摘要
为探究泥石流冲沟隧道洞口适宜工法及支护施作时机,依托九绵高速甘沟隧道,针对其穿越泥石流冲沟的特点,现场试验段采用三台阶工法并加快支护施作时机方案,效果较好,通过数值模拟对现场工法及支护施作时机进行比选验证。相关研究表明:现场冲沟附近周边收敛波动较大,在25d左右收敛下降至稳定,冲沟前收敛数值较大;周边收敛与地表沉降数值较小,稳定较快,验证了三台阶工法的适用性。开挖隧道上半侧及施作仰拱二次衬砌时,拱顶地表沉降增大,开挖下半侧时,拱顶地表沉降数值减小,CD法拱顶地表沉降表现为两段式增加;开挖台阶位置会引起周边收敛数值增大。通过对比不同工法下围岩支护结构受力、变形,可知三台阶工法在周边收敛、塑性区、锚杆小导管受力变形、初期支护及二次衬砌拉应力等各方面较优。加快初期支护施作会减小隧道特别是拱顶变形,但会增大围岩初期支护应力,因此不能一味地加快初期支护施作;加快二次衬砌施作会减小初期支护受力,略微增大二次衬砌受力,较为有利;加快仰拱施作可减小拱底隆起及稳定速率,起到反压作用。
In order to explore the appropriate construction method and support construction time at the entrance of the debris flow gully tunnel, relying on the Gangou Tunnel of Jiujiang Mianyang Expressway, and in view of its characteristics of crossing the debris flow gully, the site test section adopts a three-step method and accelerates the support construction time, which has a good effect. Through numerical simulation, the site construction method and support construction time are compared and verified. Relevant research shows that the convergence fluctuation around the gully is large, and the convergence decreases to a stable value in about 25 days, and the convergence value before the gully is large.The peripheral convergence and surface settlement are small and stable, which verifies the applicability of the three-step method. When excavating the upper half of the tunnel and constructing the secondary lining of the inverted arch, the surface settlement of the arch crown increases, and when excavating the lower half of the tunnel, the value decreases. The surface settlement of the arch crown by CD method shows a two-stage increase.Excavation at the bench position will cause the peripheral convergence value to increase. By comparing the stress and deformation of surrounding rock support structure under different construction methods, it can be seen that the three-step method is better in peripheral convergence, plastic zone, stress and deformation of anchor bolt small duct, initial support and secondary lining tensile stress. Accelerating the initial support construction will reduce the deformation of the tunnel, especially the arch crown, but will increase the initial support stress of the surrounding rock, so we can not simply accelerate the initial support construction.Accelerating the construction of secondary lining will reduce the stress of initial support, and slightly increase the stress of secondary lining, which is more favorable.Accelerating the construction of inverted arch can reduce the arch bottom heav
作者
王飞
谢金池
潘文韬
杨卓文
杨朝栋
刘洋
杨文波
WANG Fei;XIE Jinchi;PAN Wentao;YANG Zhuowen;YANG Chaodong;LIU Yang;YANG Wenbo(Sichuan Mianjiu Expressway Co.,Ltd.,Chengdu,Sichuan610041,China;Southwest Jiaotong University,Chengdu,Sichuan610031,China)
出处
《施工技术（中英文）》
CAS
2022年第20期8-13,22,共7页
Construction Technology
基金
四川省交通运输科技项目(2019ZL09)。
关键词
冲沟隧道
施工工法
支护
施作时机
数值模拟
监测
gully tunnel
construction
supporting
construction time
simulation
monitoring
