大断面软岩隧道变形特征及多层初支控制研究

以连城山大断面软岩隧道工程为依托,基于施工监测数据,对比分析了单层I22b钢拱架初期支护、单层H20b型钢拱架初期支护、双层I22b工字钢拱架初期支护和双层H20b型钢拱架初期支护4种支护方案下围岩的变形规律与支护的受力特征。结果表明,单层和双层I22b钢拱架初期支护均不能控制隧道的大变形,而双层H20b型钢拱架初期支护可以控制隧道围岩变形。采用数值软件进一步比较了4种支护措施对于控制围岩变形的有效性,计算结果表明,I22b钢拱架的支护控制围岩变形的效果明显较差,尤其是单层I22b钢拱架的支护方案条件下围岩发生了较大的变形。采用双层初期支护的方案后围岩变形分布更均匀,支护结构与围岩协同变形。研究结果可为类似工程的设计与施工提供一定的参考。

Research on the Deformation Characteristics of Soft Rock Tunnel with Large Section and the Deformation Control with Multi-layer Support

Relying on the Lianchengshan large-section soft rock tunnel project,based on the construction monitoring data,comparative analysis of deformation rules of surrounding rock under four kinds of supporting schemes and the characteristics of supporting forces are carried out,the four supporting schemes being initial support for single-layer I22b steel arch,initial support for single-layer H20b steel arch,initial support for double-layer I22b I-shaped steel arch and support for double-layer H20b steel arch.The results show that the initial support of single-layer and double-layer I22b steel arches cannot control the large deformation of the tunnel,and the initial support of double-layer H20b steel arches can control the deformation of tunnel surrounding rocks.The numerical software is used to further compare the effectiveness of the four support measures in controlling the deformation of surrounding rock.The calculation results show that the effect of I22b steel arch support to control the deformation of surrounding rock is significantly worse,especially for the single-layer I22b steel arch under the conditions of the support scheme,the surrounding rock has suffered considerable deformation.After adopting the double-layer initial support scheme,the surrounding rock deformation distribution is more uniform,and the supporting structure and the surrounding rock are deformed in coordination.The research results can provide some certain reference for the design and construction of similar projects.