千枚岩深埋隧道支护参数对结构受力与变形的影响

为探索成武高速2号隧道支护参数对结构受力与变形的影响,以室内试验、原位试验和现场测试为主要手段,研究了隧道围岩工程特性、初期支护围岩压力、二次衬砌接触压力、拱顶下沉、周边收敛-时间曲线的变化规律; 提出增加单层初支刚度、采用双层初支、增加双层初支刚度3种支护参数方案,再利用FLAC3D有限差分软件分析,以原始支护方案和3种支护参数方案为基础建立4种工况来确定不同支护参数对隧道结构受力与变形的影响。结果表明:在原始支护方案模拟结果中,拱顶竖直位移和拱脚水平位移趋于稳定时分别为185.57 mm和330.51 mm,与现场测试结果相对误差分别为5.5%和7.5%; 采用单层初支时,钢拱架间距由75 m调整为60 m,钢拱架型号由I18调整为I22,拱顶处的竖直位移为161.45 mm,相对于原始设计模拟结果减少了13%,拱脚处水平位移为273.21 mm,减少了17.3%,右拱腰处应力集中值为11.18 MPa,减少了9.1%; 采用双层初支时,2层中钢拱架间距与型号均与原始支护设计相同,为75 m与I18,拱顶处的竖直位移为130.58 mm,相对于原始设计模拟结果减少了29.6%,拱脚处水平位移为227 mm,减少了31.3%,右拱腰处应力集中值为8.24 MPa,减少了33.0%; 采用双层初支时,2层中钢拱架的间距均为60 m,型号为I22,拱顶处竖直位移为80.56 mm,相对于原始设计模拟结果减少了56.6%,拱脚处水平位移为159.34 mm,减少了51.8%,右拱腰处应力集中值为6.13 MPa,减少了50.2%,此工况下隧道支护结构的受力变形限制最好,拱顶沉降为80 mm,周边收敛为160 mm。

Influence of Supporting Parameters of Phyllite Deep Tunnel on Structural Stress and Deformation

In order to explore the influence of supporting parameters on the stress and deformation of the structure of No.2 tunnel of ChengWu Expressway, based on laboratory test, in-situ test and field test, the engineering characteristics of surrounding rock of tunnel, the variation laws of surrounding rock pressure of initial support, contact pressure of secondary lining, vault subsidence, peripheral convergence-time curve were studied. Three supporting parameter schemes were put forward, including increasing the rigidity of single initial support, adopting double initial support and increasing the rigidity of double initial support. Based on the original supporting scheme and three supporting parameter schemes, four working conditions were established to determine the influence of different supporting parameters on the stress and deformation of the tunnel structure by using FLAC3D finite difference software. The results show that in the simulation results of the original support scheme, when the vertical displacement of the arch crown and the horizontal displacement of the arch foot tend to be stable, the values are 185.57 mm and 330.51 mm, and the relative errors with the field test results are 5.5% and 7.5% respectively. When the single-layer initial support is adopted, the steel arch spacing is adjusted from 75 m to 60 m, the steel arch type is adjusted from I18 to I22, and the vertical displacement at the vault is 161.45 mm, which is 13% less than the original design simulation results. The horizontal displacement at the arch foot is 273.21 mm, reducing by 17.3%, and the stress concentration at the right arch waist is 11.18 MPa, reducing by 9.1%. When the double-layer initial support is adopted, the spacing and type of steel arch in the two layers are the same as the original support design, which are 75 m and I18. The vertical displacement of the arch crown is 130.58 mm, which is 29.6% less than the original design simulation results. The horizontal displacement of the arch foot is 227 mm, which is 31.3% less. The stress concentration value of the right arch waist is 8.24 MPa, which is 33.0% less. When the two-layer initial support is adopted, the steel arch spacings in the two floors are both is 60 m, and the model is I22. The vertical displacement at the vault is 80.56 mm, which is 56.6% less than the original design simulation result. The horizontal displacement at the arch foot is 159.34 mm, reducing by 51.8%. The stress concentration at the right arch waist is 6.13 MPa, reducing by 50.2%. In this case, the stress and deformation of the tunnel support structure are the best. The settlement of the arch crown is 80 mm, and the peripheral convergence is 160 mm.