非线性破坏准则下浅埋隧道支护参数上限解
Upper bound solutions of support parameter for shallow tunnels in nonlinear soil masses

鉴于土体材料破坏准则的非线性以及参数离散的自然属性，针对浅埋隧道的稳定性问题，提出基于极限分析非线性理论的可靠度计算方法。研究结果表明：将非线性破坏准则退化成线性破坏准则后，本文计算结果与已有研究成果基本一致，验证了文中方法的正确性。在上限解分析中，土体的非线性系数对围岩压力以及破坏范围有很大影响，建议进行支护设计时必须考虑土体破坏准则的非线性，防止因支护力过小或安全系数不足而引发坍塌事故。在可靠度计算中，非线性系数是影响隧道结构可靠度的主要因素，针对非线性系数给出了浅埋隧道满足3种安全等级所需要的安全系数与支护力，为隧道设计规范进行了补充，也为今后浅埋隧道的支护设计提供了参考价值。
Due to the nonlinear characteristic of failure criterion and variation of parameters, the stability of shallow tunnels was analyzed in this work with limit analysis nonlinear theory and reliability approach. The results show that the calculation solutions are in accordance with the existing results when the nonlinear failure criterion degrades to the linear one, which verifies the validity and correctness of proposed method in this paper. In the analysis of upper bound solutions, the nonlinear coefficient has significant impact on collapse pressure and failure range, thus the nonlinear property of soils should be taken into account in the process of bracing design so as to prevent collapse issues owing to insufficient supporting pressure and safety factor. Further, in the calculation process of reliability, the nonlinear coefficient is the dominating factor affecting reliability. Safety factor and supporting pressure were derived under 3 safety levels for shallow tunnels, which can be regarded as supplement of design criterion in tunnel engineering, and provide reference value for the design of shallow tunnels