超前自进式锚杆对断层角砾岩隧道稳定性影响研究

Study on Stability of Advance Self-propelled Anchor Rod for Fault Breccia Tunnel

对于强风化断层角砾岩隧道,超前支护时易出现卡钻及难以成孔等问题,隧道开挖易引起掌子面坍塌,造成安全隐患。为解决断层角砾岩隧道超前施工难题,结合北京玉渡山隧道自进式中空注浆锚杆超前施工技术的成功应用,阐述了在断层角砾岩隧道施工中自进式中空注浆锚杆代替普通超前小导管作为超前支护的施工优点,并结合现场情况建立了断层角砾岩隧道力学模型对围岩塑性区进行分析。通过分析得出:合理增加断层角砾岩隧道初始支护强度可以一定程度上抑制隧道围岩塑性区的扩展,提升围岩稳定性。针对该情况,通过试验对比确定了自进式锚杆合理的支护参数与注浆压力。并根据掌子面开挖后超前支护效果验证了上述参数的合理性,为同类地层提供参考依据。

For heavily weathered fault breccia tunnel,advance support is prone to problems such as jamming and difficulty in forming holes,and tunnel excavation can easily cause tunnel face collapse,resulting in safety hazards.In order to solve the problem of advance construction in fault breccia tunnel,a successful application of self-propelled hollow grouting anchor rod advanced construction technology in Beijing Yudushan Tunnel was introduced,and the advantages of self-propelled hollow grouting anchor rod as advanced support in fault breccia tunnel instead of ordinary advanced small conduits was analyzed.It is concluded that a reasonable increase in the initial support strength of the fault breccia tunnel can inhibit the expansion of the plastic zone of the tunnel surrounding rock to enhance the stability of the surrounding rock.Combined with the field situation,the mechanical model of fault breccia tunnel was established to analyze the plastic zone of surrounding rock.The reasonable support parameters and grouting pressure for the self-propelled anchor rod were determined by test comparison.The reasonableness of these parameters was also verified based on the effect of the advanced support after excavation of the tunnel face,which provides a reference for similar strata.