考虑黏土土性参数与支护压力变异性的盾构掌子面稳定性分析
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华中科技大学土木与水利工程学院

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TU431

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国家自然科学基金项目(面上项目,重点项目,重大项目),国家重点基础研究发展计划(973计划)


Face stability analysis of shield tunnel considering variability of soil parameters and support pressure in clay
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School of Civil and Hydraulic Engineering,Huazhong University of Science and Technology

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    摘要:

    盾构掌子面稳定性的不确定性分析多侧重于土性参数的变异性,鲜少考虑支护压力的变异性。为此,基于K-L级数分解法建立了描述土性参数空间变异性的三维随机场,研究了土性参数变异性对掌子面失稳模式、极限支护应力的影响规律,讨论支护压力的均值与变异系数对失效概率的影响,并依据此确定了支护压力均值特征值。结果表明:黏性土黏聚力与内摩擦角的空间变异性对掌子面稳定性有重要影响,其中内摩擦角的影响更甚;掌子面失稳模式与随机场局部分布密切相关,当掌子面前方随机场较分散时,可能发生局部破坏;掌子面的失效概率与支护压力的均值与变异系数密切相关,支护压力的均值越大,变异系数越小,失效概率越小;提出了掌子面支护压力均值特征值的概念,并结合失效概率给出了确定方法。

    Abstract:

    The probabilistic analysis of face stability of shield tunnel at present major focusing on the variability of the soil parameters. However, few researches consider the variability of support pressure. Therefore, based on K-L expansion, three dimensional random fields of soil parameters are generated to analyze the impact of variability of soil parameters made on the failure mechanism and the critical support pressure. Also, the influence of mean value and the coefficient of variation of support pressure on probability of failure is discussed for determining the characteristic mean value of critical support pressure. Results show that variability of both cohesion and friction angle influence the face stability substantially and the influence of variability of friction angle is more significant. The failure mechanism is closely related to the local distribution of random field. When the local random field of the tunnel face is dispersed, the local failure may happen. The probability of failure of the tunnel face is relevant to the mean value and the coefficient of variation of support pressure. The probability of failure decrease with the mean value of support pressure increase or coefficient of variation of support pressure increase. The definition of characteristic mean value of critical support pressure is proposed and the determination procedure is presented.

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  • 收稿日期:2020-12-01
  • 最后修改日期:2021-02-24
  • 录用日期:2021-03-25
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