Physical Simulation and Monitoring the Deformation and Fracture of Roadway in Coal Mining

Abstract

Aiming at the large deformation and the dynamic fracture of roadway during the underground excavation or mining, a physical simulation and strain testing system was established, and the deformation process of surrounding body and its inner strain characteristics of the simulated roadway under loading was carried out. Results showed that the inner strain change of the measurement points can be divided into three types: the strain firstly increases and then decreases, the strain slowly increases and then increases sharply, and strain firstly reduces and then increases. The strain starting time is closely related to the failure path and boundary of tested samples. This paper suggested two criteria for determining the instability of roadways, which are a huge and faster increase of strain at the location of the roof and floor with high absolute value, or a small increase with a peak value or irregular fluctuation. This paper provides a new idea for the simulation of roadway instability and is significant in deeper understanding the deformation and destabilization of underground roadway.

Acoustic Emission Characteristics of Graded Loading Intact and Holey Rock Samples during the Damage and Failure Process

“…Large-scale granite rock was collected from the construction site and was sent to the processing plant for initial processing to make a 100 × 100 × 100 mm 3 square rock sample by hydraulic cutting machine. Some of these intact rock samples were selected and a cylinder of 20 mm diameter was taken out from the selected sample center by the hole punching machine to make a 100 × 100 × 100 mm 3 square sample with a 20 mm diameter hole. The sample surfaces were polished and smoothed by a grinder and could be in good contact with the end face of the AE transducer during the AE test.…”

“…The development and the expansion process of the surrounding rock internal fissures under the complicated loading conditions of the underground space are closely related to its structural instability disasters. The stability monitoring has become the focus of engineering construction at home and abroad [3][4][5].…”

Instability Process of Crack Propagation and Tunnel Failure Affected by Cross‐Sectional Geometry of an Underground Tunnel

“…It is useful to analyze the process of instability and crack propagation of rock mass by large-scale physical model testing [8,9]. e process of crack propagation in the surrounding rock and the process of tunnel deformation and failure can be directly obtained through similarity simulation experiment.…”