海底隧道风化囊围岩-支护系统相互作用的流变时效研究

Weathered Rock Mass and Supporting System Interactions of a Under Sea Tunnel Considering Rheological Effects

厦门海底隧道工程穿越四条断层破碎带,破碎带处洞体围岩软弱、破碎,岩石主要为风化破碎类花岗岩,其流变时效属性非常显著。通过对风化破碎类花岗岩试样进行流变试验研究,建立适合风化囊围岩特点的流变力学模型;再在考虑围岩流变时效的基础上,采用有限元数值模拟方法,开展风化囊围岩-支护系统的相互作用研究。研究表明:松散破碎岩体的流变时效作用明显,在隧道的设计施工中必须计入粘性蠕变的影响;风化囊区段的隧道二衬厚度采用60cm是合适的,不宜再过分增厚;为确保工程安全,开挖后立即施作初期支护,紧跟施作二衬支护。最后,阐述了围岩变形速率比值判别的施工变形控制方法,在判据认定的险情区段,必须实时加固,避免塌方。

The subsea tunnel of Xiamen crosses four geologically fractured rock mass zones. The rock mass at the fractured zones is predominantly weathered broken and granite with strong rheological effect. The rheological tests are performed on samples from the fractured zones. Then, rheological constitutive model is established specifically for the weathering pockets in the rock mass. Finite element analysis that considering the interactions between the rock mass with weathered pockets and the supporting system is also conducted. The results show that the time related rheological effect of tunnels in fractured zones is significant and has to be considered in the tunnel design and construction. The thickness of the second lining supporting system in the weathered zone is appropriate. After the initial supporting, the second lining system should be immediately followed in order to ensure the tunnel construction safety. This paper also gives a method to determine the deformation rate of the rock mass and a method for the deformation control durin the construction.