Motion Characteristics of Collapse Body during the Process of Expanding a Rescue Channel

For the rapid construction of a rescue channel in the process of underground emergency rescue, a method for the expanded rescue channel in the collapse body is proposed and verified by a model test and a numerical simulation experiment. The motion characteristics and motion law of the expanded collapse body are analyzed on the basis of the mechanics of granular media, and a comparative simulation study on the main influencing factors of the collapse body motion is carried out. The results show that: (1) When the collapse body is expanded for a rescue channel, it will form three types of six relative slip planes. According to the position of the slip plane and the distribution of displacement, the collapse body can be divided into a direct displacement region, a stable region, and an indirect displacement region. (2) The expansion process can be divided into the initial start-up stage, the uplift stage, and the collapse stage, according to the formation time of the slip plane and the displacement law of the collapse body. (3) The results of the numerical simulation and the theoretical analysis of the granular media show that the dip angle of the slip plane is determined by the internal friction angle of the collapse particles, and the dip angles of the three slip planes are below θ1=90°−φ, θ2=45°+φ/2, and θ3=90°+φ/2. (4) The transverse scope and longitudinal distance is brought by the expansion increase with the increase in the expansion size, and the simulated dip angles of the slip plane are larger than the theoretical values due to the size effect. (5) In the expansion process, the strong force chain in the collapse body is concentrated in the stress arch above the expander device, and the failure and reconstruction laws of the stress arch at each stage are consistent with the formation of the slip plane and the uplift and instability law of the collapse body.