中文摘要：

为了研究隧道开挖过程中循环进尺的合理性和安全性,提出了隧道掌子面与循环进尺相结合的2种破坏模式,即循环进尺段的局部坍塌、掌子面与循环进尺段的整体坍塌,分别采用极限平衡法与上限法推导了循环进尺计算公式。通过综合考虑2种破坏模式下的循环进尺产生条件,建立了非均衡支护压力、黏聚力、内摩擦角等指标之间的相互关系。研究结果表明：循环进尺与掌子面的稳定存在关联,且掌子面的稳定是主控条件,在施工中需重点关注掌子面正前方土体加强;同时,当掌子面与循环进尺处于局部坍塌状态,则循环进尺主要受黏聚力控制,施工中可采用最大循环进尺,如处于整体坍塌,则循环进尺易受各指标影响;实际设计施工中可采用提出的图表优化得到最佳循环进尺。

英文摘要：

In order to investigate the rationality and safety of round length in tunnel excavation,two failure modes combining tunnel face and round length were proposed,namely,local collapse of round length,and overall collapse of tunnel face and round length.And limit equilibrium and upper bound method were adopted to deduce the formula of round length.Through comprehensively considering the mechanism of round length under these two failure modes,the relationships among indexes such as unbalanced support pressure,cohesion,internal friction angle were established.The results show that round length has correlation with the stability of tunnel face,and the stable of tunnel face is the most important factor.Enhancing the core soil ahead tunnel face should be focused on in the tunnel construction.Meanwhile,in local collapse of tunnel face and round length,the round length is mainly controlled by the cohesion,when the maximum round length can be adopted in the construction.If the tunnel is in the state of overall collapse,round length is easy to be influenced by indexes.In actual construction design,the optimum round length can be obtain by proposed diagram in this paper.