隧洞主支洞交叉段围岩及二衬支护有限元分析

Finite element analysis of surrounding rock and secondary lining support at intersection of main and branch tunnel

目前国内外长隧洞、超长隧洞发展迅猛,在设计与施工中常增设支洞以增加工作面及其它作用。主支洞交叉段结构型式复杂、断面较大,常规的计算方法难以准确、全面地得到其受力变形状态。利用通用有限元软件Abaqus,建立主支洞交叉段三维模型,对其施加荷载并计算得到应力分布与变形分布状态云图以及几处特殊位置断面云图。计算结果表明:隧洞交叉段交叉口位置围岩应力集中现象明显,边墙、底板应力较大,顶拱位移明显,此区域为隧洞交叉段最不利位置。建议此区域在开挖过程中应高度重视,且加强地板、边墙外层钢筋,加强顶拱初期柔性支护,二次衬砌刚性支护。可根据围岩变形阶段与稳定情况预留适当的围岩变形量,以便更大地发挥围岩自稳能力。

At present,the development of long and super-long tunnels is very rapid at home and abroad.Branch tunnels were usually designed for certain purposes such as increasing working face.The intersection of main and branch tunnels has complex structure and large section,so it is difficult to acquire accurate and comprehensive stress and deformation state by conventional calculation method.Finite element software Abaqus was used to establish the 3D model for the intersection position.After load was applied,the stress and deformation distribution clouds as well as clouds of some specific positions were calculated.The results of calculation demonstrate that obvious stress concentration of surrounding rock occurs at the intersection;stress is higher at the side wall and base slab;displacement of top arch is distinct;this area is the most disadvantageous position.It is suggested that great attention should be paid to this area in the course of excavation;the outer reinforcement of floor and side wall should be strengthened,and the flexible support at the initial stage of top arch should be strengthened.Secondary lining rigid support can reserve appropriate deformation according to the deformation stage and stability of surrounding rock,so as to give full play to the self-stability of surrounding rock.