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Time-dependent solution for non-circular tunnels considering the elasto-viscoplastic rockmass
International Journal of Rock Mechanics and Mining Sciences ( IF 7.0 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.ijrmms.2020.104395
Eugie Kabwe , Murat Karakus , Emmanuel K. Chanda

Abstract The time-dependent ground response of tunnels in squeezing ground requires a thorough understanding of the creep mechanism. Several studies conducted assume that this ground response can be characterized by elastoplastic and viscoelastic behaviour. However, the elasto-viscoplastic behaviour associated with the creep mechanism can predict this ground response realistically. Thus, this paper, presents a solution considering the elasto-viscoplastic behaviour for the ground response estimation of a non-circular tunnel under hydrostatic stress field in an isotropic and homogenous rock mass. The proposed method is an extended form of the closed-form solution based on the fractional-order derivative viscoplastic constitutive law. Thereafter, the proposed method is applied to the horseshoe tunnel ground response and support structure capacity estimation in squeezing ground. It is ascertained that delayed behaviour responsible for squeezing can be estimated realistically about 14% convergence and 24 m yield extension. Whereas the conventional solutions underestimate the convergence range between 2.5% and 5% and the yield zone extension between 12 m and 16 m. In comparison to these conventional solutions, it accounts for 10% tunnel convergence and 50% extension of the yield zone in the long-term. Additionally, the solution determines the suitable long-term safety coefficient for support structure installed at the right time and location behind the tunnel face in squeezing ground.

中文翻译:

考虑弹粘塑性岩体的非圆形隧道瞬态解

摘要 隧道在挤压地层中的时变地面响应需要对蠕变机制有透彻的了解。进行的几项研究假设这种地面响应可以用弹塑性和粘弹性行为来表征。然而,与蠕变机制相关的弹粘塑性行为可以真实地预测这种地面响应。因此,本文提出了一种考虑弹粘塑性行为的解决方案,用于在各向同性和均质岩体中的静水应力场下估计非圆形隧道的地面响应。所提出的方法是基于分数阶导数粘塑性本构律的闭式解的扩展形式。此后,将所提出的方法应用于马蹄形隧道地基响应和挤压地层支撑结构承载力估计。可以确定,在大约 14% 的收敛和 24 m 的屈服扩展时,可以实际估计导致挤压的延迟行为。而传统的解决方案低估了 2.5% 和 5% 之间的收敛范围和 12 m 和 16 m 之间的屈服区扩展。与这些传统解决方案相比,从长远来看,它可以实现 10% 的隧道收敛和 50% 的屈服区扩展。此外,该解决方案还为在挤压地层中隧道掌子面后面的正确时间和位置安装的支撑结构确定了合适的长期安全系数。可以确定,在 14% 的收敛和 24 m 的屈服扩展时,可以实际估计导致挤压的延迟行为。而传统的解决方案低估了 2.5% 和 5% 之间的收敛范围和 12 m 和 16 m 之间的屈服区扩展。与这些传统解决方案相比,从长远来看,它可以实现 10% 的隧道收敛和 50% 的屈服区扩展。此外,该解决方案还为在挤压地层中隧道掌子面后面的正确时间和位置安装的支撑结构确定了合适的长期安全系数。可以确定,在 14% 的收敛和 24 m 的屈服扩展时,可以实际估计导致挤压的延迟行为。而传统的解决方案低估了 2.5% 和 5% 之间的收敛范围和 12 m 和 16 m 之间的屈服区扩展。与这些传统解决方案相比,从长远来看,它可以实现 10% 的隧道收敛和 50% 的屈服区扩展。此外,该解决方案还为在挤压地层中隧道掌子面后面的正确时间和位置安装的支撑结构确定了合适的长期安全系数。与这些传统解决方案相比,从长远来看,它可以实现 10% 的隧道收敛和 50% 的屈服区扩展。此外,该解决方案还为在挤压地层中隧道掌子面后面的正确时间和位置安装的支撑结构确定了合适的长期安全系数。与这些传统解决方案相比,从长远来看,它可以实现 10% 的隧道收敛和 50% 的屈服区扩展。此外,该解决方案还为在挤压地层中隧道掌子面后面的正确时间和位置安装的支撑结构确定了合适的长期安全系数。
更新日期:2020-09-01
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