浅埋隧道围岩稳定性与支护效果分析

Analysis of surrounding rock stability and supporting effect of shallow buried tunnel

本文以泉州某隧道浅埋段作为研究对象,运用离散元模拟软件,研究了地表倾角为30°、45°、60°、90°四种工况下,围岩变形、地表沉降、围岩应力、塑性区体积的变化规律;基于上述研究,分析了锚喷支护与注浆加固对围岩变形和力学特性的影响。研究表明:在无支护条件下土质浅埋隧道段围岩无自稳能力,地表边坡容易发生大面积下沉甚至滑坡;随着地表倾角增大塑性区体积、地表下沉量、地表下沉范围增大。锚喷支护可以显著降低地表沉降,缩小地表沉降影响范围,大幅度抑制围岩变形,降低塑性区体积,但是并未彻底改变地表和隧道围岩失稳的风险。注浆加固形成的加固圈提高了围岩力学参数,围岩自稳能力得到提升,锚喷支护可为长期围岩蠕变提供更大安全空间。

In this paper,the shallow buried section of a tunnel in Quanzhou is taken as the research object,and the discrete element simulation software is used to study the variation law of surrounding rock deformation,surface settlement,surrounding rock stress and plastic zone volume under four working conditions of surface inclination angle of 30,45,60 and 90 degrees.Based on the above research,the influence of shotcrete-bolt support and grouting reinforcement on the deformation and mechanical properties of surrounding rock is analyzed.The research shows that the surrounding rock of the soil shallow tunnel section has no self-stability ability and the surface slope is prone to large-scale subsidence or even landslide without support.With the increasing of surface dip angle,the volume of plastic zone,surface subsidence and surface subsidence range increase.Bolting and shotcreting support can significantly reduce the surface subsidence,reduce the influence range of surface subsidence,greatly inhibit the deformation of surrounding rock and reduce the volume of plastic zone,but it does not completely change the risk of instability of surface and tunnel surrounding rock.The reinforcement ring formed by grouting reinforcement improves the mechanical parameters of surrounding rock,and the self-stabilization ability of surrounding rock is improved.Spray anchor support can provide more safe space for long-term creep of surrounding rock.