关于土体隧道掌子面开挖稳定性的量化探讨

The quantitative analysis of the face stability on soil tunnel

介绍探索土体隧道掌子面开挖稳定性与施工条件的定量关系。首先,通过分析影响掌子面稳定性的主要因素提出掌子面稳定安全系数关于材料强度参数与施工条件参数的隐函数,并利用多元函数Taylor公式将掌子面稳定安全系数的隐函数变换为关于施工条件参数变量的多项式,然后给出确定单一施工条件参数变化下掌子面稳定系数的具体表达式的技术方法;重点提出采用响应曲面法确定多施工条件参数共同变化时F_s =F(t,s_t,s_s)的Taylor展开式。通过理想隧道开挖模型试验阐释该方法的具体应用,最后以狮子垄隧道工程为背景进行实例分析表明:在初始区域U_1内Fs的一阶模型是合适的,进而利用最速上升法寻找优化区域U_2,并经中心复合设计得到了F_s的二阶模型,经过方差分析验证此模型的有效性。

The quantitative relationship between the face stability and construction conditions on soil tunnel is introduced. First, an implicit function to strength parameters and construction parameters is proposed by analyzing the safety factor of face stability. The implicit function is transformed to the polynomial expression on construction parameters via multi-function Taylor formula. A technical method of getting the approximate expressions of safety factor of face stability under a single construction parameter is introduced. Mainly, the response surface methodology is used to determine the Taylor expansions of Fs = F（t, σt, σs） under multiple variables of construction parameters. It illustrated the applications of the proposed methods in ideal tunneling model. Finally, in the Shizilong tunnel project, the results showed that a first-order Fs model of in the initial region of U1 was appropriate, and then gradient ascent method is used to optimized the regional U2. By the central composite design, a validity second-order Fs model is calculated, and the effectiveness was verified by ANOVA.