蠕变作用下埋深对结构受荷特征影响分析--以广佛环线东环隧道工程为例

Analysis of Influence of Buried Depth on Structural Load Characteristics under Creep:Take the Donghuan Tunnel of Guangzhou--Foshan Loop Line as an Example

为研究在围岩蠕变作用下不同埋深软岩盾构隧道管片结构的受荷特性,以广佛环线东环隧道工程为背景,利用FLAC3D(fast lagrangian analysis of continua in 3 dimensions)有限差分软件建立了数值分析模型,采用改进的黏弹塑性蠕变本构(burgers-creep viscoplastic model, CVISC),分析了埋深对管片的位移、内力及与围岩的接触压力影响。结果表明:隧道初期开挖之后,顶部围岩沉降,底部发生隆起,考虑围岩蠕变效应后,管片衬砌发生整体沉降,隧道埋深越大,管片体整体沉降越发显著;随隧道埋深的增大,弯矩、轴力与接触压力均逐渐增大。围岩未考虑加速蠕变下,蠕变过程中管片衬砌的内力和接触压力的变化规律基本相同,有衰减蠕变和稳定蠕变两个阶段。

In order to study the loading characteristics of the shield tunnel liner structure of different buried soft rock shield tunnels under the creep of surrounding rock, Based on the Donghuan Tunnel of Guangzhou-Foshan Loop Line, using finite difference software FLAC3 D numerical analysis model is established, taking improved Burgers(CVISC) viscoelastic creep constitutive plastic, The influence of the buried depth on the displacement, internal force and contact pressure of the surrounding rock is analyzed. The results showed that:(1) after the initial excavation of the tunnel, the surrounding rock at the top settles and the bottom upheaval. Under the creep effect of surrounding rock, segment lining settles as a whole. The larger the tunnel is buried, the more significant the overall settlement of the tube segment.(2) bending moment, axial force and contact pressure gradually increase with the increase of tunnel burial depth. When the accelerated creep is not taken into account, the internal force and contact pressure of the lining are basically the same in the creep process, and there are two stages of attenuation creep and stable creep.