郑西客专黄土隧道洞口高边坡稳定及隧道地震作用动力响应研究

Study on Stability of High Portal Slopes and Seismic Responses of Loess Tunnels on Zhengzhou～Xi’an Passenger-dedicated Railway

郑西客运专线全线隧道总延长60余km,约三分之二穿过Q3、Q2新老黄土,由于隧道所穿越黄土地区的特性及受地形、洞门形式和桥台进洞等因素影响,隧道洞口出现大量黄土高边坡,边坡稳定成为突出的工程问题,采用以极限平衡理论为基础的条分法对洞口边仰坡进行稳定性检算,并进行了边坡优化设计,使之满足规范安全系数的要求。对大断面浅埋砂质新黄土隧道,利用瞬态动力学有限元方法,计算了粘弹性边界条件下,隧道在Ⅷ度地震荷载作用下的动力响应,找出衬砌的薄弱部位和结构的受力、变形及安全性,为设计提供指导和参考作用。

The total length of the tunnels on Zhengzhou～Xi’an passenger-dedicated railway is over 60 km, two thirds of which is located in Q3 and Q2 old/new loess. Due to the features of the loess and the terrain, portal types and the bridge abutments stretching into the tunnels, a lot of high loess slopes exist at the tunnel portals. The stability of the slopes becomes one of the critical aspects of the works. In the paper, the stability of the front and side portal slopes of the tunnels is verified by means of limit equilibrium theory based slice method and the design of the slopes is optimized so as to meet the requirements of the safety coefficient specified in relevant codes. The dynamic response of the large cross-section shallow tunnels in new sand loess under viscous-elastic boundary is calculated by means of transient dynamic FEM so as to find out the weak points of the lining and the stress, deformation and safety of the tunnel structure. The paper can provide reference for the design of similar works in the future.