小尺寸模型在五峰隧道涌突水判别中的应用

Application of a small-scale model test in distinguishing of water inrush in the Wufeng Tunnel

岩溶隧道的涌突水问题对于隧道安全性存在着较大影响。以宜来高速五峰隧道为研究对象,通过现场水文地质调查、钻孔水位与降雨量观测、数值模拟并结合室内小尺寸模型试验对隧道涌突水的风险进行了判别。试验结果显示隧道涌突水风险主要受到岩溶管道与隧道相对空间位置和管道水压的影响,当试验水压为0.2 MPa时,随着隧道上覆土体的厚度增加能够有效地减小渗流作用对隧道的影响,但随着水压的增大,管道水的渗流不单以垂直渗流为主,还包括水平向的渗流,水压的增大使隔水层中的断续裂隙发生扩展,从而使隧道产生涌水破坏;数值模拟结果显示五峰隧道在拱顶和拱肩处剪力最大,在地下水渗流的条件下容易形成沿着拱顶和拱肩处的拉剪破坏,隧道涌突水是剪应力场与渗流场耦合作用下的结果。隧道涌点水破坏的首要因素为水压并与隔水岩盘的厚度息息相关。

Water inrush in karst tunnel has a great influence on tunnel safety.Taking the Wufeng Tunnel of Yilai Expressway as the research object,the risk of water inrush in the tunnel was identified though field hydrogeological investigation,borehole water level and indoor rainfall monitoring,numerical simulation and small-scale model tests.The test results show that the risk of water inrush in the tunnel is mainly affected by the relative spatial position between the karst pipeline and tunnel,including the water pressure of the pipeline.The influence of seepage on the tunnel can be effectively reduced by increasing the thickness of the overlying soil when the test water pressure is 0.2 MPa.But with the increase in water pressure,the seepage of pipeline water is not only vertical seepage but also includes horizontal seepage.The intermittent cracks in the waterproof layer expand,which finally results in water inrush damage in the tunnel.The numerical simulation results show that the maximum shear force of the Wufeng Tunnel is at the arc and shoulder,which may easily form tensile shear failure along this part under groundwater seepage.The finding is consistent with the test results of the small-scale model.The water inrush in the tunnel is the coupling effect of the shear force and seepage field.The primary factor of water inrush in the tunnel is water pressure and is closely related to the thickness of water barrier rock.