片岩隧道二衬开裂机理研究

片岩作为典型的软岩具有显著的各向异性特征,在隧道结构中围岩的各向异性特征易造成支护结构的局部偏压承载,对隧道衬砌结构安全产生严重威胁。谷竹高速公路沿线区域片岩分布较为普遍,多条隧道在施工过程中曾出现过不同程度的二衬开裂问题。通过现场监控量测及数值计算对片岩各向异性及围岩作用下的二衬开裂规律及机理进行了分析。研究结果表明:片岩各向异性特征显著,易形成结构偏压作用,产生偏压部位的支护结构承载明显大于其他区域;偏压区域二衬结构率先出现开裂,裂缝分布较其他区域严重。研究成果揭示了片岩隧道二衬开裂特征及机理,为确保谷竹高速公路片岩隧道及类似工程施工的安全及运营提供了参考依据。

Study on secondary lining cracking mechanism of anisotropic schist tunnel

As a typical kind of soft rock, schist has obvious anisotropic characteristics, which easily leads to local bias load for the tunnel passing through schist rock mass, seriously threatening to the safety of the tunnel lining structure. Schist is widely distributed along Guzhu expressway, and a number of tunnels appeared secondary lining crack problem in different degrees. The schist anisotropy and the cracking law and mechanism under anisotropic effect were analyzed through site monitoring and numerical calculation. The research shows : ①Schist has obvious anisotropic characteristics, which easily generates bias load to lining structure. The load on lining in bias region is larger than that in other regions;②Secondary lining structure in bias region is the first to crack and the fracture distribution is more serious than other regions. The study reveals the crack characteristics and mechanism of secondary lining structure under anisotropic effect, which provides reference basis for ensuring construction and operation safety of schist tunnel of Guzhu highway and other similar projects.