超大断面硐室围岩变形破坏机理及控制

针对断面面积近100 m2的大采高支架换装硐室,采用现场观测、数值模拟等方法分析其变形破坏机理:硐室断面增大致使围岩破碎区、塑性区增大,超大断面硐室塑性区半径达到普通断面硐室的2.2倍;断面增大引起掘进扰动应力增高,而锚杆加固厚度小、初期支护阻力小致使软弱围岩严重变形破坏。针对支架换装硐室0~2.5 m的破碎区、2.5~8.0 m的塑性区,提出了分区耦合支护围岩稳定控制原理:硐室围岩由浅至深破坏程度逐渐减小,达到稳定所需支护强度逐渐减小,采用高强高预紧力"锚杆、注浆锚索、锚索"支护及"分区注浆加固"技术,可形成针对破碎区、塑性区和弹性区的3个相互联系的承载圈,从而满足各个分区支护强度需要,实现支护结构和围岩共同承载,保证围岩稳定。

Deformation and failure mechanism of surrounding rock in chamber with super large section and its control

Based on the nearly 100 m2 large section chamber for large mining height support reloading，with the site observation and numerical simulation method，surrounding rock deformation and failure mechanism was analyzed.With the increase of chamber section，the failure zone and the plastic zone increase，the plastic zone radius of super large section chamber is 2.2 times about normal section chamber.The high disturbed stress because of large section，the small thickness of anchorage body with bolt support，and the low initial support resistance resulted in serious deformation and failure of weak surrounding rock.According to the 0-2.5 m failure zone and the 2.5-8.0 m plastic zone of support reloading chamber，the stability principle of zonal control of coupling support for large cross section chamber was put forward.After chamber excavation，the failure zone，the plastic zone and the elastic zone were formed，the surrounding rock damage degree was gradually reduced from shallow to deep，and also the needed support strength to be stability decreased gradually，through the high strength and high pre-stress support with bolt，grouting cable and cable，three load bearing ring can be formed according to the failure zone，the plastic zone and the elastic zone，so that the three zones are connected organically，and the support strength for the three zones can be satisfied，and a common loading of supporting structure and surrounding rock can be ensure the stability of the surrounding rock.