挤压性软岩隧道大变形灾害及控制措施研究

RESEARCH ON LARGE DEFORMATION CONTROL MEASURES FOR SQUEEZED BROKEN SOFT ROCK TUNNELS

软岩大变形隧道修建时,由于围岩自稳能力弱,隧道时常发生较大收敛问题。根据云南省云临高速公路大亮山隧道地质勘察报告,对ZK20+160~ZK20+320段初期支护大范围开裂、仰拱隆起严重等问题采用有限差分数值方法进行模拟研究。通过对数值模拟结果的分析得出软岩大变形隧道变化规律,并由此提出相应的设计施工优化措施。研究表明:隧道拱顶沉降与仰拱隆起大,隧道围岩塑性区半径大,符合高地应力下软岩大变形隧道开挖的物理力学变化特征;将数值模拟二次衬砌拱顶沉降曲线与现场实测拱顶沉降曲线对比分析,结果表明两者变化规律一致;针对现场初期支护开裂、仰拱隆起与钢拱架扭曲变形等工程问题并结合数值模拟结果,建议采用双层支护、增设锁脚锚杆和仰拱尽早封闭等优化措施控制隧道变形开裂问题。

When soft rock large deformation tunnel is constructed,due to the weak self-stabilizing ability of surrounding rock,the tunnel often has a large convergence problem.Based on the geological survey report of the Daliangshan tunnel of yunlin expressway in yunnan province,this paper uses the finite difference numerical method to simulate and study the large-scale cracking of the initial branch of the ZK20+160~ZK20+320 section and the serious uplift of the inverted arch.Through the analysis of the numerical simulation results,the change law of the soft rock large deformation tunnel is obtained,and the corresponding design and construction optimization measures are put forward.The research shows that the tunnel vault settlement and inverted arch uplift are large,and the radius of the plastic zone of the surrounding rock of the tunnel is large,which is in line with the physical and mechanical change characteristics of soft rock large deformation tunnel excavation under high ground stress.The comparison and analysis of the top settlement curves show that the change rules of the two are consistent;in view of the engineering problems such as initial support cracking,inverted arch uplift and steel arch distortion and deformation,combined with the numerical simulation results,it is recommended to use double-layer support and additional locking anchors optimization measures such as early closing of the inverted arch to control the deformation and cracking of the tunnel.