大桥隧道锚碇三维粘弹塑性数值模拟

3D visco-elasto-plastic numerical simulation for tunnel-anchorage of bridge

为了解某大桥隧道锚碇及围岩体在张拉荷载下的变形状态及时效特性,采用三维显式有限差分软件FLAC3D对该大桥隧道锚碇系统进行三维粘弹塑性数值模拟。根据地质资料以及混凝土锚碇结构尺寸,建立隧道锚碇的三维计算模型,对岩体与锚碇之间的相互作用以及锚碇结构在长期荷载作用下的破坏模式进行研究,分析了由于施工开挖引起的锚碇和隧道围岩的位移及其应力变化。分析结果表明:当考虑岩体的流变力学特性后,在设计荷载作用下,锚碇和隧道围岩的变形均有所增加;与弹塑性计算结果比较,施加荷载后经流变分析得到的隧道顶拱和底板的切向应力有所降低,拉应力的量值及拉应力区的范围减小,塑性区体积进一步扩大。

In order to study the deformation state and time-dependent characteristic of surrounding rock and tunnel-anchorage under tensile stresses, the 3D visco-elasto-plastic numerical simulation is performed on the anchorage system of a certain bridge by using the FLAC3D. Based on the geological information and the structure size of concrete anchor, the simulation model is set up for analyzing the interaction of tunnel-anchorage and surrounding rock and the failure mode of anchorage system under long-term load. The variations of displacement and stress of anchorage and surrounding rock due to the influences of excavation are studied. The results indicate that the deformations of tunnel-anchorage and surrounding rock increase under design load when the rheological characteristic of rock mass is considered. Compared with the results which only considering elasto-plastic effect, the tangential stresses of the tunnel roof and floor decrease after rheological calculating, the tensile stress and the area of tensile stress zone become less, and the plastic zone is expanded. 3 tabs, 7 figs, 10 refs.