Analysis of mechanical properties of reverse four-link top coal caving support

Due to the presence of front and rear conveyor drive motors and other equipment at the end of the fully mechanized mining face, the space is cramped. The commonly used anti-four-bar transition support system provides even support for the front and rear columns, but its structural limitations result in weaker support performance compared to the standard four-bar support system. To maintain a consistent center distance for the conveyor, the base must be slightly retracted, which leads to a reduction in support strength. Therefore, the strength and stability of the support system require validation. The mechanical properties of the anti-four-bar transition support system for caving coal were analyzed using the software ANSYS Workbench. Under the condition where the top beam is subjected to an eccentric load and the base is subjected to a torque load, the overall stress and displacement changes of the support system were not significant. However, analyzing only the entire support system can lead to unreasonable local design. By analyzing the individual components, it was determined that the top beam experiences the maximum stress of 185.29 MPa, which requires the enhancement of material strength; the diagonal beam has a maximum stress of 69.18 MPa and a maximum displacement of 0.49034 mm, which necessitates increasing the thickness of the reinforcing plates; and the base has a maximum displacement of 0.46135 mm, which requires an increase in the transition fillet radius. Modal analysis was conducted on the top beam and base, and it was found that their natural frequencies are all greater than 50 Hz, preventing mechanical resonance with other equipment. By analyzing the regular patterns of mine pressure, it was observed that the working face pressure tends to be higher in the middle and lower at both ends, with the initial peak pressure reaching 37.8 MPa and periodic pressures ranging between 30 to 37.5 MPa. The research findings provide reference data for subsequent support system studies.