土石混合回填土区小净距隧道群施工力学分析及应用  

Analysis of Construction Mechanics of Tunnel Group with Small Clear Distance in Soil-Rock Mixed Backfill Area

作　　者：申国顺 

机构地区：[1]中铁二十一局集团第五工程有限公司,重庆

出　　处：《土木工程》2021年第5期484-495,共12页Hans Journal of Civil Engineering

摘　　要：为了研究土石混合回填土区小净距隧道群施工力学行为,依据依托工程地勘、设计和相关文献研究成果,确定比较合理的土石混合回填土和加固区参数,建立小净距隧道群施工过程的三维有限元模型,分析先开挖地铁区间左线隧道、再开挖区间右线隧道、最后开挖中间出段线隧道施工过程的围岩和支护结构变形和受力特征。分析结果表明,选择的开挖顺序、施工和支护步序是比较合理的;隧道群中各分隧道的围岩拱顶竖向位移及洞群围岩拱顶竖向位移最终值均未超过洞群开挖过程中设计规定值,隧道最大主应力主要集中在二次衬砌,小于钢筋混凝土的抗压强度;各隧道围岩塑性区主要集中在隧道左、右边墙和隧道掌子面前方土体,塑性区的纵向影响范围约为10 m,与单模二次衬砌的长度相当;隧道初期支护的最大主应力、二次衬砌中部的主应力和最大剪应力皆在容许范围之内,先行隧道的二次衬砌起到了很好地约束和承载作用。In order to study the construction mechanical behavior of the small-distance tunnel group in the soil-rock mixed backfill area, based on the research results of engineering geological survey, design and related literature, a reasonable parameter of the soil-rock mixed backfill and reinforcement area is determined, and the small-distance tunnel group The three-dimensional finite element model of the construction process analyzes the deformation and force characteristics of the surrounding rock and supporting structure during the construction process of first excavating the left tunnel of the subway section, then excavating the right tunnel of the section, and finally excavating the middle section tunnel. The analysis results show that the selected excavation sequence, construction and support sequence are relatively reasonable;the final value of the vertical displacement of the surrounding rock vault of each sub-tunnel in the tunnel group and the vertical displacement of the surrounding rock vault of the tunnel group did not exceed The specified value is designed during the excavation of the tunnel group. The maximum principal stress of the tunnel is mainly concentrated in the secondary lining, which is less than the compressive strength of reinforced concrete;the plastic zone of the surrounding rock of each tunnel is mainly concentrated in the left and right walls of the tunnel and the soil in front of the tunnel face The longitudinal influence range of the plastic zone is about 10 m, which is equivalent to the length of the single-mode secondary lining;the maximum principal stress of the initial tunnel support, the main principal stress of the secondary lining and the maximum shear stress are all within the allowable range The secondary lining of the first tunnel played a good restraint and bearing role.

关 键 词：土石混合回填土 小净距隧道群 施工力学 三维有限元 数值模拟 

分 类 号：U45[建筑科学—桥梁与隧道工程]