Failure Mechanism and Optimization of Arch-Bolt Composite Support for Underground Mining Tunnel

Figure 3

Result diagrams of Scheme 4 (ground stress 15 MPa). (a)∼(e): Development curves of roadway displacement, arch axial force, arch bending moment, arch supporting force, and rock bolt axial force, respectively; (f)∼(i): diagrams of plastic zone and supporting structure inner force at the 5^th day, 10^th day, 15^th day, and the 20^th day, respectively. (Supporting arches and rock bolts are presented as the axial force diagrams; the thicker the line, the greater the axial force. When the line thickness of the bolt axial force diagrams is 0, it means the bolts are broken.)