基于土拱效应的粉土地层矩形顶管隧道摩阻力计算方法研究

    STUDY ON THE CALCULATION METHOD OF FRICTION RESISTANCE FOR RECTANGULAR PIPE JACKING TUNNELS IN SILTY SOIL LAYERS BASED ON THE SOIL ARCHING EFFECT

    • 摘要: 矩形顶管隧道施工过程中,管体周围土体的变形和应力传递是影响周围土压力的重要因素,而土拱效应与土体应力传递机理密切相关。为实现对粉土地层中矩形顶管顶进力的精准预测,本研究提出一种基于土拱效应的矩形顶管隧道摩阻力计算方法。首先,构建了完全和不完全土拱效应下的矩形顶管隧道土体应力传递模型,将其划分为外部稳定区、弹性拱和内部松散体3部分进行独立分析。其次,基于弹性拱局部区域应力传递规律,将存在应力传递的弹性拱区域定义为有效弹性拱区域,提出完全和不完全土拱效应下的摩阻力计算方法。最后,通过3个典型工程案例分析验证,发现在粉土和粉砂地层中,本研究方法的平均绝对误差(MAE)和相关性系数(R2)分别为(0.4136,0.97)、(1.2102,0.84)和(0.6893,0.94),在准确性和适应性方面均优于其他方法,可为矩形顶管隧道的设计和施工提供理论参考。

       

      Abstract: During the construction of rectangular pipe-jacked tunnels, the deformation and stress transmission of the surrounding soil emerge as pivotal factors that significantly affect the surrounding earth pressure. The phenomenon of soil arching is intrinsically linked to the mechanisms of stress transmission within the soil. To attain a precise prediction of the jacking force in rectangular pipe-jacked tunnels situated within silty soil strata, this study introduces an innovative methodology for calculating the frictional resistance of such tunnels, informed by the effects of soil arching. Initially, a comprehensive stress transmission model is developed for the soil encircling the rectangular pipe-jacked tunnel, which considers both complete and incomplete soil arching effects. This model is systematically divided into three distinct zones for independent analysis: the external stable zone, the elastic arch, and the internal loose body. Subsequently, drawing on the stress transmission principles observed within the elastic arch locality, we define the elastic arch region exhibiting effective stress transmission as the effective elastic arch region. Moreover, methods for quantifying frictional resistance under conditions of both complete and incomplete soil arching effects are meticulously articulated. Finally, an analytical review of three representative engineering case studies reveals that in silty and sandy soil strata, the proposed method yields mean absolute errors (MAE) and correlation coefficients (R2) of (0.4136, 0.97), (1.2102, 0.84), and (0.6893, 0.94) respectively. These results underscore the method's remarkable accuracy and adaptability, surpassing that of alternative methodologies. This research thereby provides a valuable theoretical foundation for the design and construction of rectangular pipe-jacked tunnels.

       

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