公路隧道衬砌裂纹扩展机理
Numerical investigation on the fracture propagation mechanism of highway tunnel lining

公路隧道衬砌裂缝作为公路隧道的主要病害，其问题日益突出，尤其是带裂纹工作衬砌的等级评价略显不足。为研究公路隧道带裂缝二次衬砌在受荷载作用下裂纹扩展规律，用离散元PFC软件对衬砌裂纹扩展规律进行数值模拟研究，揭示隧道衬砌中裂纹开裂的灾演机理，根据衬砌开裂状态进行病理灾害分析，并建立了相应的预测模型。衬砌的整体安全性受预置裂纹的影响，预置裂纹处往往是衬砌中较危险的位置；预置裂纹的深度对裂纹贯通时间有较大影响，随着预置裂纹深度的增加，预置裂纹贯通衬砌的时间逐渐减小；预置裂纹的深度对裂纹张开度的变化有较大影响，随着预置裂纹深度的增加，预置裂纹张开度逐渐增大，并在贯通衬砌时有明显的突变，这样便于确定衬砌治理时机。
As the major flaw of highway tunnels, lining cracks of highway tunnels is increasingly seriously. In order to study the mechanism of crack propagation in highway tunnels under loading, this article conducts numerical simulation on the crack propagation with discrete element software PFC, demonstrating the disaster mechanism of crack propagation in highway tunnels,and establishing the corresponding prediction models. The results showed that:integral safety of lining is subject to pre-existing flaws, and the positions of pre-existing flaws are generally relatively more dangerous in lining; the depth of pre-existing flaws plays an important role in the timing of crack coalescence,i.e.,the deeper the pre-exsiting flaws are, the less time is needed to achieve crack coalescence in the lining; the depth of pre-exsiting flaws has a great influence on the variation of crack opening, i.e. the deeper pre-exsiting flaws are, the increasing opening those fracture apertures will be, and there is an obvious abrupt change when the flaws coalesce.