衬砌背后空洞和衬砌开裂是威胁高速铁路隧道行车安全的最主要问题。高速铁路隧道衬砌背后空洞不仅是威胁隧道结构安全的重要因素，更是造成衬砌结构开裂最主要的原因。通过基于虚拟裂缝模型的扩展有限元方法( XFEM)和基于弥散裂缝模型的常规有限元分析方法( CFEM)的地层结构模型，对高速铁路隧道衬砌拱肩背后一定范围内空洞引起的衬砌开裂形态进行数值模拟分析，开裂形态表现为拱肩背后空洞近拱顶边缘的二次衬砌内侧开裂，同时初期支护环向贯通开裂。研究表明，扩展有限元法能较好地描述衬砌开裂的走向、长度等开裂形态以及扩展规律等，而ANSYS中的SOLID65单元能实现对衬砌背后空洞引起衬砌开裂范围的定性描述，两者之间相互补充和相互验证能较为准确地描述衬砌开裂的几何信息，进而有助于衬砌结构开裂应力场分析。%The lining cracks and cavity behind lining are two major potential threats to the safety of high-speed trains. The cavity behind lining is considered not only the principal factor of threatening to the safety of tunnel structure, bus also the main cause of lining cracks in the high-speed railway tunnel. Concerning the lining fracture morphology under the conditions of a range of cavities behind the lining shoulder in the high-speed railway tunnel, the paper conducts a contrastive analysis with two different numerical simulation methods based on the stratum structure model, focuses on their theories and results of calculation, which are the XFEM based on the fictitious crack model and the CFEM based on the smeared crack model. The modeling results show that the cracks inside the secondary lining occur in the longitudinal boundary of the cavities adjacent to the tunnel vault and two circumferential through cracks appear along the circular boundary of the cavities to the primary lining. It also turns out that the XFEM can better describe the lining fracture morphology, such as the strike, length and crack laws, while the SOLID65 unit of ANSYS can offer a qualitative description to the fracture area of lining caused by the cavity behind lining. The mutual authentication and complementation can be more accurate to describe the geometric information and propagation rules of lining cracks and help the stress field analysis of lining fracture.
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