地下等截面交叉洞室扩建衬砌拆除及支护方法

Lining Demolition and Support Method for Expansion of Underground Equal Cross Section Tunnel

为确保存在应力集中交叉口区域、衬砌老旧失效且为素砼结构的地下深埋废弃洞室改造扩建数据中心之后继续稳定服役,依托贵阳市地下某等截面交叉洞室改扩建数据中心工程,通过有限元数值模拟、现场监测的方法研究不同衬砌拆除方案、不同支护体系施工的围岩位移、应力以及主钢拱架变形受力特征。结果表明:首先开挖三角交叉区域衬砌,再以三角区为界,左右对称拆除衬砌的素砼衬砌拆除方案对围岩影响最小;Y形主拱架的整体竖向位移以及内力均为最小,但拱架整体有向右侧偏移的趋势;结合上述结论,提出了一种“三角交叉区开挖,Y形主拱架先行,左右对称拆除,随拆随支接搭拱架”的衬砌拆除+支护一体化施工控制方法;数值模拟与现场监测变形趋势一致,斜长拱架拱脚钢拱架应变、围岩压力、混凝土应变最大,但皆满足工程支护要求。可见该方法满足数据中心的服役要求。

In order to ensure stable service after reconstruction and expansion of data center of underground deep buried abandoned cavern with stress concentration intersection area,old and ineffective lining and plain concrete structure,the reconstruction and expansion data center project of an underground cross section tunnel in Guiyang was relied.Through finite element numerical simulation and on-site monitoring,the displacement and stress of surrounding rock and the deformation and stress characteristics of main steel arch frame under different lining demolition schemes and different support system construction were studied.The results show that first excavate the lining in the triangle intersection area,and then take the triangle area as the boundary.The demolition scheme of plain concrete lining with symmetrical demolition of lining has the least impact on the surrounding rock.The overall vertical displacement and axial force of Y type main arch are the smallest,but the arch as a whole tends to shift to the right.The above conclusions are combined,a lining demolition+support integrated construction control method of“excavation in triangular intersection area,Y-shaped main arch first,symmetrical demolition on the left and right,support and erection of arch with demolition”was proposed.The deformation trend of numerical simulation is consistent with that of field monitoring.The steel arch frame strain,surrounding rock pressure and concrete strain at the arch foot of inclined long arch frame are the largest,but the requirements of engineering support are all met by them.It can be seen that the service requirements of the data center are met by this method.