摘要
超大断面隧道穿越软岩地层时易产生较大变形,开挖方法的合理选择对于施工安全具有重要的意义。为探究双侧壁九步开挖法对超大断面隧道施工的适用性,依托重庆市500 m2超大断面软岩隧道在建工程,通过开展室内试验揭示砂质泥岩的力学特性,采用数值模拟与现场监测相结合的方法对比分析了地表与超大断面隧道结构的变形特征,并对开挖步序、临时支护措施、开挖台阶长度进行了工法优化分析。结果表明:不同围压、不同卸荷速率下砂质泥岩岩样应力应变曲线相似,岩样三轴抗压强度及变形特征均发生显著变化。随着上台阶核心岩体的开挖,超大断面隧道洞周位移发生突变,当临时支护措施拆除后,进一步加剧了超大断面隧道变形量。不同开挖步序造成围岩先后扰动,致使围岩卸荷速率不同,影响地表与隧道结构的变形。临时横撑有效限制了拱腰收敛,其全部布设工况减小拱腰收敛量约10.0 mm。此外,开挖台阶长度越短,地表及超大断面隧道变形越小。
The super-large cross-section tunnel is prone to large deformation when passing through soft rock stratum.The reasonable selection of excavation method is of great significance for construction safety.In order to explore the applicability of the double-side nine-step excavation method to the construction of super-large cross-section tunnels,based on a 500 m 2 super-large cross-section soft rock tunnel under construction in Chongqing,the mechanical properties of sandy mudstone were revealed by laboratory experiments.The deformation characteristics of surface and super-large cross-section tunnel structures were compared and analyzed by numerical simulation and field monitoring.The excavation sequence,temporary support measures and excavation step length were optimized.The results show that the stress-strain curves of sandy mudstone samples under different confining pressures and different unloading rates are similar,and the triaxial compressive strength and deformation characteristics of rock samples change significantly.With the excavation of the core rock mass of the upper step,the displacement of the super-large section tunnel is abruptly changed.When the temporary support measures are removed,the deformation of the super-large section tunnel is further aggravated.Different excavation steps cause successive disturbance of surrounding rock,resulting in different unloading rates of surrounding rock and affecting the deformation of surface and tunnel structure.The temporary transverse bracing effectively limits the convergence of the arch waist,and the convergence of the arch waist is reduced by about 10.0 mm under all the layout conditions.In addition,the shorter the length of the excavation step,the smaller the deformation of the surface and the super large section tunnel.
作者
程坤
徐强
陈海
刘新荣
王培可
CHENG Kun;XU Qiang;CHEN Hai;LIU Xin-rong;WANG Pei-ke(China Water Resources and Hydropower Seventh Engineering Bureau Co.,Ltd.,Chengdu 611730,China;School of Civil Engineering,Chongqing University,Chongqing 400045,China)
出处
《科学技术与工程》
北大核心
2025年第21期9118-9129,共12页
Science Technology and Engineering
基金
国家自然科学基金(41972266)。
关键词
隧道
软岩
超大断面
试验
变形
工法优化
tunnel
soft rock
super large cross section
experiment
deformation
optimization of construction method
