the dynamic changing process of jacking force with the jacked distance and the influencing factors of the maximum jacking force, both the indoor model test and numerical simulation were conducted. In the model test, we investigated the influence of the height of the soil and water content. The results indicated that the higher the overburden height was, the greater the jacking force. Moreover, the water content enhanced the compressibility of the soil and had little effect on the maximum jacking force. Additionally, the coupled Eulerian-Lagrangian (CEL) approach was used to simulate the vertical jacking construction. In the numerical simulation, we investigated two construction factors (jacking speed and the standpipe outer diameter) and four soil parameters (cohesion, internal friction angle, elastic modulus, and Poisson's ratio). Before that, the CEL simulation results were compared with test data to prove the rationality of the CEL approach, and the two were in good agreement. The results showed that among the six influence parameters, according to the influence degree on the maximum jacking force from large to low, the outer diameter of the standpipe, internal friction angle, cohesion, elastic modulus, jacking speed, and Poisson's ratio were ranked. In addition, the jacking speed of numerical analysis was suggested to be 0.2 m/s. The research results in this paper can provide a reference for the construction of the vertical tunnelling method.