Due to the limitation of geological conditions and route alignment, tunnel engineering will inevitably pass through special sections such as shallow buried section, broken rock layer, and loss and weak rock stratum. Tunnel construction in these special sections will easily lead to tunnel collapse, landslide of portal slope, excessive deformation of supporting structure, and even deformation and damage accidents, which are high-incidence areas of engineering safety accidents. In this paper, a 3D numerical model is established based on a practical engineering to analyze the deformation and stress variation of surrounding rock of the tunnel with the in-advance support technology. According to the monitoring results of the actual project, the deformation law of the soft rock section at the tunnel entrance is mastered. The deformation of surrounding rock of the tunnel under the support condition of changing the three main parameters, such as ring spacing, pipe diameter, and pipe length, is analyzed, and the effect of controlling the deformation of surrounding rock with different parameters is studied. The deformation, stress characteristics, and plastic zone distribution of surrounding rock by a single side wall guide method and ring excavation and retaining core soil method in advance support are numerically simulated and studied.

中文翻译：

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围岩弹性变形下近岩层隧道洞口支护研究

由于地质条件和路线线形的限制，隧道工程不可避免地要经过浅埋段、破碎岩层、漏失弱岩层等特殊路段。在这些特殊路段进行隧道施工，极易导致隧道坍塌、门廊边坡滑坡、支护结构过度变形，甚至发生变形破坏事故，是工程安全事故的高发区。本文基于工程实际建立三维数值模型，利用超前支护技术分析隧道围岩变形和应力变化。根据实际工程的监测结果，掌握了隧道入口软岩段的变形规律。对改变环距、管径、管长三个主要参数的支护条件下隧道围岩变形进行了分析，研究了不同参数控制围岩变形的效果。数值模拟研究了单边墙导引法和环挖护心土法预支护围岩的变形、应力特征及塑性区分布。