跨海峡海底隧道风化槽围岩力学特性研究

厦门海底隧道工程是我国建设的第一条海底公路隧道。隧道在建设过程中穿越F1～F4 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，该类岩石尤其是强风化花岗岩强度低，压缩性高，自稳和自承能力差，给隧道衬砌结构的设计和施工工艺的选择带来一系列特殊的问题。通过对风化破碎类花岗岩（主要包括微风化花岗岩和强风化花岗岩）试样进行一系列的室内试验，重点研究风化槽花岗岩的力学行为。强风化花岗岩三轴压缩试验及流变试验表明：强风化花岗岩强度低、变形大、弹性模量低，在达到峰值后，有明显的塑性流动，通过Mohr-Coulomb准则得到强风化花岗岩的摩擦角 约为31°，黏聚力约为0.1 MPa，且该岩石具有明显的流变特征。在流变试验的基础上，建立适合风化槽围岩特点的流变力学模型。其研究成果为海底隧道风化槽隧道围岩注浆加固和衬砌设计提供可靠依据和技术支撑。

Research on mechanical characteristics of weathered granite for subsea tunnel

Xiamen subsea tunnel is the first undersea road tunnel in China. The tunnel passes through the weathered strata F1, F2, F3 and F4 where the rock mass is weathered and fragmented, the main rock in this region is weathered and fragmented granite. The main mechanical characteristics of this kind of rock especially the strongly weathered granite is low strength, high compressibility, self-stability and bearing capacity of the rock is poor; it brings many exceptional problems to the liner design and the tunnel construction technology. In order to study the mechanical characteristics of the host rock in weathered strata, a series of laboratory tests for the rock including slightly weathered granite and strongly weathered granite have been carried out; the triaxial test results containing triaxial compression test and creep test of strongly weathered granite show that this kind of rock has the properties of low strength, large deformation and low elastic modulus; plastic flow will occur after the stress-strain curve reach the peak; and also the friction angle and cohesion are determined as about 31°and 0.1 MPa respectively through Mohr-Coulomb criterion; more over, high creep potentials of strongly weathered granite is shown through the triaxial creep test. Based on the triaxial test results, a rheological mechanics model suitable for host rock in strongly weathered strata was established through the creep test results. The results obtained from the research work are useful for soft rock engineering especially for weathered granite engineering, and it has guiding effect on the tunnels’ design and construction for this kind of rock.