厦门翔安海底隧道风化槽围岩渗透破坏及岩体流变试验研究

Study on the Destroy of Seepage and Creep Test in Weathered Groove of Xiamen Xiang'an Subsea Tunnel

厦门翔安海底隧道需穿越多处海底风化槽,该地段围岩为破碎、风化的花岗岩,渗透性强、水压高、自稳性差、施工风险大,其物理力学特性研究对设计和施工方案制定意义重大。本文对风化槽围岩的渗透破坏和流变试验进行研究。渗透稳定性评价结果表明,在全水头作用下,F1、F4风化槽强风化带岩体渗透稳定性较好,但隧道开挖将引起地层变形,围岩渗透稳定性改变,施工中需进行评估监测并采取必要措施。三轴试验结果表明,风化槽强风化花岗岩强度低、变形大、弹性模量低,在应力达到峰值后,有明显的塑性流动。三轴流变试验结果表明,风化槽强风化花岗岩变形具有明显的粘性时效特征,对围岩开挖后的掌子面稳定性和长期变形稳定性都不利,在设计和施工中应引起注意;采用非线性蠕变模型对其流变特性进行拟合,效果良好,由此建立相应的流变力学模型。研究成果为本工程风化槽围岩注浆加固和支护结构设计提供可靠依据。

Xiamen Xiang＇ an subsea tunnel passes through several weathered groove in seabed. The rock mass surrounding tunnel in weath- ered groove is weathered and fragmented granite with strong penetrabihty, high water pressure, poor self - stability, and high risk during tunneling. It is very important to carry out the physical and mechanical characteristics of weathered groove for designing and tunneling. The study on the destroy of seepage and creep test were carried our in this paper. The result indicates that the seepage stability of weathered groove（ F1, F4） under full water pressure is satisfied, however, it is necessary to monitor the seepage stability since the situation will change in tunneling due to displacement in strata. Three - axis test indicates that the strongly weathered granite shows low strength, high compressibility, low elastomeric module and presents a distinct plastic process after maximal stress. The result of three - axis creep test shows that the strongly weathered granite behaves with obvious viscosity, which is unfavorable to both the stability of surrounding rock in tunneling and the long stage stability of lining. It should be noticed in tunneling. The creep characteristics of strongly weathered granite was well imitated by a non - linearity creep model. The research in this paper provided key parameters of weathered groove for the designer and contractor of Xiang＇ an subsea tunnel.